Engineered protein nanofibrils for chain-integrated water treatment: From source monitoring to end-point purification

Escalating complexity in water pollution has catalyzed a shift toward chain-integrated management, encompassing source monitoring, targeted removal, and end-point purification. Protein nanofibrils (PNFs), self-assembled from abundant proteins, are ideal candidates for these challenges due to their rich functional groups, mild synthesis, and tunability. This review examines PNFs' potential in chain-integrated water treatment technologies. First, the evolution of PNFs reveals their advantages over conventional nanomaterials such as cellulose nanofibrils and carbon nanotubes, including simpler preparation methods, superior physicochemical properties, and versatile functionalization capabilities. Second, PNFs serve multifunctional roles across the water treatment chain: as sensitive biosensor components for contaminant detection, selective adsorbents for pollutant removal, stable catalyst supports for degradation reactions, and effective membrane modifiers for filtration enhancement. The exceptional performance of PNFs results from abundant functional groups and controllable surface charge, which provide binding sites for contaminants and attachment points for functional materials, as well as their high aspect ratio that prevents nanoparticle aggregation while maintaining catalytic efficiency. Despite their commercial emergence as adsorbents, PNF-based systems face key bottlenecks, including limited biosensing selectivity, elusive adsorption mechanisms, and inadequate stability for catalysis. Future research directions should focus on developing interference-resistant binding strategies, optimizing macrostructure preparation, creating stable catalytic systems, and advancing structural analysis through molecular engineering approaches. This comprehensive review provides insights into these novel biomaterials and their potential in next-generation water treatment technologies.