One-Step Synthesis of Carbon Quantum Dots with Antibacterial Activity Based on Andrographolide

Abstract The increasing use of antibiotics to treat bacteria has led to the emergence of many resistant bacteria. Therefore, it is crucial to research novel antibiotics and understand how they are used to combat bacteria. In this study, a green, effective, and ecologically acceptable hydrothermal approach was used to efficiently convert andrographolide and citric acid into carbon dots with vivid blue fluorescence and an emission wavelength of 430 nm. TEM, AFM, FT-IR, and XPS were used to analyze the surface morphology, particle size distribution, and surface functional groups of carbon dots. It was discovered that carbon quantum dots had different functional groups linked to the surface and had a common particle dimension of 2.75 nm. Additionally, it was unexpectedly discovered that carbon quantum dots confirmed great antibacterial motion in opposition to both Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ), with a MIC of 1.14 mg/mL. Carbon quantum dots have a positive charge of 16 eV, which can connect to the bacterial cell wall and destroy the normal form of bacteria by generating 1 O 2 , causing antibacterial effects, according to research on the antibacterial mechanism of carbon dots.