Harnessing engineered laccase and functional carrier materials for efficient dye degradation: From mechanism to application

Laccases are copper-containing oxidases that have been widely investigated for the decolorization and degradation of synthetic dyes, including azo, anthraquinone, triphenylmethane, indigo and thiazine dyes. However, their application in dye-containing wastewater remains constrained by enzyme instability under complex effluent conditions, limited oxidation of some recalcitrant or high-redox-potential dyes, mediator dependence, and poor recovery and reuse of free laccase. This review discusses recent progress in laccase-catalyzed dye degradation from a mechanism-to-engineering perspective, linking dye-structure-dependent degradation pathways with laccase discovery, recombinant expression, protein engineering and immobilization strategies. Particular attention is given to comparative evidence across dye classes, fungal and bacterial laccases, engineered variants generated through rational design, directed evolution and semi-rational mutagenesis, and immobilized laccase systems based on nanomaterials, biopolymers, magnetic carriers and porous supports. In addition, the review distinguishes laboratory model dye systems from simulated and real wastewater applications, highlighting the need for more cautious interpretation of decolorization efficiency, degradation evidence and process feasibility. Finally, we outline future prospects for laccase applications in dye degradation, including the mining of novel laccases from extreme environments, artificial intelligence-assisted laccase design, and developing new nano-scale carrier materials, which will be essential for enhancing laccase performance and broadening its application scope.