Laccase-Triggered Surface Co-Deposition of Gentisic Acid and Chitosan for Multifunctional Polymer Membranes

Co-deposition of phenols and amines inspired by mussel-inspired chemistry has attracted much attention in the field of surface and interface science and technology. However, most deposition systems are still limited to phenols with at least one catechol group. In this work, a novel enzyme-triggered co-deposition system based on a natural phenol (gentisic acid, GA) and a kind of biomacromolecule (chitosan, CS) is reported. With the catalysis of laccase, GA can be oxidized and further react with CS to form effective surface coatings on various substrates such as polypropylene microfiltration membrane (PPMM). The co-deposition process takes only 40 min at room temperature and endows the membrane with superhydrophilicity and underwater superoleophobicity. The modified membranes show excellent separation performance, reusability, and long-term stability for the separation of oil-in-water emulsions. The modified membranes are highly charged (pI approximate to 7.2) and capable of efficient dye adsorption. In addition, the modified membranes possess better protein resistance properties compared with the nascent membranes. This work demonstrates a green, mild, and highly efficient surface modification process based on laccase catalysis. The co-deposition system comes from natural sources and expands the phenol family for constructing multi-functional surface coatings.