Immobilization of laccase on Cu-MOF-alginate composite for degradation of BHPF: Characterization, optimization, and application

Growing food-safety and environmental concerns associated with fluorene-9-bisphenol (BHPF) highlight the need for sustainable remediation strategies. Herein, we report a rationally designed Cu-MOF-alginate composite for efficient laccase immobilization via glutaraldehyde cross-linking, yielding markedly enhanced operational stability and biodegrability. Comprehensive morphological characterization revealed a porous, enzyme-encapsulated architecture. Systematic optimization identified the optimal immobilization conditions as 40 °C, pH 4–5, 1.0 mg/mL enzyme loading, and 1.0 h immobilization duration. Laccase@Cu-MOF-alginate composite achieved 90% BHPF degradation within 12 h, with kinetic profiles indicating substrate-dependent turnover. Multi-spectroscopic analysis and molecular docking were used to characterize the interactions between BHPF and laccase and to identify the proposed binding mode. Notably, acute toxicity assays using Photobacterium phosphoreum demonstrated substantial detoxification of degradation intermediates (inhibition reduced from 68% to 22%). Immobilized laccase retained 48% of its initial activity after six cycles and 31% after ten cycles. These findings establish the Cu-MOF-alginate platform as a sustainable strategy for laccase immobilization, with practical advantages in reusability, operational stability, and detoxification of BHPF.