Halloysite nanotubes - An efficient ‘nano-support’ for the immobilization of α-amylase

Abstract Amylases are a class of hydrolytic enzymes which help in the conversion of starch into reduced sugars. Several solid carriers have been utilized for the immobilization of amylase. The current study focused on the utilization of halloysite nanotubes (Hal nanotubes) for the immobilization of α-amylase post their surface functionalization with APTES. The immobilized enzyme was characterized for its ultrastructure and morphology using TEM which revealed the hollow tubular structure of nanotubes. Chemical characterization of Amylase-Hal nanotubes powder was done by FTIR in which the characteristic reflections of pristine Hal nanotubes and amylase were detected in the spectra for Amylase-Hal nanotubes powder. The thermal and crystalline behavior of the immobilized enzyme was studied using DSC and XRD analysis respectively. Further, the effect of time, pH, temperature and metal ions on the enzymatic activity of immobilized enzyme had also been probed into. The optimum pH and temperature for the immobilized amylase was found to be 7.4 and 40 °C respectively. Slight increase in the enzymatic activity was also found for immobilized amylase as compared to free enzyme in the presence of Cu2 + and Mn2 + ions.