Dariush Saberi

Cellulose nanocrystals/gold nanoparticle hybrids were synthesized under extreme conditions using hydrothermal treatment without utilizing toxic chemicals. The synthesis of the designed nanohybrid and enzyme immobilization process were confirmed by FT-IR, DLS, intrinsic fluorescence, UV–Vis spectroscopy, FESEM, and EDX techniques. The enzyme, in its free form, exhibited maximum activity at a pH of 10 and a temperature of 70 ◦C. However, when the enzyme was immobilized, its optimal temperature increased to 80 ◦C while its optimal pH remained constant. This catalytic platform significantly improved the thermal and chemical stability, along with enzyme stability at significant pH levels. Following a storage period of four weeks, it was observed that immobilized α-amylase retained 67.5 % of its initial activity, while free α-amylase retained only 17 % of its initial activity. The immobilized α-amylase exhibited a catalytic efficiency of 0.488 mM􀀀 1 s􀀀 1, which was found to be twice as high as that of the free form, which had a catalytic efficiency of 0.254 mM􀀀 1 s􀀀 1. The immobilized enzyme retained its initial activity up to 75 % after 11 consecutive uses. On the basis of the obtained results, it appears that the manufactured immobilized enzyme represents an appropriate choice for industrial use under harsh conditions.