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The effect of silver nanoparticles: a chronic in vivo study for the evaluation of hepatic mitochondrial toxicity

Silva, Rui Gonçalo Teixeira da
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Dissertação de Mestrado
ENG
Relevância na Pesquisa
66.7%
Manufactured nanomaterials have been of extreme importance due to the beneficial physicochemical properties they possess compared to bulk parental materials. However, the properties that make them so attractive are also the same that can cause harm both to humans and environment. Over the last years there has been a rapid development of the nanotechnology industry and the inevitable human exposure tends rapidly to expand, accompanied by potential for adverse health effects. Among all used nanoparticles (NPs), silver nanoparticles (AgNPs) have the highest level of commercialization. Silver has been used for decades in medical healthcare due to its known antibacterial properties. One can also observe AgNPs in products used daily such as cosmetics, lotions, toothpastes, soaps, sunscreen, clothing and electronics. Over the last years, nanoparticles have been the subject of intense research for use in biomedicine, namely as biosensors, drug-delivery agents and imaging contrast agents, which take advantage of their unique optical properties. Human exposure to AgNPs can occur through different ways: inhalation, ingestion, injection and dermal contact. As a major organ of detoxification, the liver is one of the most important targets after AgNPs exposure. The main toxicological concern is the fact that AgNPs preferentially accumulate in mitochondria. Since mitochondria have an essential bioenergetic function...

Tolerance and co-tolerance of microbial communities on leaf litter to silver nanoparticles and antibiotics

Kuburić, Marina
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Dissertação de Mestrado
ENG
Relevância na Pesquisa
66.66%
Antibiotics and silver nanoparticles present emerging toxicants, more and more present in freshwater, due to their increase use in medicine and for other purposes. Th e aim of this work was to evaluate the eff ects of long-term exposure to silver nanoparticles (AgNP), silver nitrate (AgNO3) and a mixture of fi ve antibiotics (AB) on the pollution-induced community tolerance (PICT) of microbes colonizing leaf litter in streams. Furthermore, I aimed to assess the specifi city of PICT by evaluating the occurrence of co-tolerance between AgNP, AgNO3 and AB. Tolerance of pre-exposed and control communities to the toxicants were assessed in short-term bioassays by determining bacterial production measured as 14C-leucine incorporation into protein and by estimating fungal sporulation rate determined by microscopic counts of spores induced during 12 hour incubations of decomposing leaves in distilled water. In addition, I estimated fungal diversity based on microscopic identifi cation of spores produced by both control and pre-exposed communities.Th e bacterial communities pre-exposed to silver nanoparticles, silver nitrate and antibiotics increased their tolerance to these toxicants, and co-tolerance between the toxicants also occurred. In contrast to bacteria...

Hybrid nanocomposites containing carboxymethylcellulose and silver nanoparticles

Moura, Márcia R.; Aouada, Fauze A.; Mattoso, Luiz H. C.; Zucolotto, Valtencir
Fonte: American Scientific Publishers - ASP; Valencia Publicador: American Scientific Publishers - ASP; Valencia
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.67%
Silver nanoparticles have high temperature stability and low volatility, and at the nanoscale are known to be an effective antifungal and antimicrobial agent. The present investigation involves the synthesis of silver nanoparticle/carboxymethylcellulose nanocomposites. The nanoparticles synthesised in this study had sizes in the range of 100 and 40 nm. The nanocomposites formed by a combination of metallic nanoparticles and carboxymethylcellulose were characterised by contact angle measurements, solubility tests, thermal and mechanical analyses, and morphological images. Improvements in the hydrophobic properties were observed with inclusion of the nanoparticles in the nanocomposites, with the best results occurring after the addition of 40 nm nanoparticles in a carboxymethylcellulose matrix. The silver nanoparticles tend to occupy the empty spaces in the pores of the carboxymethylcellulose matrix, inducing the collapse of these pores and thereby improving the tensile and barrier properties of the film.; FINEP / MCTI; EMBRAPA (Rede AgroNano); FAPESP; CNPq; CAPES

Modulação de fluorescência de amino coumarinas e acridinas por nanopartículas de prata; Fluorescence modulation of acridine and coumarin dyes by silver nanoparticles

Sabatini, Carolina Aparecida
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/08/2007 PT
Relevância na Pesquisa
66.72%
Nanopartículas de prata foram preparadas pela redução química de íons prata (AgNO3) por borohidreto de sódio (NaBH4) na presença de poli-(N)-vinil-2-pirrolidona em solução de álcoois de cadeia curta. As nanopartículas de prata apresentaram maior estabilidade em 2- propanol, e o diâmetro aproximado das nanopartículas Ag0 obtidas neste solvente é de aproximadamente 6 nm. As propriedades fotofísicas dos corantes coumarinas e derivados de acridina, em 2-propanol, são afetados pela presença das nanopartículas de prata. A interação das nanopartículas de prata com os derivados de acridina leva a uma mudança espectral da banda de absorção de transferência de carga intramolecular ´ICT - intramolecular charge transfer´. Para dois dos derivados de acridina, há um aumento significativo de emissão com a adição inicial de nanopartículas de Ag0. Mas em altas concentrações de nanopartículas de prata, ocorre supressão estática de fluorescência, com uma progressiva diminuição da eficiência de fluorescência. A intensidade de fluorescência das amino coumarinas é somente suprimida pela presença de nanopartículas de prata em solução.; Silver nanoparticles were synthesized by chemical reduction of silver ions by sodium borohydride in the presence of poly-(N)-vinyl-2-pyrrolidone in solution of short chain alcohols. The nanoparticles are stable in 2-propanol...

Síntese e caracterização de compósitos de nanotubos de carbono e nanopartículas de prata e sua aplicação como substrato SERS; Synthesis and characterization of composites of carbon nanotubes and silver nanoparticles and their application as SERS substrate

Lima, Leandro Holanda Fernandes de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/08/2013 PT
Relevância na Pesquisa
66.7%
Neste trabalho foram produzidos compósitos de nanotubos de carbono contendo nanopartículas de prata, os quais foram testados como substratos SERS (Surface-enhanced Raman Spectroscopy) na detecção do cristal violeta. Para obter tais compósitos foram necessárias modificações de nanotubos de carbono através de funcionalizações químicas para inserção de grupos carboxila e tiol, capazes de interferir no crescimento de nanopartículas metálicas através de um processo de redução térmica do acetato de prata sobre a superfície das amostras de nanotubo. Para a preparação de tais compósitos foram utilizadas duas amostras de nanotubos, uma de parede simples (SWNT) e outra de paredes múltiplas (MWNT) a fim de avaliar diferenças nos tamanhos e homogeneidade das nanopartículas formadas. Utilizou-se como ferramenta investigativa a espectroscopia Raman na caracterização destes compósitos, que forneceu informações sobre interação dos nanotubos de carbono com as nanopartículas de prata e mudanças estruturais ocasionadas durante a gama de funcionalizações. Para avaliar a morfologia dos compósitos foi utilizada a microscopia eletrônica de varredura (MEV) e a microscopia eletrônica de transmissão (TEM) que forneceram informações sobre o tamanho e a disposição das nanopartículas formadas através do tratamento térmico dos nanotubos com acetato de prata. Os compósitos preparados foram aplicados como substrato SERS na detecção do cristal violeta. Nesta aplicação foi avaliada a capacidade dos nanotubos em adsorver estas moléculas e o potencial do substrato na intensificação do espectro Raman do analito. Observou-se que a adsorção do cristal violeta sobre uma amostra de SWNT foi máxima após o tempo de 60 minutos de agitação. Já o substrato utilizado (SWNT-COOH@Ag) permitiu a detecção do cristal violeta em solução aquosa com concentração de até 1...

Tissue Reaction to Silver Nanoparticles Dispersion as an Alternative Irrigating Solution

Gomes-Filho, Joao Eduardo; Silva, Fernando Oliveira; Watanabe, Simone; Angelo Cintra, Luciano Tavares; Tendoro, Karina Vanessa; Dalto, Luana Godoy; Pacanaro, Sara Vieira; Lodi, Carolina Simonetti; Ferreira de Melo, Fernanda Fragoso
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Conferência ou Objeto de Conferência Formato: 1698-1702
ENG
Relevância na Pesquisa
66.7%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 09/16069-4; Introduction: Nanomaterials have been used to create new consumer products as well as applications for life sciences and biotechnology. The aim of this study was to evaluate the tissue response to implanted polyethylene tubes filled with fibrin sponge embedded with silver nanoparticles dispersion. Methods: Thirty rats received individually 4 polyethylene tubes filled with sponge embedded in 47 ppm, 23 ppm silver nanoparticles dispersion, 2.5% sodium hypochlorite, or with no embedding as control. The observation periods were 7, 15, 30, 60, and 90 days. After each period of time, 6 animals were killed, and the tubes and surrounding tissue were removed, fixed, and prepared to be analyzed in light microscope with glycol methacrylate embedding, 3-mu m serial cutting, and hematoxylineosin stain. Qualitative and quantitative evaluations of the reactions were performed. Results: Both materials caused moderate reactions at 7 days. The response was similar to the control on the 15th day with 23 ppm silver nanoparticles dispersion and 2.5% sodium hypochlorite and on the 30th day with 47 ppm silver nanoparticles dispersion. Conclusions: It was possible to conclude that silver nanoparticles dispersion was biocompatible especially in a lower concentration. (J Endod 2010;36:1698-1702)

The effect of silver nanoparticles and nystatin on mixed biofilms of Candida glabrata and Candida albicans on acrylic

Silva, Sónia; Pires, Priscila; Monteiro, Douglas R.; Negri, Melyssa; Gorup, Luiz F.; Camargo, Emerson R.; Barbosa, Débora B.; Oliveira, Rosário; Williams, David W.; Henriques, Mariana; Azeredo, Joana
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 178-184
ENG
Relevância na Pesquisa
66.72%
The aim of this study was to compare biofi lm formation by Candida glabrata and Candida albicans on acrylic, either individually or when combined (single and dual species) and then examine the antimicrobial effects of silver nanoparticles and nystatin on these biofi lms. Candidal adhesion and biofi lm assays were performed on acrylic surface in the presence of artifi cial saliva (AS) for 2 h and 48 h, respectively. Candida glabrata and C. albicans adherence was determined by the number of colony forming units (CFUs) recovered from the biofi lms on CHROMagar ® Candida . In addition, crystal violet (CV) staining was used as an indicator of biofi lm biomass and to quantify biofi lm formation ability. Pre-formed biofi lms were treated either with silver nanoparticles or nystatin and the effect of these agents on the biofi lms was evaluated after 24 h. Results showed that both species adhered to and formed biofi lms on acrylic surfaces. A signifi cantly ( P < 0.05) higher number of CFUs was evident in C. glabrata biofi lms compared with those formed by C. albicans . Comparing single and dual species biofi lms, equivalent CFU numbers were evident for the individual species. Both silver nanoparticles and nystatin reduced biofi lm biomass and the CFUs of single and dual species biofi lms ( P < 0.05). Silver nanoparticles had a signifi cantly ( P < 0.05) greater effect on reducing C. glabrata biofi lm biomass compared with C. albicans . Similarly...

Hybrid nanocomposites containing carboxymethylcellulose and silver nanoparticles

De Moura, Márcia R.; Aouada, Fauze A.; Mattoso, Luiz H.C.; Zucolotto, Valtencir
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1946-1950
ENG
Relevância na Pesquisa
66.72%
Silver nanoparticles have high temperature stability and low volatility, and at the nanoscale are known to be an effective antifungal and antimicrobial agent. The present investigation involves the synthesis of silver nanoparticle/carboxymethylcellulose nanocomposites. The nanoparticles synthesised in this study had sizes in the range of 100 and 40 nm. The nanocomposites formed by a combination of metallic nanoparticles and carboxymethylcellulose were characterised by contact angle measurements, solubility tests, thermal and mechanical analyses, and morphological images. Improvements in the hydrophobic properties were observed with inclusion of the nanoparticles in the nanocomposites, with the best results occurring after the addition of 40 nm nanoparticles in a carboxymethylcellulose matrix. The silver nanoparticles tend to occupy the empty spaces in the pores of the carboxymethylcellulose matrix, inducing the collapse of these pores and thereby improving the tensile and barrier properties of the film. Copyright © 2013 American Scientific Publishers All rights reserved.

Moderating effect of ammonia on particle growth and stability of quasi-monodisperse silver nanoparticles synthesized by the Turkevich method

Gorup, Luiz F.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 355-358
ENG
Relevância na Pesquisa
66.66%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 2007/58891-7; A new method to stabilize silver nanoparticles by the addition of ammonia is proposed. Colloidal dispersions of silver nanoparticles were synthesized by the Turkevich method using sodium citrate to reduce silver nitrate at high pH and at 90 °C. After approximately 12 min, a diluted ammonia solution was added to the reaction flask to form soluble diamine silver (I) complexes that played an important growth moderating role, making it possible to stabilize metallic silver nanoparticles with sizes as small as 1.6 nm after 17 min of reaction. Colloidal dispersions were characterized by UV-visible absorption spectroscopy, X-ray diffraction, and transmission electronic microscopy.

Nanopartículas poliméricas e de prata : avaliação da toxicidade in vitro e in vivo e do processo de cicatrização em animais submetidos à queimadura térmica; Polymeric and silver nanoparticles : in vitro and in vivo toxicity and evaluation of the healing process in animals subjected to thermal burn

Larissa Barbosa de Paula
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/02/2013 PT
Relevância na Pesquisa
66.61%
Queimaduras representam um problema de saúde pública, gerando um gasto anual de cerca de R$ 55 milhões ao Sistema Único de Saúde (SUS). Os produtos destinados ao tratamento de queimaduras são em sua grande maioria importados, tornando relevantes estudos que visem ao desenvolvimento de materiais com características adequadas ao tratamento e produzidos a partir de matérias-primas de baixo custo e fácil obtenção. O objetivo deste trabalho foi avaliar os possíveis efeitos tóxicos e o potencial de cicatrização de S-Nitrosoglutationa (GSNO) encapsulado em nanopartículas poliméricas (alginato-quitosana e poli (?-caprolactona) (PCL) recobertas por quitosana) e de nanopartículas de prata (AgNPs). O GSNO foi sintetizado através de reação de S-Nitrosação direta de glutationa e caracterizado por espectrofotometria. As nanopartículas de alginato-quitosana (AG/CS) contendo GSNO foram preparadas através do método de gelificação iônica. As nanopartículas de PCL recobertas por quitosana (PCL/CS) e contendo GSNO foram preparadas através do método de dupla emulsão (água/óleo/água) e evaporação do solvente. Ambas as nanopartículas foram caracterizadas por espectroscopia de correlação de fótons (ECF) e microscopia eletrônica de varredura (MEV). As AgNPs foram produzidas extracelularmente por método biotecnológico utilizando-se o fungo Fusarium oxysporum e caracterizadas por ECF e microscopia eletrônica de transmissão (MET). A toxicidade in vitro das nanopartículas foi avaliada através de ensaios de citotoxicidade utilizando-se cultura de células de linhagens pré-estabelecidas e o potencial de cicatrização foi avaliado através de indução de queimadura térmica em ratos Wistar machos...

Citotoxicidade, endocitose e processamento celular de nanopartículas biossintéticas de prata em macrófagos peritoneais; Cytotoxicity, endocytosis and cell processing of biogenic silver nanoparticles in peritoneal macrophages

Luiz Alberto Bandeira Ferreira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/02/2015 PT
Relevância na Pesquisa
66.75%
A nanomedicina se tornou uma promessa de profundos impactos para a saúde humana através da utilização de nanopartículas, nanorobôs e outros nanomateriais para prevenir, diagnosticar ou curar doenças. Um dos exemplos de nanomateriais empregados na medicina são as nanopartículas de prata, que podem ser adquiridas por métodos químicos ou biossintéticos. As nanopartículas de prata apresentam alta atividade antimicrobiana, propriedade essa de grande interesse científico-industrial. Em vista disso, cresce também a preocupação em relação ao uso, manipulação e eliminação desse nanomaterial, visando uma aplicação mais segura. Diante dessas informações, o presente trabalho teve como objetivo investigar mecanismos moleculares envolvidos na citotoxicidade e processamento das nanopartículas biossintéticas de prata em macrófagos peritoneais obtidos de camundongos C57BL/6. Inicialmemte, demonstrando que as nanopartículas atingiram o IC50 de 25 µM em 6h de tratamento por redução do MTT. A análise de microscopia de fluorescência revelou alterações na integridade de membrana a partir de 3 h, que foram agravadas após 6 h de tratamento. Esse mesmo perfil foi observado por microscopia eletrônica de varredura, no qual revelou que após 3 h de tratamento as células já apresentavam perda de projeções celulares...

Antifungal activity against Trichophyton rubrum of inorganic vs. biogenic silver nanoparticles produced by filamentous fungi

Pereira, Leonel João Pais; Dias, Nicolina Marques; Fernandes, Sara; Santos, Cledir; Lima, Nelson
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2013 ENG
Relevância na Pesquisa
66.72%
The dermatophytoses are skin diseases caused by dermatophytes, which have the highest incidence worldwide with an estimation of 20 to 25% of the population infected [1]. Although the condition is relatively benign and easy to treat, dermatophytoses are often associated with relapses after antifungal therapy. Besides that prophylaxis with antifungals may lead to the emergence of resistant strains, there is a pressing need to search for a new generation of antifungal agents. The fungi have important and favorable characteristics for the production of nanoparticles, such as tolerance and metal bioaccumulation potential, as compared with other microorganisms, and could be used as an ecological or "green" altemative to chemical and physical methods for the production of metal nanoparticles. Due to their antimicrobial properties silver nanoparticles are produced to incorporate an increasing number of consumer products and medical devices. The present study was undertaken to investigate the antifungal activity of inorganic versus biogenic nanoparticles produced by Aspergillus oryzae MUM 97.19 and Penicillium chrysogenum MUM 03.22 comparing with conventional antifungal drugs, terbinafine, itraconazole and fluconazole. The antifungal activity was tested against eight clinical strains of Trichophyton rubrum and the reference strain T. rubrum ATCC MYA-4438. Biogenic nanoparticles from A. ozyzae MUM 97.19 and P. chrysogenum MUM 03.22 showed an average size ranging between 19-51 nm and 51-85 nm...

Silver nanoparticles flow in an aquatic trophic chain; O fluxo de nanopartículas da prata numa cadeia trófica aquática

Ribeiro, Fabianne de Araújo
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
66.66%
Silver nanoparticles (AgNP) have been produced and applied in a variety of products ranging from personal care products to food package containers, clothing and medicine utilities. The antimicrobial function of AgNP makes it very useful to be applied for such purposes. Silver (Ag) is a non-essential metal for organisms, and it has been historically present in the environment at low concentrations. Those concentrations of silver increased in the last century due to the use of Ag in the photographic industry and lately are expected to increase due to the use of AgNPs in consumer products. The presence of AgNP in the aquatic environment may pose a risk for aquatic species, and the effects can vary from lethal to sublethal effects. Moreover, the contact of aquatic organisms with AgNP may not cause immediately the death of individuals but it can be accumulated inside the animals and consequently transferred within the food chain. Considering this, the objective of this work was to study the transfer of silver nanoparticles in comparison to silver ions, which was used as silver nitrate, within an aquatic food chain model. To achieve this goal, this study was divided into four steps: the toxicity assessment of AgNP and AgNO3 to aquatic test-species...

Characterization of poly-{trans-[RuCl2(vpy)4 ]-styrene-4-vinylpyridine} impregnated with silver nanoparticles in non aqueous medium

Segala,Karen; Dutra,Rosilene L.; Oliveira,Eric N. de; Rossi,Liane M.; Matos,Jivaldo R.; Paula,Marcos M. S.; Franco,César V.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 EN
Relevância na Pesquisa
66.64%
The synthesis and characterization of a new polymeric material composed of poly-{trans-[RuCl2(vpy)4 ]-styrene-4-vinylpyridine} impregnated with silver nanoparticles are here described. This material was obtained by a non aqueous polymerization reaction involving trans-[RuCl2(vpy)4], styrene (sty) and 4-vinylpyridine (4-vpy), using benzoyl peroxide as initiator. The silver particles nanometric dimensions were confirmed by transmission electron microscopy (TEM) and UV-visible spectroscopy. The terpolymer morphology was characterized by scanning electron microscopy (SEM). Thermal properties were analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The antimicrobial action of the polymer impregnated with silver nanoparticles was evaluated by the use of Gram positive and Gram negative microorganisms, Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), respectively. The antimicrobial activity of the terpolymer with silver nanoparticles was confirmed by the presence of a bacterial growth inhibition halo in seeded culture media.

Potential use of silver nanoparticles on pathogenic bacteria, their toxicity and possible mechanisms of action

Durán,Nelson; Marcato,Priscyla D.; Conti,Roseli De; Alves,Oswaldo L.; Costa,Fabio T. M.; Brocchi,Marcelo
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
66.71%
The antimicrobial properties of silver have been known for thousands of years. Recently, silver nanoparticles have gained attention because of their antimicrobial activity which offers the possibility of their use for medical and hygiene purposes. Indeed, silver nanoparticles in different formulations and with different shapes and sizes exhibit variable antimicrobial activity. However, the mechanisms of antimicrobial activity of silver ions and silver nanoparticles, and their toxicity to human tissues are not fully characterized. This review evaluates the potential use of silver nanoparticles to control pathogens with emphasis on their action against pathogenic bacteria, their toxicity and possible mechanisms of action.

Screening of different Fusarium species to select potential species for the synthesis of silver nanoparticles

Gaikwad,Swapnil C.; Birla,Sonal S.; Ingle,Avinash P.; Gade,Aniket K.; Marcato,Priscyla D.; Rai,Mahendra; Duran,Nelson
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
66.72%
Eleven different Fusarium species were isolated from various infected plant materials and screened to select a potential species for the synthesis of silver nanoparticles. All the isolates were identified on the basis of cultural and microscopic characteristics using Fusarium identification keys. For the confirmation of preliminary identified isolates of Fusarium species, online BLAST analysis was carried out. All the eleven species demonstrated the ability for synthesis of silver nanoparticles. This was confirmed by UV-Vis spectroscopy, which gave characteristic peak around 420 nm. Further confirmation of silver nanoparticles was carried out using nanoparticles tracking analysis (NTA), zeta potential, photon correlation spectroscopy (PCS), powder X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The smallest size of silver nanoparticles was synthesized by F. oxysporum (3-25 nm) and largest size silver nanoparticles were synthesized by F. solani (3-50 nm).

Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp.

Thomas,Roshmi; Janardhanan,Anju; Varghese,Rintu T.; Soniya,E.V.; Mathew,Jyothis; Radhakrishnan,E.K.
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
Relevância na Pesquisa
66.78%
Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi...

Green synthesis and characterization of silver nanoparticles produced using 'Arbutus Unedo' leaf extract

Kouvaris, P; Delimitis, A; Zaspalis, V; Papadopoulos, D; Tsipas, Sophia Alexandra; Michailidis, N
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article
Publicado em /06/2012 ENG
Relevância na Pesquisa
66.7%
Metallic nanoparticles have received great attention from chemists, physicists, biologists and engineers who wish to use them for the development of a new generation of nanodevices. In the present study silver nanoparticles were synthesized from aqueous silver nitrate through a simple and eco-friendly route using leaf broth of Arbutus unedo, which acted as a reductant and stabilizer simultaneously. The aqueous silver ions when exposed to the leaf broth were reduced and stabilized over long periods of time resulting in the green synthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were appropriately characterized. The results revealed the formation of single crystalline Ag nanoparticles with a narrow size distribution for each sample. The particles, although discrete, were predominately coated with the organic leaf extract forming small aggregates, which makes them stable over long time periods and highly appropriate for coatings or biotechnology applications.

Nanopartículas de prata : biossíntese, investigação das atividades antibacteriana, antifúngica e citotoxicidade; Silver nanoparticles : biosynthesis, investigation of antibacterial and antifungal activity and cytotoxicity

Juliana de Cassia Silva Prado
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/01/2014 PT
Relevância na Pesquisa
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Com o objetivo de entender melhor a toxicidade das nanopartículas de prata biogênicas, estas foram preparadas utilizando a rota biotecnológica e extracelular com o fungo Fusarium oxysporum. As nanopartículas de prata biogênicas foram caracterizadas por microscopia eletrônica de transmissão (TEM) e absorbância na região do UV/Visível. O tamanho das nanopartículas foi determinado pela a técnica de análise de rastreamento de nanopartículas (NTA) utilizando o equipamento NanoSight, e por espectroscopia de correlação de fótons utilizando o equipamento ZetaSizer. O potencial zeta das partículas também foi avaliado no ZetaSizer. A atividade antimicrobiana, a citotoxicidade e os mecanismos de ação das nanopartículas de prata biogênicas em células V79 também foram investigados. A produção de nanopartículas de prata foi evidenciada pela presença da banda de absorção de plasma ('lâmbda' = 450 nm) e por TEM sendo observadas partículas esféricas com o tamanho de 15-22 nm. A atividade antibacteriana e antifúngica das nanopartículas de prata foi avaliada contra Staphylococcus aureus (MIC 1,47 µg mL-1), Salmonella typhymurium (MIC 0,36 µg mL-1), Escherichia coli (MIC 0,73 µg mL-1), Aspergillus niger (MIC 5,90 µg mL-1) e Trichophytum rubrum (MIC 2...

Silver nanoparticles biosynthesized using Opuntia ficus aqueous extract

Silva-de-Hoyos,L. E.; Sánchez-Mendieta,V.; Rico-Moctezuma,A.; Vilchis-Nestor,A. R.; Camacho-López,M. A.; Avalos-Borja,M.
Fonte: Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. Publicador: Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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Silver nanoparticles were synthesized using a green chemistry method. Stable silver nanoparticles in a colloidal aqueous solution were prepared successfully by the chemical reaction of silver nitrate (AgNO3) and Opuntia ficus indica aqueous extract, used as both, reducing and stabilizing agent. Nanoparticle size, morphology and optical properties were analyzed by using transmission electron microscopy (TEM) and UV-Vis spectroscopy, respectively. TEM images revealed a nanoparticle average size of 23 nm. An absorption band centered around 398 nm was observed, this absorption corresponds to the surface plasmon resonance (SPR) of the silver nanoparticles.