Дисертації з теми "Cyclodextrin Molecules"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Cyclodextrin Molecules.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Cyclodextrin Molecules".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Huang, Tian He. "Investigation of cyclodextrin formulations by combined experimental and molecular modeling techniques." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3952153.
Повний текст джерела
2
Binti, Mohtar Noratiqah. "Cyclodextrin-based formulations for pulmonary delivery of chemotherapeutic molecules." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10054726/.
Повний текст джерелаАнотація:
This study investigated cyclodextrin-based formulations for the delivery of fisetin (a flavonoid) and erlotinib (a tyrosine kinase inhibitor) to the lung. In the first part of the study, complexation of fisetin with β-cyclodextrin (β-CD) and its derivatives, namely hydroxypropyl-β-cyclodextrin (HP-β-CD) and sulfobutylether-β-cyclodextrin (SBE-β-CD), was conducted. Complexation efficiency between fisetin and the cyclodextrins was in the order: SBE-β-CD > HP-β-CD > β-CD. Utilisation of 20%v/v ethanol during complexation with SBE-β-CD improved the solubilisation of fisetin 5.9-fold compared to using water alone. Spray-drying of the fisetin-SBE-β-CD complex from 20%v/v ethanol feed solution, produced a powder with a 2-fold increase in the fine particle fraction (FPF) compared to the spray-dried powder produced from a feed solution containing water alone, when characterised using the Next Generation Impactor (NGI). Addition of 20%w/w leucine into the powder produced from the ethanolic feed solution further improved the FPF by 2.3-fold compared to the powder without leucine. The preparation showed an unchanged cytotoxic activity of fisetin against the human lung adenocarcinoma (A549) cell line, when compared to fisetin solution. In the second part of the study, combinations of fisetin with three tyrosine kinase inhibitors (i.e. erlotinib, gefitinib, crizotinib) were evaluated for their cytotoxic activity against the A549 cell line. Combination of erlotinib and fisetin at 1: 2 molar ratio, showed the highest synergism in cell killing, when analysed using the median effect principle method. This combination was then used to form a complex with SBE-β-CD. Further improvement in the solubility of erlotinib and fisetin, was achieved with the addition of 50%v/v ethanol during complexation, compared to using water alone. The complex solution was lyophilised and reconstituted into a 3-times more concentrated preparation, prior to nebulisation into the NGI. The preparation showed a suitable aerosol size for inhalation of both drugs. In conclusion, cyclodextrin-based formulations in the form of a dry powder inhalation and nebuliser solution, showed promise for pulmonary delivery of fisetin and its combination with erlotinib, respectively, in the treatment of non-small cell lung cancer (NSCLC).
3
Sala, Andrea. "Supramolecular derivatisation of bioactive molecules via co-crystallization and cyclodextrin inclusion complexation." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29711.
Повний текст джерелаАнотація:
The objective of this study was to modify the physicochemical properties of two common drugs via supramolecular derivatization. Sulfasalazine is a powerful anti-inflammatory drug and fluconazole has a strong antibacterial and antifungal activity. The common feature is their very low solubility in water. Cyclodextrin inclusion complexation and co-crystallization were carried out with the aim of ultimately improving the bioavailability of both drugs. Each new crystal phase isolated was analysed using X-ray diffraction, thermal and spectroscopic techniques. Sulfasalazine presents two tautomeric forms which were isolated using different preparative methods via recrystallization from different solvents. Each form was used in combination with nine different co-formers in attempts to form co-crystals. This approach yielded negative results. Cyclodextrin inclusion complexation of sulfasalazine was studied with a variety of cyclodextrins (αCD, β-CD, γ-CD, dimethylated β-CD and permethylated β-CD). The complexation attempts yielded an inclusion complex between one of the tautomers of sulfasalazine and γ-cyclodextrin. No single crystals were obtained and hence it was impossible to resolve the crystal structure. However, it was possible to analyse the complex thermally and spectroscopically. The co-crystallization of fluconazole with biocompatible co-formers was not investigated due to the appearance of extensive previous reports on its co-crystal formation in the literature. Thus, only cyclodextrin inclusion complexation (with the same CDs listed above) was studied. Three inclusion complexes with native CDs were successfully prepared. Two crystallographically distinct complexes of β-CD with fluconazole as guest having 2:1 host-guest stoichiometry were isolated. While these two hydrated complexes had been identified recently by previous researchers and the X-ray structure of one of the crystal forms had been partially resolved, their characterization was incomplete. In the present study, significant advances on the previous work included the complete X-ray structural resolution of both crystal forms, designated TBCDFLU (triclinic) and MBCDFLU (monoclinic), as well as a systematic study of the conditions under which these individual forms could be isolated. The occurrence of these crystal forms was dependent on two variables, namely β-CD concentration in the aqueous mother liquor and the incubation temperature of the solution. Careful examination of the sensitive crystallization equilibrium indicated that, at a solution concentration of 6.52 10-2 M, pure TBCDFLU could be isolated at an incubation temperature of 45 C or lower, while pure MBCDFLU crystallized at an incubation temperature of 60 C (for both cases the incubation period is more than 48 h). MBCDFLU and TBCDFLU crystals displayed different stabilities with respect to dehydration when exposed to air and hence determination of their respective water contents was performed using thermogravimetry on fresh crystals immersed in silicone oil. From a phase solubility study, it was established that the association constant for complex formation between - CD and fluconazole in solution was very low (27.2 M-1), implying weak host-guest binding. Finally, a 1:1 inclusion complex between -CD and fluconazole was isolated and characterized by thermal and spectroscopic techniques.
4
Mvula, Eino Natangwe. "Preparation and solid state properties of cyclodextrin complexes of selected drug molecules." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/17902.
Повний текст джерелаАнотація:
Includes bibliographical references.A large number of pharmaceutically important drugs are poorly soluble in water. This study focuses on the 'smart' molecule that can enhance the solubility and hence increase the bioavailability of these drugs. This molecule is a cyclodextrin and is known to form inclusion compounds with various drug molecules. The preparation of β-cyclodextrin CP-CD), y-cyclodextrin (y-CD), heptakis(2,6-di-OJ, methyl)-β-cyclodextrin (Dimeb) and heptakis(2,3,6·tri-0-methyl)- β-cyclodextrin (Trimeb) 3, complexes with clofibric acid as well as the heptakis(2,3,6j·tri-O-methyl)- β-cyclodextrin (Trimeb) complex with clofibrate is reported. The complexes were characterised by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), ultraviolet spectrophotometry (UV), infrared spectroscopy (IR), X-ray powder diffraction (XRD) and single crystal X-ray analysis.
5
Wandstrat, Michelle Marie. "MATERIALS AND MODIFICATION OF ELECTRODES FOR THE DETECTION OF BIOLOGICAL MOLECULES." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1164817458.
Повний текст джерела
6
Dutta, Ashutosh. "Exploration of diversified interactions of some significant compounds prevalent in several environments by physicochemical contrivance." Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2787.
Повний текст джерела
7
Wahlström, Anna. "NMR studies on interactions between the amyloid β peptide and selected molecules". Doctoral thesis, Stockholms universitet, Institutionen för biokemi och biofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-60346.
Повний текст джерелаАнотація:
Alzheimer’s disease is an incurable neurodegenerative disorder linked to the amyloid β (Aβ) peptide, a 38-43 residue peptide. The detailed molecular disease mechanism(s) is (are) unknown, but oligomeric Aβ structures are proposed to be involved. In common for the papers in this thesis is interactions; interactions between Aβ(1-40) and selected molecules and metal ions. The purpose has been to find out more about the structural states that Aβ can adopt, in particular the β-sheet state, which probably is linked to the oligomeric structures. The methods used have been nuclear magnetic resonance (NMR), circular dichroism (CD) and fluorescence spectroscopy using Thioflavin T (ThT). Upon addition of SDS/LiDS detergent or Congo red (CR) to Aβ(1-40), the initial random coil/PII-helix state was transformed into β-sheet and, in the case of detergent, a final α-helical state. In contrast to SDS/LiDS and CR, the dimeric Affibody molecule locks monomeric Aβ(1-40) in a β-hairpin state. It was found that by truncating the flexible N-terminal end of the Affibody molecule its affinity to Aβ was improved. The aggregation of Aβ(1-40) was further studied in the presence of a β-cyclodextrin dimer by a kinetic assay using ThT. Although having a weak dissociation constant in the millimolar range, the β-cyclodextrin dimer modified the aggregation pathways of Aβ. Finally Aβ(1-40) was studied in presence of Cu2+ and Zn2+ at physiological and low pH. Cu2+ was observed to maintain its specific binding to Aβ when decreasing the pH to 5.5 while Zn2+ behaved differently. This could be of importance in the Alzheimer’s disease brain in which the environment can become acidic due to inflammation. In conclusion the results show that Aβ(1-40) is very sensitive to its environment, responding by adopting different conformations and aggregating in aqueous solutions. The β-sheet state is induced by varying molecules with different properties, properties that govern the final Aβ state.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.
8
Brown, Susan Elizabeth. "Molecular recognition by cyclodextrins /." Title page, contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phb8798.pdf.
Повний текст джерела
9
Cherraben, Sawsen. "Machines moléculaires à base de cyclodextrines fonctionnalisées." Thesis, Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2019SORUS633.pdf.
Повний текст джерелаАнотація:
Le contrôle du mouvement et de sa directionnalité à l’échelle moléculaire est un défi actuel. Ce travail de thèse s’est intéressé à l’élaboration d’une famille de machines moléculaires à base de cyclodextrines (CDs). L’objectif a été d’exploiter l’asymétrie intrinsèque des CDs et de les fonctionnaliser sélectivement afin de pouvoir leur appliquer directement un stimulus. Nous pouvons dès lors contrôler leurs mouvements dans des architectures supramoléculaires. Dans une première approche, nous avons développé un commutateur pH-sensible de type pseudo-rotaxane à base de CDs sélectivement fonctionnalisées par des amines sur le col primaire. Un contrôle de l’enfilage et du désenfilage par un stimulus pH et une modulation de la cinétique de désenfilage par variation du nombre d’amines ont été obtenus. Dans une deuxième approche, nous avons conçu un système utilisant un carburant chimique pour obtenir un mouvement unidirectionnel par le transport actif d’une CD fonctionnalisée. Le point clé est l’étape de clivage de groupements protecteurs sur l’axe par la fonction catalytique portée par la CD, qui devrait avoir lieu préférentiellement par le col primaire et assurer son transport dirigé. Pour cela, un premier [2]rotaxane modèle de CDMe à trois stations a été synthétisé par une approche de post-fonctionnalisation d’un [2]rotaxane, avec des bouchons amides. Son étude a montré la formation de 3 mécano-isomères lors de la réaction de protection avec une distribution non-statistique indiquant un probable biais cinétique. Ces travaux prometteurs ouvrent des perspectives à plus long terme sur l’obtention de moteurs moléculaires à énergie chimique avec un transport actif de la CDControlling motion and directionality at the molecular level is a major challenge. This thesis project focused on the development of a family of cyclodextrin (CDs) based molecular machines. The objective was to exploit the inherent asymmetry of CDs and to functionalize them selectively in order to be able to apply a stimulus directly to them. Hence, controlling their movements in supramolecular architectures becomes possible. In the first approach, we developed a pH-sensitive switch of the pseudo-rotaxane type based on CDs selectively functionalized by amines on the primary rim. A remarkable control of threading and dethreading by a pH stimulus were obtained, along with a modulation of the dethreading kinetics by variation in the number of amines. In a second approach, we designed a system using a chemical fuel to obtain unidirectional motion of a functionalized CD through its active transport. The key step is the cleavage of protective groups located on the axis by the catalytic function carried by the CD, which should preferably take place through the primary rim, ensuring its directed transport. For this purpose, a first three-station [2]rotaxane CDMe model was synthesized by a post-functionalization approach of a one-station [2]rotaxane with amide stoppers. Its study showed the formation of 3 mechano-isomers during the protective reaction with a non-statistical distribution indicating a probable kinetic bias. This promising work opens up longer-term perspectives on the development of chemically fueled molecular motors with active CD transport
10
Mansour, Ali Taher. "New enantioselective transformations induced by cyclodextrins : applications in the preparation of molecular building blocks of biological interest." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS186/document.
Повний текст джерелаАнотація:
Le but de ce travail était la préparation de dérivés cyclobutaniques du GABA optiquement purs et leur utilisation dans la préparation de γ/α-peptides pouvant adopter une structure tridimensionnelle bien définie. Pour cela, deux stratégies ont été développées. La première consistait en l’utilisation de la β-Cyclodextrine comme hôte supramoléculaire chirale lors de cyclizations photochimiques énantiosélectives. La tentative de cyclisation [2+2] intramoléculaire du N-allyl-N-(4-methoxyphenyl)acrylamide n’a conduit qu’à un δ-lactame issu d’une électrocyclisation 6π. L’électrocyclisation de la 1,3-dihydro-2H-azepin-2-one nous a permis d’obtenir le γ-latame bicyclique précurseur du (+)-cis-3,4CB-GABA avec un excès énantiomérique de 45%. La deuxième stratégie était basée sur une synthèse racémique du N-Boc-cis-3,4CB-GABA suivi d’une séparation des deux énantiomères par CLHP semi-préparative avec une colonne chirale. Les (-) et (+)-cis-3,4CB-GABA optiquement purs ont ainsi été obtenu à l’échelle du gramme. Ces deux énantiomères (-) et (+)-cis-3,4CB-GABA ont ensuite été utilisés pour la préparation de deux séries de peptides mixtes γ/α, diastéréoisomères [(S,S/R) et (R,R/R)] à courtes chaines contenant alternativement le cis-3,4CB-GABA et le D-Alanine. L'analyse des conformations des dipeptides des deux séries par Diffraction des Rayons X, n'a montré aucune interaction intramoléculaire mais plutôt un assemblage de liaisons d'hydrogène intermoléculaires entre les molécules du dipeptide. D'autre part, les études RMN 1D et 2D (en solution) ont montré que le tétrapeptide des séries (S,S/R) pourraient avoir une structure hélicoïdale 12/10, tandis que son analogue diastéréoisomères des séries (R,R/R), a montré, en solution, une nouvelle structure sous forme de ruban 7/9This work revolves around the synthesis of ennatiomerically pure cyclobutane derivatives of GABA, and their use in the preparation of hybrid γ/α-peptides that could adopt a well-defined three dimensional secondary structure. In this aim we developed two strategies. The first one employed native β-Cyclodextrin as a supramolecular chiral host to achieve enantiodifferentiating photochemical cyclizations. Attempting to perform an intramolecular [2+2] cyclization of N-allyl-N-(4-methoxyphenyl)acrylamide, we only obtained a δ-lactam resulting from a 6π electrocyclization, whereas the electrocyclization of 1,3-Dihydro‑2H‑azepin-2-one allowed access to a 45% enantiomerically enriched bicyclic γ-lactam precursor of (+)-cis-3,4CB-GABA. The second strategy was based on a racemic synthesis of N-Boc-cis-3,4CB-GABA followed by a separation of the two enantiomers using a semi-preparative HPLC fitted with a chiral column. This allowed access to optically pure (-) and (+)-cis-3,4CB-GABA, on a gram scale. Furthermore, the enantiomerically pure (-) and (+)-cis-3,4CB-GABA, were used to synthesize, and fully characterize two series [the (S,S/R) and the (R,R/R)] of short diasteriomeric hybrid γ/α-peptides composed of alternating cis-3,4CB-GABA and D-Alanine. Analysis of the conformational behavior of the dipeptides from both series by X-Ray diffraction on a single crystal, showed no intramolecular interactions but rather an array of intermolecular hydrogen bonding between the dipeptide molecules. On the other hand, a series of 1D and 2D NMR experiments showed that the tetrapeptide of the (S,S/R)-series could attain a 12/10 helical structuration, whereas its diasteriomeric analog of the (R,R/R)-series, displayed evidence of an unprecedented 7/9 folding pattern in solution
11
Lock, Julia. "Cyclodextrins : molecular wheels for supramolecular chemistry /." Title page, table of contents and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phl8131.pdf.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2005?"July 2004" Includes copies of publications by the author as appendix. Includes bibliographical references.
12
Dodds, Devric Reginald. "Physicochemical study of inclusion of drug molecules in cyclodextrins." Doctoral thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/9721.
Повний текст джерелаАнотація:
Includes bibliographical references.Inclusion of drug molecules in cyclodextrins can significantly improve various aspects of their performance and has resulted in the use of cyclodextrins (CDs) for a wide variety of pharmaceutical applications. Consequently, the cyclodextrin inclusion of drugs has received great interest in the pharmaceutical and chemical fields. For this study the inclusion of nine pharmaceutical drugs with CDs was investigated in the solid state. The objectives of the study were i.) the preparation, ii.) determination of the chemical composition, iii.) analysis of thermal behaviour and iv.) investigation of the solid state features of the complexes. Ultraviolet spectrophotometry, elemental analysis and thermogravimetric analysis were the principal techniques used for determination of composition. Hot stage microscopy, differential scanning calorimetry and thermogravimetric analysis were the principal techniques used for the analysis of thermal behaviour. Single crystal x-ray diffraction and x-ray powder diffraction were the principal techniques used for investigation of structural features. This thesis reports the preparation by crystallisation from solution of eight beta cyclodextrin (β-CD) and four gamma cyclodextrin (γ-CD) inclusion complexes with selected drugs as guests, as well as the determination of their chemical compositions and analysis of their thermal behaviours. Investigation of the structural features of these complexes includes the determination of the crystal structures of five β-CD complexes and one γ-CD complex. The preparation of hydnoxypropyl-β-CD complexes by kneading and co-grinding is also reported.
13
HETTLER, ODILE. "Modes de fixation de molecules actives au sein de cyclodextrines." Strasbourg 1, 1990. http://www.theses.fr/1990STR15025.
Повний текст джерела
14
Haskard, Carolyn Anne. "Multiple recognition by modified cyclodextrins." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phh349.pdf.
Повний текст джерелаАнотація:
Copy of author's previously published article inserted. Includes bibliographies This thesis studies the B-cyclodextrins which are modified at the primary rim to incorporate an additional coordination or hydrophobic recognition site. The natural organic host, cyclodextrin and its chemically modified derivatives, are utilised as hosts for the inclusion of a range of guests. The study contributes to understanding the fundamental factors influencing selectivity of binding and the stability of the complexes formed when a guest is bound essentially at two recognition sites.
15
Ollila, Fredrik. "Characterizing the interactions of small molecules with lipid membranes and cyclodextrins /." Turku : Åbo Akademi university, 2002. http://catalogue.bnf.fr/ark:/12148/cb399337651.
Повний текст джерела
16
Faiz, Jonathan Antony. "Directional molecular wires constructed from photo- and electroactive cyclodextrins." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419740.
Повний текст джерела
17
Masai, Hiroshi. "Synthesis and Properties of Functionalized Molecular Wires Based on Fixed Cyclic Insulation." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215560.
Повний текст джерела
18
Burusco, Goñi Kepa Koldo. "Methodological Approach to Conformational Search. A Study Case: Cyclodextrins." Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/3296.
Повний текст джерелаАнотація:
No és difícil trobar exemples que mostrin la inqüestionable importància de la estereoquímica en temes com la salut o l'economia: D'una banda, la quiralitat és tristament ben coneguda a causa del desastre de la Talidomida. Per altra banda, varem trobar recentment un altre exemple no menys important dins el camp de les conformacions de macromolècules: La Malaltia de Creutzfeld-Jacob. Per això, creiem que és rellevant examinar amb més detall aquells temes relacionats amb els estudis conformacionals.A la present Tesi Doctoral es proposa un procés en dues etapes per a estudiar espais conformacionals de macromolècules mitjançant Simulated Annealing (SA) i Dinàmica Molecular (DM). Ambdues metodologies són ben conegudes dins el camp de la Modelització Molecular; no obstant això, la principal contribució aportada per aquest treball és el desenvolupament d'eines metodològiques millorades -descriptors moleculars adequats, anàlisi de saturació de conformacions i grau de solapament de trajectòries- per mesurar quantitativament l'evolució i convergència dels càlculs SA i MD.
No es difícil encontrar ejemplos que muestren la incuestionable importacia de la estereoquímica en temas como la salud o la economía: Por una parte, la quiralidad es tristemente bien conocida debido al desastre de la Talidomida. Por otra parte, encontramos recientemente otro ejemplo no menos importante dentro del campo de las conformaciones de macromoléculas: La Enfermedad de Creutzfeld-Jacob. Por ello, creemos que es relevante examinar más detenidamente aquellos temas relacionados con los estudios conformacionales.
En la presente Tesis Doctoral se propone un proceso en 2 etapas para estudiar espacios conformacionales de macromoléculas mediante Simulated Annealing (SA) y Dinámica Molecular (DM). Ambas metodologías son bien conocidas dentro del campo de la Modelización Molecular; sin embargo la principal contribución aportada por este trabajo es el desarrollo de herramientas metodológicas mejoradas -descriptores moleculares adecuados, análisis de saturación de conformaciones y grado de solapamiento de trayectorias- para medir cuantitativamente la evolución y convergencia de los cálculos SA y MD.
It is not difficult to find examples that show the unquestionable importance of stereochemistry in human life and economy: On the one hand, chirality is unfortunately the most well known one due to the Thalidomide Disaster. On the other hand, there is a no less important example in recent years in the field of molecular conformations: the Creutzfeldt-Jakob Disease. In this sense, we think that it is worth paying more attention to conformational studies due to their indisputable relevance.
A 2-stage process for studying Conformational Spaces of large macromolecules involving Simulated Annealing (SA) Conformational Search followed by series of Molecular Dynamics (MD) calculations is proposed in this PhD Thesis. Both methodologies are well-known ones in the Molecular Modelling area of knowledge; nevertheless, the main contribution made by this research work is the development of enhanced methodological techniques -suitable molecular descriptors, saturation analysis and trajectory overlapping ratio- for monitoring quantitatively how SA and MD calculations evolve.
19
Ennen, Franka. "Protein-Glycopolymer Biohybrid Structures Based on Molecular Recognition Processes for Biomedical Applications." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-158789.
Повний текст джерелаАнотація:
The design of versatile biohybrid nanosized materials has revealed itself as a promising avenue towards biomedical applications in today´s life sciences. In this regard the combination of components of synthetic and natural origin facilitates an applicability which is supposed to be far beyond the sum of their single components. These biohybrid structures (BHS) can be built by a huge variety of building blocks including solid or soft nanoparticles, peptides/proteins, polynucleotides or low molecular weight drugs. Along with the latter the attachment of biologically active entities or imaging moieties, e. g. enzymes, fluorescence markers or targeting motifs display thereby a key step towards the development of carrier systems for drug delivery purposes.
Among the soft nanoparticles especially dendritic polymers such as perfectly branched dendrimers or hyperbranched polymers are considered as ideal building blocks, since they allow an easy tailoring of crucial properties such as solubility, biocompatibility or bioactivity by means of surface functionalization. Especially in the field of targeted drug delivery the crucial role of sizes and size distributions of carriers has been highlighted recently, since it critically influences important factors such as circulation time or biodistribution within the body.
The ability of avidin to form high molecular weight associates with biotinylated macromolecules as well as its inherent properties makes it a suitable candidate for passive and active targeting in combination with biotinylated (bio-)polymers. Furthermore, along with the covalent attachment of bioactive moieties, non-covalent attachment is a frequently used approach, because it is assumed to only require stoichiometric mixing. In context of the latter molecular recognition processes such as the avidin-biotin, β-cyclodextrin-adamantane or Ni(II)-NTA-histidine-tag interactions have shown to be fruitful strategies for the attachment of bioactive entities.
The overall aim of this work was to fabricate BHS based on dendritic glycopolymers with varied sizes in the nano- and micrometer range as models for biomedical applications e. g. carriers for drug delivery. Therefore the molecular recognition of avidin with biotin derivatives and β-cyclodextrin with adamantane derivatives was utilized in order to tailor final sizes, functionality or catalytic activity of those BHS.
20
Zhang, Qiong. "Molecular Dynamics Simulations of Biomimetic Carbohydrate Materials." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33439.
Повний текст джерелаАнотація:
The present thesis honors contemporary molecular dynamics simulation methodologies which provide powerful means to predict data, interpret observations and widen our understanding of the dynamics, structures and interactions of carbohydrate systems. With this as starting point my thesis work embarked on several cutting edge problems summarized as follows. In my first work the thermal response in crystal cellulose Iβ was studied with special emphasis on the temperature dependence of the crystal unit cell parameters and the organization of the hydrogen bonding network. The favorable comparison with available experimental data, like the phase transition temperature, the X-ray diffraction crystal structures of cellulose Iβ at room and high temperatures, and temperature dependent IR spectra supported our conclusions on the good performance of the GLYCAM06 force field for the description of cellulose crystals, and that a cautious parameterization of the non-bonded interaction terms in a force field is critical for the correct prediction of the thermal response in cellulose crystals. The adsorption properties of xyloglucans on the cellulose Iβ surface were investigated in my second paper. In our simulations, the interaction energies between xyloglucan and cellulose in water were found to be considerably lower than those in vacuo. The van der Waals interactions played a prevailing role over the electrostatic interactions in the adsorption. Though the variation in one side chain did not have much influence on the interaction energy and the binding affinity, it did affect the structural properties of the adsorbed xyloglucans. The interaction of the tetradecasaccharide XXXGXXXG in complex with the hybrid aspen xyloglucan endo-transglycosylase PttXET16-34 was studied in the third paper. The effect of the charge state of the “nucleophile helper” residue Asp87 on the PttXET16-34 active site structure was emphasized. The results indicate that the catalysis is optimal when the catalytic nucleophile is deprotonated, while the “helper” residue and general acid/base residue are both protonated. In my forth paper, the working mechanism for a redox-responsive bistable [2]rotaxane based on an α-cyclodextrin ring was investigated. The umbrella sampling technique was employed to calculate the free energy profiles for the shuttling motion of the α-cyclodextrin ring between two recognition sites on the dumbbell of the rotaxane. The calculated free energy profiles verified the binding preferences observed experimentally. The driving force for the shuttling movement of the α-cyclodextrin ring was revealed by the analysis of the free energy components.QC 20110513
21
Pereira, Ana Bárbara Ferreira Neves Quatorze. "Flavonoid-cyclodextrin complexes and their incorporation in milk products." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15325.
Повний текст джерелаАнотація:
Mestrado em Bioquímica - Bioquímica AlimentarThe presented work describes the inclusion of the flavonoid quercetin into β and γ cyclodextrins and the subsequent incorporation of such complexes into a dairy product — fresh cheese. The characterization of the complexes was made using various techniques, and antioxidant assays were also performed to assess their antioxidant and anti-lipid peroxidation capacity in comparison to quercetin. The incorporation of the complexes in fresh cheese resulted in the modification of some of the characteristics of the food product, having these also presented promising antioxidant capacity.
O trabalho apresentado descreve a inclusão do flavonóide quercetina nas ciclodextrinas β e γ, com posterior incorporação dos complexos em laticínios, nomeadamente queijo fresco. A caracterização dos complexos de inclusão foi feita utilizando várias técnicas, tendo sido também realizados ensaios antioxidantes para avaliar a sua capacidade antioxidante e de anti-peroxidação lipídica, em comparação com a quercetina. A incorporação dos complexos no queijo fresco resultou na modificação de algumas características do produto alimentar, tendo estes complexos também apresentado uma promissora capacidade antioxidante.
22
Akkaya, Engin Umut. "Synthesis and study of cyclodextrin-based metalloenzyme mimics and fluorescence probes of molecular recognition /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487599963592456.
Повний текст джерела
23
Wattoom, Jirut. "Studies of molecular interactions of cyclodextrins and benzene analogues on polymer back bone." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495818.
Повний текст джерелаАнотація:
A new route for sequencing complex macromolecules such as polysaccharides, RNA and DNA, which offers a quicker, cheaper and more reliable method than the existing methods, has been long desired. This has been achieved using an atomic force microscopy (AFM) to identify the position of an "aromatic bead" on a poly(ethylene oxide). These studies comprised three key areas, synthesis of the string-bead polymer model, the molecular recognition of host-guest system and a computational study of the dethreading process.
24
Liang, Hongxi. "An investigation into the use of #beta#-cyclodextrins as additives to effect enantiometric separation by reversed phase HPLC." Thesis, Robert Gordon University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260042.
Повний текст джерела
25
Cucolo, Gisele Rodrigues. "Produção de ciclodextrinas a partir de amidos de diferentes fontes vegetais e seu emprego na inclusão molecular de aroma cítrico /." Rio Claro : [s.n.], 2009. http://hdl.handle.net/11449/103943.
Повний текст джерелаАнотація:
Orientador: Roberto da SilvaBanca: Eleonora Cano Carmona
Banca: Maria de Lourdes Teixeira de Morais Polizeli
Banca: Hamilton Cabral
Banca: Rodrigo Simões Ribeiro Leite
Resumo: Ciclodextrina-glicosil-transferase (CGTase, EC 2.4.1.19) é uma enzima capaz de formar ciclodextrinas (CDs), tendo o amido como substrato. A enzima é de grande interesse industrial, principalmente nas indústrias alimentícias, cosméticas, químicas e farmacêuticas. CDs são moléculas cíclicas formadas por monômeros de glicoses, unidos por ligações α-1,4. Os tipos mais comuns de ciclodextrinas, α-, β- e γ- CD, consistem de 6, 7 e 8 monômeros de glicose, respectivamente. A molecula de CD possui uma estrutura única com a cavidade interna hidrofóbica e a região externa hidrofílica, sendo possível a formação de complexos de inclusão com uma variedade de compostos, que pode melhorar ou proteger as propriedades físicoquímicas da molécula encapsulada. Este estudo foi dividio em três capitulos, o primeiro foi uma revisão bibliografica, e os outros dois são trabalhos de pesquisa. No primeiro trabalho estudou-se a produção de CDs pela CGTase do Bacillus clausii subgrupo E16, tanto em relação ao efeito da concentração do amido na produção das CDs, como em relação a utilização de fontes alternativas de amido (amido solúvel de batata PA, de milho, de trigo e de mandioca) como substrato. Observouse que a enzima produziu preferencialmente β-CD nos diferentes tipos de substrato utilizados. O mais alto grau de conversão de CDs foi obtido com o uso de amido de mandioca, tendo convertido 95,30% (p/p) em β-CD, seguido de 86,60% (p/p) do amido solúvel. A concentração de 1% de amido de mandioca apresentou o melhor rendimento na produção de CDs. No segundo trabalho de desquisa, o objetivo foi a produção de CDs pela CGTase do Bacillus clausii E16 em fontes alternativas de substrato (farelo de trigo, farelo de mandioca; farinhas de milho, trigo e mandioca). Observou-se que a enzima produziu β-CD nos diferentes tipos de substratos utilizados. O grau de conversão de CDs... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) is an enzyme capable of converting starch into cyclodextrins (CDs) molecule. CDs are becoming increasingly popular in pharmaceutical, chemical, cosmetics and food industries. CDs are cyclic oligosaccharides compounded of glucose units jointed by α-1,4 linkages. The most common types of cyclodextrins, α-, β- and γ- CD, consist of 6, 7 and 8 glucose units, respectively. A CD molecule has a unique torus-shaped structure with a hydrophobic internal cavity and a hydrophilic external surface. As a result, CDs can form inclusion complexes with many hydrophobic guest molecules and thereby change their physical and chemical properties. This study was divided in three chapters, the first is about one bibliographic review, and the other are about two research approaches. The aim of the first work was to verify the effect of different starch botanical sources and the concentration of starch in the production of cyclodextrins by CGTase enzyme from Bacillus clausiii E16. It was noticed that the enzyme mainly produced β-CD with the different types of starch (soluble potato starch, corn starch, wheat starch and cassava starch) used substrate. The higher degree of conversion of CDs was obtained with the use cassava starch, of which 95,30% (w/w) was converted in β-CD, followed by 86,60% (w/w) of soluble starch. The concentration 1% of cassava starch showed the best efficiency in the production of CDs. In the second research work, the aim was studied the application of a CGTase from Bacillus clausiii E16 in alternative substrate sources (cassava bran, wheat bran; corn meal, wheat flour e cassava flour) for production of cyclodextrins. It was noticed that the enzyme produced β-CD with the different types of used substrate. The degree of conversion of CDs obtained with the use cassava bran was 40,48% (w/w) in β-CD and preliminary studies... (Complete abstract click electronic access below)
Doutor
26
Koontz, John L. "Controlled Release of Natural Antioxidants from Polymer Food Packaging by Molecular Encapsulation with Cyclodextrins." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26757.
Повний текст джерелаАнотація:
Synthetic antioxidants have traditionally been added directly to food products in a single initial dose to protect against oxidation of lipids and generation of free radicals. Natural antioxidants have been shown to undergo loss of activity and become prooxidants at high concentrations; therefore, a need exists to develop active packaging which can gradually deliver antioxidants in a controlled manner. The objectives of this research were to (1) form and characterize cyclodextrin inclusion complexes with the natural antioxidants, alpha-tocopherol and quercetin, (2) incorporate cyclodextrin inclusion complexes of natural antioxidants into linear low density polyethylene (LLDPE), and (3) measure the release kinetics of inclusion complexes of natural antioxidants from LLDPE into a model food system. Cyclodextrin inclusion complexes of alpha-tocopherol and quercetin were formed by the coprecipitation method and characterized in the solid state by NMR, IR spectroscopy, and thermal analyses. Solid inclusion complex products of alpha-tocopherol:beta-cyclodextrin and quercetin:gamma-cyclodextrin had molar ratios of 1.7:1 as determined by UV spectrophotometry, which were equivalent to 18.1% (w/w) alpha-tocopherol and 13.0% (w/w) quercetin. Free and cyclodextrin complexed antioxidant additives were compounded with a twin-screw mixer into two LLDPE resin types followed by compression molding into films. Release of alpha-tocopherol and quercetin from LLDPE films into coconut oil at 30 °C was quantified by HPLC during 4 weeks of storage. The total release of alpha-tocopherol after 4 weeks was 70% from the free form and 8% from the complexed form averaged across both LLDPE resins. The mechanism by which alpha-tocopherol was released was modified due to its encapsulation inside the beta-cyclodextrin cavity within the LLDPE matrix as indicated by its diffusion coefficient decreasing by two orders of magnitude. Molecular encapsulation of natural antioxidants using cyclodextrins may be used as a controlled release mechanism within polymer food packaging to gradually deliver an effective antioxidant concentration to a food product, thereby, limiting oxidation, maintaining nutritional quality, and extending shelf life.Ph. D.
27
Toma, Sergio Hiroshi. "Química supramolecular e aplicações nanotecnológicas de compostos polipiridínicos de rutênio." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/46/46134/tde-24082007-074550/.
Повний текст джерелаАнотація:
Através da abordagem bottom-up, foram desenvolvidos novos sistemas supramoleculares baseados em complexos metálicos ligados por meio do ligante conjugado, trans-1,4-bis[2-(4-piridil)etenil]benzeno (BPEB). A combinação adequada de várias espécies selecionadas, conduziu a compostos bastante interessantes que foram caracterizados por meio 1H-RNM, voltametria cíclica e de espectrometria de massa, espectroscopia eletrônica, espectroeletroquímica. Seus correspondentes filmes moleculares também foram investigados por meio de microscopia de força atômica. Um desses sistemas foi constituído por clusters triangulares de acetato de rutênio com pontes µ-oxo e BPEB. Nesses casos, a espectrometria de massa acoplada à técnica de dissociação induzida por colisão, foi uma ferramenta poderosa para a investigação do processo de fragmentação em fase gasosa, permitindo a caracterização de novos intermediários, bem como a avaliação das energias de ligação envolvidas nos sistemas. Uma correlação linear das energias de ligação e parâmetros eletroquímicos foi demonstrada neste trabalho. Além disso, o comportamento eletrocrômico dos clusters de BPEB suportados sobre dióxido de titânio nanocristalino, também foi explorado na elaboração de dispositivos eletrocrômicos, com ótimo desempenho em termos de mudanças ópticas, reversibilidade e reprodutibilidade. Outro tipo de sistema foi baseado em complexos de rutênio-bipiridina e BPEB. Esses complexos foram empregados com bons resultados como sensibilizadores em células fotoeletroquímicas baseadas em dióxido de titânio nanocristalino, bem como em dispositivos eletrocrômicos de mesma natureza. Finalmente, as características estruturais do BPEB mostraram ser adequadas para exploração do reconhecimento molecular dos complexos na presença de β-ciclodextrina (β-CD). Neste estudo, foram gerados rotaxanos por meio da automontagem coordenativa do complexo binuclear µ-BPEB- bis[pentacianoferrato(II)] na presença de β-CD. Também foi demonstrado por meio de 1H-NMR, que a agregação do complexo de BPEB é bastante pronunciada em espectros de solução aquosa, sendo porém inibida na presença de β-CD.The bottom up approach has been applied for the development of new supramolecular systems based on metal complexes connected by the linear, conjugated bridging ligand trans-1,4-bis[2-(4-pyridyl)ethenyl]benzene (BPEB). The combination of the many selected species led to very interesting compounds, which have been extensively characterized by means of ESI-MS, electronic spectroscopy, 1H-NMR, cyclic voltammetry and spectroelectrochemistry. Their molecular films have also been investigated by means of atomic force microscopy. One of such systems was constituted by triangular µ-oxo bridged ruthenium acetate clusters containing BPEB. In particular, mass spectrometry coupled with a collision induced dissociation technique provided a versatile tool for the investigation of their fragmentation process, allowing the characterization of novel intermediates, as well as, the evaluation of the binding energies involved in the systems. A linear correlation of the binding energies and electrochemical parameters has also been demonstrated in this work. In addition, the electrochromic behavior of the cluster-BPEB complexes supported on nanocrystalline titanium dioxide has also been exploited for the design of novel electrochromic devices, exhibiting sharp optical changes, high reversibility and great reproducibility. Another interesting type of system was based on polypyridine ruthenium(II) complexes and BPEB. Such species have been successfully employed as sensitizers in nanocrystalline titanium dioxide photoelectrochemical cells, and in photoelectrochromic devices. Finally, the suitable structural characteristics of BPEB have been explored in molecular recognition processes involving the corresponding complexes in the presence of ß-cyclodextrin (ß-CD). In this study, rotaxanes have been generated by coordination self-assembly of the binuclear µ-BPEB- bis[pentacyanoferrate(II)] complex and ß-CD. It has also been shown that the aggregation of the BPEB complexes, which proceeds to a high extent in aqueous solution, can be inhibited by adding ß-CD, as deduced by means of 1H-NMR spectroscopy
28
Roy, Aditi. "Study to explore molecular inclusion complexes of cyclic hosts with vital guests in various environments." Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2633.
Повний текст джерела
29
Mokhtar, Mohd Noriznan. "Biocatalytic Production, Preparation and Characterization of Large-ring Cyclodextrins." Doctoral thesis, Universitätsbibliothek Chemnitz, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900431.
Повний текст джерелаАнотація:
Cyclodextrins (CD) are cyclic oligosaccharides composed of six to more than sixty
glucose units. Large-ring cyclodextrins (LR-CD) are novel CD comprised of more than eight
glucose units with cavity structures and sizes different from that of commercially available
CD6 – CD8. LR-CD may offer unique molecular recognition properties and can be produced
biocatalytically from starch using cyclodextrin glucanotransferase (CGTase, E.C. 2.4.1.19) in
a short reaction time. LR-CD were isolated from glucose, CD6 – CD8 and other compounds by
complexation of CD6 – CD8 as well as precipitation techniques. The yield of LR-CD (degree
of polymerization from 9 to 21) was optimized using central composite design. Addition of
polar organic solvents to the synthesis resulted in higher yields of LR-CD. LR-CD composed
of 9 to 21 glucose units were successfully separated using reversed-phase of ODS-AQ
chromatography and normal-phase of polyamine II chromatography. Maintaining optimized
reaction conditions aided in a high yield of CD9; it could be separated with reasonable yield
using a single step of polyamine II chromatography. A co-grinding method helped to obtain
higher solubilization levels of glibenclamide, vitamin A acetate and vitamin D3 in CD13, CD10
and CD11, respectively when compared to other CD. Vitamin K1 was solubilized in distilled
water with CD6 – CD13 using a co-precipitation method. When compared with other CD, CD9
was seen to be the best solubilizer. The analysis of complexes using ESI MS showed
spironolactone and glibenclamide complexed with CD9 and CD13, respectively.
30
Cucolo, Gisele Rodrigues [UNESP]. "Produção de ciclodextrinas a partir de amidos de diferentes fontes vegetais e seu emprego na inclusão molecular de aroma cítrico." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/103943.
Повний текст джерелаАнотація:
Made available in DSpace on 2014-06-11T19:32:54Z (GMT). No. of bitstreams: 0
Previous issue date: 2009-12-23Bitstream added on 2014-06-13T20:04:37Z : No. of bitstreams: 1
cucolo_gr_dr_rcla.pdf: 912012 bytes, checksum: bb2f52ae986d8910d4d4ba1e27a6db3e (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Ciclodextrina-glicosil-transferase (CGTase, EC 2.4.1.19) é uma enzima capaz de formar ciclodextrinas (CDs), tendo o amido como substrato. A enzima é de grande interesse industrial, principalmente nas indústrias alimentícias, cosméticas, químicas e farmacêuticas. CDs são moléculas cíclicas formadas por monômeros de glicoses, unidos por ligações α-1,4. Os tipos mais comuns de ciclodextrinas, α-, β- e γ- CD, consistem de 6, 7 e 8 monômeros de glicose, respectivamente. A molecula de CD possui uma estrutura única com a cavidade interna hidrofóbica e a região externa hidrofílica, sendo possível a formação de complexos de inclusão com uma variedade de compostos, que pode melhorar ou proteger as propriedades físicoquímicas da molécula encapsulada. Este estudo foi dividio em três capitulos, o primeiro foi uma revisão bibliografica, e os outros dois são trabalhos de pesquisa. No primeiro trabalho estudou-se a produção de CDs pela CGTase do Bacillus clausii subgrupo E16, tanto em relação ao efeito da concentração do amido na produção das CDs, como em relação a utilização de fontes alternativas de amido (amido solúvel de batata PA, de milho, de trigo e de mandioca) como substrato. Observouse que a enzima produziu preferencialmente β-CD nos diferentes tipos de substrato utilizados. O mais alto grau de conversão de CDs foi obtido com o uso de amido de mandioca, tendo convertido 95,30% (p/p) em β-CD, seguido de 86,60% (p/p) do amido solúvel. A concentração de 1% de amido de mandioca apresentou o melhor rendimento na produção de CDs. No segundo trabalho de desquisa, o objetivo foi a produção de CDs pela CGTase do Bacillus clausii E16 em fontes alternativas de substrato (farelo de trigo, farelo de mandioca; farinhas de milho, trigo e mandioca). Observou-se que a enzima produziu β-CD nos diferentes tipos de substratos utilizados. O grau de conversão de CDs...
Cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) is an enzyme capable of converting starch into cyclodextrins (CDs) molecule. CDs are becoming increasingly popular in pharmaceutical, chemical, cosmetics and food industries. CDs are cyclic oligosaccharides compounded of glucose units jointed by α-1,4 linkages. The most common types of cyclodextrins, α-, β- and γ- CD, consist of 6, 7 and 8 glucose units, respectively. A CD molecule has a unique torus-shaped structure with a hydrophobic internal cavity and a hydrophilic external surface. As a result, CDs can form inclusion complexes with many hydrophobic guest molecules and thereby change their physical and chemical properties. This study was divided in three chapters, the first is about one bibliographic review, and the other are about two research approaches. The aim of the first work was to verify the effect of different starch botanical sources and the concentration of starch in the production of cyclodextrins by CGTase enzyme from Bacillus clausiii E16. It was noticed that the enzyme mainly produced β-CD with the different types of starch (soluble potato starch, corn starch, wheat starch and cassava starch) used substrate. The higher degree of conversion of CDs was obtained with the use cassava starch, of which 95,30% (w/w) was converted in β-CD, followed by 86,60% (w/w) of soluble starch. The concentration 1% of cassava starch showed the best efficiency in the production of CDs. In the second research work, the aim was studied the application of a CGTase from Bacillus clausiii E16 in alternative substrate sources (cassava bran, wheat bran; corn meal, wheat flour e cassava flour) for production of cyclodextrins. It was noticed that the enzyme produced β-CD with the different types of used substrate. The degree of conversion of CDs obtained with the use cassava bran was 40,48% (w/w) in β-CD and preliminary studies... (Complete abstract click electronic access below)
31
Robertis, Laurence de. "Synthèse de cyclodextrines régiosélectivement modifiées." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10131.
Повний текст джерелаАнотація:
Notre travail a consisté en la synthèse et la caractérisation de nouveaux transporteurs de principes actifs formes par un molécule de cyclodextrine pour le piégeage du médicament, et par un motif galactose pour le ciblage de l'ensemble vers des cellules portant des lectines à galactoses sur leur surface. Deux familles de molécules ont été obtenues: - celles ayant une ou plusieurs unités thiogalactosyles liées sur un ou plusieurs hydroxyles primaires de la cyclodextrine ; - celles constituées par un polymère biocompatible portant sur des chaines pendantes, les cyclodextrines et les galactoses. La capacité de complexation des unités cyclodextrines a, dans les deux cas, été étudiée par la méthode rmn, et la reconnaissance des unités galactosyles a été testée à l'aide d'une lectine de levure galactose spécifique. Ces nouveaux types de transporteurs de médicaments ont donné des résultats positifs in vitro et peuvent présager des résultats intéressants in vivo
32
Tang, Chuan. "Chemical Modification Effects on Molecular Dynamics of Complex Poly(rotaxane) Investigated by Solid-state NMR." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366798928.
Повний текст джерела
33
BERGAMINI, JEAN-FRANCOIS. "Modulations chimique et electrochimique de l'inclusion de molecules electroactives dans les cyclodextrines. Application a l'elaboration d'oligomeres conjugues encapsules." Paris 7, 1999. http://www.theses.fr/1999PA077026.
Повний текст джерелаАнотація:
L'objectif de ce travail est, d'une part, de comprendre les mecanismes mis en jeu lors de l'electrochimie de complexes a base de cyclodextrine et de molecules electroactives et, d'autre part, de realiser la synthese de polymeres conducteurs encapsules. Le premiere axe presente l'etude en presence de cyclodextrine d'une molecule electroactive, le 4-amino n,n-diphenylamine (adpa). Differentes etudes spectroscopiques montrent la formation d'un complexe d'inclusion. L'etude electrochimique du complexe conclut a un mecanisme redox reversible faisant intervenir deux electrons et deux protons et precise que le complexe ne participe pas a la reaction redox. Des etudes par spectroscopie d'absorption in situ et par modelisation moleculaire montrent que l'espece oxydee de l'adpa est complexee par la cyclodextrine avec une meilleure affinite que l'espece reduite. Par ailleurs, la complexation induit la deprotonation de l'espece oxydee a ph quasiment neutre. Le second axe de ce travail est consacre a l'etude d'un second complexe d'inclusion forme entre la biphenylamine (bpa) et la cyclodextrine. La formation d'un complexe d'inclusion est confirmee par des etudes spectroscopiques qui precisent que la forme neutre de la bpa est mieux complexee que sa forme protonee. La modelisation moleculaire montre que la bpa, en raison de sa structure allongee, est entierement incluse dans la cavite de la cyclodextrine. L'etude electrochimique du bpa en milieu aqueux permet de definir un mecanisme redox irreversible impliquant deux electrons et deux protons et montre que le complexe se dissocie lors de son oxydation. La polymerisation electrochimique du bpa en presence de cyclodextrine donne des produits solubles observes a proximite de l'electrode. Leur caracterisation par spectroscopie d'absorption et par spectrometrie de masse a determine que ce sont des oligomeres du bpa et qu'ils sont encapsules dans une ou plusieurs molecules de cyclodextrine.
34
Egidio, Fernanda do Carmo. "Estudo sobre a solvatação de ciclodextrinas por RMN atraves da relaxação das moleculas de agua." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250163.
Повний текст джерелаАнотація:
Orientadores: Edvaldo Sabadini, Fred Yukio FujiwaraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-05T11:17:03Z (GMT). No. of bitstreams: 1 Egidio_FernandadoCarmo_M.pdf: 997650 bytes, checksum: 3662c5dade756ee697c267ad8996aa15 (MD5) Previous issue date: 2005
Resumo: Ciclodextrinas (CD) são oligossacarídeos cíclicos produzidos pela ação enzimática microbiológica sobre o amido. As três ciclodextrinas naturais disponíveis comercialmente são a-CD, b-CD e g-CD, constituídas por 6, 7 e 8 unidades glicosídicas, respectivamente. Possuem estrutura rígida representada como um cone truncado oco com cavidade hidrofóbica, formada pelos grupos CH2 e éter, e exterior hidrofílico, contendo os grupos hidroxila. Esses oligossacarídeos interagem com uma ampla variedade de moléculas, formando complexos de inclusão, e a interação com polímeros pode levar à formação de estruturas supramoleculares. As ciclodextrinas apresentam uma solubilidade anômala em água, com uma tendência irregular, sendo a b-CD aproximadamente dez vezes menos solúvel que as outras duas ciclodextrinas da série homóloga. O mesmo comportamento é observado quando D2O é o solvente, mas, neste caso, a solubilidade é ainda menor para as três ciclodextrinas. Pode-se explicar esse comportamento em termos do efeito causado pelas ciclodextrinas na estrutura do solvente e pela solvatação destas moléculas. A solvatação pode ser estudada por Ressonância Magnética Nuclear, RMN, através de medidas do tempo de relaxação transversal T2 do solvente. Os valores de T2 são diferentes para moléculas de solvente livres e ligadas à superfície do soluto, devido à processos dinâmicos, como a rotação molecular. O T2 é muito sensível à interação do solvente com o soluto, de forma que a presença de um soluto diminui o T2 das moléculas do solvente diretamente ligadas ao soluto. Este trabalho fez o estudo da solubilidade e solvatação das ciclodextrinas considerando também o equilíbrio entre o estado sólido e a solução saturada. Os cristais de ciclodextrinas foram estudados por Difração de Raios-X e Análise Termogravimétrica. A estrutura molecular dos oligômeros afetam sua flexibilidade, solvatação e acomodação no meio líquido, resultando na anomalia na solubilidade em H2O e D2O.
Abstract: Cyclodextrins (CD) are cyclic oligomers produced by the action of certain microbial enzymes on starch. The commercially available members of this series are a-CD, b-CD and g-CD, having 6, 7 and 8 glucose units, respectively. They have a rigid structure pictorially represented as a truncated cone with a hydrophobic cavity, which are formed by CH2 and ether groups, and a hydrophilic exterior with hydroxyl groups at the rims. The cyclodextrins are known to interact with different types of molecules, including polymers, forming supramolecular inclusion compounds. The cyclodextrins molecules present an anomalous solubility in water and an irregular trend is observed in the series. b-CD is almost ten times less soluble than the others two cyclodextrins. The same behavior is observed when D2O is the solvent, however, in this solvent the solubility of three cyclodextrins is much lower. This behavior is explained in terms of the effect caused by cyclodextrins on the water lattice structure and by the solvation of these molecules. The cyclodextrins solvation was studied using transversal relaxation time (T2) of water in Nuclear Magnetic Resonance experiments. The T2 of free water and the water bounded on the surface of a solute are different due to the differences in their molecular dynamics (mainly the rotation). Hence, T2 of the solvent is very sensitive to interaction between solute and solvent and becomes lower as the solute concentration increases. In this work, not only the solubility and solvation of cyclodextrins were studied, but also the solid phase in equilibrium with the concentrated solution. The solid phase was studied by X-Ray Diffraction and Thermogravimetric Analysis. The molecular structures of cyclodextrins influence their flexibility and solvation, which leads to the anomalous solubility of the three cyclic oligomers in H2O and D2O.
Mestrado
Físico-Química
Mestre em Química
35
Granero-García, Rubén. "Investigating the hydration and structural changes of molecular organic materials under high-pressure conditions." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-002B-7CB2-2.
Повний текст джерела
36
Guo, Zhen. "Insights of Taste Masking from Molecular Interactions and Microstructures of Microspheres." Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/17420.
Повний текст джерелаАнотація:
The effects of taste masking are determined by interactions between drug and excipients as well as the microstructures of the particulate drug delivery systems (DDS). Cyclodextrin (CD) is a widely used taste masking agent, to which the relationship between kinetic parameters (Ka and Kd) of a drug and taste masking remains unexplored, which is investigated for the first time in this study. A data base of the kinetic parameters for drug-CD was established by Surface Plasmon Resonance Imaging (SPRi) and High Performance Affinity Chromatography (HPAC). Combined with the electronic tongue, Ka and Kd based models for the taste masking effect of HP-β-CD were successfully established and applied to the prediction of taste masking effects. Paracetamol was used as a model drug for taste masking formulation optimization. As well as drug release the microstructure of solid DDS has considerable influence on drug taste. The microstructure of lipid microspheres and the molecular distribution of drug and excipients in lipid microspheres were investigated by Synchrotron radiation-based micro-computed tomography (SR-μCT) and Synchrotron radiation-based Fourier-transform infrared spectromicroscopy (SR-FTIR), respectively. The results demonstrated that the polymeric formulation components as well as shape and particle size of the drug were the key factors to taste masking of paracetamol by inhibiting bust release thereby reducing the interaction intensity of the bitterness. The FTIR absorption spectra confirmed the deposition and formation of chitosan and gelatin films on the drug microsphere surface by layer-by-layer coating. In conclusion, this research demonstrates the molecular kinetic basis of CD taste-masking as well as microstructural basis of particle systems for bitter taste masking.
37
Lobo, Francine Albernaz Teixeira Fonseca. "Inclusão de carotenoides de pimentão amarelo em β-Ciclodextrina e avaliação da sua estabilidade, visando aplicação em alimentos". Niterói, 2017. https://app.uff.br/riuff/handle/1/3279.
Повний текст джерелаАнотація:
Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-04-03T18:29:32Z
No. of bitstreams: 1
Lobo, Francine Albernaz Teixeira Fonseca [Dissertação, 2013].pdf: 2381011 bytes, checksum: c7adb766e00b44a8578b1529e9a43161 (MD5)Made available in DSpace on 2017-04-03T18:29:32Z (GMT). No. of bitstreams: 1 Lobo, Francine Albernaz Teixeira Fonseca [Dissertação, 2013].pdf: 2381011 bytes, checksum: c7adb766e00b44a8578b1529e9a43161 (MD5)
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Os pigmentos naturais oriundos do pimentão amarelo (Capsicum annuum) foram extraídos, caracterizados e incluídos em β-ciclodextrina, utilizando-se duas metodologias modificadas de inclusão molecular, visando aumentar a solubilidade e a estabilidade dos pigmentos frente a fatores envolvidos no processamento e armazenamento de alimentos. Foi realizada a extração dos pigmentos utilizando a mistura de solventes etanol:água (90:10), seguida da partição com hexano. A determinação dos principais pigmentos presentes no extrato foi realizada por cromatografia líquida de alta eficiência (CLAE) identificando-se a luteína, zeaxantina, α-criptoxantina, α-caroteno e β-caroteno. Os testes preliminares de inclusão molecular foram realizados com três proporções de extrato/β-ciclodextrina (1:2, 1:4 e 1:6) m/m, com a proporção 1:2 sendo escolhida para dar seguimentos aos experimentos. Os complexos obtidos foram caracterizados por espectrofotometria no infravermelho, ressonância magnética nuclear de hidrogênio (RMN1H), análise térmica diferencial (DSC) e potencial Zeta. Os complexos obtidos pelos dois procedimentos e o extrato de pimentão amarelo foram utilizados em experimentos para avaliar o efeito combinado das variáveis pH, temperatura e tempo de aquecimento sobre a estabilidade da cor, os resultados demonstraram que o extrato está mais sujeito a ação dos parâmetros avaliados em comparação ao complexo, indicando que a inclusão em β-ciclodextrina elevou a estabilidade da cor do extrato do pimentão amarelo em solução. Para aproximar a cor dos produtos industrializados foram medidos os índices L*,a* e b* de iogurte e bebida isotônicas vendidos no mercado nacional. Avaliou-se a estabilidade do complexo no iogurte natural durante 60 dias e em bebidas isotônicas armazenadas sob irradiância (1400 lx) e ausência de luz, em temperatura ambiente (25 - 31 °C), durante 70 dias de armazenamento para avaliar a estabilidade da cor. O extrato bruto do pimentão amarelo e a tartrazina foram utilizados como controle. Os melhores resultados foram obtidos com as amostras adicionadas de complexo, comparadas às amostras de extrato bruto, as quais apresentaram maior alteração na cor
The natural pigments from yellow pepper (Capsicum annuum) were extracted, characterized and inclused in β-cyclodextrin, using two modified methodologies for molecular inclusion, aiming to increase the solubility and stability of pigments in front of factors involved in the processing and storage of food. Extraction was performed using the as solvent mixture ethanol: water (90:10) followed by partition with hexane. The determination of the major pigments was carried out by hight performance liquid chromatography (HPLC) identifying lutein, zeaxanthin α- cryptoxanthin,α-carotene and β-carotene. Preliminary tests of molecular inclusion by method A were performed with three ratios of extract/β-cyclodextrin (1:2, 1:4 and 1:6) m/m, with 1:2 being chosen to give the segments experiments. The complexes obtained by both molecular inclusion procedures were characterized by fourier transform-infrared spectroscopy, nuclear magnetic resonance (RMN1H), differential scanning calorimetry (DSC) and Zeta potential. The complex obtained by two molecular inclusion and the extract from yellow pepper were used in the experiments to verify the combined effect of the variables pH, temperature and heating time on the color stability, and the results showed that the extract is more liable to the action of these parameters compared with the complex, indicating that the inclusion in β-cyclodextrin increased the color stability from the yellow pepper extract. To approximate the color of sample added of yellow pepper extract with the color of yogurt and isotonic beverage sold in national market. The stability of the complex in the natural yogurt for 60 days and isotonic beverage stored under irradiance (1400 lx) and absence of light in temperature between 25 – 31 °C, for 70 days. The crude extract of yellow pepper and the tartrazine were used as control. The best results were obtained with the samples added of complex, compared to the added of crude extract, which showed the greatest change in color
38
Rodríguez, Bonilla María Pilar. "Molecular nanoencapsulation of stilbenes by cyclodextrins : study of biochemical, chromatographic and antioxidant applications= Nanoencapsulación molecular de estilbenos por ciclodextrinas: aplicaciones bioquímicas, cromatográficas y antioxidantes." Doctoral thesis, Universidad de Murcia, 2015. http://hdl.handle.net/10803/363919.
Повний текст джерелаАнотація:
INTRODUCCIÓN Y OBJETIVOS En los últimos años ha cobrado gran fuerza la aparición de los alimentos funcionales, entendiéndose como tales aquellos que le confieren al consumidor un beneficio para la salud más allá de sus propiedades puramente nutritivas. Uno de los grupos de alimentos funcionales que más cuota de mercado está obteniendo es el de los enriquecidos en sustancias bioactivas con un alto valor biológico. En esta tesis doctoral se propone la investigación necesaria para el diseño de alimentos funcionales enriquecidos en diversos tipos de estilbenos, moléculas que han demostrado poseer propiedades beneficiosas para la salud. El estudio de los estilbenos favorecerá, además, su uso en las industrias farmacéutica y cosmética. El hecho de que, por una parte, los miembros de esta familia de compuestos muestren un alto grado de inestabilidad y que, por otra, la gran mayoría de ellos presenten un carácter poco hidrofílico, dificulta el enriquecimiento de productos con estas moléculas por lo que se hace necesario el diseño de nuevas estrategias para que puedan ser empleados, como es el caso de la encapsulación molecular. Por ello, el objetivo general de la presente tesis es la nanoencapsulación de diferentes estilbenos mediante ciclodextrinas con el fin de incrementar, por un lado, su estabilidad frente a diversos agentes físico-químicos y, por otro, la solubilidad de los derivados más hidrofóbicos. METODOLOGÍA La metodología utilizada se ha basado en ensayos fluorimétricos, espectrofotométricos y cromatográficos para caracterización de la formación de distintos complejos de inclusión de los estilbenos con diferentes tipos de ciclodextrinas naturales y modificadas. También se han utilizado diferentes métodos (ORAC, ABTS y FRAP) para evaluar la capacidad antioxidante de estilbenos, en ausencia y presencia de ciclodextrinas. Por último se han empleado técnicas de docking molecular. CONCLUSIONES La conclusión principal de esta Tesis Doctoral es que se ha conseguido encapsular diferentes estilbenos (oxyresveratrol, resveratrol, pinosilvina y pterostilbeno) mediante distintos tipos de ciclodextrinas, lo que abre la oportunidad al uso de estos importantes compuestos bioactivos en la industria alimentaria, farmacéutica y cosmética. Además sea demostrado la utilidad de los nanocomplejos ciclodextrina/estíbenos en áreas como la cromatografía, la enzimología o la actividad antioxidante.INTRODUCTION AND OBJECTIVES In recent years the growth of the functional foods industry has increased research into new compounds with high added value for use in the fortification of traditional products. One of the most promising functional food groups are those enriched in antioxidant compounds of a lipophilic nature. As a result, in this thesis are required for the design of functional foods rich in various types of stilbenes, molecules that have been shown to have large beneficial properties for health research is proposed. In spite of the numerous advantages reported for such antioxidant molecules, they may also have disadvantages that impede their use in functional foods, although these problems may well avoided by the use of encapsulant agents such as cyclodextrins. Therefore, the overall objective of this thesis is the nanoencapsulation of different stilbenes by cyclodextrins in order to increase firstly, its stability against various physical and chemical agents and, secondly, the solubility of the more hydrophobic derivatives. MATERIAL AND METHODS The methodology is based on fluorimetric and chromatographic assays for characterization of the formation of inclusion complexes of various stilbene (oxyresveratrol, resveratrol pterostilbene and pinosylvin) with different types of natural and modified cyclodextrins. Have also been used different methods, ORAC, ABTS and FRAP, to evaluate the antioxidant capacity of stilbenes, in the absence and presence of cyclodextrins. Finally, we have used a molecular docking. CONCLUSIONS The main conclusion of this thesis is have been encapsulated different stilbene (oxyresveratrol, resveratrol and pterostilbene pinosylvin) through different types of cyclodextrins, which opens the opportunity to use these important bioactive compounds in food, pharmaceutical and cosmetic. In addition we have demonstrated the utility of nanocomplex stilbene/cyclodextrin in areas such as chromatography, enzymology or antioxidant activity.
39
Östervall, Jennie. "Conformational Dynamics of Carbohydrates Studied by NMR Spectroscopy and Molecular Simulations." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1023.
Повний текст джерелаАнотація:
Carbohydrates play important roles in biological processes. Their function is closely related to their conformation. In this thesis, conformational studies of carbohydrates by NMR spectroscopy and molecular dynamics computer simulations are described. The first two papers discuss the anomalous solubility of β-cyclodextrin compared to other cyclodextrins. Time correlation functions revealed flexibility in all cyclodextrins. Molecular dynamics computer simulations showed that the glycosidic linkages were rather rigid and the flexibility was suggested to be macrocyclic. From spatial distribution functions β-cyclodextrin was found to have greater ability to order the surrounding water than the other cyclodextrins. Paper III deals with some of the difficulties of conformational studies. In Paper IV, a new method, Additative Potential Maximum Entropy, APME, is applied to a disaccharide. Conformational distribution functions are derived from NOEs, J-couplings and residual dipolar couplings and calculated from computer simulations. All distribution functions were found to be in good agreement. In papers V and VI oligosaccharides from human milk are studied. Residual dipolar coupling, J-couplings and cross relaxation rates were measured by NMR spectroscopy and molecular dynamics computer simulations were carried out. Both oligosaccharides showed high flexibility for the β-D-GlcpNAc-(1→3)-β-D-Galp linkage.
40
RABELLO, Marcelo Montenegro. "Desenvolvimento e automação de metolodogias in silico para o estudo de complexos de inclusão utilizados na inova o terapêutica." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17588.
Повний текст джерелаАнотація:
Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-07-29T17:57:19Z
No. of bitstreams: 2
license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)
MMR-TESE.pdf: 16044503 bytes, checksum: 1c3b4963930b3b75a91e718bd1893e50 (MD5)Made available in DSpace on 2016-07-29T17:57:19Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) MMR-TESE.pdf: 16044503 bytes, checksum: 1c3b4963930b3b75a91e718bd1893e50 (MD5) Previous issue date: 2016-02-29
Facepe
Este trabalho apresenta uma metodologia in silico para o estudo de complexos de inclus o utilizados na inova o terap utica. Um complexo de inclus o formado por um host (hospedeiro), e por um guest (h spede). Neste trabalho, o host estudado a ciclodextrina (e seus derivados) e o guest, um ligante (f rmaco, em potencial), formando o complexo host:guest. O objetivo desse projeto desenvolver uma plataforma (CycloMolder) capaz de realizar estudos in silico dos complexos de inclus o de forma autom tica e precisa, fazendo uso de uma interface gr fica de usu rio. Esse objetivo foi tra ado para facilitar os estudos de modelagem molecular para este tipo de sistema qu mico, com interesse farmac utico. A plataforma composta por dois m dulos: CycloGen e CycloDock. O primeiro m dulo (CycloGen) constr i modelos com mais de uma estrutura para representar um derivado de ciclodextrina. O segundo m dulo (CycloDock) realiza o c lculo de docking molecular entre as mol culas host e guest, utilizando o programa Autodock Vina e apresenta os resultados obtidos, incluindo gr ficos que mostram a distribui o energ tica e as intera es intermoleculares do complexo. O programa CycloMolder foi testado atrav s de estudos de casos inspirados em problemas farmac uticos reais. Os testes realizados destacaram a import ncia da gera o de mais de uma configura o para representar significativamente um derivado de ciclodextrina, e tamb m mostrou o potencial anal tico do programa, proporcionado pela automa o do estudo de modelagem, execu o dos c lculos e an lise dos resultados. De forma geral, o programa CycloMolder atinge seus objetivos, automatizando e simplificando os estudos in silico dos complexos de inclus o, contribuindo desta forma para a inova o terap utica.
This work presents an in silico methodology for study of inclusion complexes used in therapeutic innovation. An inclusion complex is formed by a host and a guest. In this work, the host is the cyclodextrin and their derivatives and the guest is a potential drug, forming a host:guest complex. The goal of this work is to development a platform (CycloMolder) able to perform in silico studies of inclusion complexes in an automated and precise fashion, making use of a graphical user interface. The platform (CycloMolder) consists of two modules: CycloGen and CycloDock. The first module (CycloGen) builds models with more than one chemical structure to represent a cyclodextrin derivative. The second module (CycloDock) performs the molecular docking calculations between the host and guest molecules, using the AutoDock Vina program, and displays the results, including graphs showing the energy distribution and intermolecular interactions present in the host:guest complexes. The CycloMolder program was tested through case studies inspired by real pharmaceutical problems. The tests highlighted the importance of generating more than one chemical structure to better represent a ciclodextrin derivative, also showed the analytical potential of the program, provided by the automation of the modeling study, execution of calculations and analysis of results. Overall, the CycloMolder program achieves its goals by automating and simplifying the in silico studies of inclusion complexes, thus contributing to the therapeutic innovation.
41
Apparu, Christine. "Synthèses chimioenzymatiques de cyclodextrines symétriquement substituées et de thiooligosaccharides." Grenoble 1, 1993. http://www.theses.fr/1993GRE10099.
Повний текст джерелаАнотація:
L'etude du centre actif de la cyclodextrine glycosyltransferase (cgtase) a ete menee en utilisant des analogues de substrat. Ces derniers correspondent a des maltoses et des fluorures de maltosyle et maltotriosyle, tous modifies sur l'hydroxyle primaire de leur unite terminale non reductrice. Parmi tous ces composes, deux d'entre eux ont conduit a la formation de l'alpha-cyclodextrine tri-iodee symetrique et de l'alpha-cyclodextrine di-iodee symetrique avec des rendements respectifs de 25 a 38%. De meme, l'etude des glucoamylases a ete realisee a l'aide de thiooligosaccharides. Ces composes ont ete prepares en deux etapes de synthese et ont ete obtenus avec d'excellents rendements. Des tests enzymatiques ont montre que ces produits sont de meilleurs substrats que les oligosaccharides naturels correspondants. Enfin, les cyclodextrines obtenues ci-dessus sont des molecules pouvant servir de base a la construction d'edifices supramoleculaires. C'est donc dans cet objectif que l'alpha-cyclodextrine di-iodee symetriquement a ete utilisee afin de synthetiser un modele de la tyrosinase. Ce dernier a ete obtenu avec 69% de rendement
42
Petito, Nicolly de Lima. "Complexação de carotenoides de pimentão vermelho com hidroxipropil-β-ciclodextrina: caracterização, avaliação da solubilidade e estabilidade em formulações alimentícias". Niterói, 2017. https://app.uff.br/riuff/handle/1/3054.
Повний текст джерелаАнотація:
Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-03-14T18:47:43Z
No. of bitstreams: 1
Petito, Nicolly de Lima [Dissertação, 2015].PDF: 2998524 bytes, checksum: 0048771f6748f57c822ca4612196e146 (MD5)Made available in DSpace on 2017-03-14T18:47:43Z (GMT). No. of bitstreams: 1 Petito, Nicolly de Lima [Dissertação, 2015].PDF: 2998524 bytes, checksum: 0048771f6748f57c822ca4612196e146 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Carotenoides são pigmentos naturais amplamente distribuídos na natureza, responsáveis pelas cores vermelhas, laranjas e amarelas. São substâncias amplamente estudadas por apresentarem potencial antioxidante e atividade pró-vitamina A. Devido a seu caráter lipofílico, são pigmentos naturais de difícil aplicação em alimentos como aditivos, além de apresentarem alta instabilidade frente a fatores comuns no processamento, como pH, luz, calor e oxigênio. O uso de ciclodextrinas como agentes encapsulantes é recomendado a fim de aumentar a solubilidade dos carotenoides em meio aquoso, e possivelmente, protegê-los dos fatores químicos e ambientais. Portanto, o objetivo deste trabalho foi conduzir a inclusão molecular de carotenoides de pimentão vermelho (Capsicum annuum L.) em hidroxipropil-β-ciclodextrina visando o aumento de sua solubilidade e estabilidade frente a fatores envolvidos no processamento e armazenamento de bebidas isotônicas. A extração dos carotenoides de pimentão vermelho foi realizada por meio de maceração em solvente etanol e água (9:1), seguida de partição com hexano e evaporação em baixa temperatura. O perfil de carotenoides do extrato obtido foi determinado por cromatografia líquida de alta eficiência (CLAE-UV). A inclusão do extrato de pimentão vermelho em hidroxipropil-β-ciclodextrina foi realizada por meio de sonda de ultrassom em quatro proporções (1:4, 1:6, 1:8 e 1:10 v/v). Misturas físicas nas mesmas proporções foram preparadas para efeito comparativo. O extrato de pimentão vermelho, os complexos de inclusão obtidos e as misturas físicas foram caracterizados por espectrofotometria no infravermelho (FT-IR), ressonância magnética nuclear de hidrogênio (RMN1H), calorimetria exploratória diferencial (DSC), difusão dinâmica da luz (DLS), espectrofotometria de absorção na região do UV-visível e ensaio de solubilidade. No extrato de pimentão vermelho foram identificados cinco carotenoides, a saber: β-caroteno, β-criptoxantina, 9-cis-β-caroteno, capsantina e 13-cis-β-caroteno. Observou-se que a inclusão molecular foi efetiva para as diferentes proporções de complexo ao compará-las com os resultados das misturas físicas, principalmente pelos resultados dos ensaios de solubilidade, onde foi identificado o aumento de solubilidade em até 660 vezes comparado ao do extrato isolado. Devido à relação custo-benefício, optou-se por dar continuidade aos experimentos com os complexos com proporção 1:6 (m/m). A estabilidade de cor dos complexos e do extrato de pimentão foi avaliada sob o efeito combinado das variáveis pH, tempo e temperatura. Os resultados demonstraram que se pode esperar maior retenção dos parâmetros de cor com o uso do complexo do que com o uso do extrato. A fim de avaliar a estabilidade de cor dos complexos em condições de armazenamento durante 40 dias, foram formuladas bebidas isotônicas adicionadas de complexo ou de corantes artificiais, adicionadas de conservante ou pasteurizadas, submetidas à 10 ou 25 μmol de fótons.m2.s-1, ou armazenadas na ausência de luz. Os resultados revelaram que as amostras armazenadas ao abrigo de luz apresentaram menor variação da cor, tendo as pasteurizadas apresentado melhor resultado. Em conclusão, a inclusão molecular permite o aumento da solubilidade dos carotenoides de pimentão vermelho, permitindo assim a sua aplicação em formulações alimentícias, e atribui o efeito protetor a estes carotenoides frente a fatores inerentes ao processamento de alimentos
Carotenoids are natural pigments widely distributed in nature, responsible for the red, orange and yellow colors. They are known and studied due to their antioxidant potential and pro-vitamin A activity. However, due to their lipophilic nature and high instability under influence of common processing factors, such as pH, light, heat and oxygen, it is difficult to apply them in food . Use of cyclodextrins as encapsulating agent is recommended in order to increase their aqueous solubility and protect the molecules against chemical and environmental factors. The aim of this study was to perform molecular inclusion of red bell pepper carotenoids (Capsicum annuum L.) in hydroxypropyl-β-cyclodextrin, in order to increase their solubility and stability in front of factors involved in processing and storage of food. The extraction of red bell pepper carotenoids was carried out by soaking in solvent ethanol and water (9: 1), followed by partition with hexane and evaporation at low temperature. In order to characterize the extract obtained, analysis by high performance liquid chromatography was performed (HPLC), identifying β-carotene, β-cryptoxanthin, 9-cis-β-carotene, capsanthin and 13-cis-β-carotene. Inclusion of red pepper extract in hydroxypropyl-β-cyclodextrin was performed using ultrasound probe in four different ratios (1: 4, 1: 6, 1: 8 and 1:10). Additionally, physical mixtures in the same ratios were prepared for comparative purposes. The obtained inclusion complexes, red pepper extract, hydroxypropyl-β-cyclodextrin and physical mixtures were characterized by infrared spectroscopy (FT-IR), nuclear magnetic resonance (1 H NMR), differential scanning calorimetry (DSC), dynamic light scattering (DLS), UV-visible spectroscopy and solubility assay. Molecular inclusion was effective for the different proportions of the complex, by comparing them with the results of physical mixtures, mainly the results of the solubility tests, where the increased solubility was identified up to 660 times, compared to the pure extract. Due to cost-effectiveness, it was decided to continue the experiment with the 1:6 complex. The color stability of the complex and of red bell pepper extract was evaluated under the combined effect of pH, time and temperature. Results demonstrated greater retention of color parameters using complex than the use of extract. In order to evaluate the stability of complex color storage conditions for 40 days, isotonic drinks added of artificial colors or complex were formulated, adding preservative or pasteurized, subjected to 10 or 25 micromol photons.m2.s-1 or stored in the absence of light. Results showed that the samples stored in the absence of light had less color variation, being the pasteurized the best condition. In conclusion, molecular inclusion allows increasing of solubility, thereby allowing its application in food formulations, and assigns the protective effect for carotenoids against inherent factors in food processing
43
Tanwar, Shivalika. "Investigation of encapsulation of Aromatic polluants by β-Cyclodextrin in presence of linear aliphatic alcohols". Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCD076.
Повний текст джерелаАнотація:
La pollution de l’environnement par les composés organiques est devenue une préoccupation mondiale majeure. Les molécules aromatiques comme les cycles benzéniques et leurs dérivés ont attiré une attention considérable en raison de la toxicité reconnue et de la cancérogénicité. Principalement utilisées en chimie supramoléculaire,les cyclodextrines sont des structures moléculaires en forme de cône tronqué ayant une surface externe hydrophile et une cavité hydrophobe. Ainsi, ils peuvent théoriquement encapsuler un grand nombre de molécules organiques hydrophobes pour former des complexes d'inclusion solubles dans l'eau. Cette propriété de complexation a une application potentielle dans le domaine de la détection et de la quantification des polluants polycycliques aromatiques dans les eaux environnementales par des moyens spectroscopiques portables. Nous souhaitons comprendre ce phénomène d’inclusion en combinant des approches théoriques et expérimentales appliquées à l’état solide et en solution. Il a été observé que seules quelques structures cristallines de complexes de cyclodextrines, molécules aromatiques pures, apparaissent dans les bases de données structurelles après un court examen. L'objectif principal de nos recherches est donc de nous concentrer plus précisément sur les interactions entre les alcools aliphatiques et les molécules de cyclodextrine. Pour cela,afin de corréler nos études expérimentales et théoriques, les résultats obtenus ont été suivis de manière systématique par différentes techniques spectroscopiques afin d'observer l'interaction entre les molécules. De plus, les poudres et les cristaux obtenus en faisant varier la solubilité des mélanges ont été soumis à une analyse physico-chimique, à une diffraction des rayons X et à une surveillance DSC pour étayer nos résultats. Ce travail comprend également la modélisation de complexes d'inclusion en utilisant différentes approches, comme la combinaison de méthodes semi-empiriques de la chimie quantique (DFT / TD-DFT) et de la mécanique moléculaire polarisable. Des calculs ont été effectués sur des clusters internes, ce qui permettra de mettre en évidence des facteurs structurels et énergétiques de complexationEnvironmental water pollution by organic compound has become a major worldwide concern. Aromatic molecules like benzene rings and their derivatives have gained considerable attention due to officially documented toxicity and carcinogenicity. Mostly used in supramolecular chemistry, Cyclodextrins are truncated cone-shaped molecular structures having a hydrophilic outer surface and a hydrophobic cavity. Thus, they can theoretically encapsulate a large number of hydrophobic organic molecules to form water-soluble inclusion complexes. This complexation property has potential application in the field of detection and quantification of aromatic polycyclic pollutants in environmental water by portable spectroscopic means. We are interested in understanding this phenomenon of inclusion by combining theoretical and experimental approaches applied to solid state and in solution. It has been observed that only a few crystalline structures of cyclodextrin- pure aromatic molecule complexes appear in the structural databases after a brief review. Therefore, the main objective of our research is to focus more precisely on the interactions between the aliphatic alcohols and cyclodextrin molecules. For this purpose, to correlate our experimental and theoretical studies, the results obtained were monitored by various spectroscopic techniques in a systematic manner to observe the interaction between the molecules. Moreover, the powders and crystals obtained by varying the solubility of the mixtures were further subjected to physico-chemical analysis, X-ray diffraction, and DSC monitoring to support our findings. This work also includes modeling of inclusion complexes using different approaches like combining semi-empirical methods of quantum chemistry (DFT / TD-DFT) and polarizable molecular mechanics. Calculations were carried out on homemade clusters, which will allow the implementation of evidence of structural and energetic factors for complexation
44
Khemtong, Chalermchai. "Synthesis and Supramolecular Chemistry of 2,4,9-Trithiaadamantane Derivatives." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1123084162.
Повний текст джерела
45
Bertaut, Éléonore. "Développement de nouvelles méthodologies pour la calorimétrie de titration isotherme : Applications aux domaines de l'environnement et de la santé." Thesis, Littoral, 2016. http://www.theses.fr/2016DUNK0424/document.
Повний текст джерелаАнотація:
Ce travail de thèse a été consacré au développement de nouvelles méthodologies de caractérisation des affinités intermoléculaires par le biais de la calorimétrie de titration isotherme (ITC), après validation de systèmes modèles par l'intermédiaire des spectroscopies UV-visible, RMN et de l'électrophorèse capillaire. Nous avons en particulier montré que la mise en place et le couplage d'expériences non conventionnelles avec les protocoles classiques permettait d'améliorer la caractérisation calorimétrique, avec notamment une diminution parfois spectaculaire des incertitudes liées aux paramètres thermodynamiques. Ce potentiel de l'analyse globale d'expériences différenciées a été évalué sur un plan théorique, permettant ainsi la définition et l'optimisation des expériences à mettre en oeuvre en fonction du type de complexe étudié. L'exploitation expérimentale de ces stratégies a également permis l'étude de complexations problématiques sur le plan analytique, dans le cadre de complexes impliquant des molécules telles que les cyclodextrines ou l'albumine, et s'inscrivant dans des applications liés aux domaines de l'environnement et de la santé. Ainsi, nos stratégies ont levé les difficultés liées aux complexes athermiques, aux complexes de faibles affinités, aux équilibres multiples et aux faibles solubilités de l'un ou l'autre des partenaires de la complexation. Enfin, l'évaluation d'un nouveau modèle de traitement thermo-cinétique du thermogramme ITC a été réalisée, accroissant encore le potentiel de cette technique vis-à-vis de la caractérisation des interactions moléculairesThis work was dedicated to the development of new isothermal titration calorimetry (ITC) methodologies for the characterization of intramolecula affinities, after validation of model system via capillary electrophoresis, UV-visible and NMR spectroscopy. We have demonstrated that the coupling of unconventional experiments with the conventional protocols generally improves the calorimetric characterization, with a dramatic decrease of the uncertainties on thermodynamic parameters. The potential of global analysis applied to differentiated experiments was evaluated on a theoretical level, allowing the definition of optimal experiments, depending on the type of studied complex. These strategies also enabled, on a experimental point of view, the study of complexations which cannot be analyzed by conventional approaches, in the case of complexes involving cyclodextrins or albumin. Indeed, our strategies overcomes the difficulties associated with athermic complexes, with complexes of low affinity, with multiple equilibria and with the low solubility of interacting partners. Finally, the evaluation of a new thermo-kinetic treatment of ITC thermograms has been achieved, further increasing the potential of this technique in the characterization of molecular interactions
46
Gomes, Lidiane Martins Mendes. "Inclusão de carotenoides de pimentão vermelho em β-ciclodextrina e avaliação da sua estabilidade, visando aplicação em alimentos banca examinadora". Niterói, 2017. https://app.uff.br/riuff/handle/1/3313.
Повний текст джерелаАнотація:
Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-04-11T16:50:03Z
No. of bitstreams: 1
Gomes, Lidiane Martins Mendes [Dissertação, 2012].pdf: 2213358 bytes, checksum: e982a0f913569884682b2ed86d6de244 (MD5)Made available in DSpace on 2017-04-11T16:50:03Z (GMT). No. of bitstreams: 1 Gomes, Lidiane Martins Mendes [Dissertação, 2012].pdf: 2213358 bytes, checksum: e982a0f913569884682b2ed86d6de244 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
O uso das ciclodextrinas como agente encapsulante é uma tecnologia que melhora a solubilidade e aumenta a estabilidade de substâncias frente a fatores químicos e ambientais. O objetivo do presente trabalho foi conduzir a inclusão de carotenoides extraídos do pimentão vermelho (Capsicum annuum L.) em ciclodextrinas, visando favorecer a sua solubilidade e estabilidade frente a fatores envolvidos no processamento e armazenamento de alimentos. Inicialmente, testes foram realizados para escolha dos solventes mais adequados sendo eleita a mistura etanol: água (90:10), seguida da partição com hexano, para extração dos pigmentos. A determinação dos principais pigmentos presentes no extrato foi realizada por cromatografia líquida de alta eficiência (CLAE) identificando-se a capsantina, capsorubina, β-caroteno, β- criptoxantina, 13-cis- β-Criptoxantina e 9 cis- β- caroteno. Os testes preliminares de inclusão molecular que foram realizados com α-, β- e metil-β-ciclodextrina, indicaram a β- ciclodextrina como sendo a mais adequada para dar seguimento aos experimentos. A escolha do procedimento de inclusão foi feita com base nos resultados obtidos com os ensaios de caracterização, em especial o rendimento e a eficiência de inclusão. O procedimento de inclusão molecular entre o extrato e a β-ciclodextrina com sonda de ultra-som demonstrou maior rendimento (54,48 %) e eficiência de inclusão (62,43%) comparado ao processo com agitação magnética, que apresentou os valores de 40,49% e 52,95%, respectivamente. Os complexos obtidos através dos dois procedimentos de inclusão molecular foram caracterizados por espectrofotometria no infravermelho, ressonância magnética nuclear de hidrogênio (RMN1H), análise térmica diferencial (DSC), tamanho e distribuição de partícula, e potencial Zeta. As caracterizações indicaram que sonda de ultra-som promoveu maior interação entre o extrato e a β-ciclodextrina comparado ao procedimento com agitação magnética. A atividade antioxidante do extrato e do complexo obtidos foram avaliados pelo método ORAC (Oxygen Radical Absorbance Capacity), e demonstrou que o complexo apresentou maior atividade antioxidante comparado ao extrato. O complexo obtido por sonda de ultra-som e o extrato de pimentão vermelho foram utilizados em experimentos para avaliar o efeito combinado das variáveis pH, temperatura e tempo de aquecimento sobre a estabilidade da cor, e os resultados demonstraram que o extrato está mais sujeito a ação dos parâmetros avaliados em comparação ao complexo, indicando que a inclusão em β- ciclodextrina elevou a estabilidade da cor do extrato do pimentão vermelho em solução. As mesmas amostras também foram adicionadas em iogurte para avaliar a estabilidade da cor durante sessenta dias de armazenamento. Os resultados revelaram que o complexo promoveu maior proteção da cor comparado ao iogurte que recebeu extrato não complexado. Em conclusão, a inclusão do extrato de pimentão vermelho em β-ciclodextrina usando sonda de ultra-som foi eficiente para obtenção de complexo com bom rendimento e eficiência de inclusão, além de colaborar para a elevação da estabilidade da cor frente a parâmetros que podem estar envolvidos no processamento e armazenamento de alimentos
The use of cyclodextrins as encapsulating agent is a technology that improves the solubility and increases stability of the substances in front of chemical and environmental factors. The aim of the present work was carry the inclusion of carotenoids obtained from red bell pepper (Capsicum annuum), in cyclodextrins, ordering promote its solubility and stability in front of the factors involved in processing and storage of foods. Initially, tests were performed to choose the most appropriate solvents, being elected the ethanol:water (90:10) mixture, followed by partition mixture solvents hexane:acetone to extraction of the pigments. The determination of the major pigments was carried by hight performance liquid chromatography (HPLC) identifying capsanthin, capsorubin, β-carotene, β-cryptoxanthin, 13-cis-β- cryptoxanthin and 9 cis-β-carotene. Preliminary tests of molecular inclusion which were carried with α-,β-and metil-β-cyclodextrins indicated β–cyclodextrins as being more appropriate to follow up the experiments. The selection of the inclusion procedure was based on the results obtained with characterizations tests, in particular, the yield and inclusion efficiency. The procedure inclusion molecular of the extract in β–cyclodextrin by ultrasound probe showed higher yield (54,48 %) and inclusion efficiency (62,43%) compared to magnetic stirring,which showed values of 40,49% and 52,95%, respectively. The complexes obtained by both molecular inclusion procedure were characterized by fourier transforminfrared spectroscopy, nuclear magnetic resonance (RMN1H), differential scanning calorimetry (DSC), size and particle distribution and Zeta potential. The characterizations indicated that the ultrasound probe promoted greater interaction between the extract and β– cyclodextrin compared to magnetic stirring. The antioxidant activity of the obtained extract and complex were available by ORAC (Oxygen Radical Absorbance Capacity) method, and demonstrated that the complex showed higher antioxidant activity compared to extract. The complex obtained by ultrasound probe and the extract from red bell pepper were used in the experiments to asses the combined effect of the variables pH, temperature and heating time on the color stability, and the results showed that the extract is more liable to the action of these parameters compared with the complex, indicating that the inclusion in β-cyclodextrin increased the color stability from the red bell pepper extract while in solution. The same samples were added in yogurt to assess the color stability during sixty days of storage. The results revealed that the complex promoted a greater color protection compared to the added yogurt extract not complexed. In conclusion, the inclusion of the red bell pepper extract in β- cyclodextrin using ultrasonic homogenizer was efficient to the complex obtention with a good yield and inclusion efficiency, beside collaborating to the color stability elevation in front of the parameters that may be involved in the processing and storage of foods
47
Manoel, Tabata Cruz [UNESP]. "Estudo das interações de complexos de inclusão flavonoide/ciclodextrina com modelos de membrana biológica por simulações de dinâmica molecular." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/136327.
Повний текст джерелаАнотація:
Submitted by TABATA CRUZ MANOEL null (tabatacm@hotmail.com) on 2016-03-18T13:04:54Z
No. of bitstreams: 1
ultima versao defesa.pdf: 3979971 bytes, checksum: 9e1ee9e6a385c2ba53c2341fe29ccecc (MD5)Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-21T19:29:22Z (GMT) No. of bitstreams: 1 manoel_tc_me_sjrp.pdf: 3979971 bytes, checksum: 9e1ee9e6a385c2ba53c2341fe29ccecc (MD5)
Made available in DSpace on 2016-03-21T19:29:22Z (GMT). No. of bitstreams: 1 manoel_tc_me_sjrp.pdf: 3979971 bytes, checksum: 9e1ee9e6a385c2ba53c2341fe29ccecc (MD5) Previous issue date: 2016-02-23
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
As ciclodextrinas são um grupo de oligossacarídeos cíclicos, que apresentam um formato de cone truncado com cavidade hidrofóbica e exterior hidrofílico. Isto faz com que as ciclodextrinas possam encapsular fármacos, o que propicia melhoras na biodisponibilidade, estabilidade e proteção das moléculas encapsulada. Por esta característica, as ciclodextrinas constituem uma nova classe de excipientes farmacêuticos de grande utilidade, por formar complexos de inclusão reversíveis com moléculas apolares e atuarem como moléculas carregadoras de substancias de interesse biológico e baixa solubilidade. Dentre os compostos com ação farmacológica encontra-se os flavonoides, em destaque a molécula de quercetina, um fármaco natural com diversas propriedades biológicas, como anticâncer, antioxidante, antialérgica, porém devido sua baixa solubilidade torna-se necessária a formação de complexos de inclusão com moléculas carregadoras como a β-ciclodextrina. O presente trabalho busca investigar, por meio de simulações computacionais, as diferentes formas de interação dos flavonoides com a ciclodextrina e do complexo formado por bicamadas lipídicas, a fim de contribuir para um melhor entendimento do processo de formação com complexo de inclusão ciclodextrina/flavonoide e de entrega do fármaco à célula.
The cyclodextrins are cyclic oligosaccharides that present a structure in form of a truncated cone, with a hydrophobic inside surfaces and hydrophilic outside. This causes the cyclodextrin can encapsulate drugs provides improvements in bioavailability, stability and protection of encapsulated molecules. By this feature, the cyclodextrins are a new class of pharmaceutical excipients useful for forming inclusion complexes with reversible nonpolar molecules and act as carrier of molecules with high biological interest and low solubility. Among the compounds with pharmacological action it is the flavonoid, featured the quercetin molecule; a drug with natural biological proprieties such as anticancer, antioxidant, antialergic, however, due to its low solubility, it becomes necessary the formation of inclusion complexes with carrier molecules. This study aims to investigate, through computer simulation, different forms of interaction of flavonoids with cyclodextrin and the complex formed by lipid bilayers, in order to contribute to a better understanding of the formation process with inclusion complex cyclodextrin/flavonoids and the drug delivery to cell.
48
Saha, Subhadeep. "Study to explore the formation of host - guest inclusion complexes of cyclodextrins with biologically active moleculars and crown ethers with ionic liquids by spectroscopic and physicochemical techniques." Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2648.
Повний текст джерела
49
Pholosi, Agnes. "Synthesis, characterization and application of a novel biosorbent-magnetic nanomaterial cross-linked with cyclodextrin using epichlorohydrin and hexamethylene diisocyanate as adsorbents for heavy metals and organics." Thesis, Vaal University of Technology, 2019. http://hdl.handle.net/10352/412.
Повний текст джерелаАнотація:
D. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of TechnologyIn the present era of water resources scarcity, efficient treatment of wastewater is a major prerequisite especially for growing economy. Numerous approaches have been studied for the development of cheaper and more effective adsorbents for removal of both organic and inorganic pollutants from wastewater. The present study seeks to harness the potential of biosorption and nanotechnology by producing more efficient, selective, mechanically stable and effective adsorbents for removal of organic and inorganic pollutants. The biosorbent-magnetic nanomaterial was synthesized by coating magnetite nanoparticles with sodium hydroxide treated pine cone by co-precipitation method. Magnetite coated pine bio-composite was then modified by cross-linking with hexamethylene diisocyanate and epichlorohydrin to the molecular recognition compound “cyclodextrin”. These novel biosorbent-magnetic nanoparticle materials were explored in overcoming the drawbacks of the biosorbent alone and selectively remove inorganic and organic pollutants from complex matrices. The synthesized materials were characterized by several analytical techniques including, Fourier Transformed Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM–EDX), Transmission Electron Microscopy (TEM), Brunauer, Emmett and Teller Isotherm (BET) surface area analysis, X-ray Photoelectron Spectroscopy (XPS), Vibrating Sample Magnetometer (VSM) and pH at point of zero charge (pHpzc). Sodium hydroxide treated pine cone and magnetite coated pine cone were applied for both chromium(VI) and arsenic(III) adsorption while the magnetite coated pine cone, magnetite coated pine cone crosslinked to cyclodextrin using both epichlorohydrin and hexamethylene diisocyanate were applied for 4-nitrophenol removal from aqueous solution. Batch adsorption studies were performed to optimize operating parameters such as solution pH, adsorbent dose, contact time, temperature and initial concentration. Pseudo first, pseudo second, intraparticle diffusion, pore and film diffusion kinetic models were determined to investigate the mechanism of adsorption process. Coefficient of correlation, r2, and variable error, methods were also applied in the determination of the best fit of the kinetic method. Structural characterization of magnetite coated pine cone and the magnetite coated pine crosslinked to cyclodextrin using 1,6-hexamethylene diisocyanate and epichlorohydrin were confirmed by characterization techniques applied. The adsorption of Cr(VI), As(III) and 4-nitrophenol was found to be dependent on the solution pH, adsorbent dose, initial concentration, temperature and ionic strength. Kinetic modelling revealed that the adsorption of Cr(VI), As(III) and 4-nitrophenol is controlled by pseudo second order kinetic model suggesting surface adsorption and intraparticle diffusion model. Intraparticle, pore and film diffusion models gave further insight into the controlling diffusion mechanism involved in the adsorption process for all pollutants investigated. Equilibrium studies indicated that the adsorption of all pollutants followed Langmuir isotherm indicating that adsorption sites are homogeneous in nature. The obtained thermodynamic parameters demonstrated that the adsorption of Cr(VI), As(III) and 4-nitrophenol were spontaneous, favourable and endothermic in nature. Anionic effect positively affected Cr(VI) and As(III) removal but had a negative effect on the 4-nitrophenol adsorption. Adsorption of 4-nitrophenol onto the nanocomposite adsorbents was attributed to multiple adsorbent-adsorbate interactions such as hydrogen bonding, hydrophobic attraction and guest host interaction. Magnetite coated pine better removed Cr(VI) and As(III) from aqueous solution than NaOH treated pine cone biomaterial while the magnetite coated pine crosslinked to cyclodextrin using 1,6-hexamethylene diisocyanate exhibited better adsorption performance for 4-nitrophenol removal than the nanocomposite crosslinked using epichlorohydrin and the magnetite coated pine cone.
50
Ribeiro, Maycon Carvalho. "Bioprospecção e caracterização de bactérias produtoras de ciclodextrina glicosiltranferase em solos de biomas brasileiros." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4730.
Повний текст джерелаАнотація:
Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-10-22T16:02:34Z
No. of bitstreams: 2
Dissertação - Maycon Carvalho Ribeiro - 2014.pdf: 1028131 bytes, checksum: 34ecaebcaac3768726bacc1c6c4f694b (MD5)
license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-10-22T16:03:56Z (GMT) No. of bitstreams: 2 Dissertação - Maycon Carvalho Ribeiro - 2014.pdf: 1028131 bytes, checksum: 34ecaebcaac3768726bacc1c6c4f694b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)
Made available in DSpace on 2015-10-22T16:03:56Z (GMT). No. of bitstreams: 2 Dissertação - Maycon Carvalho Ribeiro - 2014.pdf: 1028131 bytes, checksum: 34ecaebcaac3768726bacc1c6c4f694b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-08-04
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) is an important industrial enzyme for being the only one able to convert starch and related glucans in cyclic oligosaccharides called cyclodextrins (CDs). The arrangement of the glucose units in the formation of CD results in a molecule with the shape of a cone, with hydrophobic interior and hydrophilic surface. This arrangement of glucose molecules in CDs allows its use as a host molecule in the formation of inclusion complexes with organic and inorganic compounds. This mechanism is advantageous in protecting the guest molecule from light, heat and oxidizing conditions and also enable the "dissolution" of compounds of low solubility in aqueous media. Cyclodextrins are used from the food industry to the pharmaceutical, in controlled drug delivery systems and immobilization of toxic compounds for environmental protection. The CGTases are mainly produced by bacteria of the genus Bacillus, found degrading starch rich substrates. The aim of this study was to identify, isolate, select and characterize strains of CGTase-producing bacteria from soil samples from different regions of Brazil as well as calculate the enzymatic production of these bacteria on low-cost substrates. With this work, it was possible to identify 17 bacteria producing cyclodextrin glycosyltransferase enzyme, with nine of them had values above 1.5 for enzymatic production. Of these, all were characterized as gram positive Bacillus. Bioprospecting of bacteria in soils of different cultures led to the identification of bacteria that may be used in studies for the production of cyclodextrin glycosyltransferase and subsequent implementation by various industries.
Ciclodextrina glicosiltransferase (CGTase, EC 2.4.1.19) é uma enzima industrial importante, sendo a única capaz de converter o amido e glucanos afins em oligossacarídeos cíclicos chamados ciclodextrinas (CDs). O arranjo das unidades de glicose na formação da CD resulta em uma molécula com a forma de cone, com interior hidrofóbico e superfície hidrofílica. Este arranjo das moléculas de glicose permite seu uso como molécula hospedeira na formação de complexos de inclusão com compostos orgânicos e inorgânicos. Este mecanismo é vantajoso na proteção de moléculas contra luz, calor e condições oxidantes e também possibilita melhorar a solubilidade de compostos hidrofóbicos. Ciclodextrinas são utilizadas desde a indústria de alimentos até a farmacêutica, em sistemas de liberação controlada de drogasse e imobilização de compostos tóxicos para proteção ambiental. As CGTase são principalmente produzidas por bactérias do gênero Bacillus, encontradas degradando substratos ricos em amido. O objetivo deste estudo foi identificar, isolar, selecionar e caracterizar linhagens de bactérias produtoras de CGTase a partir de amostras de solo de diferentes regiões do Brasil bem como calcular o índice enzimático destas bactérias em substratos de baixo custo. Com a realização deste trabalho, foi possível identificar 17 bactérias produtoras da enzima ciclodextrina glicosiltransferase, sendo que nove delas apresentaram valores para índice enzimático acima de 1,5. Destas, todas foram caracterizadas como sendo Bacillus gram positivos. A bioprospecção de bactérias em solos de diferentes culturas possibilitou a identificação de bactérias que poderão ser usadas em estudos para a produção da ciclodextrina glicosiltransferase e posterior aplicação pelas mais diversas indústrias.