FABRICATION OF ANISOTROPIC SILVER NANOPARTICLES BY COMBINATION OF BLUE AND GREEN LED IRRADIATION FOR MELAMIN DETECTION APPLICATIONS

Abstract

This paper presents anisotropic silver nanoparticles fabricated by photochemical method by changing from blue to green radiation at different exposure times on small spherical seed nanoparticles (~7 nm). Morphology and size of obtained nanoparticles were investigated by field-emission scanning electron microscopy (FESEM). Crystal structure, elemental composition was investigated by X-ray diffraction (XRD) and energy dispersion spectroscopy (EDX). Optical properties of obtained silver nanoparticles product were analyzed by UV-Vis absorption spectroscopy. The obtained anisotropic silver nanoparticles were triangular, rounded triangular and cross-shaped flat plates and nanodecahedra. Silver nanodecahedra were formed by stimulating on spherical silver nanoparticles under blue LED (BLED). Triangular silver nanoparticles were formed when the seeds are excited by a green LED (GLED). The results of investigating the applicability of silver nanoparticles for melamin detection by using surface enhancement Raman scattering (SERS) technique reached high sensitivity (10^-6 M). The anisotropic silver nanoparticles promise to many interesting researches in analysis method and detecting toxic substances in food safety thanks to silver nanoparticles such as Raman sensors in the future.