Preparation of enzyme nanoparticles and studying the catalytic activity of the immobilized nanoparticles on polyethylene films

Using high-intensity ultrasound, in situ generated α-amylase nanoparticles (NPs) were immobilized on polyethylene (PE) films. The α-amylase NP-coated PE films have been characterized by E-SEM, FTIR, DLS, XPS and RBS. The PE was reacted with HNO₃ and NPs of the α-amylase were also deposited on the activated PE. The PE impregnated with α-amylase (4 μg per 1 mg PE) was used for hydrolyzing soluble potato starch to maltose. The immobilization improved the catalytic activity of α-amylase at all the reaction conditions studied. The kinetic parameters, K_m (5 and 4 g L^-1 for the regular and activated PE, respectively) and V_max (5 × 10^-7 mol ml^-1 min^-1, almost the same numbers were obtained for the regular and activated PEs) for the immobilized amylase were found to slightly favor the respective values obtained for the free enzyme (K_m = 6.6 g L ^-1, V_max = 3.7 × 10^-7 mol ml^-1 min^-1). The enzyme remained bound to PE even after soaking the PE in a starch solution for 72 h and was still found to be weakly active.