Cellulase Adsorption on Magnetic Hyper-Cross-Linked Polystyrene Enhances Carboxymethylcellulose Conversion

Here, we develop a novel magnetically recoverable biocatalyst based on hyper-cross-linked polystyrene (HPS) with incorporated magnetite nanoparticles (NPs) and adsorbed cellulase (Cel) for the hydrolysis of carboxymethylcellulose (CMC, a water-soluble analogue of cellulose) to glucose. The biocatalyst demonstrates excellent performance both in a single reaction (preserved 95% of activity of native Cel) and in repeated use (preserved 93% of its initial activity after five consecutive reactions). To understand the origin of such behavior, the biocatalyst has been extensively studied using a combination of multiple physicochemical methods. HPS–Fe3O4–Cel porosity has been found to be lower compared to that of HPS upon incorporation of iron oxide NPs and Cel adsorption; nevertheless, this decrease does not block the majority of larger mesopores, thus allowing for efficient mass transfer. The HPS–Fe3O4 support allows for high Cel loading, attributed to a combination of hydrophobic interactions of Cel with HPS (similar to HPS–Cel) and, most importantly, specific interactions of Cel with Fe3O4 NPs, creating optimal conditions for the preservation of the Cel conformation. We believe the commercially available HPS along with facile preparation of magnetic NPs and Cel adsorption paves the way for the fabrication of a family of enzymatic catalysts for sustainable processes.