Reusable magnetic nanobiocatalyst for synthesis of silver and gold nanoparticles

• Rational enzymatic approach for the synthesis of silver and gold nanoparticles on large scale is developed.
• Nanobiocatalyst was prepared by covalently linking α-amylase enzyme on iron oxide nanoparticles.
• The nanobiocatalyst was used up to three consecutive cycles for the synthesis of nano silver and gold.
• Nanoparticles of same morphology and size were obtained in each cycle.

In the present work, we describe a simple procedure for the biosynthesis of nanosilver and gold by the reduction of silver nitrate and auric chloride respectively using a nanobiocatalyst. The nanobiocatalyst was prepared by covalent coupling of alpha amylase on (3-aminopropyl)triethoxysilane (APTES) modified iron oxide magnetic nanoparticles. The nanobiocatalyst retains 77% of its activity as compared to free alpha amylase. The nanobiocatalyst can be used up to three consecutive cycles for the synthesis of nano silver and gold. The biosynthesized nanoparticles after each cycle were characterized by UV–vis spectrophotometer, Dynamic Light Spectroscopy (DLS), Transmission Electron Microscope (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Silver and gold nanoparticles of same morphology and dimensions were formed in each cycle. The procedure for synthesis of nanoparticles using an immobilized enzyme is eco-friendly and can be used repeatedly.

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