Immobilization of yeast alcohol dehydrogenase on polyaniline coated silver nanoparticles formed by green synthesis

• Silver nanoparticles have been synthesized by green synthesis.
• Alcohol dehydrogenase has been immobilized on polyaniline coated silver nanoparticles.
• The immobilized enzyme exhibited high activity and stability.
• This provides a cost-effective and eco-friendly industrial application of the enzyme.

In this study, silver nanoparticles (AgNPs) have been synthesized by green synthesis using Ziziphus mauritiana fruit extract and then yeast alcohol dehydrogenase (YADH) has been immobilized on polyaniline coated AgNPs. The AgNPs were characterized using UV–Vis spectroscopy, TEM and FT-IR. These NPs consisted of almost mono-dispersed spherical NPs of average diameter of ∼30 nm and exhibited high storage stability at 4 °C for many days. YADH immobilized on polyaniline coated AgNPs exhibited good activity with effectiveness factor (η) value of 0.73. Immobilization did not alter the optimum pH (pH 8.0) of YADH, however the optimum temperature increased by 5 °C. The immobilized enzyme retained greater fraction of activity both in the acidic and alkaline pH range and at higher temperatures as compared to the soluble enzyme. At 70 °C, immobilized YADH retained about 78% activity as compared to 26% retained by the soluble enzyme. The immobilized enzyme also exhibited high thermal stability at 50 °C. Therefore, inexpensive and eco-friendly green synthesis of NPs and excellent activity and stability of YADH immobilized on polyaniline coated AgNPs provides a cost-effective industrial application of the enzyme.

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