Dissertations / Theses on the topic 'Functionalized gold nanoparticle'
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D'ALICARNASSO, MARCO. "SURFACE FUNCTIONALIZED GOLD NANOPARTICLES AS ATTACHMENT INHIBITORS FOR HEPARAN SULFATE-BINDING VIRUSES." Doctoral thesis, Università degli Studi di Milano, 2016. http://hdl.handle.net/2434/366392.
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Infectious diseases account for one fifth of global mortality. Although many efforts have been made to prevent and treat specific viral diseases (e.g. hepatitis B, AIDS) with vaccines and drugs, we still lack effective and biocompatible broad-spectrum antiviral agents, especially against re-emerging (e.g. Dengue virus) and newly emerging viruses (e.g. Ebola virus). Current advances in nanotechnology opened new frontiers in developing novel antivirals that can interact and inactivate a large number of viral pathogens. Nanoparticles (NPs) – particles in the size range 1-100 nm – can be finely engineered on their surface to interfere with key events of infections shared by many viruses, above all the attachment to the host cell. The aim of the present work is to assess the role of gold nanoparticles (Au- NPs) capped with sulfonate molecules as potential inhibitors toward human viruses binding sulfated polysaccharides on the cell membrane. Results showed that sulfonated NPs have powerful antiviral as well as virucidal activity. Their applications may lead to substantial improvements in virus-spread control not only as novel wide-spectrum therapeutic agents but most importantly as novel active materials to be employed in emergency situations, for example in personal protective equipment, waste management, virus containment.
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Cheng, Xiang. "Gold-Nanoparticle Cored Carbazole Functionalized Star-like Copolymer Hybrid Nanomaterial with Tunable Properties." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522803372777943.
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FATEHBASHARZAD, PARISA. "Functionalized Concave Cube Gold Nanoparticles as Dual probe for Magnetic Resonance Imaging and Surface Enhanced Raman Scattering." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/273768.
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An innovative class of MRI CAs is represented by Gd-loaded gold nanoparticles. Differently from other nano-sized systems, the size, shape and chemical functionalization appear to affect the observed relaxation enhancement of water protons in their suspensions. The herein reported results shed more light on the determinants of the relaxation enhancement brought by Gd-loaded concave cube gold nanoparticles. It has been found that the role of the concave surface of these nanoparticles in the relaxivity is remarkable and it provides high contribution of second sphere water molecules. The specific shape of concave cube nanoparticles increases the relaxivity from 20.9 mM-1S-1 for spherical nanoparticles to 36.3 mM-1S-1.
On the other hand, our studies prove that this special shape gold nanoparticles show high efficiency as a SERS probe. In the single-particle surface-enhanced Raman spectroscopy, the use of tunable plasmonic nanoparticles, having tipped surface structures, as being substrates revealed a highly feasible and promising approach to optimize SERS-based imaging and sensing applications. The concave cubic morphology has shown a remarkable plasmonic response, representing high sensitivity to the concavity degree. hence they can provide strong Raman signal which can be use in Raman imaging.
Magnetic resonance and optical imaging are complementary techniques. By applying same nanoparticles as a contrast agent for both methods simultaniusly, screening total body with very clear identification become possible. This progress in imaging technologies associated with the advance of nanotechnology makes feasible the cancer detection and localization in its early stage.An innovative class of MRI CAs is represented by Gd-loaded gold nanoparticles. Differently from other nano-sized systems, the size, shape and chemical functionalization appear to affect the observed relaxation enhancement of water protons in their suspensions. The herein reported results shed more light on the determinants of the relaxation enhancement brought by Gd-loaded concave cube gold nanoparticles. It has been found that the role of the concave surface of these nanoparticles in the relaxivity is remarkable and it provides high contribution of second sphere water molecules. The specific shape of concave cube nanoparticles increases the relaxivity from 20.9 mM-1S-1 for spherical nanoparticles to 36.3 mM-1S-1. On the other hand, our studies prove that this special shape gold nanoparticles show high efficiency as a SERS probe. In the single-particle surface-enhanced Raman spectroscopy, the use of tunable plasmonic nanoparticles, having tipped surface structures, as being substrates revealed a highly feasible and promising approach to optimize SERS-based imaging and sensing applications. The concave cubic morphology has shown a remarkable plasmonic response, representing high sensitivity to the concavity degree. hence they can provide strong Raman signal which can be use in Raman imaging. Magnetic resonance and optical imaging are complementary techniques. By applying same nanoparticles as a contrast agent for both methods simultaniusly, screening total body with very clear identification become possible. This progress in imaging technologies associated with the advance of nanotechnology makes feasible the cancer detection and localization in its early stage.
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Selegård, Robert. "Polypeptide functionalized gold nanoparticles for bioanalytical applications." Doctoral thesis, Linköpings universitet, Molekylär fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-106719.
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Detection strategies that allow for simple, rapid, cost efficient and sensitive monitoring of proteins and their interactions with biomolecules are of great importance in drug development and diagnostics. This thesis describes the development of bioanalytical applications based on the tunable self-assembly of gold nanoparticles functionalized with a de novo designed polypeptide. Strategies for protein affinity sensing and for detection of several fundamentally important biological processes have been investigated, including Zn2+-mediated coordination between polypeptides and low molecular weight chelants and protease and phosphatase activity. A Zn2+ responsive synthetic polypeptide designed to fold into a helix-loop-helix motif and dimerize into a four-helix bundle has been used to control the stability and self-assembly of gold nanoparticles. This polypeptide has a high negative net charge at neutral pH as a consequence of its many glutamic acid residues, efficiently preventing folding and dimerization due to charge repulsion. Zn2+ coordination provides a means to trigger folding and dimerization at neutral pH. The polypeptide can be readily attached to gold nanoparticles via a cysteine residue in the loop region, retaining its folding properties and responsiveness to Zn2+. The polypeptide functionalized gold nanoparticles display excellent colloidal stability but aggregate reversibly after addition of millimolar concentrations of Zn2+. Aggregates are dense with a defined interparticle distance corresponding to the size of the four-helix bundle, resulting in a distinct red shift of the localized surface plasmon resonance band. Three completely different strategies for colorimetric biosensing have been developed, all being based on the same responsive hybrid nanomaterial. In the first strategy a synthetic receptor was co-immobilized on the gold nanoparticles together with the Zn2+ responsive polypeptide. Protein analyte binding to the receptor could be detected as this interaction sterically prevented aggregation induced by Zn2+. In the second strategy the reduction in colloidal stability caused by specific proteolytic cleavage of the immobilized polypeptide was exploited to monitor the enzymatic activity. The third strategy utilized the sensitivity of the system to small variations in Zn2+ concentration. The presence of low molecular weight chelants was found to influence the mode of aggregation, both by sequestering Zn2+ and through the formation of ternary complexes involving the polypeptides, which prevented dimerization and thus aggregation. This approach was further developed into a generic concept for phosphatase detection exploiting the different affinity of enzyme substrates and reaction products for Zn2+. The flexibility of the different detection schemes enables detection of a large number of analytes by exploiting the tunable stability of the nanoparticles and the possibilities to effectively decouple the recognition event and the nanoparticle stability modulation.
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Padilla, Barriento Marc. "Photoactive materials based on cyclodextrin-functionalized gold nanoparticles." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/459116.
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L’objectiu d’aquesta tesi és la preparació, la caracterització I l’aplicació de nous materials fotoactius basats en nanopartícules d’or (Au NPs). Degut a les seves interessants propietats òptiques, les potencials aplicacions d’ aquests nanomaterials estant sent intensament explorades en diversos camps d’estudi com la ciencia de materials, la nanomedicina I la nanotecnologia. En moltes d’aquestes aplicacions es crucial la interaccio del nanomaterial amb d’altres molècules, i per això es necessari induir l’apropament entre aquestes estructures i d’altres especies químiques. En aquesta tesi, s’ha explorat la utilització de la química supramolecular com a estratègia per afavorir aquesta aproximació i intentar millorar les aplicacions d’aquestes nanoestructures. Per dur a terme aquesta estrategia, s’han preparat derivats tiolats de ciclodextrines (CD) que s’han incorporat a la superfície de les Au NPs per tal de: i) millorar l’activitat fotocatalítica de les Au NPs en front de reaccions químiques ii) induir l’agregació i desagregació de Au NPs de forma controlada amb llum. En el primer cas, es va poder fotocatalitzar la reacció unimolecular d’isomerització de Z-estilbens amb Au NPs funcionalitzades amb B-CD de forma més eficient que amb Au NPs no funcionalitzades, però quan es van intentar aplicar aquests resultats a processos bimoleculars, Au NPs funcionalitzades amb y-CD no van proporcionar cap tipus de conversió en la reacció de dimerització d’antracens assajada. Pel que fa als estudis d’agregació, els nostres resultats posen de relleu la importància de tenir en compte les interaccions inespecífiques quan s’intenta desenvolupar nous sistemes a través d’associació supramolecular del tipus amfitrió-hoste. En conclusió, en la present tesi doctoral, s’ha demostrat el gran potencial que té la combinació de nanoestructures plasmòniques amb la química supramolecular per al desenvolupament de nous materials fotoactius amb propietats millorades, contribuint així al creixent coneixement en el camp de la nanociència.The present thesis aimed at the preparation, characterization and application of new photoactive materials based on gold nanoparticles (Au NPs). Due to their interesting optical properties, the potential applications of these nanomaterials are being intensively explored in diverse fields of research like medicine, meterials science and technology. In many of these applications it is crucial the interaction between the nanomaterial and other molecules, and therefore it is necessary to induce the approximation between the nanomaterial and other chemical species. In this thesis we explored the utilization of supramolecular chemistry as an strategy to favor such approximation and try to enhance the potential applications of such nanostructures. For that, proper thiolated derivatives of the cyclodextrin (CD) family of supramolecular hosts have been prepared and subsequently incorporated onto the surface of Au NPs to: i) enhance the photocatalytic activity of Au NPs towards chemical reactions, ii) to induce the aggregation and disaggregation of Au NPs controlled with light. In the former case, B-CD-functionalized Au NPs were able to photocatalyze the isomerization of Z-stilbenes more efficiently than non-functionalized particles, but when trying to expand these results to bimolecular processes, y-CD-functionalized particles did not provide any conversion towards the selected reaction. Regarding the assembly studies, our results highlighted the importance of considering unspecific interactions when trying to develop new systems via specific host-guest association. In conclusion, in the present thesis we have demonstrated the great potential of combining plasmonic nanostructures with supramolecular chemistry to develop new photoactive materials with improved properties, contributing with our work to the increasing knowledge in the expanding field of the nanosicience.
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Kumar, Dhiraj. "Co-Functionalised Gold Nanoparticles for Drug Delivery Applications." Thesis, Ulster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.649271.
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Warsi, Muhammad F. "Lanthanide functionalised gold nanoparticles as MRI contrast agents." Thesis, University of York, 2010. http://etheses.whiterose.ac.uk/1105/.
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The aim of this Ph. D. project was to synthesize and characterise nanoparticle-based MRI contrast agents. In the first instance, the DTPA (diethylenetriaminepentaacetic acid) based ligand was designed, synthesized and characterised. This ligand was utilised for stabilisation of gold nanoparticles. The gold nanoparticles protected by DTPA based ligand were characterised using UV-Vis, NMR spectroscopies, TGA and TEM. The nanoparticles were then loaded with gadolinium. The relaxivity of gadolinium loaded gold nanoparticles were studied using inversion recovery method and compared with commercially available MRI contrast agents (i.e. Gd-DTPA). The Gd-loaded AuNPs showed only a moderate increase in their relaxivity as compared to the Gd-DTPA complex. The factors limiting the relaxivity of Gd-loaded AuNPs were explored using EPR spectroscopy. For EPR measurements, Gd3+ was replaced with vanadyl (VO2+) which gives EPR spectra sensitive to the rate of molecular tumbling on nanosecond time scale. The EPR measurements of VO2+-loaded AuNPs showed that the nanoparticle attached metal ion retains high molecular mobility. This is likely responsible for only a moderate increase in relaxivity. We next explored different strategies for increasing the relaxivity of gold nanoparticles based MRI contrast agents. In the first strategy, in order to enhance ligand packing at AuNPs surface, the size of the AuNPs was increased from ~2.0 nm to ~6.0 nm. The relaxivity was found to increase with the increased size of the AuNPs. Secondly, polyelectrolyte coating of charged Gd-loaded AuNPs surface also resulted in increase of relaxivity due to better immobilisation of the Gd3+ ions. Gold nanoparticles were also used as templates for nitroxide based redox sensitive MRI contrast agents. The reducing behaviour and relaxivity of nitroxide protected AuNPs was measured and found slightly better than that of free nitroxide. Finally other useful applications of nanoparticles protected by DTPA based ligand were explored. For example, the DTPA ligand can also chelate strongly with other lanthanides such as Eu3+, Tb3+etc. The luminescence measurements of lanthanides (Eu3+ and Tb3+) loaded onto AuNPs were explored. Lanthanide-loaded AuNPs were also used as model compounds to test an important EPR methodology after labelling with a nitroxide based spin label.
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Chen, Yu-Su. "Phosphonium-functionalised gold nanoparticles for mitochondria targeted therapeutics." Thesis, Sheffield Hallam University, 2014. http://shura.shu.ac.uk/19454/.
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The work presented in this thesis demonstrates that triarylphosphoniopropyl-thiosulfate zwitterions and w-thioacetylpropyl(triphenyl)phosphonium salts can be used to prepare cationic, water-soluble gold nanoparticles with mean core sizes in the range of 2.5-5 nm. Phosphonium-functionalised gold nanoparticles have been characterised by a number of techniques including NMR, LDI-MS, SIMS, XPS, TGA, ICP-MS, MALDI-MS and TEM.Cytotoxicity studies illustrated that phosphonium ligands are relatively non-toxic to human prostate cancer cells and therefore can be used as a delivery vector to delivery gold nanoparticles specifically to the site of the mitochondria for other therapeutic applications such as photothermal therapy. Cellular uptake studies of phosphonium ligands by MALDI-MS showed that they are rapidly taken-up by cells within ten minutes. Phosphonium-functionalised gold nanoparticles are soluble in biological media which is of great importance for cell biology studies. Initial photothermal therapy studies demonstrated that the gold nanoparticles responds specifically to a green light excitation source (510-550 nm) which overlaps the surface plasmon resonance band of the phosphonium-functionalised gold nanoparticles at 525 nm. Preliminary data also showed that phosphonium-functionalised gold nanoparticles can selectively induce apoptosis in cells followed by irradiation, this was confirmed by Hoechst and caspase-3 staining. Quantification studies of phosphonium-functionalised gold nanoparticles by ICP-MS illustrated that these nanoparticle have good uptake in cells (above 75%). TEM data confirmed that phosphonium-functionalised gold nanoparticles are taken-up by human prostate cancer cells and are localised in the mitochondria.
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António, Maria de Almeida Vasconcelos. "Detection of C-reactive protein using functionalized gold nanoparticles." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22538.
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Mestrado em BiotecnologiaEste projeto teve como objetivo desenvolver novas estratégias para funcionalizar nanopartículas de ouro (Au NPs) de forma a detetar a proteína C-reativa (CRP). Assim, foram sintetizadas nanopartículas de ouro esféricas com tamanhos médios de aproximadamente 10 e 40 nm. Posteriormente, a superfície das Au NPs foi modificada utilizando duas abordagens diferentes. Na primeira abordagem as Au NPs estabilizadas com citrato foram funcionalizadas com grupos ácidos carboxílicos pela modificação da superfície com os ligandos: ácido 11-mercaptoundecanóico (MUDA) e ácido mercaptopropiónico (MPA). Posteriormente a citidina difosfocolina (CDP) foi acoplada covalentemente à superfície das Au NPs utilizando 1-etil-3-(3’- dimetilaminopropil)carbodiimida (EDC) para promover a reação. Na segunda abordagem as Au NPs estabilizadas com citrato foram modificadas com um aptâmero específico para a CRP. Estes materiais foram caracterizados utilizando diversas técnicas de análise nomeadamente espectroscopia de UVvis e de infravermelho (FTIR), medidas de potencial Zeta e de diâmetro hidrodinâmico e microscopia eletrónica de transmissão (TEM). Amostras selecionadas de Au NPs modificadas com aptâmero (Au NPs@ssDNA+NaCl+KCl) e de Au NPs bioconjugadas com CDP (Au NPs@MUDA@CDP_40nm e Au NPs@MPA@CDP_10nm) foram utilizadas para o estudo da deteção da proteína: CRP. As Au NPs foram adicionadas a soluções de concentração conhecida (10 - 100 nM). A deteção da CRP foi investigada através da aquisição de espectros de UV-vis. O aumento da razão de agregação, isto é entre a absorvância a 620 nm e a absorvância da banda de ressonância de plasmão de superfície localizada (A620/ALSPR), foi monitorizada ao longo do tempo, indiciando a deteção da CRP para todas as amostras testadas. Para os sistemas Au NPs@MUDA@CDP_40nm e Au NPs@ssDNA+NaCl+KCl foi possível correlacionar a razão A620/ALSPR com a concentração da CRP através de uma relação linear nas gamas de concentração de 20 - 50 nM (R2=0.9425) e de, 20 - 45 nM (R2=0.9382) respetivamente. Os resultados obtidos, embora preliminares, são promissores sendo necessário avaliar em estudos futuros aspetos tais como reprodutibilidade e interferência de outras proteínas em estudos futuros, tendo em vista o desenvolvimento de biossensores válidos para a deteção de CRP
The main goal of this project was to develop novel strategies for the functionalization of gold nanoparticles (Au NPs) aiming the detection of Creactive protein (CRP). Au NPs with an average size of 10 and 40 nm were synthesized. Then, the surface of Au NPs was modified following two different approaches. The first approach consisted on the surface functionalization of citrate stabilized Au NPs with carboxylic acid groups, by surface modification using 11-mercaptoundecanoic acid (MUDA) and mercaptopropionic acid (MPA). The cytidine diphosphocholine (CDP) was covalently attached to the surface of functionalized Au NPs using 1-(3-dimethylaminopropyl)-3- ethylcarbodiimide hydrochloride (EDC) to promote the coupling reaction. In the second approach, citrate stabilized Au NPs were modified with a CRP specific aptamer. These materials were characterized using several analysis techniques namely UV-vis spectroscopy, infra-red spectroscopy (F-T IR), zeta potential and hydrodynamic diameter measurements and transmission electron microscopy (TEM). Selected samples of Au NPs modified with aptamer (Au NPs@ssDNA+NaCl+KCl) and CDP bioconjugated Au NPs (Au NPs@MUDA@CDP_40nm e Au NPS@MPA@CDP_10nm) were used for studying CRP detection. Au NPs samples were added to CRP solutions of known concentration (10-100 nM). The detection was measured through acquisition of the UV-vis spectra. The increase of aggregation ratio between absorbance at 620 nm and the absorbance of localized surface plasmon resonance band (A620/ALSPR) was monitored along time and, indicated that CRP was detected for all the Au NPs samples tested. For the systems Au NPs@MUDA@CDP_40nm and Au NPs@ssDNA+NaCl+KCl it was possible to find a linear correlation between the ratio A620/ALSPR and the CRP concentration, within the concentration range 20 - 50 nM (R2=0.9425) and, 20 - 45 nM (R2=0.9382), respectively. The results obtained are very promising but still preliminary. Further studies are needed to evaluate key aspects such as reproducibility and interference of other proteins, keeping as main objective the development of valid biosensors for CRP detection.
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Zoppi, A., J. R. Molina-Contreras, P. Marsili, M. Muniz-Miranda, G. Margheri, S. Trigari, A. Leva, E. Giorgetti, and F. Giammanco. "Glutathione-Induced Release of Zeatin From Functionalized Gold Nanovectors." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42489.
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The paper shows our preliminary results on the different spectroscopic behavior of three types of gold nanoparticles (obtained respectively by chemical synthesis, laser ablation in pure water and laser ablation in a citrate solution) modified with trans-zeatin, a plant growth regulator, in presence of glutathione. The reaction of ligand substitution of the adsorbed zeatin with glutathione is studied through surface enhanced Raman spectroscopy and is revealed to occur only when citrate-laser ablated gold nanoparticles are employed, making these particles potentially good candidates as vehicles of zeatin inside plant cells for future agricultural applications.
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Lalwani, Nikhil Narendra. "Arsonium and phosphonium-functionalized gold nanoparticles for mitochondria targeted therapeutics." Thesis, Sheffield Hallam University, 2017. http://shura.shu.ac.uk/16989/.
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This thesis presents a body of original research describing the synthesis, characterisation and biological properties of novel arsonium- and phosphonium- alkylthiosulfate zwitterions and thioacetate salts and gold nanoparticles functionalized with triphenylarsoniumpropylthiolate ligands. Chapter 1 presents a systematic literature review of the preparation of functionalized gold nanoparticles, their biomedical properties, the biological applications of phosphonium and arsonium ions and phosphonium-functionalized nanomaterials. Details of the analytical methods employed to characterize all the compounds produced in this study are outlined in chapter 2. Chapter 3 reports the synthesis of the triphenylarsoniopropylthiosulfate zwitterion and ω- thioacetylpropyl(triphenyl)arsonium bromide salt. Both compounds have been characterized spectroscopically and by single crystal X-ray diffraction. The thiosulfate group of the triphenylarsoniopropylthiosulfate zwitterion and the thioacetate group of the ω- thioacetylpropyl(triphenyl)arsonium salt undergo reductive cleavage, forming the corresponding triphenylarsoniumpropylthiolate ions that attach to the surface of gold in a modification of the established Brust-Schiffrin method for preparing gold nanoparticles. TEM studies show the triphenylarsonium-functionalized gold nanoparticles to be spherical with diameters of c.a. 3nm. The presence of the triphenylarsonium groups has been confirmed by Raman and XPS spectroscopy and mass spectrometry. It also describes the synthesis, characterisation and biological properties of a family of phosphoniopropylthiosulfate zwitterions and ω-thioacetylpropyl(triaryl)phosphonium salts derived from tri(4-methoxyphenyl)phosphine, tri(2,6-dimethoxyphenyl)phosphine and tri(2,4,6-trimethoxyphenyl)phosphine. The IC50 values of the triphenylarsoniopropylthiosulfate zwitterion, ω-thioacetylpropyl- (triphenyl)arsonium bromide salt, triphenylarsonium-functionalized gold nanoparticles and family of phosphoniopropylthiosulfate zwitterions and ω- thioacetylpropyl(triaryl)phosphonium salts derived from tri(4-methoxyphenyl)phosphine, tri(2,6-dimethoxyphenyl)phosphine and tri(2,4,6-trimethoxyphenyl)phosphine have been determined against PC3 prostate cancer cells using MTT and CellTiter-Glo assays and are reported in Chapter 4. The uptake of the triphenylarsonium-functionalized gold nanoparticles by PC3 and Human Fibroblast cells has also been determined by ICP-OES spectroscopy.
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Payne, Jason N. "Development of Dihydrochalcone Functionalized Gold Nanoparticles for Augmented Antineoplastic Activity." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1749.
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Phloridzin, an antidiabetic and antineoplastic agent usually found in fruit trees, is a dihydrochalcone constituent that has a clinical/pharmaceutical significance as a sodiumglucose linked transport 2 (SGLT2) inhibitor. Phloridzin never experienced widespread clinical usage in the pharmaceutical market due to its side effects and poor bioavailability when compared to other antidiabetic therapeutics. The poor bioavailability is primarily attributed to the degradation of the glycosidic bond of the phloridzin, resulting in the formation of phloretin, the aglycone of phloridzin and glucose. While phloretin displays a reduced capacity of SGLT2 inhibition, this nutraceutical shows enhanced antineoplastic activity in comparison to phloridzin. Gold nanoparticles (AuNPs) have been explored in improving the bioavailability of many drugs and therefore we opt for gold nanoparticle mediated delivery of phloridzin and phloretin and exploration of their anticancer mechanism. In this study, we have synthesized phloridzin and phloretin conjugated gold nanoparticles (Phl-AuNP and Pht-AuNP) in a single-step, rapid, biofriendly processes. The synthesized AuNPs morphology and elemental composition was characterized via transmission electron microscopy, UV-Vis spectroscopy, scanning electron microscopyenergy dispersive x-ray spectroscopy, and thermogravimetric analysis. Assessment of the antineoplastic potency of the dihydrochalcone-conjugated AuNPs against cancerous cell lines was accomplished through monitoring via flow cytometry. We posit that the functionalization of these chalcones onto the gold nanoparticles’ surface has improved the pharmacokinetic profile of phloridzin and phloretin.
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Gurung, Anant Singh. "Visual Detection of Cancer Biomarkers with Aptamer-Functionalized Gold Nanoparticles." Diss., North Dakota State University, 2015. https://hdl.handle.net/10365/27605.
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Cancer biomarkers may hold the key for the early detection of cancer, distinguishing between benign and malignant cells, and differentiating tumor types. The detection of cancer biomarkers can be used for cancer diagnosis, monitoring the response to therapy, and providing real-time prognostic information for cancer patients. Most of the traditional cancer biomarker detections are based on specific antibodies or expensive instrumentations/complex operations. In this dissertation, we have developed aptamer-based bioassays for visual detection of cancer protein biomarkers with low-cost and short assay time. Aptamers with specific sequences are immobilized on gold nanoparticle (AuNP) surface through self-assembling process. Combining the excellent molecular recognition properties of aptamers and the unique optical properties of AuNPs, colorimetric assay for carcinoembryonic antigen (CEA) and mucin 1 (MUC1) (breast cancer biomarkers) and lateral flow assay for platelet-derived growth factor (PDGF) and thrombin have been developed. The methods were applied to detect protein biomarkers in human plasma and blood successfully. The sensitivities of the assays were further improved by using enzyme-coated AuNP dual labels and designing the cross-flow test strips. The developed approaches have the potential to be extended for detecting other biomarkers, and show great promise for point-of-care or in-field detection.National Science Foundation (NSF)
NDEPSCoR
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Ivanov, Michael Robert. "Covalently functionalized gold nanoparticles: synthesis, characterization, and integration into capillary electrophoresis." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/987.
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Nanomaterials are widely used as pseudostationary and stationary phases in electrically driven capillary separations. The advantages of nanomaterial incorporation into capillary electrophoresis (CE) are numerous and include tunable sizes, multiple core compositions, flexible injection/introduction methods in separation techniques, and diverse surface chemistry options. Nanomaterials, however, exhibit inherently large surface energies which induce aggregation and as a result, yield unpredictable function in separations. Because nanomaterials can modify buffer conductivity, viscosity, and pH; separation optimization and nanoparticle stability must be considered. Successful incorporation of nanomaterials into reproducible separations requires (1) strict nanomaterial synthetic control and (2) detailed characterization of the nanoparticle in terms of both core material and surface chemistry.
For this reason, this dissertation investigates how the surface chemistry on and morphology of gold nanoparticles impact capillary electrophoresis separations. The gold nanoparticle core composition, shape, size, self assembled monolayer (SAM) formation kinetics, and SAM ligand packing density are all evaluated for thioctic acid, 6-mercaptohexanoic acid, or 11-mercaptoundecanoic acid monolayers. Transmission electron microscopy (TEM), 1H NMR, extinction spectroscopy, zeta potential, X-ray photoelectron spectroscopy (XPS), and flocculation studies are used to assess the morphology, surface chemistry, optical properties, surface charge, SAM packing density, and effective stability of carboxylated nanoparticles, respectively.
Using these well-characterized nanostructures, applications of gold nanoparticle pseudostationary phases in capillary electrophoresis is studied. Gold nanoparticles functionalized with mixed SAMs composed of thioctic acid and either 6-mercaptohexanoic acid or 6-aminohexanethiol impact the mobility of possible Parkinson's disease biomarkers in a concentration and surface chemistry dependent manner. From these data, a critical nanoparticle concentrations is developed to characterized nanoparticle stability during capillary electrophoresis separations.
To understand the function of these and other carboxylated gold nanoparticles, extended DLVO theory is used to model interparticle interactions during electrically driven flow. 11-Mercaptoundecanoic acid functionalized gold nanoparticles suppress current, while 6-mercaptohexanoic acid and thioctic acid functionalized nanoparticles enhance separation current. Nanoparticle aggregation leads to electron tunneling effects between nanoparticles thereby increasing currents in poorly ordered SAMs while highly packed monolayers induce reversible flocculation characteristics and reduce current. In all cases, these effects are dependent on nanoparticle concentrations.
Finally, surface chemistry optimized carboxylic acid functionalized gold nanoparticles effect the separation of hypothesized Parkinson's disease biomarkers. SAM composition and surface coverage impact separation efficiency, resolution, and selectivity. These effects are most systematic with well ordered SAMs. To understand the mechanism functionalized gold nanoparticles exhibit during a separation, their zeta potential with and without dopamine are evaluated. Nanoparticle to dopamine mole ratios (i.e. large dopamine concentrations), neutralize the three functionalized gold nanoparticles according to a dose response curve. The positively charged dopamine molecules saturate the negatively charged nanoparticle surfaces and aggregate thereby providing a plausible explanation to the biomarker concentration trends observed in capillary electrophoresis. These and future studies provide a rigorous experimental and theroretical evalauation of how nanoparticle structure impacts their function as pseudostationary phases in separations and other applications.
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Warner, Marvin Glen. "Synthesis and characterization of functionalized gold nanoparticles and their rational arrangement on DNA scaffolds /." view abstract or download file of text, 2003. http://wwwlib.umi.com/cr/uoregon/fullcit?p3095284.
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Thesis (Ph. D.)--University of Oregon, 2003.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 184-204). Also available for download via the World Wide Web; free to University of Oregon users.
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Müller, Christian [Verfasser], and Christoph [Akademischer Betreuer] Lambert. "Physical Properties of Chromophore Functionalized Gold Nanoparticles / Christian Müller. Betreuer: Christoph Lambert." Würzburg : Universitätsbibliothek der Universität Würzburg, 2011. http://d-nb.info/1014316308/34.
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Conners, Christopher. "Bisphosphonate Functionalized Gold Nanoparticles for the Study and Treatment of Osteoporotic Disease." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6818.
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The use of nanoparticles for disease treatment is an increasingly popular area of research. The potential for multi-functionality allows nanoparticles to be used as transport and delivery vehicles for drugs and as diagnostic aides, among other applications, to address the unmet needs of many disease treatments. One such class of disease is osteoporosis including severe disorders, like Paget’s disease, Osteogenesis Imperfecta and Legg Calve Perthes disease. In this dissertation, we discuss a nanoparticle system consisting of gold nanoparticles surface functionalized with primary amine bisphosphonates, which is a classification of pharmaceuticals that is common in the treatment of osteoporosis. Functionalized nanoparticles allow for greater intracellular concentrations of pharmaceutical, while the properties of the gold nanoparticles provide the ability to track the pharmaceutical and enhance imaging.
We have synthesized and characterized bisphosphonate functionalized gold nanoparticles of controlled size of approximately 15 nm, which are suitable for cellular uptake, and functionalized the surface using self-assembly with pamidronate and alendronate. In one major finding of this study, inductively coupled plasma mass spectrometry was used to estimate approximate surface density of the bisphosphonates on the gold nanoparticles. This resulted in concentrations of approximately 0.65 molecules per nm2 (approximately 154 Å2/molecule) for pamidronate functionalized on gold, and approximately 2.6 molecules per nm2 (approximately 39 Å2/molecule) for alendronate functionalized on gold. This allows for more accurate estimates of pharmaceutical concentrations, during in vitro and in vivo studies.
Additionally, we investigated the effects of bisphosphonate functionalized gold nanoparticles on the viability and morphology of osteoclast and osteoblast cells in vitro. We found that attaching the bisphosphonates to the surface of the nanoparticles leads to increased apoptotic effects of the bisphosphonates on the osteoclast cells compared to free bisphosphonates. Further, we showed bisphosphonate functionalized gold nanoparticles may have an effect on nuclei morphology that may provide an additional means of modulating bone resorption rather than just through influencing viability. Further we showed that it may be possible to target concentrations that are safe for osteoblasts, which is critical in determining potential treatment concentrations. These viability results bring to light a number of potential considerations into the optimization of potential treatments, such as dosing concentrations.
Finally, detailed results are given on effects of bisphosphonate functionalized gold nanoparticles on important behavior and activity of osteoclast and osteoblast cells in vitro. We showed that while using concentrations below the toxicity threshold, some of the normal activity of the cells could be maintained. RANKL and ALP expression in osteoblasts were maintained when removing viability as a variable. Additionally, bone nodule formation was also maintained for osteoblasts and co-cultured in vitro systems. Finally, we showed that the introduction of bone in the in vitro studies adds a new degree of consideration as to the interaction of the bisphosphonates with the hydroxyapatite surface. This strong interaction with bone is an important consideration in further developing potential treatments for osteoporotic disease.
This dissertation provides insights into the use of bisphosphonate functionalized gold nanoparticles as a potential treatment and means of study for bone remodeling disorders.
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Schiller, Tara Louise. "Synthesis and characterisation of hybrid gold/polymer nanoparticles for bioassay application." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/43445/1/Tara_Schiller_Thesis.pdf.
Full textAbstract:
A bioassay technique, based on surface-enhanced Raman scattering (SERS) tagged gold nanoparticles encapsulated with a biotin functionalised polymer, has been demonstrated through the spectroscopic detection of a streptavidin binding event. A methodical series of steps preceded these results: synthesis of nanoparticles which were found to give a reproducible SERS signal; design and synthesis of polymers with RAFT-functional end groups able to encapsulate the gold nanoparticle. The polymer also enabled the attachment of a biotin molecule functionalised so that it could be attached to the hybrid nanoparticle through a modular process. Finally, the demonstrations of a positive bioassay for this model construct using streptavidin/biotin binding. The synthesis of silver and gold nanoparticles was performed by using tri-sodium citrate as the reducing agent. The shape of the silver nanoparticles was quite difficult to control. Gold nanoparticles were able to be prepared in more regular shapes (spherical) and therefore gave a more consistent and reproducible SERS signal. The synthesis of gold nanoparticles with a diameter of 30 nm was the most reproducible and these were also stable over the longest periods of time. From the SERS results the optimal size of gold nanoparticles was found to be approximately 30 nm. Obtaining a consistent SERS signal with nanoparticles smaller than this was particularly difficult. Nanoparticles more than 50 nm in diameter were too large to remain suspended for longer than a day or two and formed a precipitate, rendering the solutions useless for our desired application. Gold nanoparticles dispersed in water were able to be stabilised by the addition of as-synthesised polymers dissolved in a water miscible solvent. Polymer stabilised AuNPs could not be formed from polymers synthesised by conventional free radical polymerization, i.e. polymers that did not possess a sulphur containing end-group. This indicated that the sulphur-containing functionality present within the polymers was essential for the self assembly process to occur. Polymer stabilization of the gold colloid was evidenced by a range of techniques including, visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and Raman spectroscopy. After treatment of the hybrid nanoparticles with a series of SERS tags, focussing on 2-quinolinethiol the SERS signals were found to have comparable signal intensity to the citrate stabilised gold nanoparticles. This finding illustrates that the stabilization process does not interfere with the ability of gold nanoparticles to act as substrates for the SERS effect. Incorporation of a biotin moiety into the hybrid nanoparticles was achieved through a =click‘ reaction between an alkyne-functionalised polymer and an azido-functionalised biotin analogue. This functionalized biotin was prepared through a 4-step synthesis from biotin. Upon exposure of the surface-bound streptavidin to biotin-functionalised polymer hybrid gold nanoparticles, then washing, a SERS signal was obtained from the 2-quinolinethiol which was attached to the gold nanoparticles (positive assay). After exposure to functionalised polymer hybrid gold nanoparticles without biotin present then washing a SERS signal was not obtained as the nanoparticles did not bind to the streptavidin (negative assay). These results illustrate the applicability of the use of SERS active functional-polymer encapsulated gold nanoparticles for bioassay application.
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Pelliccia, M. "STRATEGIES FOR ENHANCING VIRAL GENE TRANSFER AND THE THERMOSTABILITY OF VIRAL VECTORS IN VACCINE APPLICATIONS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/265518.
Full textAbstract:
At the most basic level viruses are biological nano-containers constituted by genetic material enclosed in a protein shell, capsid. A peculiar feature of viruses, both bacterial and some eukaryotic viruses, lies in the high packaging density of the genome in order to fit itself in the small capsid and hence the high internal osmotic pressure. Virus is a relatively stable particle equipped with fascinating mechanical properties of the capsid that are crucial for the virus lifecycle. Viruses have only one purpose: infect a host cell for reproducing themselves in order to generate new viral progeny (Roos et al. 2007). Therefore, the first and foremost consideration arising from the concept of virus reflects its pathogenesis and virulence that can ultimately result in many important infectious diseases such as common cold, influenza, hepatitis, rabies, measles, cancer and AIDS. As a consequence, pathogenic viruses represent a heavy hurdle for the global health and there is a strong need for developing robust strategies such as vaccines or antiviral drugs against virus infections (Baram- Pinto et al. 2010). On the other hand, viruses in the course of evolution have become efficient specialized gene delivery agents. Therefore they represent powerful tools in biomedicine for gene therapy and vaccine purposes (Schaffer et al. 2008). For successful gene therapy and immunization programs, the efficiency and stability of viral vectors are fundamental aspects (Jorio et al. 2006).
To address this challenge, in the present research project we have investigated the interaction between viruses and nanomaterials. In the last years materials on the nanoscale for their unique properties have provided a broad range of potential biomedical uses (Verma et al. 2008) and for that reason we decided to explore their application with viruses. More specifically, we have examined three types of sulfonate- functionalized gold nanoparticles (AuNPs), namely, MUS:OT, MUS and MUS:brOT NPs, which are less than 5 nm in size, negatively charged and poorly cytotoxic (Verma et al. 2008). The NPs are coated with self-assembled monolayer (SAM) of thiolated organic molecules and one of the ligand is a sulfonated molecule, MUS (Verma et al. 2008). The MUS ligand itself was tested in our experiments as well. As virus models we focused on human recombinant adenovirus type 5 (Ad), one of the most promising viral vector as vaccine and gene therapy carrier and two picornaviruses of the genus enterovirus, namely, EV1 and CVB3, important human pathogens associated with several infectious diseases (e.g. myocarditis, aseptic meningitis, encephalitis, paralysis)(Kossila et al. 2002)(Marjomäki et al. 2014a). In spite of their medical impact, there are no therapeutic treatments available against picornavirus infections and the only vaccine products are against three types of poliovirus and hepatitis A virus (Merilahti et al. 2012).
Two sets of experiments were carried out: (1) Short-term incubation of Ad with nanomaterials for 1 h at 37°C prior
transducing HeLa cells or before in vivo administration in zebrafish and mice. The results demonstrated that Ad shortly pre-treated with nanomaterials showed a significant increase in the gene expression in vitro and in vivo The NPs’enhanced adenovirus transduction aims to reduce Ad vector doses in vivo thereby minimizing the adverse reactions of the immune response due to high vector dosage; (2) Long-term thermostabilization studies of Ad, EV1 and CVB3 in vitro in the presence and in the absence of our nanomaterials and other substances such as sugars (sucrose, glucose, glycerol) and Polyethylene glycol (PEG) molecules at 37°C or room temperature for extensive periods of time. Our results showed the capability of the nanomaterials and sucrose to increase substantially the heat stability of the viruses. In order to elucidate the thermal inactivation mechanism of viral particles and the stabilizing effect provided by some compounds on viruses we set out to formulate an analytical theory. This line of research fits in the context of developing more thermo-stable viral vector preparations for vaccine purposes that do not require the maintenance of the challenging cold chain system in order to preserve the effectiveness of viral vaccines during the storage, shipment and administration to the patients and hence to ensure the success of global immunization programs (Alcock et al. 2010).
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Ilankoon, Nirmala Damayanthi. "Adsorption of Gold from Thiosulfate Leaching Solutions using Polyethylenimine Functionalised Magnetic Nanoparticles." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/80605.
Full textAbstract:
In this research polyethylenimine coated iron oxide magnetic nanoparticles (PEI-MNPs), as a novel adsorbent, was evaluated for the adsorption of gold from thiosulfate leaching solutions that contain gold, copper and calcium thiosulfate. This novel adsorbent can simply be separated from the solution using an external magnetic field, followed by gold adsorption. Gold elution from the adsorbent was simple and rapid.
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Chan, Chen Hui. "Theoretical Modeling from Functionalized Gold Nanoparticles to Repair of Lesions in DNA for cancer radiotherapy." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN020.
Full textAbstract:
Le potentiel des nanoparticules d'or (AuNPs) pour améliorer l’efficacité de la radiothérapie est démontré par de nombreuses études expérimentales in vivo et in vitro. Ces particules métalliques augmentent significativement l’effet de la radiosensibilisation. La réaction en jeu est la radiolyse de l’eau: une fois excitées par un rayon X, elles génèrent des espèces réactives oxygénées qui amplifient les dégâts d’ADN et mènent à une plus grande destruction des cellules cancéreuses. Cependant, pour une efficacité thérapeutique plus optimale, plusieurs propriétés des AuNPs doivent être prises en compte lors de la synthèse comme leur taille, leur forme et leur surface qui sont suspectibles d’influencer ses effets catalytiques dans l’environnement biologique (majoritairement de liquide d’eau). Ces aspects structuraux ne sont pas encore examinés dans l’état de l’art, ni expérimentalement ni théoriquement. Ce travail de thèse a pour but de rationaliser la stabilité de AuNPs dans un environnement chimique ou biologique avant l’irradiation par des outils de modélisation théorique. Dans un premier temps, nous nous sommes intéressés à la stabilité des AuNPs dans la gamme de 1- 3.4 nm. Nous étudions ensuite le comportement de ces nanoparticules dans un environnement biologique (hydratation) et chimique modèle (PEGylation), et la combinaison des deux environnements. Quand les nanoclusters de 0.9-1.8 nm sont en interaction avec une couche de molécules d’eau à saturation, nous avons montré qu’il y a une transformation de NPs métastables (dans le vide) telles que l'ino-décaèdre en NPs métastables plus favorables telles que l'icosaèdre. Alors qu’en présence d’une couche de ligands PEG, la liaison forte Au-S et les liaisons hydrogène entre les ligands entraînent une déformation significative de la morphologie de la nanoparticule, à savoir une stellation du décaèdre Au54. Par ailleurs, nous avons montré que les ligands PEG promeuvent le confinement de quelques molécules d’eau à proximité des AuNPs. Nos conclusions ouvrent des perspectives intéressantes pour la modélisation théorique de la radiolyse de l’eau. Parallèlement à ces études, nous nous sommes intéressés à la caractérisation de différents types de lésions d’ADN. Deux projets ont été menés: premièrement, nous démontrons l’interaction d’un peptide trilysine avec un oligonucléotide qui pourrait conduire à la formation de pontage d’ADN-polyamine. Ensuite, le deuxième projet porte sur la rationalisation de différents taux de réparation de dimères de cyclobutanemathide iochella pyrimidine en présence de l’enzyme de reconnaissance DDB2 à l’échelle atomiqueThe potential of gold nanoparticles (AuNPs) to improve the performance of radiotherapy is demonstrated by numerous in vivo and in vitro experimental studies. These metallic particles increase significantly the radiosensitization effect. Upon water radiolysis, AuNPs generate reactive oxygen species that amplify DNA damage and lead to a greater destruction of cancerous cells. Nevertheless, for a more optimal therapeutic efficacy, several properties of AuNPs must be taken into account during the synthesis, such as their size, shape and surface which can tune their catalytic effects in the biological environment (mainly liquid water). These structural aspects are not yet examined in the state-of-the-art, either experimentally or theoretically. This thesis aims to rationalize the stability of AuNPs in the presence of chemical or biological environment before irradiation by using theoretical approaches. Firstly, we have modeled the stability of AuNPs in the range 1- 3.4 nm. We have then studied the behavior of these nanoparticles in a biological (hydration) and chemical (PEGylation) model environment, and the combination of the two environments. When 0.9-1.8 nm nanoclusters interact with a complete shell of water molecules, we have shown that metastable ino-decahedrons (in vacuum) are transformed into more favourable metastable icosahedrons. While in the presence of monoshell of PEG ligands, the strong Au-S bond and the hydrogen bonds between the ligands induce a significant deformation on the nanoparticle morphology, i.e. stellation of the Au54 decahedron. In addition, we have shown that PEG ligands promote the confinement of a few water molecules in the vicinity of AuNPs. Our conclusions open interesting perspectives for the theoretical modeling of water radiolysis. In parallel with these studies, we have focused on the characterization of different types of DNA lesions. Two projects have been performed: firstly, we have studied the interaction of a trilysine peptide with an oligonucleotide which could lead to the formation of DNA-polyamine cross link. Then, the second project focuses on rationalizing different repair rates of cyclobutane pyrimidine dimers in the presence of the DDB2 recognition enzyme at the atomic scale
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Morelli, Laura. "Study of graphene-based gas sensors functionalized with gold nanoparticles for NO2 detection." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17577/.
Full textAbstract:
Obiettivo della tesi è la ricerca di un metodo volto a migliorare le attuali prestazioni dei sensori di gas realizzati in grafene. Negli ultimi anni il grafene ha attirato particolare attenzione nel campo dei sensori di gas. Tuttavia, l’utilizzo del grafene presenta limitazioni che rendono difficile lo sviluppo di sensori utilizzabili commercialmente. Tra queste, la mancanza di selettività, nonché la difficoltà del segnale a raggiungere la saturazione e a ritornare al livello iniziale durante la fase di ripristino, rappresentano i maggiori ostacoli. La funzionalizzazione del grafene risulta essere tra i metodi più promettenti per rimediare alle predette limitazioni. Nella tesi, l’oggetto della ricerca è un resistore chimico, il cui materiale sensibile è costituito da grafene multi-strato realizzato tramite deposizione chimica da fase vapore. Il processo di funzionalizzazione scelto si basa sulla deposizione di nanoparticelle di oro sulla superficie del grafene multi-strato. Le caratteristiche fisiche ed elettriche del materiale e le prestazioni del sensore vengono analizzate e confrontate prima e dopo il processo di funzionalizzazione. In particolare, la tesi sviluppa i seguenti punti:
Nel Capitolo 1 vengono introdotte le caratteristiche fisiche ed elettriche del grafene, e le sue potenzialità nelle applicazioni di tipo "gas-sensing".
Nel Capitolo 2 viene presentato lo stato dell’arte sul processo di funzionalizzazione.
Il Capitolo 3 contiene le analisi delle caratteristiche fisiche ed elettriche del materiale, esaminando le differenze riscontrate dopo la funzionalizzazione.
I risultati dei test su gas, prima e dopo la funzionalizzazione, sono presentati nel Capitolo 4. SI usa NO2 come "target gas", N2 come gas portante. Per alcuni test, una percentuale di umidità relativa viene aggiunta al flusso di gas.
Infine, i risultati vengono confrontati e discussi in dettaglio.
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Czescik, Joanna. "Cleavage of phosphate diesters by functionalized gold nanoparticles: from simple models to plasmid." Doctoral thesis, Università degli studi di Padova, 2020. http://hdl.handle.net/11577/3425788.
Full textAbstract:
For many decades, scientists have attempted to understand and replicate nuclease efficiency. These enzymes are responsible for the cleavage of phosphodiester bonds, bonds that constitute the backbone of nucleic acids. By studying nuclease active sites, as well as reported examples of artificial enzymes able to cleave DNA and RNA models, chemists aim to achieve systems possessing better catalytic properties.
Designing artificial nucleases which can overcome the structural complexity and compete with the efficiency observed in Nature’s enzymes can be achievable with complex, nevertheless easy to prepare architectures, like gold nanoparticles (AuNPs). Indeed, functionalized AuNPs are one of the most attractive architectures reported so far in terms of phosphodiester cleavage. The necessity for a multistep synthesis can be easily overcome by using thiols as passivating agents that strongly interact with the metal cluster. By precisely tuning the organic thiol structures, it is possible to modulate AuNPs functionalization and properties of the reaction environment. Moreover, taking advantage of supramolecular chemistry principles, multivalency of gold nanoparticles may provide the cooperativity of several active and identical groups, enhancing the catalytic efficiency.
Herein, studies on the cleavage of DNA and RNA models, such as:
1) 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP)
2) bis-p-nitrophenyl phosphate (BNP)
3) uridine 3’-(LG) phosphates
and easy to manipulate DNA (plasmid pBR322 DNA), using self-assembled gold nanoparticles (AuNPs) are presented. Five different catalytic systems (AuNP1-5) were functionalized with at least one zinc complex of 1,4,7-triazacyclononane (TACN), either connected to a hydrocarbon chain (AuNP1,2) or decorated with different flanking species (a second Zn(II) complex, triethyleneoxymethyl derivative or the guanidinium unit of arginine; AuNP3-5).
In particular, chapters 1-3 describe the fundamental aspects of phosphates and nucleic acids, as well as cover the most relevant features contributing to the acceleration of the hydrolysis of nucleic acids by artificial nucleases. Furthermore, the principles of gold nanoparticles, including their properties, synthetic methods, application, as well as techniques of their characterisation are described.
Chapter 4 covers the synthesis and kinetic studies on the hydrolysis of 2-hydroxypropyl p-nitrophenyl phosphate. Performed Michaelis-Menten-like kinetics, Zn(II) titration, pH-profiles, kinetic isotopic effect as well as competitive inhibition with dimethyl phosphate enabled the proposal of two mechanisms towards the cleavage of HPNP, based on type of catalytic units present on the AuNP monolayer. Studied AuNPs were able to hydrolyse HPNP almost 1 million times compared to background reaction, being so far one of the most efficient systems cleaving this RNA model substrate.
Chapter 5 reports the results of the cleavage of bis-p-nitrophenyl phosphate and pBR322 DNA, as a DNA model substrate (the former one) and an example of a real polymer (the latter one). Thorough studies revealed significant differences in AuNPs catalytic activity in the hydrolysis of BNP and plasmid DNA. Among all studied nanozymes, only a Y-shaped species decorated with a peptide comprising serine and arginine in its sequence (AuNP4) was able to efficiently convert the supercoiled DNA into its nicked form in less than 3-4 hours at 35 μM concentration. Interestingly, in the hydrolysis of much simpler model BNP, the most reactive were nanozymes AuNP1-3, displaying only a minimal efficiency in the plasmid DNA cleavage.
Chapter 6 reports studies dedicated to the leaving group departure from uridine 3’-(LG) phosphates with the most efficient in HPNP and BNP cleavage, AuNP1. Final results of the hydrolysis of chosen nucleotides were presented in the form of Brønsted plot, displaying no change throughout the explored pKa range of leaving groups. Furthermore, a great negative value of the Brønsted constant suggested a significant development of anionic charge in the transition state (βLG = -0.86).
Taking advantage of the reactivity and ease in monitoring the cleavage of uridine 3’-p-nitrophenyl phosphate, more detailed UV-Vis-based kinetic studies in the presence of either AuNP1 or the zinc complex of 1,3-di(1,4,7-triazonan-1-yl)propan-2-ol Zn2(4e) were performed, providing additional information about Zn(II)-TACN interactions with uracil. Moreover, the reactivity and catalytic properties of AuNP1 vs Zn2(4e) in nucleotide cleavage revealed that, due to conformational flexibility, nanoparticles 1 were able to easily accommodate bulky substrates, contrary to what happens with the rigid Zn2(4e).
The presented supramolecular systems appear to be among the best reported catalysts for the cleavage of studied nucleic acids model substrates. Mechanistic investigations afforded a detailed information of the way AuNPs hydrolyse phosphodiester linkages. It has been demonstrated that the proper design and synthesis of nanoparticles may embrace significant factors that make nucleases one of the most efficient enzymes encountered in Nature.
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Aldewachi, Hasan. "Chromogenic detection of dipeptidyl peptidase IV (DPP-IV) activity using peptide-functionalized gold nanoparticles." Thesis, Sheffield Hallam University, 2017. http://shura.shu.ac.uk/18152/.
Full textAbstract:
Metal nanoparticles offer a useful platform for a wide range of biological applications especially for biosensing, bioimaging and drug delivery. This thesis presents a body of original research describing the synthesis, characterisation and development of a novel and convenient biosensing assay for detection of dipeptidyl peptidase IV (DPP-IV) enzyme activity using peptide functionalized gold nanoparticles. The distinctive optical and physical properties of gold nanoparticles (Au NP) were harnessed for the development of a colorimetric assay for rapid sensing of DPP-IV activities and screening DPP-IV inhbitors. The citrate reduction method for Au NPs synthesis was optimised and several potential peptide substrates (GPDC, VP-EN-DC, C/G dipeptide, GPG-EN-PEG4-LA, GPDCALNNC) were designed to provide substrates that mimic the DPP-IV natural substrates. The performances of the substrate functionalized Au NPs were assessed for their appropriateness for the detection of the enzyme activity. Addition of DPP-IV to the solutions containing the functionalized Au NPs resulted in cleavage of the substrate and thus causing the aggregation of the Au NPs which in turn led to a shift of the surface plasmon peak toward longer wavelengths, and a change of the colour of the colloidal suspension from red to blue. Overall, real-time detection of DPP-IV activity over a broader range (0-40 U/L) with high selectivity and stability was obtained, thus providing a method that can be used to determine the levels of DPP-IV/CD26 in biological fluids such as serum and plasma. Further assay developments were conducted to overcome limitations encountered with the original Au NP assay, especially the narrow dynamic linear range and stability in high ionic strength solutions. Validation and comparison of the Au NP assay developed has revealed that this method is highly correlated to the gold standard chromogenic Gly-Pro-pNA method for detection of enzyme activity in biological samples. Very good recoveries (in the range 83.6 –114.9%) were obtained in spiked serum samples, which indicate that this assay could provide a suitable alternative for enzyme activity detection with the naked eye and without the need for sophisticated instruments. Investigations into the effects of incorporating different stabilizers in order to improve the stability of the peptide functionalized Au NP in high ionic strength solutions were also investigated. Gold nanoparticles have different shapes and structures and an alternative approach for detection of DPP-IV activity using gold nanorods due to their higher refractive index sensitivities was explored. As a conclusion, three out of five approaches, all utilising Au NP-ligand conjugates were demonstrated useful for the detection of the DPP-IV activity. The system developed here is portable and would permit on-site analysis of samples, which offers a real alternative approach from traditional assays and reduces the need for laboratory testing. The logical next step in this research would be the continuation of experiments to transform this test into a point of care testing device that could offer an early detection tool for disease management.
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Woehrle, Gerd Heinz. "Synthesis of functionalized gold nanoparticles and their controlled organization into ordered one- and two-dimensional assemblies on DNA templates /." view abstract or download file of text, 2004. http://wwwlib.umi.com/cr/uoregon/fullcit?p3147838.
Full textAbstract:
Thesis (Ph. D.)--University of Oregon, 2004.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 184-204). Also available for download via the World Wide Web; free to University of Oregon users.
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Hau, Hon Chung Herman. "The use of polysulfone to encapsulate chemotherapeutically functionalised gold nanoparticles to enhance cancer treatment." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16506.
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Radiotherapy and chemotherapy are the main cancer treatment modalities but poor selectivity of these treatments to cancerous cells continues to limit their efficacy. Gold nanoparticles have been proposed as a way to enhance the localised radiation dose delivered to tumour cells and has also been demonstrated to increase the uptake of chemotherapeutic drugs. The aim of this project was to create an x-ray sensitive drug delivery carrier with externally activated drug release and localisation achieved by means of effective targeting with functionalised surfaces for co-administration of gold nanoparticles, drug and radiotherapy. Polysulfone and polyhexadecene sulfone polymers were investigated for their ability to depolymerise and release a drug surrogate through a release test as well as chemical and physical characterisation before and after irradiation. Self-produced gold nanoparticles were examined for its in vitro toxicity in colon cancer cells, its ability to conjugate with 5-fluorouracil and its radiation dose enhancement potential. The results of the release test could not definitively conclude that the drug surrogate was released but through characterisation, the polymer showed signs of cross-linking and/or branching. The gold nanoparticles were non-toxic up to 10 μg/mL in 2D and 25 μg/mL in 3D cultures but were not able to conjugate with 5-fluorouracil. Ultimately, it was shown that the gold nanoparticles were able to enhance radiation dose delivered to cells and its role in cancer treatment warrants further investigations.
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Bachelet, Marie. "Synthesis, physicochemical characterisation and biological evaluation of polymer-functionalised gold nanoparticles for cancer treatment." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/58270.
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Most of the chemotherapeutics employed today are facing important limitations, including the inability to provide targeted therapy and intracellular drug degradation within the lysosomal compartments. These explain why the average survival rate, throughout all cancer types, is still as low as 50%. The aim of the present thesis is to develop multifunctional AuNPs for intracellular delivery. PEGylated AuNPs were prepared via grafting poly(ethylene glycol) onto the AuNP surface. The influence of the PEG chain length and grafting densities on the colloidal stability, the grafted polymer conformation, the stealth character and the interparticle interactions have been extensively investigated. Longer chain lengths favoured the stability of the colloids in aqueous solution and the preparation of long-range and ordered assemblies via “flexible” interparticle interactions whereas shorter chain lengths led to denser layers and “hard-to-contact” spheres. Highly stable biocompatible pH-responsive AuNPs were obtained through the grafting with the anionic poly(L-lysine isophthalamide) (PLP) conjugated with L-phenylalanine at 75 mol% (PP75). The polymer pH dependent coil-to-globule conformational change was retained between pH 5-6, tuned to the endosomal pH. The AuNPs@PP75 nanohybrids demonstrated a quick and highly reversible agglomeration-deagglomeration cycle. Doxorubicin was loaded at 0.6 wt% onto the nanohybrids without compromising the overall stability in biological media and was effectively delivered into drug-resistant human uterus sarcoma cell line. The synergistic effect of the chemotherapy with photothermal treatment increased the killing efficiency by 6 folds compared to the conventional free drug. The nanohybrids were finally entrapped into pH-responsive PLP hydrogels. The composite hydrogels retained a high pH-responsive swelling behaviour and demonstrated improved mechanical properties compared to the bare hydrogel. Controlled drug release ability and biocompatibility confirmed their suitability as potential cancer therapeutics via oral administration.
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Waghwani, Hitesh Kumar. "One-Step Synthesis of Kanamycin Functionalized Gold Nanoparticles With Potent Antibacterial Activity Against Resistant Bacterial Strains." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1455.
Full textAbstract:
On the verge of entering the post-antibiotic era, numerous efforts are in place to regain the losing potential of antibiotics which are proving ineffective against common bacterial infections. Engineered nanomaterials, especially gold nanoparticles (GNPs) capped with antibacterial agents are proving to be an effective and novel strategy against multi-drug resistant (MDR) bacteria. In this study, we report a one-step synthesis of kanamycin-capped GNPs (20 ± 5 nm) utilizing the combined reducing and capping ability of the aminoglycoside antibiotic, kanamycin. Antibacterial assays showed dosedependent broad spectrum activity of Kan-GNPs against Gram-positive (Staphylococcus epidermidis and Enterococcus durans), Gram-negative (Escherichia coli and Enterobacter aerogenes) and Kan-resistant and MDR bacterial strains. A significant reduction in the minimum inhibitory concentration (MIC) of Kan-GNPs was observed as compared to free kanamycin against all the sensitive and resistant bacterial strains tested. Mechanistic studies using TEM and fluorescence microscopy showed that Kan- GNPs exerted their bactericidal action through disrupting the cellular membrane resulting in leakage of cytoplasmic content and death of bacterial cells. Results of this study provide a novel method in the development of antibiotic capped GNPs as potent next-generation antibacterial agents.
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Zayed, Gamal. "Development of colloids for cell and tissue targeting : bisphosphonate-functionalized gold nanoparticles for the investigation of bone targeting." kostenfrei, 2009. http://www.opus-bayern.de/uni-regensburg/volltexte/2010/1167/.
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Kang, Chan-kyu. "Preliminary study of tribology uniform control of the density control of the functionalized gold nanoparticles on a modified silicon surface /." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/KANG_CHAN_40.pdf.
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Köhntopp, Anja [Verfasser], Friedrich [Akademischer Betreuer] Temps, and Gernot [Gutachter] Friedrichs. "Photochemical Properties and Ultrafast Dynamics of Azobenzene-Functionalized Gold Nanoparticles / Anja Köhntopp ; Gutachter: Gernot Friedrichs ; Betreuer: Friedrich Temps." Kiel : Universitätsbibliothek Kiel, 2015. http://d-nb.info/1213724945/34.
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Sunday, Christopher Edozie. "The design of ultrasensitive immunosensors based on a new multi-signal amplification gold nanoparticles-dotted 4-nitrophenylazo functionalised graphene sensing platform for the determination of deoxynivalenol." Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3361.
Full textAbstract:
Philosophiae Doctor - PhDA highly dispersive gold nanoparticle-dotted 4-nitrophenylazo functionalised graphene nanocomposite (AuNp/G/PhNO2) was successfully synthesised and applied in enhancing sensing platform signals. Three label-free electrochemical immunosensors for the detection of deoxynivalenol mycotoxin (DON) based on the systematic modification of glassy carbon electrodes (GCE) with AuNp/G/PhNO2 was effectively achieved. General electrochemical impedance method was employed for the sensitive and selective detection of DON in standard solutions and reference material samples. A significant increase in charge transfer resistance (Rct) of the sensing interface was observed due to the formation of insulating immune-complexes by the binding of deoxynivalenol antibody (DONab) and deoxynivalenol antigen (DONag). Further attachments of DONab and DONag resulted in increases in the obtained Rct values, and the increases were linearly proportional to the concentration of DONag. The three immunosensors denoted as GCE/PDMA/AuNp/G/PhNH2/DONab, GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2/DONab and GCE/Nafion/[Ru(bpy)3]2+/G/PhNH2/DONab have detection range of 6 – 30 ng/mL for DONag in standard samples. Their sensitivity and detection limits were 43.45 ΩL/ng and 1.1 pg/L; 32.14ΩL/ng and 0.3 pg/L; 9.412 ΩL/ng and 1.1 pg/L respectively. This result was better than those reported in the literature and compares reasonably with Enzyme Linked Immunosorbent Assay (ELISA) results. The present sensing methodology represents an attractive alternative to the existing methods for the detection of deoxynivalenol mycotoxin and other big biomolecules of interest due to its simplicity, stability, sensitivity, reproducibility, selectivity, and inexpensive instrumentation. And they could be used to develop high-performance, ultra-sensitive electrochemiluminescence, voltammetric or amperometric sensors as well.
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Chan-Yi, Yang, and 楊正義. "The Application of Functionalized Gold Nanoparticle on Biotechnology." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/65701209710329669500.
Full textAbstract:
博士國立臺灣師範大學
化學系
95
Metal and semiconductor nanoparticles coupling with biomolecules have attracted great interests recently because the resulting materials may bring new applications in biological systems. The strong and selective binding of carbohydrate-AuNP to bacterial presents a novel method of labeling specific protein on the cell surface using carbohydrate conjugated nanoparticles. Moreover, in comparison with the conventional sandwich immunoassay, the biomolecule conjugated nanoparticles can provide a relatively easy and direct method to visualize the target receptors on the cell surface under an electron microscope. On the other hands, the multivalent interactions between carbohydrate-AuNPs and target lectins were studied by the SPR technique to quantitatively analyze the binding affinity. The results showed that the binding of mannose encapsulated AuNPs with Con A and galactose encapsulated AuNPs with VAA-I exhibited a strong multivalent effect, and the binding specificity between carbohydrate-AuNP and the lectin was similar to that of the monovalent counterparts. The relative inhibit potency (RIP) values of carbohydrate-AuNPs indicate that the larger size of AuNP and longer ligand length present excellent binding affinity both in interaction with Con A and VAA-I, respectively. Our results demonstrate that gold nanoparticle can serve as an excellent multivalent carbohydrate ligand carrier, providing a new route for designing inhibitors and biological effectors for target proteins.
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Chen, Chung-Wein, and 陳崇文. "Aptamer-functionalized gold nanoparticle as a potential vascular endothelial growth factor inhibitor." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/48845022545112446771.
Full textAbstract:
碩士國立臺灣海洋大學
生命科學暨生物科技學系
103
Angiogenesis was an essentially physiological process when cancer cells grew to 1 mm which suffered low nutrient and hypoxia. Vascular endothelial growth factor (VEGF) was a key protein in stimulating angiogenesis and regulating endothelial cells proliferation, migration and tube formation. VEGF was also an important target for cancer detection and therapy. In our study, we used human umbilical vein endothelial cells (HUVECs) as model to investigate the inhibition capacity of VEGF by non-covalent aptamer-modified gold nanoparticles (Apt−Au NPs). Two kinds of specific anti-VEGF aptamer (Del5-1, V7t1) conjugated with Au NPs could inhibit VEGF activity efficiently and suppress HUVECs growth. We prepared Apt−Au NPs through the terminal polyA of aptamer capped on the Au NPs. The non-covalent Apt−Au NPs bioconjugates possess advantages such as low cost, high binding affinity, simple preparation and easy control of aptamer density on Au NPs. In our results, we demonstrated aptamer Del5-1 and aptamer V7t1 conjugated with Au NPs could inhibit 30% cell survival by cell viability assay. In cell proliferation assay, we found that Apt−Au NPs could suppress 30% cell growth. In wound healing assay, Apt−Au NPs induced the decrease in 50% of cell migration. Therefore, AptDel5-1/V7t1−Au NPs have a great potential as a drug for anti-angiogenesis.
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Gomez, Hernandez Mario 1980. "Explorations of Functionalized Gold Nanoparticle Surface Chemistry for Laser Desorption Ionization Mass Spectrometry Applications." Thesis, 2011. http://hdl.handle.net/1969.1/149214.
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Functionalized nanoparticles provide a wide range of potential applications for Biological Mass Spectrometry (MS). Particularly, we have studied the effects of chromophore activity on the performance of gold nanoparticles (AuNPs) capped with substituted azo (-N=N-) dyes for analyte ion production in Laser Desorption Ionization Mass Spectrometry (LDI-MS) conditions. A series of aromatic thiol compounds were used as Self-Assembled Monolayers (SAM) to functionalize the surface of the AuNPs. Results indicate that AuNPs functionalized with molecules having an active azo chromophore provide enhanced analyte ion yields than the nanoparticles capped with the hydrazino analogs or simple substituted aromatic thiols.
We have also conducted experiments using the azo SAM molecules on 2, 5, 20, 30, and 50 nm AuNPs exploring the changes of Relative Ion Yield (RIY) with increased AuNP diameters. Our results indicate that the role of the SAM to drive energy deposition decreases as the size of the AuNP increases. It was determined that 5 nm is the optimum size to exploit the benefits of the SAM on the ionization and selectivity of the AuNPs.
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Lee, Dai Yoon. "Therapeutic Peptide-functionalized Gold Nanoparticles for the Treatment of Acute Lung Injury." Thesis, 2013. http://hdl.handle.net/1807/43003.
Full textAbstract:
Acute lung injury (ALI) is a major cause of mortality after lung transplantation. Recent studies indicate protein kinase C delta (PKCδ) could be an effective target to treat ALI. We have developed a gold nanoparticle (GNP)-peptide hybrid that can inhibit PKCδ signaling. PKCδ inhibitor peptide (PKCi) and 95P2P4 stabilizing peptides were conjugated onto GNP. Physicochemical properties of the nanoformulations were examined. A lung transplant-simulated cell culture model was used to evaluate therapeutic efficacy in vitro. A pulmonary ischemia-reperfusion (IR) model was used to test therapeutic efficacy in vivo. GNP-Peptide hybrids showed good stability with high cellular uptake. GNP-PKCi formulations demonstrated anti-inflammatory and anti-apoptotic effects in vitro. When administered to rats under IR stress, GNP-PKCi formulation improved blood oxygenation, reduced pulmonary edema and histological lung injury. In conclusion, we have successfully formulated a clinically-applicable nanoparticle with therapeutic potential to ameliorate lung injury and inflammation. Our formulation strategy could be used to deliver other peptide-based drugs.
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Müller, Christian. "Physical Properties of Chromophore Functionalized Gold Nanoparticles." Doctoral thesis, 2011. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-57657.
Full textAbstract:
n this work the synthesis and analysis of chromophore functionalized spherical gold nanoparticles is presented. The optical, electrochemical and spectroelectrochemical properties of these hybrid materials are furthermore studied. The work therefore is divided into two parts. The first part deals with triarylamine and PCTM-radical functionalized gold nanoparticles. The focus thereby was on the synthesis and on the investigations of chromophore-chromophore interactions and gold core-chromophore interactions. The chromopores, especially triarylamines, were attached to the gold core via different bridging units and were studied with optical and electrochemical methods. The purity and dimensions of the nanoparticles was determined by 1H-NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), TGA, XPS and STEM. Furthermore a cyclic voltammetry technique was used to determine the composition of the particles via the Randles-Sevcik equation. An analysis of these parameters led to a model of a sea urchin-shaped nanoparticle. Optical measurements of the particles revealed an anisotropic absorption behavior of the triarylamine units due to gold core-chromophore interaction. However this behavior depends strongly on the relative orientation of the transition dipole moment of the chromophore to the gold surface and the distance of the chromophore to the surface. Hence, the anisotropic behavior was exclusively detected in the spectra of the Au-Tara1 particles. The short and rigid pi-conjugated bridging unit thereby facilitates this gold core-chromophore interaction. It was shown from electrochemical investigations that the triarylamine units can be chemically reversibly oxidized to the triarylamine monoradical cation. Furthermore, the measurements revealed a strong interligand triarylamine-triarylamine interaction which was only seen for the Au-Tara1 particles. The long pi-conjugated bridging units of the Au-Tara2 and Au-Tara3 particles as well as the aliphatic bridging unit of Au-Tara4 prevent any detectable interligand interactions. One may conclude that both the gold core-chromophore and the interligand triarylamine-triarylamine interaction depend on the length and the rigidity of the bridging unit. The electron transfer behavior of the triarylamine units adsorbed onto the gold core was additionally studied via spectroelectrochemical (SEC) measurements which are able to reveal weaker interactions. The investigations of Au-Tara1 and Au-Tara2 revealed a significant strong coupling between neighboring triarylamine units which is due to through-space intervalence interactions. This behavior was not detected for Au-Tara3 or for Au-Tara4. The SEC analysis also revealed that these observed interligand interactions depend on the length and the rigidity of the bridging unit. Thus, the systematic variation of the bridging unit gave a basic insight in the optical and electrochemical properties of triarylamines, located in the vicinity of a gold nanoparticle. The second part of this work aimed at the synthesis of new molecules, denoted as SERS-markers, for immuno SERS applications. For this purpose, the SERS-markers were designed to have a Raman-active unit and a thiol group for chemisorptions to Au/Ag nanoshells. In cooperation with the group of Schlücker (University of Osnabrück) the SERS-markers were absorbed onto Au/Ag nanoshells, denoted as SERS-labels, and characterized. The SERS spectra of the SERS-labels exhibited intense and characteristic SERS-signals for each marker. For immuno SERS investigations SEMA3 was functionalized with a hydrophilic end unit. This marker was adsorbed onto an Au/Ag nanoshell and encapsulated with silica. An anti-p63 antibody was bound to the silica surface in order to generate a SERS-labeled antibody for the detection of the tumor suppressor p63 in benign prostate. Immuno-SERS imaging of prostate tissue incubated with SERS-labeled anti-p63 antibodies demonstrated the selective detection of p63 in the basal epithelium. The results show the potential of the method for the detection of several biomolecules in a multiplexing SERS experimentIn dieser Arbeit wurde die Synthese und Analyse von neuen Nanopartikel-Hybrid-Strukturen gezeigt. Darüber hinaus wurden die optischen, elektrochemischen und spektroelektrochemischen Eigenschaften dieser Materialien untersucht. Die Arbeit gliederte sich dabei in zwei Teile. Der erste Teil beschäftigt sich mit Triarylamin- und PCTM-Radikal-funktionalisierten Gold-Nanopartikeln. Im Zentrum dieser Untersuchung stand neben der Synthese vor allem die Untersuchung von Chromophor-Chromophor Wechselwirkungen und Goldkern-Chromophor Wechselwirkungen. Dazu wurden in erster Linie Triarylamine mit verschiedenen Brückeneinheiten an den Goldkern angeknüpft und mit optischen und elektrochemischen Methoden untersucht. Die Reinheit und die Abmessungen der Nanopartikel konnte mit 1H-NMR Spektroskopie, diffusion-ordered-NMR Spektroskopie-(DOSY), TGA, XPS und STEM genau bestimmt werden und die Zusammensetzung der Partikel mit einer elektrochemischen Analysemethode errechnet werden. Aus diesen Parametern wurde dann die Seeigel-artige Struktur der Partikel abgeleitet. Die optischen Untersuchungen der Partikel zeigte ein anisotropes Absorptionsverhalten der Triarylamine, welches eine Folge von Goldkern-Chromophor Wechselwirkungen ist. Dieses Verhalten war allerdings sehr stark von der Orientierung des Übergangdipolmoments des Chromophors zur Goldoberfläche abhängig und vom Abstand des Chromophors zur Goldoberfläche. So war das anisotrope Verhalten nur bei Au-Tara1 zu beobachten. Die kurze und starre pi-konjugierte Brückeneinheit begünstigte dabei die Chromophor-Goldkern Wechselwirkung. In elektrochemischen Untersuchungen konnte gezeigt werden, dass die Triarylamin-Einheiten chemisch reversibel zum Monoradikal-Kation oxidiert werden können. Darüber hinaus konnte in den Messungen eine starke Interligand-Triarylamin-Triarylamin-Wechselwirkung für die Au-Tara1 Partikel beobachtet werden. Die längeren Brückeneinheiten der Au-Tara2 und Au-Tara3 Partikel als auch die aliphatische Brücke des Au-Tara4 Partikels verhinderten eine elektronische Interligand-Wechselwirkung. Somit zeigt sich, dass nicht nur die Triarylamin-Goldkern-Wechselwirkung sondern auch die Interligand-Wechselwirkung sehr sensitiv auf die Länge und Starrheit der Brücke reagieren. In einer weiteren Untersuchung wurde das Elektronentransferverhalten der Triarylamin-Einheiten auf dem Partikel untersucht. In den dafür durchgeführten spektroelektrochemischen Untersuchungen wurde eine starke Kopplung zwischen benachbarten Triarylamin-Einheiten beobachtet. Dieses Verhalten wurde den Intervalenz-Wechselwirkungen durch den Raum zugeordnet und war weder für Au-Tara3 noch für Au-Tara4 zu beobachten. Diese Analyse zeigte, dass auch diese interligand Wechselwirkung stark von dem Abstand und der Orientierung der Triarylamin-Einheiten zueinander abhängt. Somit konnte durch die systematische Variierung der Brückeneinheit ein detailierter Einblick in die optischen und elektrochemischen Eigenschaften von Triarylaminen adsorbiert auf kleinen runden Gold-Nanopartikeln gegeben werden. Im zweiten Teil dieser Arbeit wurden neue Moleküle, sogenannte SERS-Marker, für den Einsatz in immuno-SERS-Mikroskopie Experimenten synthetisiert. Zu diesem Zweck wurden die Moleküle mit verschiedenen Raman-aktiven Einheiten und einer Thiol-Funktion ausgestattet. In Zusammenarbeit mit der Arbeitsgruppe von Prof. S. Schlücker (Universität Osnabrück) wurden die Marker mittels Thiol-Einheit auf Au/Ag-Hohlkugeln aufgebracht (SERS-Label) und dann untersucht. Die SERS-Spektren der SERS-Label zeigten intensive und für jeden Marker charakteristische SERS-Signale. Für immuno-SERS-Experimente wurde dann SEMA3 mit einer hydrophilen Schwanzeinheit versehen. Dieser Marker wurde wiederum auf eine Au/Ag-Hohlkugel aufgebracht und an den hydrophilen Schwanzeinheiten mit einer Silikatschicht überzogen. Anschließend wurde zusätzlich ein anti-p63 Antikörper aufgebracht, um den Tumorsuppressor p63 zu detektieren, der vor allem in gutartigen Prostata-Gewebe vorkommt. Mit dem SERS-markierten Antikörper konnte an Prostata-Gewebe p63 im Basal-Epithel nachgewiesen werden. Diese Untersuchungen zeigen das Potential dieser Methode zum gleichzeitigen Nachweis verschiedener Biomoleküle in einem Multiplexing Experiment
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Reis, Daniel Pedro Pires Alves. "Functionalized gold nanoparticles as anticancer drug delivery systems." Master's thesis, 2015. https://repositorio-aberto.up.pt/handle/10216/88279.
Full text
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Shiao, Yi-Syun, and 蕭義勳. "Aptamer Functionalized Gold Nanoparticles for Targeted Cancer Therapy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/73075527938542515060.
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Reis, Daniel Pedro Pires Alves. "Functionalized gold nanoparticles as anticancer drug delivery systems." Dissertação, 2015. https://repositorio-aberto.up.pt/handle/10216/88279.
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"Synthesis, purification, characterization and application of discretely functionalized gold nanoparticles." Thesis, 2011. http://library.cuhk.edu.hk/record=b6075517.
Full textAbstract:
Chak, Chun Pong.Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 190-202).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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Chan-HuaChen and 陳健豪. "Fabrication and Application of Functionalized Gold Nanoparticles for Immunoprecipitation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50867749808517062300.
Full textAbstract:
碩士國立成功大學
化學系碩博士班
98
In this study, we fabricated and characterized gold nanoparticle (AuNPs)-based immuno probes and further applied the synthesized probes for imunoprecipitation against estrogen receptor alpha (ERα) in MCF-7 breast cancer cells. We first utilized 2-iminothiolane to modify the amine groups of protein G in order to form a thiol linker, which could subsequently bind to the surface of AuNPs. Anti-ERα antibody was then bound to the probe surface via protein G through its Fc domain to form well orientated antibodies on the probe for immuno-capturing. The immobilized antibodies were further cross linked with protein G to minimize the leakage of antibodies that could interfere the subsequent detection by mass spectrometry (MS). The fabrication conditions were systematically optimized and the final probe was characterized to have 1.4 μg protein G and 4.52 μg anti-estrogen receptor alpha on 100 μL AuNP. Compared to agarose beads which are conventionally used in immunoprecipitation, our data showed that AuNPs-based probe has comparable specificity and recovery rate but possesses higher resistance against non-specific binding, which, however, is very crucial for MS detection. Finally, we demonstrated that from as little as 500 μ g total proteins of MCF-7 whole cell lysate, ERα could be successfully isolated and identified by proteomics approach using MS detection.
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Zhou, Jingfang. "Thymine-functionalized gold nanoparticles : synthesis, surface structure and colloid stability." 2008. http://arrow.unisa.edu.au:8081/1959.8/47049.
Full textAbstract:
Monolayer protected nanoparticles (MPNs) display fascinating size-dependent electronic, optical and catalytic properties. They are promising candidates to be used as building blocks with which to construct new generation nanoarchitectures and nanodevices for sensing, electronic and optoelectronic applications. The aggregation and dispersion of colloidal nanoparticles is one of the key issues closely related to their potential applications. Our knowledge of the colloid stability of nanoparticle dispersions with small sizes is still in its infancy, however, thymine is one of the bases in DNA, and is a pH sensitive and chromatic molecule. In the present study, thymine-functionalized self-assembled monolayer protected gold nanoparticles were synthesized. Their morphology and surface structure were characterized using TEM, UV-vis, FTIR, DSC-TGA and XPS techniques. The colloid stability of thymine-capped gold nanoparticle dispersions as a function of the type and concentration of monovalent salt, pH and particle size in alkaline aqueous solution were investigated. The manipulation of colloid stability with light was further explored. The results and conclusions are summarized inthis thesis.
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Chen, Chuan-Kuo, and 陳川國. "Development and Applications of Capillary Electrophoresis and Functionalized Gold Nanoparticles." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24191699153452461371.
Full textAbstract:
碩士臺灣大學
化學研究所
98
Three different analytical approaches are demonstrated in this thesis. First, naphthalene-2,3-dicarboxaldehyde (NDA)-amino acid and -amine derivatives were separated and detected by capillary electrophoresis in conjunction with light-emitting diode-induced fluorescence (LEDIF) detection using poly(ethylene oxide) (PEO) containing cetyltrimethylammonium bromide (CTAB). In the presence of CTAB and acetonitrile (ACN), adsorption of PEO on the capillary wall was suppressed, leading to generation of a fast and reproducible electroosmotic flow (EOF). In order to optimize separation resolution and speed, 100 mM Tris–borate solution (pH 7.0) containing 20 mM CTAB and 25% ACN was used to fill the capillary and to prepare 1.2% PEO that entered the capillary via EOF. The analysis of 14 NDA-amino acid and -amine derivatives by this approach was rapid (< 4 min), efficient [(0.9–6.4) × 105 theoretical plates], and sensitive [the LODs (S/N = 3) range from 9.5 to 50.5 nM]. The RSD values (n = 5) of the migration times and peak heights of the analytes for the intraday analysis were less than 1.5 and 1.2%, respectively. The practicality of this approach was validated by quantitative determination of 10 amino acids and amines in a beer samples within 4 min. Secondly, a novel, label-free, colorimetric assay – using fibrinogen (Fib) and gold nanoparticles (Au NPs) –was developed for the highly selective and sensitive detection of thrombin. Addition of fibrinogen to a solution of Au NPs (average diameter: 56 nm) led to ready conjugation, forming Fib–Au NPs through electrostatic and hydrophobic interactions. Introduction of thrombin (a serine protease) into the Fib–Au NPs solutions in the presence of excess fibrinogen induced the formation of insoluble fibrillar fibrin–Au NPs agglutinates through the polymerization of the unconjugated and conjugated fibrinogen. After centrifugation, the absorbance at 532nm of the supernatants decreased upon increasing the concentration of thrombin. This Fib–Au NP probe provided high sensitivity [limit of detection (LOD): 0.04 pM] for thrombin, with remarkable selectivity over other proteins and proteases. The range of linearity for the absorbance against the thrombin concentration was 0.1–10 pM (R2 = 0.96). This approach provided an LOD for thrombin that is lower than those obtainable using other nanomaterial- and aptamer-based detection methods. The utility of this Fib–Au NP probe was validated through separate analyses of thrombin and Factor Xa at picomolar levels in plasma samples—without the need for sample pretreatment. This technique appears to have practical potential in the diagnosis of diseases associated with coagulation abnormalities and cancers (e.g., pulmonary metastasis). Last, detection of DNA hybridization was demonstrated using a Fib-Au NPs-based assay. Two thrombin binding aptamers (TBAs)－TBA15 (15 bases long) and TBA27 (27 bases long)－that are specific towards thrombin were used to form a TBA15-TBA27 assembly in the presence of a complementary DNA (cDNA). The TBA15-TBA27 assembly relative to TBA15 and TBA27 provided a greater inhibition activity for thrombin, showing bivalent binding capacity. The activity of thrombin decreased upon increasing the concentration of cDNA. This new sensing strategy provides high sensitivity [limit of detection (LOD): 25 pM] and remarkable specificity for cDNA. To test the practicality, another probes [TBA15’ (P-TBA15’) and TBA27’ (P-TBA27’)] were used for the detection of the single-nucleotide polymorphism (SNP) responsible for hepatocellular carcinoma. Unlike conventional approaches, this method requires neither postsynthetic modification of the probe oligonucleotides nor precise temperature control for SNP typing.
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Lai, Yi-Jhen, and 賴宜珍. "Using functionalized gold nanoparticles to determinate environmental samples and biomolecules." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/93122377857172761747.
Full textAbstract:
碩士國立中山大學
化學系研究所
99
一、Role of 5-thio-(2-nitrobenzoic acid)-capped gold nanoparticles in the sensing of chromium(VI): remover and sensor This study describes a simple, rapid method for sensing Cr(VI) using 5-thio-(2-nitrobenzoic acid) modified gold nanoparticles (TNBA-AuNPs) as a remover for Cr(III) and as a sensor for Cr(VI). We discovered that TNBA-AuNPs were dispersed in the presence of Cr(VI), whereas Cr(III) induced the aggregation of TNBA-AuNPs. Due to this phenomenon, TNBA-AuNPs can be used as a sorbent material for the removal of > 90% Cr(III), without removing Cr(VI). After centrifuging a solution containing Cr(III), Cr(VI), and TNBA-AuNPs, Cr(III) and Cr(VI) were separately present in the precipitate and supernatant. In other words, TNBA-AuNPs are capable of separating a mixture of Cr(III) and Cr(VI). The addition of ascorbic acid to the supernatant resulted in a reduction of Cr(VI) to Cr(III), driving the aggregation of TNBA-AuNPs. The selectivity of this approach is more than 1000-fold for Cr(VI) over other metal ions. The minimum detectable concentration of Cr(VI) was 1 μM using this approach. Inductively coupled plasma mass spectrometry provided an alternative for the quantification of Cr(III) and Cr(VI) after a mixture of Cr(III) and Cr(VI) had been separated by TNBA-AuNPs. The applicability of this approach was validated through the analysis of Cr(VI) in drinking and tap water. 二、Fluorescent Sensing of Total, Protein-bound, Free, and Oxidized Homocysteine in Plasma through the Combination of Tris(2-carboxyethyl)Phosphine Reduction, Fluorosurfactant-Capped Gold Nanoparticles Extraction, and o-Phthaldialdehyde Derivatization This study reports a simple, selective, and sensitive method for fluorescent detection of total, protein-bound, free, and oxidized homocysteine (HCys) using tris(2-carboxyethyl)phosphine (TCEP) as a reducing agent, fluorosurfactant-capped gold nanoparticles (FSN-AuNP) as a preconcentrating probe, and o-Phthaldialdehyde (OPA) as a derivatizing agent. TCEP was used to reduce the disulfide bonds of protein-bound and oxidized HCys. FSN-AuNPs were capable of extracting HCys from a complicated complex because the FSN capping layer can stabilize the AuNPs in a high-salt solution and inhibit non-specific adsorption. HCys was selectively derivatized with OPA in the absence of a nucleophile. By taking advantage of these features, the selectivity of the proposed system is greater than 100-fold for HCys and homocystine (HCys-HCys disulfide; diHCys) compared to any aminothiols. The limits of detection (LODs) for HCys and diHCys were 4.4 and 4.6 nM, respectively. Compared to other sensors, the proposed system provides an approximately 3-300-fold improvement in the detection of HCys. Different forms of plasma HCys were determined by varying the order of disulfide reduction with TCEP. The proposed system was successfully applied to determine the total, protein-bound, free, and oxidized HCys in plasma. To the best of our knowledge, the proposed system not only provides the first method for detecting various forms of plasma HCys, but also has the lowest LOD value for HCys when compared to other sensors.
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CHOU, HUI-WEN, and 周慧雯. "Using functionalized−gold nanoparticles for rapid detection of trivalent chromium." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/6ja4u4.
Full textAbstract:
碩士高雄醫學大學
醫學檢驗生物技術學系碩士班
106
Analytical techniques for trace element analysis have been well established based on the combination of various techniques and instruments, such as atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). However, the practicability of these analytical methods was limited by various requirements, such as sample volume, apparatus required and sample pretreatment processes. Recently, due to the unique optical characteristics of nanomaterials, various nanomaterial-based analytical methods have been reported. The aim of the study was to develop a simple nanomaterial-based analytical method for the quantification of trivalent chromium (Cr3+). An eco-friendly and highly selective gold nanoparticles (AuNPs) has been prepared and functionalized by glutathione (GSH). The presence of Cr3+ induced aggregation of GSH@AuNPs, yielding a color change from red to blue by the naked eye and monitored using UV–Vis spectroscopy. To optimize the analytical characteristics of the proposed method, the concentration and reaction time of GSH, the working pH, reaction times, and the selectivity were evaluated. Under the optimized conditions, the concentration of GSH was 1.0 mM, the reaction time was 10 minutes, and the reaction pH was 3.0. According to the experimental results, the analytical performance was as the following: the absorbance ratio (A700/522) is linearly related to the Cr3+ concentration in the range of 0.3-1.5 mg L-1 (R2 = 0.9971), and the limit of detection (LOD) was 0.03 mg L-1 (n = 7), RSD was 3.9 %, and the average recovery values was 105.6%; the GSH-AuNPs bound to Cr3+ with excellent selectivity relative to other metal ions (Cr6+, Cu2 +, Cd2 +, Mn2 +, Mg2 +, Ni2 +, Co2 +, Zn2 +, Fe2 +, Pb2 +, Hg2 +and As5+), leading to a prominent color change. After optimization the preparation conditions, the GSH@AuNPs was used to detect the amounts of Cr3+ species in tap water and nutritional supplementary milk samples.
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Cunha, Lídia Maria Carvalho. "Functionalized Gold Nanoparticles as a versatile vehicle to delivery anticancer drugs." Master's thesis, 2016. https://hdl.handle.net/10216/93490.
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Cunha, Lídia Maria Carvalho. "Functionalized Gold Nanoparticles as a versatile vehicle to delivery anticancer drugs." Dissertação, 2016. https://hdl.handle.net/10216/93490.
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Soldan, Giada. "Nanostructured Membranes Functionalized with Gold Nanoparticles for Separation and Recovery of Monoclonal Antibodies." Thesis, 2017. http://hdl.handle.net/10754/626206.
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The need of purified biomolecules, such as proteins or antibodies, has required the biopharmaceutical industries to look for new recovering solutions to reduce time and costs of bioseparations. In the last decade, the emergent field of membrane chromatography has gained attention as possible substituent of the common used protein A affinity chromatography for bioseparations. In this scenario, gold nanoparticles can be used as means for offering affinity, mainly because of their biocompatible and reversible binding behavior, together with their high surface area-to-volume ratio, which offers a large number of binding sites.
This work introduces a new procedure for purification of monoclonal antibodies based on polymeric membranes functionalized with gold nanoparticles. This novel approach shortens the process of purification by promoting selective binding of antibodies, while separating a mixture of biomolecules during a filtration process. The effects of gold nanoparticles and the surrounding ligand on the proteins adsorption and filtration are investigated.
The results confirm that the functionalization helps in inducing a selective binding, preventing the non-selective one, and it also improves the selectivity of the separation process.
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Wu, Chung-Shu, and 吳中書. "An Enzymatic kinetics Investigation into the Significantly Enhanced Activity of Functionalized Gold Nanoparticles." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/76105910639742047851.
Full textAbstract:
碩士國立交通大學
奈米科技研究所
96
Enzymes immobilize onto gold nanoparticles (AuNPs) in the absence of a linker, using rapid and uncomplicated processes, generally possess higher activity bound to the surfaces through chemical modification. In previous reports, catalytic activity of enzyme-functionalized AuNPs has been investigated with the surface modification of linkers. Although the surface modification of linkers protects AuNPs from aggregation upon reactant’s entering, it will be perplexed at examination the coverage of the enzyme onto nanoparticles because less or much enzyme can not be identified by salt titration. Herein, linker-free immobilization is beneficial for developing precise activity assays. AuNP-bound lipase exhibits significantly enhanced catalytic activity relative to that of the free enzyme. In this work, we have systematically investigated the interactions between the NP monolayer and the affected substrates by quantifying the kinetic parameters kcat and KM to understand the enzymatic behavior of AuNP-bound lipase. Investigation of the kinetic parameters reveals that these two systems operate with the same value of kcat; i.e., the AuNPs exert no influence on the process of product release in the rate-limiting step. The Michaelis–Menten curves revealed that the AuNP-bound lipase provided the lower value of KM. Thus, the addition of AuNPs is an efficacious means of tuning enzyme–substrate association. We suspect that such fundamental research will aid in the development of new nanobiotechnological applications.