Biocompatible N-doped carbon dots for the eradication of methicillin-resistant S. aureus (MRSA) and sensitive analysis for europium (III)

Plant leaves have more attracted in the preparation of carbon dots (CDs) owing to natural phytochemicals. Herein, we performed a one-pot hydrothermal process for the synthesis of Nitrogen doped CDs (N@CDs) from glossy heart-shaped Piper betel leaves (P. betel). The prepared N@CDs were effectively applied for the eradication of E. coli, S. aureus, and methicillin-resistant S. aureus (MRSA). The N@CDs were also used as a sensor for lanthanides detection with notable selectivity for Eu³⁺. The results revealed that the water-soluble N@CDs displayed narrow size particle distribution with a mean diameter of 2.6 nm. The bright fluorescence was estimated to be at λ_ex: 350 with λ_em: 430 nm. The functional groups on N@CDs were confirmed by FTIR and XPS. The antimicrobial effect of N@CDs was concentration-dependent and effectively against E. coli and S. aureus at 1000 μg/mL. The antibacterial results reveal that the N@CDs exhibit the selective and superior killing effect against antibiotic-resistant bacteria (MRSA). The biocompatibility of CDs explored using THP- 1 monocytes cells. The N@CDs were also applicable for sensitive and selective detection of Eu³⁺ with LOD of 68 μM over other lanthanides in an aqueous solution by fluorescence quenching.