A Comprehensive Study on the Antibacterial Activities of Carbon Quantum Dots Derived from Orange Juice against <i>Escherichia coli</i>

Abstract

Carbon quantum dots (CQDs) are known for their intriguing optical properties, low toxicity, and high biocompatibility, which make them promising for biomedical applications. In this study, CQDs were synthesized by subjecting orange juice to microplasma as a carbon source at atmospheric pressure and low temperatures. The resulting CQDs exhibited a narrow size distribution, with an average diameter of approximately 4.5 nm and a pH value of 5.67. These CQDs exhibited strong blue emission characteristics. The antibacterial properties of the CQDs against Escherichia coli (E. coli) strains were evaluated using minimum inhibitory concentration assays. The study revealed that an effective inhibition of E. coli was achieved at a minimum inhibitory concentration of 0.1 ppm, while the minimum bactericidal concentration for this bacterial strain was 1 ppm, resulting in an average antibacterial efficacy of 57%. Notably, the antibacterial effects of the CQDs were observed without the need for additional light or oxidants, demonstrating the applicability of CQDs in combating bacterial strains.

Keywords

• carbon quantum dots
• plasma
• antibacterial
• <i>Escherichia coli</i>
• bacteria strains