SBA-15 with short channels for laccase immobilization

Abstract

Ordered Mesoporous Materials offer wide application areas in chemistry and biotechnology. SBA-15 displays hexagonal arrangement of parallel unidirectional channels, where pore size and particle morphology are the controlling parameters when used as enzyme support to favour the diffusion of the protein molecules. The synthesis conditions can be controlled to yield the desired structural and morphological features of the material, as well as the functionalization of its surface to improve chemical affinity with the enzyme. Functionalization with amine groups has been performed to immobilize laccase on SBA-15. Particles of SBA-15 with short channels (300–500 nm length) and large pore diameter (10–14 nm) have been obtained. The experimental parameters varied to control the structural features were surfactant, micelle expander and silica source. Upon functionalization with amine groups, laccase was immobilized at a pH in the range between the isoelectric point of the enzyme (pI = 4.2) and the pKa value of the amino groups (~10) via non-covalent (electrostatic) interaction between carboxylate groups of the enzyme and the protonated amino groups. The enzyme was successfully immobilized on all the supports tested (loading from 18 to 57 mg/g) with fair catalytic activity and observing enzyme desorption (leaching) below 9% after 48 h in all cases.