Precise Regulation of Enzyme-Nanozyme Cascade Reaction Kinetics by Magnetic Actuation toward Efficient Tumor Therapy.

Spatiotemporal regulation of multi-enzyme catalysis with stimuli is crucial in nature to meet different metabolic requirements but presents a challenge in artificial cascade systems. Here, we report a strategy for precise and tunable modulation of enzyme-nanozyme cascade reaction kinetics by remote magnetic stimulation. As a proof of concept, glucose oxidase (GOx) was immobilized onto a ferrimagnetic vortex iron oxide nanoring (FeO NR) functionalized with poly(ethylene glycol) of different molecular weights to construct a series of FeO NR@GOx with nanometer linking distances. The activities of GOx and the FeO NR nanozyme in these systems were shown to be differentially stimulated by FeO NR-mediated local heat in response to an alternating magnetic field (AMF), leading to modulated cascade reaction kinetics in a distance-dependent manner. Compared to the free GOx and FeO NR mixture, FeO NR(D2)@GOx with an optimum linking distance of 1 nm exhibits a superior kinetic match between GOx and the FeO NR nanozyme and over a 400-fold higher cascade activity under AMF exposure. This enables remarkable intracellular reactive oxygen species production and significantly improved tumor inhibition of AMF-stimulated FeO NR(D2)@GOx in 4T1 tumor-bearing mice. The strategy reported here offers a straightforward new tool for fine-tuning multi-enzyme catalysis at the molecular level using magnetic stimuli and holds great promise for use in a variety of biotechnology and synthetic biology applications.