Carbon Dots with Integrated Photothermal Antibacterial and Heat-Enhanced Antioxidant Properties for Diabetic Wound Healing.

Diabetic wounds pose a persistent challenge due to their slow healing nature, primarily caused by bacterial infection and excessive reactive oxygen species (ROS)-induced inflammation. In this study, carbon dots with synergistic antibacterial and antioxidant properties, referred to as AA-CDs, are developed specifically for diabetic wound healing using a straightforward solvothermal method. By utilizing cost-effective precursors like citric acid and ascorbic acid, AA-CDs are engineered to possess tailored functions of photothermal sterilization and ROS scavenging. The resulting AA-CDs demonstrats broad-spectrum antibacterial activity, particularly against multidrug-resistant strains, along with efficient ROS scavenging both in solution and within cells. Additionally, AA-CDs exhibits a protective effect against oxidative stress-induced damage. Notably, with a high photothermal conversion efficiency (41.18%), AA-CDs displays heat-enhanced antioxidant performance, providing not only augmented ROS scavenging but also additional protection against oxidative stress, yielding a true "1 + 1 > 2" effect. To facilitate their use in vivo, AA-CDs are incorporated into a thermally responsive hydrogel, which exhibits evident anti-inflammatory properties by modulating inflammatory factors and significantly promots the healing of diabetic wounds. This study underscores the value of integrated platforms for diabetic wound healing and highlights the potential of versatile CDs as promising therapeutic agents in biomedical applications.

Controllable Assembly of Cu2+ and Chlorin E6 for H2 S-Activatable Recognition of Bacterial Infection and Enhanced Antibacterial Therapy.

Antibacterial photodynamic therapy (APDT) has emerged as one of the intriguing strategies to combat bacterial resistance. However, the antibacterial efficacy of APDT is found to be severely impacted by the hydrogen sulfide (H2 S)-overproduced bacterial infection microenvironment. Herein, a multifunctional APDT platform is developed by assembling Cu2+ and chlorin e6 (Ce6), which exhibits unique H2 S-activatable fluorescence (FL) and antibacterial features. Noteworthily, the assembly conditions are crucial for achievement of Cu-Ce6 nanoassemblies (NAs) with the on-demand responsive properties. The quenched FL and photosensitization of Cu-Ce6 NAs can be selectively activated by the overexpressed H2 S in infected area, enabling specific recognition of bacterial infection and localized antibacterial therapy with minimized side effects. Significantly, amplified oxidative stress is achieved owning to the effective consumption of H2 S by Cu2+ in the NAs, leading to an enhanced APDT. The antibacterial mechanisms including broad-spectrum APDT activity of released Ce6, inherent sterilization effects of produced copper polysulfides and the accompanying disturbance of bacterial sulphide metabolism are further identified. This study may pave a new avenue for the rational design of intelligent APDT platform using minimalist biological building units and thus facilitating the clinical translation of nano-antibacterial agents.