Rapid and low-temperature synthesis of N, P co-doped yellow emitting carbon dots and their applications as antibacterial agent and detection probe to Sudan Red I

The preparation of long-wavelength emitting carbon dots (CDs) with good antibacterial function and biosensing ability through element doping method is the hotspot of present researches. This paper reports the rapid synthesis of nitrogen and phosphorus co-doped long wavelength-emitting CDs (N, P-CDs, λ_em = 530 nm) under low reaction temperature (30 min, 60 °C). This method used glucose, polyethyleneimine and phosphoric acid as raw materials, and each raw material worked multi-functionally during the synthesis process. The impacts of raw materials and reaction parameters upon optical properties of prepared N, P-CDs have been studied, and the synthesis mechanism has been discussed. Meanwhile, N, P-CDs were used as antibacterial material with minimum inhibitory concentrations against Staphylococcus aureus and Escherichia coli at 7.5 μg·mL^-1 and 0.5 mg·mL^-1 respectively. The prepared CDs were also used to realize fluorescence imaging of S. aureus, and work as fluorescence probe to detect Sudan Red I with limit of detection at 43 nM.