Solanum nigrum L-derived carbon Dots:Antimicrobial applications and detection of ciprofloxacin in milk samples

This paper reports a one-step hydrothermal carbonation method for the synthesis of yellow-green carbon dots from Solanum nigrum L, with phosphoric acid as dopant. The phosphorus-doped carbon dots ( P-CDs) were characterized with TEM, XRD, FT-IR, XPS, and UV–Visible. P-CDs provided good fluorescence enhancement of ciprofloxacin with excellent selectivity and sensitivity, while maintaining robust performance against ionic interference and pH variations. The P-CDs demonstrated high sensitivity toward (ciprofloxacin) CIP, with a wide linear detection range of 0.01–0.1 μM and an ultralow detection limit of 6.37 × 10 −3  μM. Moreover, the P-CDs effectively inhibited S. aureus and E. coli growth at a MIC of 0.27 mg/mL. The P-CDs enable rapid antibiotic detection within 5 min while demonstrating potent antibacterial efficacy with a remarkably low propensity for inducing drug resistance, thereby opening new avenues for combating drug-resistant bacterial infections. Notably, the P-CDs offer a simple, rapid, and highly sensitive detection method for CIP analysis in milk samples, making them a promising tool for food safety monitoring. This finding will support the future development of carbon dots for food chemistry applications.