Photo-irradiation induced green synthesis of highly stable silver nanoparticles using durian rind biomass: effects of light intensity, exposure time and pH on silver nanoparticles formation

Abstract

The purpose of this work is to single-pot biosynthesize silver nanoparticles (AgNPs) using the extract from mesocarp and endocarp of durian rind under photo-irradiation. Without adding chemical substance, flavonoids, phenolic compounds and glucose dissolved in the extract served as the reducing agent; while proteins acted as the particle-stabilizing agent in the formation of AgNPs. The synthesis parameters i.e. light intensity, exposure duration, and pH value directly associated with the nucleation, growth, and aggregation of nanoparticles. The amount of synthesized AgNPs increased with increasing visible light intensity and exposure duration, while the size and stability of nanoparticles were decided by pH value adjustment. The size of synthesized AgNPs decreased when the pH value increased, on the contrary, the size increased when the pH value decreased. Under the optimized synthesis conditions (visible light intensity of 13,430 lx and pH value of 8.5), approximately 99% of silver ions was reduced to the spherical AgNPs with the mean diameter of 11.4 ± 3.2 nm within 5 min. The AgNPs remained uniformly dispersed in de-ionized water at no less than six months. The present environmental-friendly method is facile, rapid, and cost effective for the large scale preparation of AgNPs. The obtained AgNPs synthesized under optimum conditions could be applied for use in various fields such as antimicrobial activity, biosensors, and catalysis in the near future.