P-doped carbon quantum dots from potato starch as antimicrobial materials for food applications

Carbon dots (CDs) are a new type of nanomaterials that have attracted great research interest due to their unique physico-chemical properties. In this study, CDs were efficiently synthesized from potato starch using a hydrothermal method. The effect of surface modification of CDs with phosphorus and light exposure on antimicrobial activity of these nanomaterials were investigated. The diameters of P-doped and unmodified CDs were 9.04±4.21 and 7.47±3.64 nm, respectively. P-doped CDs showed notable fluorescence properties, being about 1.5 times higher than that of unmodified CDs. FTIR analysis confirmed the successful doping of CDs with phosphorus. According to antimicrobial results obtained by the well diffusion assay, the P-doped CDs showed more potent antibacterial activity against foodborne pathogens including Staphylococcus aureus , Escherichia coli , Pseudomonas aeruginosa , and Salmonella Enteritidis. Moreover, the minimum inhibitory concentrations bactericidal concentrations (MIC and MBCs) of P-doped CDs against tested bacterial pathogens were ≥ 2 times lower than values obtained by unmodified CDs. The MTT assay demonstrated low cytotoxicity of CDs towards HFF cells at concentrations ≤ 256 mg/L indicating good biocompatibility. Our results revealed that P-doped quantum dots show significantly enhanced bactericidal properties that can have excellent potential for application as preservatives in food systems. • The carbon dots (CDs) with high fluorescent intensity produced from potato starch • Phosphorus doping enhanced physical and antimicrobial properties of CDs • Doped CDs showed twice the antimicrobial activity compared to unmodified one • Visible light enhanced antimicrobial properties of Doped CDs