Photo-programmable AgCl@Ag nanoparticles enable sequential antibacterial action and durable dentin bonding for deep caries management

Deep caries management faces a critical dilemma: preserving pulp vitality versus ensuring durable restoration. Current dentin bonding technique and materials fail to eliminate residual pathogens in preserved soft dentin or stabilize resin-dentin interfaces against enzymatic/microbial degradation. Here, we present a light-programmable AgCl@Ag nanoparticle system that overcomes these dual challenges through dynamic nanochemistry. By orchestrating in situ AgCl deposition and photoreduction, our strategy achieves three breakthroughs: (1) Structural reinforcement: Polarity-driven Ag + chelation masks polar groups in demineralized dentin matrix (DDM), releasing interface confined water while doubling DDM modulus, greatly enhancing BisGMA infiltration to realize hermetic seal at the cavity periphery; (2) Sequential antibacterial action: Ag + rapidly penetrates biofilms to form AgCl NPs, followed by light-triggered transformation from AgCl NPs to AgCl@Ag NPs to generate Cl₂/HClO for residual pathogen eradication, to achieve a bacteria-free environment; (3) Self-stabilizing interface: Reducible AgCl@Ag nanoparticles inhibit MMPs and resist microbes and aging-induced delamination. This photo-responsive system eliminates secondary caries risk while maintaining pulp vitality, seamlessly integrating with clinical workflows. Through spatiotemporal control of silver chemistry, we redefine dental adhesion as intelligent platform to construct a biointerface that concurrently achieve sterilization, structural optimization, and enzymatic resistance. Our work establishes a paradigm for adaptive material design in moist biological environments, with implications extending to bone adhesives and chronic wound management.