Citric acid-based carbon dots: From revealing new insights into their biological properties to demonstrating their enhanced wound healing potential by in vitro and in vivo experiments

Citric acid, as a carbon precursor, has extensively been considered by researchers to synthesize fluorescent carbon nanodots (CNDs), which emit strongly in the blue spectral range. In an endeavor to repurpose CNDs for applications other than those until now reported, non-doped, nitrogen-doped, and nitrogen/sulfur co-doped CNDs, were synthesized using citric acid as one of the most exploited carbon sources. This study explored the effect of heteroatom doping on the biological properties of CNDs placing more emphasis on wound healing. The three CND species were examined with respect to cell proliferation/toxicity, cell migration, bactericidal, anti-inflammatory, and antioxidant properties. From the results, it became apparent that the N,S-doped CNDs exhibit remarkable bactericidal properties, while the N-doped CNDs exhibit the best anti-inflammatory and antioxidant properties. Based on it, in-vitro antioxidant experiments were carried out for the N-doped CNDs, which validated our findings. Next, the N-doped CNDs were evaluated for their wound healing potency by carrying out relevant in-vivo experiments. The results showed that wounds treated with the CNDs were healed four days faster than control wounds. This study provides valuable insights into inspiring new advancements of CNDs and draws a roadmap towards their broader range of biomedical applications underlining the potency in wound healing.