Multimetal-Based Inorganic–Protein Hybrid System for Enzyme Immobilization

Here, a novel multimetal-based inorganic–protein hybrid was developed to immobilize laccase as a model enzyme using copper (Cu) and zinc (Zn) metal ions in phosphate-buffered saline. The synthesized multimetallic Cu3/Zn3(PO4)2–laccase hybrid (Cu/Zn-Lac) showed a significantly higher encapsulation yield of 96.5% compared with 87.0% with Cu3(PO4)2–laccase (Cu-Lac) and 90.2% with Zn3(PO4)2–laccase (Zn-Lac), respectively. The relative activity of Cu/Zn-Lac was 1.2-, 1.5-, and 2.6-fold higher than Zn-Lac, Cu-Lac, and free enzyme, respectively. The catalytic efficiency of Cu/Zn-Lac was 3.2-fold higher than the free enzyme (71.0 s–1 μM–1). The anodic peak current for the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid by Cu/Zn-Lac was 2.0- and 2.7-fold higher than Zn-Lac (1.05 μA) and Cu/Lac (0.77 μA), respectively. Remarkably, Cu/Zn-Lac displayed 2.1- and 2.7-fold lower charge transfer resistance compared with Zn-Lac (112 Ω) and Cu/Lac (145 Ω), respectively. Under repeated batch conditions, the residual activity of multimetal hybrids to degrade bisphenol A was 1.9- and 5.1-fold higher than Zn-Lac (43.7%) and Cu-Lac (16.5%), respectively, even after ten cycles of reuse. The multimetallic system exhibited higher enzyme efficiency, electrochemical substrate oxidation, and degradation potential for bisphenol A compared with individual metal-based hybrid systems. This approach to synthesizing multimetallic-based protein hybrids could be extended to enhance the catalytic properties and reusability of enzymes.