Novo método de síntese de nanopartículas de prata e avaliação de seu efeito antimicrobiano

• Autor(a) principal: Fernandes, Patrícia érica
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2885
• topic: Superfície com atividade microbiana; Polietileno de baixa densidade; Quitosana; Íons prata; Nitroprussiato de sódio; Surface microbial activity; Low density polyethylene; Chitosan; Silver ions; Sodium nitroprusside; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS

In this work, we present a new synthesis method of colloidal dispersions of silver nanoparticles (AgNPs) with antimicrobial effect. The formation of AgNPs was achieved by the dispersion of silver sulfadiazine (SS) 1% w/v in dodeciltrimetil ammonium bromide (DTAB) at concentrations of 15.6 mM and 31.2 mM, which corresponds to the critical micellar concentration (1 x CMC) and twice the critical micelle concentration (2 x CMC), respectively. The formation of nanoparticles (NPs) was measured by dynamic light scattering (DLS), fluorescence spectroscopy and transmission electron microscopy (TEM). The average particle size by dynamic light scattering was 3 ± 1 nm and 2.8 ± 0.4 nm for each of the dispersions prepared from DTAB at concentrations of 1 x CMC and 2 x CMC, respectively. The fluorescence emission of the samples was verified by irradiation with UV light, wavelength of 369.7 nm, only in colloidal dispersions obtained by the dispersion of SS in DTAB, indicating the formation of NPs. In the dispersion containing only SS 1% w/v or DTAB 1 x CMC and 2 x CMC there was no fluorescence emission. The formation of AgNPs was confirmed by TEM, where the crystallographic analysis of the image revealed interplanar distances near 2.3 Å, characteristic of silver in the orientation {111} (2.359 Å). The antimicrobial effect of colloidal dispersions of AgNPs and reagents was analyzed by inhibition of microbial growth by agar diffusion against Gram-positive Staphylococcus aureus ATCC 6538 and Staphylococcus epidermidis ATCC 12228 and against Gram-negative Escherichia coli ATCC 11229 , Pseudomonas aeruginosa ATCC 15442, ATCC 10031 Klebsiela pneumoniae and Enterobacter aerogenes ATCC 13048. The colloidal dispersion of AgNPs using DTAB 1 x CMC showed greater antimicrobial effect (p <0.05) against E. coli in relation to the used reagents, which were SS 1% w/v and DTAB 1 x CMC. However, the colloidal dispersion of AgNPs obtained by using DTAB 2 x CMC showed a greater antimicrobial effect (p <0.05) on P. aeruginosa in relation to the reagents used, which were SS 1% w/v and DTAB 2 x CMC. This increased efficiency was attributed to the presence of AgNPs. Both colloidal dispersions of AgNPs showed the same antimicrobial effect (p> 0.05) for five of the six bacteria studied, except S. epidermidis, in which the colloidal dispersion containing the highest concentration of surfactant (2 x CMC) was better (p <0.05). In this case, the greatest antimicrobial effect should be attributed to the higher concentration of surfactant and not the presence of AgNPs, because the dispersion containing AgNPs in DTAB 2 x CMC was not different (p> 0.05) of dispersion containing only DTAB 2 X CMC to S. epidermidis.