A Green Photoregulated Quadruple‐Action Selenium Nanozyme Platform for Rapid and Ferroptosis‐Like‐Enhanced Photodynamic Bacterial Killing with Integrated Biosensing Capabilities

Abstract The rise of bacterial infections globally necessitates alternatives to traditional antibiotic therapy. Herein, a photoregulated quadruple‐action selenium nanozyme platform (LG‐CS@SeNPs), synthesized sustainably using food‐grade lauryl gallate‐modified chitosan (LG‐ g ‐CS) as a stabilizer is developed. The LG‐CS@SeNPs exhibit uniform spherical morphology (54 nm), and high colloidal stability (ζ‐potential: +32 mV). Under visible light (420 nm), LG‐CS@SeNPs completely eradicates both bacteria and biofilms within 5 min. This high efficiency is attributed to a unique four‐pronged antibacterial mechanism involving rapid bacterial capture and contact‐killing, synergistic ROS generation from photo‐activated oxidase‐mimicking enzymatic activity and photodynamic inactivation, and ferroptosis‐like bacterial death induction. Additionally, LG‐CS@SeNPs seamlessly switch from potent, light‐driven antibacterial activity to robust antioxidant and wound‐healing functionalities in darkness, enhancing clinical adaptability. Moreover, their intrinsic fluorescence and catalytic properties ( K _m = 0.11 m m , V _max = 2.48 µ m min ⁻¹ ) enable sensitive and rapid biosensing, including detection of total antioxidant capacity in saliva, on‐off‐on sensing of Fe ³ ⁺ (limit of detection: 2.3 µ m ) and ascorbic acid (limit of detection: 2.59 µ m ). This light‐empowered, ferroptosis‐like‐enhanced selenium nanozyme thus establishes a new paradigm for rapid, multimodal antibacterial action integrated with diagnostic capabilities for intelligent healthcare and personalized medicine.