Antimicrobial activity of carbon dots against aquatic spoilage Bacteria synthesized from Banana Peel waste

In this study, we used biomass banana peel (BP) as the precursor to synthesize CDs (defined as BP-CDs). The average sizes of BP-CDs were found to be around 5.9 nm. The prepared BP-CDs presented blue fluorescence under ultraviolet irradiation at 365 nm and exhibited excitation-wavelength-dependent fluorescence properties. Furthermore, the nitrogen-containing, oxygen-containing and sulfur-containing functionalities on/in the surface of carbon structure were observed in the resulting CDs. The antioxidant assays in vitro suggested that BP-CDs displayed strong free-radical scavenging abilities. The results of antimicrobial experiments revealed that BP-CDs exhibited noteworthy antimicrobial effects against spoilage bacteria of aquatic products. Metabolomics analysis revealed that BP-CDs exerted antibacterial activity mainly by impeding normal cell metabolism, disrupting cell wall integrity, affecting substance transport and signal transduction. Taken together, these data suggest that BP-CDs could be used as an antioxidant and antibacterial agent for the development of new preservation technologies for aquatic products.