Immobilization of GOD and HRP enzymes on nanostructured substrates

The study of the entrapment of glucose oxidase (GOD) and horseradish peroxidase (HRP) enzymes on different solid-state substrates has been carried out. By using conventional methods, these enzymes have been immobilized on the following substrates: commercial Si wafers, thin films of nanostructured TiO2 and gold nanotubes grown on polycarbonate membranes. Surface chemical composition and morphology of the samples have been investigated by means of X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Peak-fitting analysis of the main XPS signals permitted identification of the fingerprints of GOD and HRP enzymes and comparison of their entrapment on different substrates. The highest amount of attached enzymes was registered on the nanostructured TiO2 films prepared by using the sol-gel technique. Moreover, the surface impurities, remaining on the samples after the immobilization of the phosphate buffer solution, were identified, and their removability by sample washing in deionized water was demonstrated.