Wrinkled Silica Nanoparticles: Efficient Matrix for beta-Glucosidase Immobilization

beta-Glucosidase (BG) was immobilized by adsorption on wrinkled silica nanoparticles (WSNs) giving an active and stable biocatalyst for the hydrolysis of cellobiose. WSNs exhibiting both a central-radial pore structure and a hierarchical trimodal micro-/mesoporous pore size distribution were synthesized. They were used as a matrix to immobilize BG, obtaining a biocatalyst (BG/WSNs) containing 150 mg of enzyme per gram of matrix. A complete textural and morphological characterization of BG/WSNs performed by the Brunauer-Emmett-Teller (BET) method, thermogravimetric (TG), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) analyses showed that this matrix can generate a microenvironment particularly suitable for this enzyme. The immobilization procedure used allowed preserving most of the secondary structure of the enzyme and, consequently, its catalytic activity. The kinetic parameters of the cellobiose hydrolysis performed with the biocatalyst were determined and compared with those of the free enzyme. It was found that the apparent KM value of the biocatalyst was slightly lower than that of the free enzyme, indicating that the enzyme-substrate affinity was increased. A complete hydrolysis of cellobiose was observed for four consecutive runs, showing a high operational stability of the biocatalyst.