Single-Layer MnO₂ Nanosheets for Immobilization of <i>Agrobacterium radiobacter</i> Halohydrin Dehalogenase via Adsorption

Adsorption-based enzyme immobilization is a simple carrier bound technique that is cost-effective and readily implementable, requiring minimal activation steps and reagents. Single-layer nanosheets represent the optimal carriers for the adsorption of enzymes as they can expose maximal active sites for the binding of biomolecules. This study demonstrated that single-layer MnO2 nanosheets can serve as carriers for the effective immobilization of Agrobacterium radiobacter halohydrin dehalogenase (HheC) via a facile adsorption process without the use of any cross-linking reagents or additional surface modification. The immobilization of HheC on single-layer MnO2 nanosheets resulted in a high loading of 1026 mg·g–1 enzyme on the carrier, which represented the highest enzyme loading for HheC to date. Furthermore, the immobilized HheC on single-layer MnO2 nanosheets demonstrated a high enzyme activity recovery of 80.9%, which was employed for the efficient asymmetric synthesis of chiral epichlorohydrin from 1,3-dichloro-2-propanol. The efficient immobilization of HheC single-layer MnO2 nanosheets can be attributed to the enhanced molecular interactions (e.g., electrostatic interactions, hydrogen bonding and van der Waals forces) between the enzyme and carriers, which are facilitated by the large surface areas and the negative charge of the surface of single-layer MnO2 nanosheets. This work presents a general and efficient strategy that employs single-layer MnO2 nanosheets as carriers for enzyme immobilization, thereby enabling highly efficient biocatalysis.