Synthesis of gold and silver nanoparticles using purified URAK.

This study aims at developing a new eco-friendly process for the synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using purified URAK. URAK is a fibrinolytic enzyme produced by Bacillus cereus NK1. The enzyme was purified and used for the synthesis of AuNPs and AgNPs. The enzyme produced AgNPs when incubated with 1mM AgNO3 for 24h and AuNPs when incubated with 1mM HAuCl4 for 60h. But when NaOH was added, the synthesis was rapid and occurred within 5min for AgNPs and 12h for AuNPs. The synthesized nanoparticles were characterized by a peak at 440nm and 550nm in the UV–visible spectrum. TEM analysis showed that AgNPs of the size 60nm and AuNPs of size 20nm were synthesized. XRD confirmed the crystalline nature of the nanoparticles and AFM showed the morphology of the nanoparticle to be spherical. FT-IR showed that protein was responsible for the synthesis of the nanoparticles. This process is highly simple, versatile and produces AgNPs and AuNPs in environmental friendly manner. Moreover, the synthesized nanoparticles were found to contain immobilized enzyme. Also, URAK was tested on RAW 264.7 macrophage cell line and was found to be non-cytotoxic until 100μg/ml.