Visible Light-Activated Photodynamic Therapy Microneedle Arrays with Carbon Dots Modified CuTCPP for Deep Bacterial Infection Treatment

Abstract Photodynamic therapy has attracted significant attention in treating serious bacterial skin infections. Herein, the carbon dots@Cu Tetrakis (4-carboxyphenyl) porphyrin microneedle arrays (CDs@CuTCPP MNs) were prepared by using a 3D printing technology for efficient photodynamic therapy of deep bacterial infected wounds. The CDs decorated on CuTCPP nanosheets facilitated the spatial charge separation for reactive oxygen species generation under irradiation. The CDs as a nanozyme could help to alleviate the local oxidative stress once they power off the light. Importantly, the release of ROS from the microneedle (length about 800 μm) to the deeply infected sites for damaging the bacteria can be achieved in a short time by the dissolution of the hyaluronic acid. As expected, the typical CDs@CuTCPP MNs achieved an average antibacterial rate of more than 95% against Staphylococcus aureus and Escherichia coli under visible-light irradiation (λ ≥ 420 nm). Moreover, during the wound healing evaluation test, the microneedle arrays achieved a remarkably high wound closure rate of 96.8%. The antibacterial mechanism of the CDs@CuTCPP MNs was investigated through reactive oxygen capture experiments, electrochemical characterization, and density functional theory calculations. This work offers a viable, visible light-driven approach for the treatment of deep-seated bacterial infections, highlighting the synergy between charge-decoupling photosensitizers and microneedle-assisted delivery.