A simple and effective method to synthesize fluorescent nanoparticles using tryptophan and light and their lethal effect against bacteria

A simple, environmentally friendly and cost-effective method was used to synthesize silver nanoparticles using typtophan and light. To prepare the nanoparticles, the following components were used: deionized water, silver nitrate, light and tryptophan. the effects of the tryptophan concentration and light exposure time on the formation of tryptophan silver nanoparticles (Tnnps) were studied. the synthesized Tnnps were characterized using transmission electron microscopy (TEM), absorption and fluorescence spectroscopy and zeta potential measurements. the synthesized Tnnps were nearly spherical, with sizes of approximately 17 nm. in addition, the antibacterial activity of Tnnps was determined by monitoring the growth curves of strains of Escherichia colt, Pseudomonas aeruginosa, Staphylococcus epidermidis, Serratia marcescens, and Enterococcus faecalis using the microdilution test. the Minimum Inhibitory Concentration (MIC) for 4 of 5 tested bacteria was determined to be between 20.0 and 17.5 mu g/mL for 48 h and between 22.5 and 20.0 mu g/mL for 72 h. (C) 2014 Elsevier B.V. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo UNIFESP, BR-09972270 Diadema, SP, BrazilUniversidade Federal de São Paulo UNIFESP, BR-09972270 Diadema, SP, BrazilWeb of Scienc

Green synthesis of stable silver nanoparticles using Euphorbia milii latex

We report a simple method to create silver nanoparticles that consists in the irradiation of a silver nitrate and Euphorbia milii solution by light from a xenon lamp followed by ultrashort laser pulses. the formation of silver nanoparticles has been confirmed with UV-visible and TEM microscopy, and no additives, such as solvents, surfactants or reducing agents, were used in the procedure. Nanoparticles are present after the xenon lamp illumination, and after the laser irradiation the silver nanoparticles sizes are reduced drastically to the range of 10-50 nm. A concentration variation study of silver nitrate and aqueous latex extract was carried out, as well as with the laser irradiation energy and time. the size reduction can be explained by a multiphoton process that promotes the photoexcitation of the surface plasmon band, breaking the particles due to charge accumulation. the utilization of environmentally friendly solvents is one of the key issues that merits important consideration in a green synthesis strategy. (C) 2011 Elsevier B.V. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, UNIFESP, São Paulo, BrazilIPEN CNEN SP, São Paulo, BrazilUniversidade Federal de São Paulo, UNIFESP, ICAQF, Diadema, BrazilWeb of Scienc