Дисертації з теми "CHITOSAN-SILVER NANOPARTICLE"
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Neto, Elias Antonio Berni. "Desenvolvimento de nanobiocompósitos contendo nanopartículas de prata para aplicações bactericidas." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14062010-162736/.
Повний текст джерелаThe work reported here was aimed at developing chitosan/AgNPs based nanobiocomposits for bactericidal applications. The studies were divided into four main steps, viz.,: i) optimization of the silver colloids stabilition process, in which the use of chitosan resulted in the best stability, ii) a detailed investigation on the interactions between chitosan and AgNPs, as well as the optimization of the chitosan :AgNPs ratio to promote the best bactericidal effect, iii) development of a new synthetic route without using NaBH4, in a search for an environmentally-friendly route, and iv) incorporation of the chitosan:AgNps nanobiocomposites in a PVA matrix for application as smart food packaging. The nanobiocomposites were characterizaed via UV-vis and FT IR spectroscopies, DLS, Zeta potential, TEM and DR-X. Biological essays had also been carried out, as well as tensilestress and thermo analyses (DSC and TGA). The best bactericidal effect was observed for a nanobiocompostie comprising chitosan:AgNPs at a ratio of 4:1 (wt/wt). The synthetic route employing sodium citrate as reducing agent resulted in AgNPs with average diameters of 2 5 nm, as well as bigger nanoparticles with diameters of ca. 300 nm, depending on the reaction time and citrate concentration. The incorporation of the chitosan:AgNPs composites in the PVA matrix resulted in the formation of a bactericidal composite with good mechanical and thermal properties, suitable for applications as smart food packing.
Neves, Mariana Silva Lopes. "Potencial antibacteriano de nanopartículas de prata associadas ou não a quitosana e às drogas antimicrobianas." Universidade Federal de Juiz de Fora (UFJF), 2013. https://repositorio.ufjf.br/jspui/handle/ufjf/5850.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
A prata é conhecida por sua atividade antibacteriana e tem se mostrado eficiente como alternativa no contexto da resistência bacteriana a drogas, sobretudo na forma de nanopartículas (AgNPs). Nossos objetivos foram a avaliação da susceptibilidade de bactérias representativas contra AgNPs e pesquisa de efeito sinérgico ou antagônico quando associadas a quitosana (QIT) e antimicrobianos de uso terapêutico humano. Foram utilizadas oito linhagens bacterianas de referência, representativas de: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, S. epidermides e Enterococcus faecalis. O perfil de susceptibilidade foi determinado através do método de microdiluição em caldo, de acordo com as recomendações do CLSI. A concentração inibitória mínima (CIM90) das AgNPs para as amostras testadas foi de 64μg/mL, enquanto que para a combinação AgNPs-QIT foi de 16μg/mL. Considerando-se atividade antimicrobiana somente da QIT, a CIM90 foi de 16 μg/mL. Entre os antimicrobianos testados (meropenem, amicacina, gentamicina, levofloxacina, rifampicina, sulfametoxazol-trimetropim, tetraciclina, e oxacilina e vancomicina, estes apenas para Gram positivos), apesar de a CIM para cada linhagem bacteriana estar de acordo com os valores determinados pelo CLSI observou-se diminuição significativa para todas as drogas testadas quando combinadas com AgNPs-QIT. De modo geral, para todas as espécies bacterianas avaliadas, a associação de AgNPs com QIT ou drogas antimicrobianas apresentaram grande potencial inibitório que pode estar relacionado a estabilidade das AgNPs associadas ao polímero ou a interação positiva das nanopartículas com os antimicrobianos. O ensaio de Checkerboard foi realizado para estabelecer os efeitos sinérgicos ou antagônicos em cada combinação. A possibilidade da interação das AgNPs e da QIT com antimicrobianos já existentes é altamente relevante e reforça as recomendações da literatura acerca da reformulação de uso de antimicrobianos tradicionais, além da pesquisa de novas drogas e estratégias para sobrepujar o crescente fenômeno da resistência bacteriana aos antimicrobianos.
Silver is known for its antibacterial activity and has been shown to be effective as a potential alternative in the context of bacterial resistance to drugs, particularly in the form of nanoparticles (AgNPs). Our objectives were to evaluate the susceptibility of bacteria against AgNPs and representative survey of synergistic or antagonistic when combined with chitosan (QIT) and antimicrobials for human therapeutic use. A total of eight reference strains were evaluated of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, S. epidermidis and Enterococcus faecalis. The susceptibility patterns were determined by broth microdilution method, according to the CLSI guidelines. The minimum inhibitory concentration (MIC90) of AgNPS to the samples tested was 64μg/mL, while for the combination AgNPs-QIT was 16μg/mL. Considering only antimicrobial activity of QIT, the MIC90 was 16 mg / mL. Among the antimicrobials (meropenem, amikacin, gentamicin, levofloxacin, rifampicin, sulfamethoxazole- trimethoprim, tetracycline, and vancomycin and oxacillin, these only to Gram positive), while the MIC for each bacterial strain is in accordance to the reference CLSI, significant decrease was observed for all tested drugs when combined with AgNPs-QIT. In general, association of AgNPs with QIT or with antimicrobial drugs showed higher inhibitory potential, which may be related to the stability of the polymer associated AgNPs or positive interaction of nanoparticles with antibiotics. The Checkerboard assay was then performed to establish antagonistic or synergistic effects in each combination. The possibility of interaction of AgNPs and QIT with existing antimicrobials is highly relevant and reinforces the recommendations of the literature on the reformulation of traditional antimicrobial use, as well as research into new drugs and strategies to overcome the growing phenomenon of bacterial resistance to antimicrobials.
Cano, Embuena Amalia Isabel. "Different strategies to improve the functionality of biodegradable films based on starch and other polymers." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/55383.
Повний текст джерела[ES] En la Tesis Doctoral, se han analizado diferentes estrategias para mejorar las propiedades funcionales de películas de almidón para aplicaciones de envasado de alimentos: el estudio del ratio amilosa:amilopectina, mezclas con otros polímeros (alcohol de polivinilo-PVA), y la incorporación de diferentes refuerzos (salvado de arroz y nanocristales de celulose-CNCs) y agentes antimicrobianos (aceite de neem-N, aceite esencial de orégano-O y nanopartículas de plata-AgNPs). También se realizó un estudio de biodegradación de las películas observando el efecto de los antimicrobianos. Entre los diferentes almidones con distinto ratio amilosa:amilopectina, se seleccionó el almidón de guisante con altos valores de amilosa. El alto contenido en amilosa dio lugar a películas más rígidas y resistentes a la fractura, con baja permeabilidad al oxígeno, la cual disminuyó durante el almacenamiento. Las películas de mezcla de almidón-PVA (S-PVA) representaron una buena estrategia para mejorar las propiedades de las películas sin incrementar notablemente el precio. La adición de PVA dio lugar a películas menos solubles en agua, menos sensibles a su absorción y más extensible y resistentes que las de almidón puro, mientras mantuvieron alta barrera al oxígeno y dieron estabilidad a la matriz durante el envejecimiento. Son recomendables los ratios de S-PVA cercanos a 1:1. El salvado de arroz con menor tamaño de partícula, mejoró el modulo elástico de las películas, pero su extensibilidad y propiedades barrera empeoraron debido a la mejor capacidad de retención de agua y a las discontinuidades introducidas. La incorporación de CNCs en las películas de S-PVA incrementó la separación de fases de los polímeros, sin cambios en la permeabilidad al vapor de agua, y mejoró las prestaciones mecánicas: películas más rígidas y extensibles, mientras que inhibió parcialmente la cristalización del PVA. Las películas de S-PVA con partículas de plata exhibieron actividad antimicrobiana contra dos hongos y dos bacterias, dependiendo de la concentración de plata. Las AgNPs provocaron cambios en el color de las películas así como en su transparencia. La plata fue completamente liberada en los primeros 60 minutos en contacto con simulantes acuosos, sin embargo la liberación disminuyó en simulantes no polares, donde se cumple el límite de migración global. Por lo tanto, el uso de las películas desarrolladas para envasado de alimentos debe ser restringido a productos alimenticios ricos en grasas. La incorporación de O en la matriz de S-PVA dio lugar a películas activas contra bacterias y hongos, mientras que las películas con N no fueron efectivas. Se necesitaron concentraciones más altas de O en las películas para observar un efecto antifúngico respecto a la actividad bactericida. Los aceites no afectaron notablemente la sensibilidad ni las propiedades barreras al agua de las películas, aunque la mayor proporción de aceite dio lugar a películas con una red más débil, afectando sus prestaciones mecánicas. La mezcla de S con PVA mejoró significativamente el comportamiento de biodegradación y desintegración de las películas. La incorporación de AgNPs a películas de S-PVA disminuyó su cinética de biodegradación mientras aumentó su ratio de degradación. La adición de O no presentó efecto significativo en el índice de biodegradación a pesar de la actividad antimicrobiana detectada. El N incluso mejoró la biodegradación de las películas. Finalmente, se realizó una aplicación de recubrimientos basados en biopolímeros, usando quitosano-CH y aceite esencial de orégano o romero para evitar la pérdida de peso y el desarrollo de hongos en quesos de cabra semicurados. Los recubrimientos fueron efectivos en la reducción del crecimiento fúngico y la pérdida de peso de los quesos, mientras que la actividad lipolítica y proteolítica ligeramente disminuyó. El análisis sensorial reveló q
[CAT] S'han analitzat diferents estratègies per a millorar les propietats funcionals de pel·lícules de midó per a aplicacions d'envasat d'aliments: l'estudi de la ràtio amilosa:amilopectina, mescles amb altres polímers (alcohol polivinílic-PVA), i la incorporació de diferents reforços (segó d'arròs i nanocristalls de celulosa-CNCs) i agents antimicrobians (oli de neem-N, oli essencial d'orenga-O i nanopartícules de plata). També es va fer un estudi de biodegradació de les pel·lícules per observar l'efecte dels antimicrobians. Entre els diferents midons amb distint ràtio amilosa:amilopectina, es va seleccionar el midó de pèsol amb alts valors d'amilosa. L'alt contingut en amilosa va donar lloc a pel·lícules més rígides i resistents a la fractura, amb baixa permeabilitat a l'oxigen, la qual va disminuir durant l'emmagatzemament. Les pel·lícules de mescla de S-PVA van representar una bona estratègia per a millorar les propietats de les pel·lícules sense incrementar notablement el preu. L'addició de PVA va donar lloc a pel·lícules menys solubles en aigua, menys sensibles a la seua absorció i més extensible i resistents que les de midó pur. A més van mantenir l'alta barrera a l'oxigen i van donar estabilitat a la matriu durant l'envelliment. Son recomanables les ràtios de S- PVA pròxims a 1:1. El segó d'arròs amb menor tamany de partícula, va millorar el mòdul elàstic de les pel·lícules, però la seua extensibilitat i propietats barrera van empitjorar. La incorporació de CNCs en les pel·lícules de S-PVA, va incrementar la separació de fases dels polímers, sense implicar canvis en la permeabilitat al vapor d'aigua, però millorant les prestacions mecàniques: pel·lícules més rígides i extensibles, al mateix temps que es va inhibir parcialment la cristal·lització del PVA. Les pel·lícules de S-PVA amb partícules de plata van exhibir activitat antimicrobiana front a dos de fongs i dos bacteris, depenent de la concentració de plata. Les AgNPs van provocar canvis en el color de les pel·lícules així com en la seua transparència. La plata va ser completament alliberada en els primers 60 minuts en contacte amb simulants aquosos. La capacitat d'alliberament va disminuir en simulants no polars, on es complix el límit de migració global. Per tant, l'ús de les pel·lícules desenvolupades per a l'envasat d'aliments ha de ser restringit a productes alimentaris rics en greixos. La incorporació d'O en la matriu de S-PVA va donar lloc a pel·lícules actives front a bacteris i fongs. Pel contrari les pel·lícules amb N no van ser efectives. Van ser necessàries concentracions més elevades d'O en les pel·lícules per a observar un efecte antifúngic respecte a l'activitat bactericida. Els olis no van afectar la sensibilitat a l'aigua ni les propietats barrera a l'aigua de les pel·lícules, però la major proporció d'oli va donar lloc a pel·lícules amb una xarxa més dèbil, afectant les seues prestacions mecàniques. La mescla de S amb PVA va millorar significativament el comportament de biodegradació i desintegració. La incorporació de partícules de plata a pel·lícules de S-PVA va disminuir la seua cinètica de biodegradació mentre que va augmentar la seua ràtio de degradació. No obstant això, l'addició d'O no va presentar un efecte significatiu en els índexs de biodegradació a pesar de l'activitat antimicrobiana detectada. L'N fins i tot va millorar la biodegradació de les pel·lícules de S-PVA. Finalment, es va realitzar una aplicació de recobriments basats en biopolímers, fent ús de quistosà-CH i olis essencials de orenga i romer per evitar la pèrdua de pes i el desenvolupament de fongs en formatges de cabra semi-curats. Els recobriments van ser altament efectius en la reducció del creixement fúngic i la pèrdua de pes dels formatges. L'activitat lipolítica i proteolítica en els formatges va disminuir suaument. L'anàlisi sensorial va revelar que els form
Cano Embuena, AI. (2015). Different strategies to improve the functionality of biodegradable films based on starch and other polymers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/55383
TESIS
Premiado
Gabriel, Juliana dos Santos. "Bionanocompósitos de derivados de quitosana/montmorilonita/nanopartículas de prata preparadas via fotoquímica." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-09082017-154353/.
Повний текст джерелаThe present work presents the synthesis and characterization of chitosan derivatives, as well as the preparation and characterization of nanocomposite films based on commercial chitosan (or its derivatives), clay (MMT) and silver nanoparticles (NPs-Ag) obtained by photochemical method. Therefore, were prepared from commercial chitosan (QC): deacetylated chitosan (Q30des); purified chitosan (QP); partially depolymerized chitosans (QD30, QD21 and QD5); hydrophilic chitosans (QD21-40DEAE and QD5-QD5) and amphiphilic chitosans (QD21-40DEAE-6DD, QD21-40DEAE-18DD, QD5-49DEAE-6DD and QD5-49DEAE-17DD). The deacetylation degrees of QC, QP and Q30des were determined by Nuclear Magnetic Resonance Spectroscopy (1H-NMR). This technique also used to determine the degrees of substitution by DEAE and dodecyl groups. In addition, the biopolymers were characterized by Infrared Spectroscopy (FTIR-ATR), Viscosimetry, Thermogravimetry and Scanning Electron Microscopy. Moreover, the NPs-Ag synthesis under UV radiation was studied on nanocomposite films of commercial chitosan or its derivatives and clay. At first, the Ag-NPs formation was studied on QC films with different formulations and secondarily, on films of chitosan derivatives containing 10 wt % of MMT. The X-Ray Diffraction (XRD) was used to determine the interlamellar spacing of pure montmorillonite clay and in the nanocomposites prepared. The synthesis of the NP-Ag was accompanied by UV-vis Spectroscopy. Its morphological characteristics, as well as the clay dispersion in the nanocomposites were examined by Electron Transmission Electron Microscopy (TEM). Finally, the antimicrobial activities of materials were investigated by the disk diffusion method against the bacteria Escherichia coli e Bacillus subtilis.
Praxedes, Ana Paula Perdigão. "Propriedades termo-ópticas interfaciais e morfológicas de quitosana dopada com nanopartículas de prata." Universidade Federal de Alagoas, 2015. http://www.repositorio.ufal.br/handle/riufal/1680.
Повний текст джерелаO estudo de materiais formados pela associação da quitosana a nanopartículas de prata tem atraído a atenção de pesquisadores de diferentes áreas devido à grande variedade de aplicações destes sistemas, tais como a fabricação de dispositivos eletro-ópticos e o tratamento de doenças como câncer. Apesar da existência de inúmeros trabalhos voltados à caracterização da atividade biológica destes materiais, diversas propriedades físicas ainda não foram devidamente caracterizadas. Neste trabalho, estudaremos as propriedades termo-ópticas, interfaciais e morfológicas de fluidos e filmes baseados em quitosana, considerando os efeitos associados à adição de nanopartículas de prata. Usando uma grande variedade de técnicas experimentais, é investigado como a concentração de nanopartículas de prata altera os processos de difusão de calor, de adesão à fluidos e de fotodegradação nas amostras de quitosana. A partir de medidas de varredura Z resolvida no tempo em soluções de quitosana e nanopartículas de prata, é averiguado como o transporte de calor induzido pela radiação visível incidente é modificado pela inserção da nanopartículas metálicas. Nossos resultado mostram que o coeficiente termo-óptico e a difusidade térmica são sensíveis à variação da concentração de nanopartículas de prata. No que diz respeito às propriedades morfológicas de filmes de quitosana dopada com nanopartículas de prata, é observado que a introdução das partículas hóspedes tende a transformar a estrutura super cial dos lmes, com a formação de grandes aglomerados de nanopartículas. Com relação as propriedades de interfaciais associadas ao fenômeno de molhagem, é observado um comportamento não-monotônico do ângulo de contato de gotículas de óleo de mamona, à medida que a concentração de nanopartículas aumenta. Os parâmetros associados ao fenômeno de molhagem são calculados a partir da análise da evolução temporal do espalhamento das gotas, usando a teoria cinética-molecular. Além disso, os efeitos da concentração de nanopartículas sobre a fotodegradação dos filmes de quitosana dopada são verificados, quando submetidos à radiação eletromagnéticas nas regiões do visível e ultravioleta. Os presentes resultados revelam que o processo de fotodegradação dos filmes depende do comprimento de onda e do regime de excitação utilizado.
Rufino, Cassyo de Araujo. "Uso de quitosana, própolis e nanoprata no tratamento de sementes de arroz." Universidade Federal de Pelotas, 2015. http://repositorio.ufpel.edu.br:8080/handle/prefix/3362.
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Sem bolsa
A utilização de produtos naturais conjuntamente com nanopartículas de prata tem atraído interesse de pesquisadores, tanto do ponto de vista tecnológico quanto cientifico devido à ação desses produtos no controle de doenças e pragas. O objetivo desse trabalho foi testar produtos naturais (associados ou não a nanoprata) com ação antimicrobiana sobre Bipolaris oryzae, in vitro, e no tratamento de sementes de arroz. Para o estudo dos compostos contendo quitina e própolis adicionadas opcionalmente nanoprata foram utilizados sementes de arroz na cultivar IRGA 424 inoculadas com um isolado de Bipolaris oryzae. Os compostos utilizados são naturais, têm propriedades antiadesivas e atividade antimicrobiana contra microrganismos, possuem propriedades biocompatíveis e não fitotóxicas aos vegetais em geral. O processo de sínteses dos compostos contendo própolis, quitina e nanoprata, foi realizado por meio da aplicação de sonicação para a dispersão e mistura entre as substâncias. Foram testados os produtos no desenvolvimento e crescimento do fungo Bipolaris oryzae em placas de petri e em sementes de arroz infectadas. Os tratamentos foram: quitina, própolis, prata, quitina+própolis, quitina+própolis+nanoprata, quitina+prata, própolis+nanoprata e testemunha (T - sementes sem tratamentos), totalizando neste estudo 10 tratamentos. Logo a eficiência dos produtos e suas soluções foram testados por meio do blotter test (teste de sanidade de sementes), porcentagem de inibição e diâmetro de crescimento do fungo, germinação e comprimento de plântulas das sementes tratadas com os produtos. Os resultados demonstram que os oligômeros de quitosana e os compósitos de quitosana com extrato de própolis e nanopartículas de prata controlam o crescimento do patógeno. A importância deste achado reside no fato de que é um passo em direção ao objetivo de diminuir o uso de fungicidas químicos. A partir de testes de germinação poderá concluir-se que os melhores resultados foi o tratamento com quitosano/prata compósito NPs, com uma taxa de germinação de 91%. Os novos materiais poliméricos são considerados como muito promissores para o controle de Bipolaris oryzae no arroz, tornando-se assim alternativas ecológicas aos fungicidas químicos.
The use of natural products in conjunction with silver nanoparticles has attracted interest of many researches, from both scientific and technological point of view due to their action for disease and pests control. The objective was to test natural products (with or without nanosilver) with antimicrobial action against Bipolaris oryzae, in vitro, and in the treatment of rice seeds. To study the compounds containing chitin and propolis optionally added nanosilver rice seeds were used in IRGA inoculated with an isolated 424 Bipolaris oryzae. The compounds used are natural, have anti-adhesive properties and antimicrobial activity against microorganisms, have biocompatible properties and not phytotoxic to plants in general. The process of synthesis of compounds containing propolis, chitin and nanosilver was performed by applying the sonication for the dispersion and mixing of the substances. Products were tested on the development and growth of Bipolaris oryzae fungus in petri dishes and infected rice seeds. The treatments were: chitin, propolis, silver, chitin + propolis, chitin + Propolis + nanosilver, chitin + silver, propolis + nanosilver and control (T - treatments seeded), totaling 10 treatments in this study. The results were conclusive in showing that chitosan oligomers and the composites of chitosan with propolis extract and silver nanoparticles led to a remarkable reduction in growth of the pathogen. The importance of this finding lies in the fact that it is a step towards the goal of decreasing the use of chemical fungicides in plant pathology. From germination tests it could be concluded that the best results was the treatment with chitosan/silver NPs composite, with a germination rate of 91%. The novel polymeric materials can thus be deemed as very promising for the control of the Bipolaris oryzae of rice and pave the way towards eco-friendly alternatives to chemical fungicides.
SOLANKI, REENA. "PREPARATION, CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF CHITOSAN-SILVER NANOPARTICLE BY GREEN APPROACH." Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15289.
Повний текст джерелаWang, Lung-Shuo, and 王隆碩. "Novel Synthesis and Application of Silver Nanoparticles-Chitosan Composite Particles." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/94628028759663679029.
Повний текст джерела義守大學
電機工程學系
103
Silver nanoparticles (AgNPs) have been widely applied in various fields including nanotechnology, biotechnology, and medical industry. In order to reduce the AgNPs potential toxicity for human body, various synthesis strategies have been developed in recent years. The stability and distribution characteristics of the synthesized AgNPs are two crucial parameters in synthetic techniques. In our study, we established two synthetic systems to fabricate AgNPs-embedded chitosan particles with different size scales. In the first system, a novel approach for the one-step synthesis of AgNPs-embedded chitosan particles was proposed by using the pump-driven syringe method. The method was planned to simultaneously obtain and stabilize AgNPs in chitosan polymer matrix in situ, and the product was called silver nanoparticles-chitosan composite particles (Ag@chitosan). The diameters of the synthesized Ag@chitosan spheres ranged from 1.7 to 2.5 mm, and those of embedded AgNPs were measured to be 15±3.3 nm. Furthermore, we utilized various instruments to analyze the characteristics of the prepared Ag@chitosan spheres including the ultraviolet-visible absorbance spectrophotometer (UV-Vis), Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), energy dispersive spectroscopy (EDS), scanning electron microscope (SEM), and transmission electron microscope (TEM). The results showed that the AgNPs were homogeneously distributed over the chitosan sphere, and these synthesized spheres possessed porous structure that could be utilized in multiple fields. Then, the antifungal effect of the Ag@chitosan spheres was evaluated, and it was found that they could inhibit the growth of Cordyceps militaris (Cm) but not Antrodia cinnamomea (Ac). Ac is an important cash crop with highly economic value in Taiwan, and our products might be an option to become a beneficial additive for cultivating Ac by inhibiting other fungi and bacteria. In the second system, we developed the microfluidic chip device made by Polymethyl methacrylate (PMMA) to synthesize the Ag@chitosan spheres with micrometer scale. The diameters of the Ag@chitosan spheres synthesized by the microfluidic method ranged from 262 to 558 μm, and their sizes could be controlled by altering the concentration of chitosan, concentration of NaOH, flow rate of continuous phase, and flow rate of dispersed phase. Moreover, we utilized various instruments to analyze the characteristics of the prepared Ag@chitosan spheres including the UV-Vis spectrophotometer, FTIR spectrometer, EDS, and SEM. The results showed that the AgNPs were also homogeneously distributed and the sphere structure was also porous as expected. In order to assess the possible toxicity of Ag@chitosan for human cells, we executed the MTT assay on both NIH-3T3 and MCF-7 cell lines. The results demonstrated that there was no observable toxicity even if the concentration of Ag@chitosan up to 1000μg/mL. Furthermore, the antibacterial effect of Ag@chitosan was evaluated by using Escherichia coli (E. Coli) broths, and the results showed that E. Coli growth could be inhibited by Ag@chitosan with dose-dependent relationship. Generally speaking, we have established two novel systems to synthesize homogeneous and stable AgNPs embedded in the chitosan particles successfully, and have confirmed the product to be highly biocompatible, non-toxic, antibacterial, and antifungal. Our synthetic systems and the synthesized products will provide a novel option of the antimicrobial research, and may be utilized in medicine and other fields in the future.
DhyahAnnur and 涂黛亞. "Plasma- synthesized Silver Nanoparticles Embedded in the Electrospun Chitosan Nanofibers." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/51357685889463485808.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
100
Chitosan, known as sustainable materials with high metal binding activity and potential antibacterial properties is a promising natural polymer for high performance filtration. In case of “environmental concern”, creating an antibacterial material with a “green technology” and is an urgent. Through this research, low pressure plasma is used to synthesize silver nanopaticles in electrospinning chitosan nanofibers. Low pressure plasma offers way to reduce the usage of toxic chemical, time efficiency, and lower temperature processing in compare to other method such as chemical reduction, thermal, and UV- irradiation. This incorporation is expected to increase antibacterial properties of chitosan nanofibers. Chitosan nanofibers had been successfully electrospun on pvc grid from 5.4% w/v of chitosan and 0.6% PEO. Fibers diameter was 136 nm ± 18% without bead structures. AgNO3 addition up to 2% did not significantly change chitosan nanofibers diameter. Plasma treatment reduced Ag+ from AgNO3 precursor into Ag0 so that Ag nanoparticles were created. Besides, plasma also etched chitosan nanofibers so that reduction of fibers diameter is observed. UV- visible spectroscopy and XPS analysis revealed silver intensity will be increasing proportionally with plasma treatment time. XPS analysis also observed interaction between chitosan and Ag nanoparticles (N--Ag). Furthermore, TEM evaluation showed particle size average after 1.5 minutes plasma treatment was 1.5 nm in average. By addition of Ag nanoparticles, antibacterial activity of chitosan nanofibers could be enhanced.
Wang, Wen-Chieh, and 王文傑. "Preparation and analysis of silver nanoparticles in the Carboxymethyl chitosan solution." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/67004237298945285302.
Повний текст джерела明志科技大學
化學工程研究所
101
The carboxymethyl chitosan is an amphiprotic ether derivative, which contains carboxyl, hydroxyl and amine groups in the molecule, and makes it possible to offer enough chelate groups. The carboxymethyl chitosan has a higher chelation capacity than chitosan, which has potential implications for improved Ag nanoparticle formation and immobilization. By adjusting the concentration of carboxymethyl chitosan, and the reduction temperature and time of silver nanoparticles, the silver nanoparticle solution with optical properties could be synthesized. Observations through a UV-Vis absorption spectrometer discovered that the Ag nanoparticle solution had a surface plasmon absorption peak of 400 nm. Under optimal conditions, transmission electron microscopy analysis showed that the size of Ag nanoparticles was in the range from 5 to 10 nm, and the uniform dispersion. The synthesized Ag nanoparticle solution was stable; its optical properties do not change over time. When adding solutions of different metal ions (Pb2+, Ni2+, Cr3+, Co2+, Cu2+, Cd2+, Hg2+) to the silver nanoparticle solution, observations discovered that only Hg2+ions would cause the surface plasmon absorption peak of the silver nanoparticles to displace and decrease. It was possible to use these changes in optical properties for the detection of mercury ions (Hg2+).
Chen, Chia-Lin, and 陳佳琳. "Physicochemical Property of the Chitosan/ Carboxymethyl Cellulose Hydrogels Containing Silver Nanoparticles." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/56801905429108377043.
Повний текст джерела亞東技術學院
應用科技研究所
100
The research prepared silver nanoparticles by NaBH4 chemical reduction method, and it were added to blending hydrogel by chitosan (Ch)/carboxymethyl cellulose (CMC):(ChxCy) to prepare GCwChxCyAgz polymer solutions and membranes at last by adjusting pH and concentration of silver nanoparticles and genepin, and analyzed with UV-Vis, FTIR-ATR spectrum, DSC, mechanical properties, SEM morphology and antibacterial test. UV-Vis spectrums reveal that CMCAg3 stabilizer works on dispersibility of silver nanoparticles and better than ChAg3 stabilizer. Besides, polymer solution of low concentration of (Ch5C1)0.25Ag3 shows supreme absorbance (1.91). Ionic strength decreases with concentration of ionic stabilizer, but dispersibility of silver nanaparticles increases and obtains miniaturization. FTIR-ATR spectrums show that the highest hydrogen bond strength of 1.0wt%Ch1C1 membrane, it provides with approximate hydrogen bond sites. The sample of ChxCyAgz membrane displays absorption (1595cm-1) of COO- of CMC and NH3+ of chitosan ,and both rising substantially. Ag+ destroyed the ionic bond between COO- and NH3+ by electrostatic attraction and valence electrons of O, N. In addition, because of silver nanoparticles were added to Ch5C1 and Ch1C1 membrane, it resulting intercalation reaction with CMC and Ch sites of matrices, hydrogen bond strength descends sharply. Blend hydrogel cross-linking by genipin shows that tertiary amine (1262 cm-1 and 1735 cm-1) of six-ring diene three nitrogen amine absorption peaks and of C=O of ester group raises, would get membrans in blue. DSC thermal characterizations show that Tm and enthalpy of blend hydrogen membrane in first amd secondary heating that it’s higher than both of CMC and Ch, it means hydrogel blends well and make new interaction, and Ch1C1 membrane is the best. 0.3mM of Ag added to blend hydrogel that its sites were occupied and ionic bond attraction were destruct. Mechanical property tests suggest that (Ch1C1)0.1 membrane has the highest tensile strength (59.37 MPa) and elongation (36%). Young’s modulus ,tensile strength and elongation of 1.0wt% (Ch1C1)Ag3 membrane which is still better than others after addition of silver nanoparticles. But young’s modulus and tensile strength of 1.0wt%Ch3C1Ag2 and 1.0wt%Ch5C1Ag2 membranes enhance obviously, it’s similar to 0.5wt%Ch5C1Ag2 membrane, and it obtained the highest tensile strength (85.24MPa). Tensile strength of blend cross-linking hydrogel will increase with concentration of chitosan and cross-linking agent, but elongation is contrary. SEM observations show that irregular surface of CMC and many particles spreaded on it that it is cause of weak acid. CMC surface attracted and covered with silver nanoparticles by electrostatic attraction or chelating that it made many raised globes, otherwise cross-linking CMC surface was pocked that it is cause of bond strength shortened the distance. Antibacterial test results show that inhibition rate of Staphylococcus aureus increases with concentration of chitosan and time. In conclusion, the inhibition rate is about 96.09-100% when contacted with Staphylococcus aureus for 6 hours.
Yang, Ya Ru, and 楊雅如. "Evaluation of Sulfated Chitosan Oligosaccharides/Silver Nanoparticles for the Treatment of Bacterial Keratitis." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ezhumt.
Повний текст джерелаZhi-KaiWang and 王致凱. "Dual-Supplied Electrospinning of Chitosan Nanofibers with Plasma-Synthesized and Surface-Immobilized Silver Nanoparticles." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/43835305248642166557.
Повний текст джерела國立成功大學
材料科學及工程學系
104
Plasma-synthesized silver nanoparticles (Ag NPs) were immobilized on the surface of chitosan-based nanofibers fabricated by two kinds of dual-supplied electrospinning processes. In the first fabrication approach, the dual-supplied electrospinning was conducted by two flows that carried the chitosan and the crosslinking agent separately. The two flows were mixed right before the ejection of the electrospinning solutions. The second approach involved the use of a lab-made co-axial nozzle that constructed the chitosan nanofiber cores and the poly(ethylene oxide) (PEO) outer sheath which also carried the crosslinking agent and the silver precursor. Electrospinning processes were carefully investigated in this research project. The resulting chitosan nanofibers with an average fiber diameter as small as about 135 nm were then treated with the argon plasma bombardment. Silver precursors, the silver nitrate, within the chitosan nanofibers were converted to metallic Ag NPs, which were immobilized on the surface of these nanofibers. Water resistance confirmed these robust chitosan nanofibers, as well as the stabilities of surface-immobilized Ag NPs. Following antibacterial tests based on the water filtration apparatus were investigated. And the antibacterial performance of these electrospun chitosan nanofibers were proportionally enhanced by the population of the surface-immobilized Ag NPs.
張香偉. "Studying of Burn Injury Wound Dressing of Chitosan Based Thermosensitive Hydrogel Containing Silver Nanoparticles." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/01455441692771997173.
Повний текст джерелаGhosh, Somnath. "Investigation On Ag And ZnO Based Nanohybrids As Bactericides For The Purification Of Water And Elucidation Of Possible Mechanisms For Their Bio-activity." Thesis, 2012. https://etd.iisc.ac.in/handle/2005/2492.
Повний текст джерелаGhosh, Somnath. "Investigation On Ag And ZnO Based Nanohybrids As Bactericides For The Purification Of Water And Elucidation Of Possible Mechanisms For Their Bio-activity." Thesis, 2012. http://hdl.handle.net/2005/2492.
Повний текст джерелаGanadhas, Divya Prakash. "From Transformation to Therapeutics : Diverse Biological Applications of Shock Waves." Thesis, 2014. https://etd.iisc.ac.in/handle/2005/3182.
Повний текст джерелаGanadhas, Divya Prakash. "From Transformation to Therapeutics : Diverse Biological Applications of Shock Waves." Thesis, 2014. http://hdl.handle.net/2005/3182.
Повний текст джерела