Atomically precise Au nanocluster-embedded carrageenan for single near-infrared light-triggered photothermal and photodynamic antibacterial therapy

In this study, we report atomically precise gold nanoclusters-embedded natural polysaccharide carrageenan as a novel hydrogel platform for single near-infrared light-triggered photothermal (PTT) and photodynamic (PDT) antibacterial therapy. Briefly, atomically precise captopril-capped Au nanoclusters (Au25Capt18) prepared by an alkaline NaBH4 reduction method and then embedded them into the biosafe carrageenan to achieve superior PTT and PDT dual-mode antibacterial effect. In this platform, the embedded Au25Capt18, as simple-component phototherapeutic agents, exhibit superior thermal effects and singlet oxygen generation under a single near -infrared (NIR, 808 nm) light irradiation, which enables rapid elimination of bacteria. Carrageenan endows the hydrogel platform with superior gelation characteristics and wound microenvironmental regulation. The Au25Capt18-embedded hydrogels exhibited good water retention, hemostasis, and breathability, providing a favorable niche environment for promoting wound healing. In vitro experiments confirmed the excellent anti-bacterial activity of the Au25Capt18 hydrogels against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The antibacterial effect and promoting wound healing function were further validated in a S. aureus-infected wound model. Biosafety evaluation showed that the Au25Capt18 hydrogel has excellent biocompatibility. This PTT/PDT dual-mode therapy offers an alternative strategy for battling bacterial infections without antibiotics. More importantly, this hydrogel is facile to prepare which is helpful for expanding applications.

Automated summary

In this study, atomically precise gold nanoclusters are embedded in natural polysaccharide carrageenan to create a hydrogel platform for single near-infrared light-triggered photothermal and photodynamic antibacterial therapy. The embedded nanoclusters exhibit thermal effects and singlet oxygen generation under near-infrared light, enabling rapid elimination of bacteria. The carrageenan endows the hydrogel with gelation characteristics and wound microenvironment regulation, promoting wound healing. The hydrogel demonstrates excellent antibacterial activity and biocompatibility, offering an alternative strategy for battling bacterial infections without antibiotics.