Novozym435-Gold Nanoparticles Biohybrids as an Efficient Catalyst for Synthesis of Ferulic Acid Starch Ester.

Abstract

Novozym435-gold nanoparticles biohybrids (NAuB) were synthesized and characterized in this work, with subsequent investigations on their catalytic activities and stability in compared with the initial form of Novozym435. This is a new way to modify immobilized enzyme by physical means. The elemental analysis of NAuB showed that Au was also the major element except C and O. The results of TEM and EDX demonstrated that gold nanoparticles (AuNPs) could be formed in the protein molecular network structure or on the surface of protein in the pores of Novozym435. The optimal process parameters for synthesis NAuB: synthesis temperature of 35 °C, HAuCl₄ concentration of 0.02 mg/mL, synthesis time of 24 h. Using the transesterification of starch with ferulic acid ethyl ester as the reaction model, preliminary results pointed to excellent stabilities, solvent tolerance and activities as compared with Novozym435. As for a isooctane:dimethyl sulfoxide system, transesterification of starch with ferulic acid ethyl ester was carried out at 6% (w/w) NAuB and 60 °C for 24 h, a maximum DS of 0.2650 was obtained.