Facile synthesis of amino-functionalized mesoporous TiO2 microparticles for adenosine deaminase immobilization

Abstract

Fabrication of biocompatible micro- and nanoparticles is attractive because of their potential for application as enzyme immobilization tools. Mesoporous TiO2 microparticles with high crystallinity, high hydroxyl density, and large pore size (20 nm) were prepared by solid-state calcination and a soft chemistry method. The large pores of the microparticles were efficient in adenosine deaminase (ADA) encapsulation. The hydroxyl-coated microparticles could optimize amino-silane modification and be efficiently utilized as ADA-immobilization carriers. However, the adsorbed enzymes were easily leached when cycled. Sequential application of the coupling agent 3-aminopropyltriethoxysilane and cross-linker glutaraldehyde (GLU) enabled effective ADA coupling. After eight batch cycles, the immobilized ADA retained 80% of its initial activity, much higher than that by direct enzyme adsorption (30%). GLU prevented enzyme desorption and loss of activity. We thus improved ADA loading efficiency, recycling, and stability. TiO2 microparticles could be suitable ADA immobilization candidates for detection and industrial inosinic acid production.