Sunlight-Driven Wearable and Robust Antibacterial Coatings with Water-Soluble Cellulose-Based Photosensitizers

Herein, a simple, effective, and general strategy is demonstrated to obtain a water-soluble and nontoxic cellulose-based photosensitizer (CPS) with enhanced photodynamic antibacterial activity through introducing protoporphyrin IX (PpIX) and quaternary ammonium salt (QAS) groups onto the cellulose backbone. The synergistic effect of the anchoring and diluting effect of the cellulose backbone and the electrostatic repulsion between QAS groups effectively inhibit the π-π stacking of PpIX groups, thus the as-prepared CPS exhibits markedly enhanced reactive oxygen species (ROS) yield. Meanwhile, the positively charged QAS groups endow the CPS with water-solubility and a strong attractive force to bacteria. As a result, the CPS can rapidly and efficiently kill drug-resistant bacteria strains, including E. coli and S. aureus, with a low light dose (2.4 J cm^-2 ) and low concentration of PpIX groups (0.35 × 10^-6 m). Benefiting from the excellent processability and formability, the CPS is readily applied as a sunlight-driven wearable and robust antibacterial coating by a spray coating and later crosslinking procedure.