Photo- and temperature-dependent formation of tryptophan/silver nanoparticles

摘要

Amino acid tryptophan is an advantageous reagent for preparation of biocompatible noble metal nanoparticles as promising anticancer agents. The reduction of metal ions in the presence of tryptophan proceeds through the indole moiety of the molecule. The formation of silver nanoparticles, namely the redox process between Ag+ and Trp, was activated by UV-C LED irradiation at 278nm, corresponding to the position of the indole absorption band. The experimental parameters of irradiation were varied systematically aiming to influence the kinetics of the process and properties of prepared Ag nanoparticles. The dependence of optical spectra and size distribution of Agnanoparticles on temperature of reaction (25, 40 and 60 degrees C) and output optical power density (0.4, 0.6 and 1.0mW/cm(2)) were investigated by UV-vis absorption spectroscopy and dynamic light scattering data. Under UV irradiation, the rate of Ag nanoparticles formation can be accelerated by a factor of 10 with increase of the temperature from 25 to 60 degrees C, leading to the shift of plasmon absorption band maxima from 422 to 412nm. The optimal UV irradiation parameters and temperature of reaction can be a basis for preparing colloids with tailored dispersity and optical properties.