Fabrication of Cellulase Catalysts Immobilized on a Nanoscale Hybrid Polyaniline/Cationic Hydrogel Support for the Highly Efficient Catalytic Conversion of Cellulose

A novel conductive nanohydrogel hybrid support was prepared by in situ polymerization of polyaniline nanorods on an electrospun cationic hydrogel of poly(ε-caprolactone) and a cationic phosphine oxide macromolecule. Subsequently, the cellulase enzyme was immobilized on the hybrid support. Field-emission scanning electron microscopy and Brunauer-Emmett-Teller analyses confirmed a mesoporous, rod-like structure with a slit-like pore geometry for the immobilized support and exhibiting a high immobilization capacity and reduced diffusion resistance of the substrate. For comparison, the catalytic activity, storage stability, and reusability of the immobilized and free enzymes were evaluated. The results showed that the immobilized enzymes have higher thermal stability without changes in the optimal pH (5.5) and temperature (55 °C) for enzyme activity. A high immobilization efficiency (96%) was observed for the immobilized cellulose catalysts after optimization of parameters such as the pH, temperature, incubation time, and protein concentration. The immobilized enzyme retained almost 90% of its original activity after 4 weeks of storage and 73% of its original activity after the ninth reuse cycle. These results strongly suggest that the prepared hybrid support has the potential to be used as a support for protein immobilization.