Enhanced enzymatic degradation of viscous marine polysaccharide by the self-propulsion of urease-driven micromotor

Efficient enzymatic degradation of marine polysaccharides is hindered by the limited mass transfer induced from the high viscosity. In this study, taking viscous chitosan as an example, a urease-powered hollow mesoporous silica micromotor (UHMSMM) was prepared as the carrier to immobilize chitosanase (Chi), aiming at improving the degradation of chitosan by self-propulsion. At a urea concentration of 300 mM, Chi@UHMSMM exhibited the maximum motion behavior, confirmed by the doubled diffusion coefficient, even in viscous chitosan. The enhanced motion behavior improved the enzymatic performance. The catalytic efficiency was significantly increased, confirmed by the enhancement (3.8 times) of k c at / K m value. It is demonstrated that the autonomous movement could induce the micromixing of fluid in the microenvironment around Chi according to the simulated result, contributing to improved substrate affinity and catalytic efficiency. Also, the immobilization of Chi on UHMSMM induced a common improvement of enzyme immobilization, including enhanced thermo-stability and acid resistance. As a result, Chi@UHMSMM could work as an efficient platform for degrading chitosan, with a 125.75 % yield enhancement within 40 min. In this work, the reported strategy, which accelerates the enzymatic degradation of chitosan by the self-propulsion of enzyme-driven micro/nanomotors offers a novel approach for improving enzyme reactions in high-viscosity systems.