Enhanced antibacterial activity with increasing P doping ratio in CQDs

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Antibiotic resistance poses a significant threat to public health, necessitating novel antibacterial agents.
• Carbon quantum dots (CQDs) offer promising properties such as stability, low toxicity, and biocompatibility for biomedical applications.

Purpose of the Study:

• To synthesize phosphorus (P)-doped carbon quantum dots (CQDs) with tunable properties.
• To evaluate the antibacterial efficacy of these P-doped CQDs against resistant bacteria, specifically Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).
• To elucidate the mechanism underlying the antibacterial activity of P-doped CQDs.

Main Methods:

• CQDs were synthesized using a hydrothermal method with valine, triethylamine, and phosphoric acid.
• The size and surface charge of CQDs were modulated by varying phosphorus content.
• Antibacterial activity was assessed by determining the minimal inhibitory concentration (MIC) and observing morphological changes in bacteria.
• Singlet oxygen generation was measured to understand the antibacterial mechanism.

Main Results:

• Increasing phosphorus content in CQDs reduced their average diameter and increased positive surface charge.
• P-doped CQDs demonstrated significant antibacterial activity against both E. coli and S. aureus, with decreasing MIC values as P content increased.
• Bacterial cell morphology was disrupted upon treatment with P-doped CQDs.
• The antibacterial mechanism involves the generation of singlet oxygen and disruption of bacterial cell integrity through electrostatic interactions.

Conclusions:

• Phosphorus-doped CQDs are effective antibacterial agents against resistant bacteria.
• The tunable properties and potent antibacterial activity of P-doped CQDs make them promising candidates for treating bacterial infections.
• This study contributes to understanding the antibacterial mechanisms of CQDs, paving the way for novel antimicrobial drug development.