Reversible immobilization of enzyme on the “deck” for high-efficiency heterogeneous catalysis

Abstract Enzyme immobilization has emerged as one of the pivotal technologies in enzyme engineering, offering substantial cost reductions associated with enzyme isolation and utilization. However, efficient catalysis of solid substrates with solid immobilized enzymes remains a challenge, typically exemplified by the hydrolysis of cellulose using immobilized cellulase. In this study, a novel system of reversible release and recycling of cellulase on the surface of low-density polyethylene (LDPE) "hull" was developed, inspired by the operational dynamics of carrier-based aircraft. The reversible formation and disruption of multiple hydrogen bonds between the grafted gelatin molecular chain on the LDPE surface and the modification arm of cellulase (poly(methacrylic acid-propenoic acid; PAA-PMAA) can be achieved through temperature control, thus enabling the reversible release and recycling of modified cellulase molecules on the LDPE surface. Results demonstrated that the release of modified cellulase (PLANE) from the LDPE surface overcame the mass transfer barrier inherent in traditional immobilized enzyme systems for catalyzing insoluble substrates. This was attributed to the dissolution of PLANE in the developed system, rendering its hydrolysis of the insoluble cellulose substrate comparable to that of the free enzyme. Upon completion of the reaction, the PLANE could be reversibly recycled on the surface of the macroscopic LDPE membrane, facilitated by the regeneration of multiple hydrogen bonds. Furthermore, the facile removal of the membrane aided in the convenient recycling of cellulase. Notably, the cellulase molecules in the system retained more than 50% of their biological activity even after 8 batches of reuse, making the process cost-effective. This method addressed the limitations of traditional immobilized enzymes, allowing the catalysis of solid substrates with elevated mass transfer and simultaneous easy recovery, thus standing out as a universal immobilization method.