A robust carbon dot-based antibacterial CDs-PVA film as a wound dressing for antibiosis and wound healing.

Developing highly effective antibacterial films to promote wound healing remains a huge challenge. Herein, homogeneous and self-standing CDs-PVA composite films (PVA3, PVA5 and PVA8) were constructed by doping various mass ratios (3, 5 and 8 wt%) of carbon dots (CDs) into polyvinyl alcohol (PVA), which had no cracks or macroscopic defects. Moreover, the robust mechanical strength and flexibility enabled them to be cut into diverse patterns as required, which provided unique advantages for being employed as a wound dressing. PVA5 and PVA8 were powerful broad-spectrum bactericides and they could kill both Gram-negative bacteria and Gram-positive bacteria like Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with the antibacterial efficacy over 90.0%. More significantly, the biocompatible films could be readily processed into a "band-aid" type dressing for wound healing. The PVA5 band-aids were just pasted on the wounds for two days and then removed, and the wounds were completely closed after fourteen days. Neither introducing any metals or antibiotics, nor with the help of any external activation, these kinds of CD-based films have the strengths of low cost, being easy to use, excellent biocompatibility and outstanding antibacterial performance, and are desirable wound dressings for various skin injuries.

Positively charged BODIPY@carbon dot nanocomposites for enhanced photomicrobicidal efficacy and wound healing.

Even with advances in diverse antibiotics, bacterial infectious diseases with high mortality and morbidity still seriously endanger human health, which spurs the development of alternative antiseptic and therapeutic strategies for combatting bacteria. Antimicrobial photodynamic inactivation (aPDI) has emerged as an effective treatment protocol for different types of infection. Moreover, the risk from Gram-positive organisms cannot be overlooked. In the present work, fluoroborondipyrrole (BODIPY) was assembled with cationic and anionic carbon dots (CDs) to construct positively charged (termed p-BDP) and negatively charged (termed n-BDP) nanophotosensitizers. Compared with n-BDP, p-BDP showed a stronger photoinactivation activity against Staphylococcus aureus, and its minimal inhibitory concentration (MIC) was as low as 128 ng mL-1. In addition, p-BDP could act as a more efficacious wound dressing to accelerate the healing of S. aureus infections. This work opens up alternative thinking for the design of highly effective nanobactericides.

Injectable self-healing hydrogel fabricated from antibacterial carbon dots and ɛ-polylysine for promoting bacteria-infected wound healing.

Developing highly efficient pharmaceuticals to eradicate pathogens and facilitate wound healing is of great concern. Despite some cationic carbon dots (CDs) have been used for sterilization, hardly any anionic CDs with antimicrobial activity have appeared. In the present work, we engineered a string of anionic CDs (especially CD31) as valid broad-spectrum bactericides to kill bacteria. Furthermore, CD31 conjugated with ɛ-polylysine (Plys) to construct injectable, and self-healing hydrogel (CD-Plys) that possess the advantages of remarkable broad spectrum antibacterial activity, excellent wound healing ability and satisfied biocompatibility. CD-Plys could dramatically accelerate wound healing with epithelization and enhanced angiogenesis. Taken together, this work provides a two-pronged strategy to explore CDs-based antimicrobial agents for disease therapy and tissue engineering.

Exploring BODIPY derivatives as photosensitizers for antibacterial photodynamic therapy.

There is an urgent need to develop efficient and safe antimicrobials to augment traditional antibiotics for fighting drug-resistant bacteria. Antimicrobial photodynamic therapy (aPDT), is a promising antimicrobial stize antibiotic resistance and may reduce systemic side effects. Boron-dipyrromethene (BODIPY) is a type of photosensitizer (PSs) for aPDT with tunable structures and rational photophysical features. Herein, six kinds of BODIPY derivatives (BDP1-BDP6) modified with different atoms or groups such as iodine atoms, thiophene, cyano, phenyl, aldehyde and nitro groups were synthesized and their photophysical behaviors were characterized. The results indicated that BDP3, which had 2, 6-diiodo and 8-phenyl substitution, was the best PS candidate with the highest reactive oxygen species (ROS) generation efficacy. BDP3 and BDP5 could rapidly kill Staphylococcus aureus (S. aureus) with the minimum inhibitory concentration (MIC) of 10 nM upon illumination. They also possessed excellent biofilm inhibition ability against S. aureus and could efficaciously restrain the formation of bacterial biofilm. The results of Live/Dead staining assay and scanning electron microscopy (SEM) demonstrated that BDP3 destroyed the cell membrane structure of bacteria by generating ROS, which ultimately led to bacterial lysis and death. Finally, the biosafety evaluation toward the mouse fibroblasts (L929 cells) suggested BDP3 had good cytocompatibility. This work exhibits the great potential of rational designs of PS for aPDT applications.