Sucrose hydrolysis by invertase immobilized on functionalized porous silicon

A successful recipe for the production of immobilized invertase/porous silicon layer with appropriate catalytic behavior for the sucrose hydrolysis reaction is presented. The procedure is based on support surface chemical oxidation, silanization, activation with glutaraldehyde and finally covalent bonding of the free enzyme to the functionalized surface. The catalytic behavior of the composite layer as a function of pH, temperature, and the current density applied in the porous silicon (PS) preparation is investigated. Interestingly, V_max undergoes a substantial increase (ca. 30%) upon immobilization. The value of K_m increases by a factor of 1.53 upon immobilization. The initial activity is still preserved up to 28 days while the free enzyme undergoes a 26% loss of activity after the same period. Based on the outcomes of this study, we believe that tailored PS layers may be used for the development of new bioreactors in which the active enzyme is immobilized on the internal walls and is not lost during the process.