Dual-End Interfacial Regulation via Phase-Transitioned BSA-Assisted Layer-by-Layer Assembly of Metal–Phenolic Networks for Antifouling and Antibacterial Coatings

Abstract Biofilm formation poses a persistent health risk, yet conventional antibacterial coatings offer limited resistance to the initial conditioning-film stage that precedes bacterial colonization. Herein, we report a phase-transitioned BSA (PTB)-assisted layer-by-layer strategy that constructs a sequence-controlled metal–phenolic network (MPN) coating with dual-end interfacial regulation. A bottom PTB layer serves as a versatile adhesive primer, anchoring the MPN core to chemically inert LDPE via hydrophobic and coordination interactions at the interface, while a top PTB capping layer suppresses nonspecific protein adsorption and early stage biofouling. Stepwise coating growth was confirmed spectroscopically and microscopically, with thickness and Cu-associated signal intensity increasing progressively with cycle number. Capping the MPN coating with a PTB layer markedly reduced protein adsorption and bacterial adhesion. Antibacterial activity scaled with MPN layer number, reaching near-complete eradication of E. coli and S. aureus for the 3-layer configuration. The PTB-primed architecture withstood acid, alkali, ethanol, and sonication treatments that readily delaminated the counterpart lacking the bottom PTB layer, demonstrating pronounced interfacial robustness. Moreover, the strategy translated seamlessly to glass and porous fabric without loss of structural and functional fidelity. These findings establish PTB as a versatile interfacial building block that bridges adhesion and antifouling, offering a substrate-independent platform for contamination-resistant coatings.