Space-Confined Synthesis of Thin Polypyrrole Nanosheets in Layered Bismuth Oxychloride for a Photoresponse Antibacterial within the Near-Infrared Window and Accelerated Wound Healing.

Bacterial infection greatly affects the rate of wound healing. Both photothermal and photodynamic antibacterial therapies activated by near-infrared (NIR) light with semiconductor nanomedicine are two effective approaches to address bacterial infections, but they cannot coexist synergistically to kill bacteria more efficiently because of the limitation of the band structure. Here, inspired by the natural core-shell structure and photosynthesis simultaneously, polypyrrole (PPy) is synthesized in the two-dimensional restricted area of the layered bismuth oxychloride (BiOCl) nanosheets through the in situ ultrasonic recombination method. The atomic-level interface contact and bonding formed in the PPy-BiOCl intercalated nanosheets not only improve the light-to-heat conversion capabilities of PPy but also promote the transmission of PPy photogenerated charge carriers to the BiOCl semiconductor. The nanocomposites take advantage of the deeper tissue penetration under NIR light irradiation and exhibit excellent photothermal and photodynamic synergistic antibacterial activity. In addition, PPy-BiOCl intercalated nanosheets have good biocompatibility and accelerate wound healing through their antimicrobial activity and skin repair function. The space-confined synthesis of thin PPy nanosheets in layered structures offers an efficient NIR photoresponsive nanomedicine for the treatment of pathogen infection, with promising applications in infected wound healing.

Programmable biological state-switching photoelectric nanosheets for the treatment of infected wounds.

Recurrent bacterial infection is a major problem that threatens the tissue repair process. However, most current therapeutic strategies fail to deal with management of the overlap dynamics of bacterial killing and tissue repair. Here, in accord with the different responses of eukaryotic and prokaryotic cells to electric potential, we developed high performance photoelectric BiOCl nanosheets that dynamically switch between conditions that favor either tissue regrowth or antibacterial microenvironments due to light stimulated and bi-modal switching of their surface electrical polarization. In vitro assays demonstrate that, under light illumination, the mannitol modified BiOCl nanosheets show high relative surface potential and achieve robust antibacterial performance. Conversely, under dark conditions, the nanosheets exhibit relatively low surface potential and promote Bone Marrow Stem Cell (BMSCs) proliferation. In vivo studies indicate that BiOCl nanosheets with light switch capabilities promote the significant regeneration of infected skin wounds. This work offers a new insight into treating recurrent bacterial infections with photoelectric biomaterials for light controlled selection of alternative electrical microenvironments, thereby benefiting the capability for either antisepsis or repair of damaged tissues.