Functionalized hierarchical wrinkled-silica spheres for laccases immobilization

Abstract

Functionalized mesoporous SiO2 are common supports for some enzymes of industrial interest, such as laccases. However, the incorporation of specific functionalities and the loading of enzymes with dimensions close to the diameters of the pores obstructs the porous system. For biotechnological applications, tailored porous supports are still needed to enhance the laccase loading. The hierarchical meso/macroporous system in wrinkled-SiO2 spheres (w-SiO2) is a suitable option to overcome this issue. Herein, (3-aminopropyl) triethoxysilane and glutaraldehyde were use as functionalizing agents for the immobilization of laccase on w-SiO2. The functionalization occurs in the mesopores of the wrinkled walls and the preservation of the macroporous entries facilitates the diffusion of the laccase inside the particle. The enzyme performance was evaluated by means of the crystal violet bleaching. The enzyme is stabilized through the imine groups provided by glutaraldehyde, allowing the retention of the activity after several reaction cycles. The bleaching can be boosted by acetosyringone, highlighting the possibility of using redox mediators to expand the range of oxidizable substrates. Understanding the effect of w-SiO2 functionalization on laccases loading and performance could be extrapolated to other enzymes with biotechnological interest that requires this type of hierarchical porous silica.