Ag/Ag@AgCl/ZnO hybrid nanostructures are embedded in a hydrogel by a simple two-step technique. The Ag/Ag@AgCl nanostructures are assembled in the hydrogel via ultraviolet light chemical reduction followed by incorporation of ZnO nanostructures by NaOH precipitation. The hydrogel accelerates wound healing and exhibits high antibacterial efficiency against both Escherichia coli and Staphylococcus aureus under visible light irradiation. The Ag/Ag@AgCl nanostructures enhance the photocatalytic and antibacterial activity of ZnO due to the enhancement of reactive oxygen species by visible light. This hydrogel system kills 95.95% of E. coli and 98.49% of S. aureus within 20 min upon exposure to simulated visible light, and rapid sterilization plays a crucial role in wound healing. In addition, this system provides controllable, sustained release of silver and zinc ions over a period of 21 days arising from the reversible swelling-shrinking transition of the hydrogel triggered by the changing pH value in the biological environment. About 90% Zn release is observed in the acidic environment after 3 days, whereas only 10% Zn release occurs in the neutral environment after 21 days. In vivo results show that release of Ag and Zn stimulates the immune function to produce a large number of white blood cells and neutrophils (2-4 times more than the control), thereby producing the synergistic antibacterial effects and accelerated wound healing.

Bone-implant-associated infections are common after orthopedic surgery due to impaired host immune response around the implants. In particular, when a biofilm develops, the immune system and antibiotic treatment find it difficult to eradicate, which sometimes requires a second operation to replace the infected implants. Most strategies have been designed to prevent biofilms from forming on the surface of bone implants, but these strategies cannot eliminate the biofilm when it has been established in vivo. To address this issue, a nonsurgical, noninvasive treatment for biofilm infection must be developed. Herein, a red-phosphorus-IR780-arginine-glycine-aspartic-acid-cysteine coating on titanium bone implants is prepared. The red phosphorus has great biocompatibility and exhibits efficient photothermal ability. The temperature sensitivity of Staphylococcus aureus biofilm is enhanced in the presence of singlet oxygen ( O ) produced by IR780. Without damaging the normal tissue, the biofilm can be eradicated through a safe near-infrared (808 nm) photothermal therapy at 50 °C in vitro and in vivo. This approach reaches an antibacterial efficiency of 96.2% in vivo with 10 min of irradiation at 50 °C. Meanwhile, arginine-glycine-aspartic-acid-cysteine decorated on the surface of the implant can improve the cell adhesion, proliferation, and osteogenic differentiation.

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