α-amylase was immobilized covalently on Fe3O4 magnetic nanoparticles via carbodiimide activation. The efficiency of immobilization and residual activity of the immobilized α-amylase was dependent upon the immobilization temperature and mass ratio of nanoparticles: carbodiimide: α-amylase. Confirmation of the binding was demonstrated by Fourier transform infrared (FTIR) spectroscopy. At room temperature, immobilized amylase displayed more binding efficiency and less residual activity compared with of 4°C, hence 4°C was chosen as optimum immobilization temperature. The 4:1:1 ratio displayed maximum residual activity therefore, it was chosen as a best ratio for immobilization. The optimum pH value for both free and immobilized amylase was at pH 5 but immobilized amylase exhibited more pH sensitivity at the pH values 6, 7 compared with free amylase and there were no differences in pH profiles for amylase that immobilized in room temperature or 4°C.

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