Cellulase assisted synthesis of nano-silver and gold: Application as immobilization matrix for biocatalysis

In the present study, we report in vitro synthesis of silver and gold nanoparticles (NPs) using cellulase enzyme in a single step reaction. Synthesized nanoparticles were characterized by UV–VIS spectroscopy, Dynamic Light Spectroscopy (DLS), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), Circular Dichroism (CD) and Fourier Transform Infrared Spectroscopy (FTIR). UV–visible studies shows absorption band at 415 nm and 520 nm for silver and gold NPs respectively due to surface plasmon resonance. Sizes of NPs as shown by TEM are 5–25 nm for silver and 5–20 nm for gold. XRD peaks confirmed about phase purity and crystallinity of silver and gold NPs. FTIR data shows presence of amide I peak on both the NPs. The cellulase assisted synthesized NPs were further exploited as immobilization matrix for cellulase enzyme. Thermal stability analysis reveals that the immobilized cellulase on synthesized NPs retained 77–80% activity as compared to free enzyme. While reusability data suggests immobilized cellulase can be efficiently used up to sixth cycles with minimum loss of enzyme activity. The secondary structural analysis of cellulase enzyme during the synthesis of NPs and also after immobilization of cellulase on these NPs was carried out by CD spectroscopy.