Effect of physicochemical factors on extracellular fungal pigment-mediated biofabrication of silver nanoparticles

The extracellular pigment produced by Talaromyces purpurogenus was used as a reducing agent in the production of silver nanoparticles (AgNPs), and the effect of physicochemical parameters (pH and light) on the synthesis were examined. To evaluate the effect of pigment constituents on AgNP synthesis, fractions were obtained by thin layer chromatography. Ultraviolet-visible spectroscopy, transmission electron microscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy were used to characterize the biofabricated AgNPs. The synthesis of AgNPs was enhanced under alkaline conditions, emphasizing the role of sodium hydroxide (NaOH) as an accelerator, and the effect of light on yield could be clearly perceived up to pH 10. As the pH value was increased further, the light dependency of the reaction decreased, although the DLS data suggested variation in the size of AgNPs obtained in the presence and absence of light. The AgNPs produced at optimum pH in the presence of light were nearly spherical with a size distribution of 5-40 nm. The AgNP production process was pH-dependent and light-mediated, indicating that AgNPs with different properties could be generated by controlling these physicochemical factors.