Efficient synthesis of green nitrogen-doped carbon dots as a versatile nanoprobe for antibacterial, cytotoxic, in-vitro imaging, and anti-counterfeit applications

Abstract

In this study, nitrogen-doped carbon dots (N-CDs) were synthesized using Boerhavia diffusa leaves as a novel & natural carbon source. These N-CDs serve as fluorescent nanoprobes for imaging tumour cells and exhibit multifunctional properties, including non-toxicity, antibacterial effectiveness, and suitability for anti-counterfeiting applications. The structural, optical, and morphological characteristics of the N-CDs were confirmed through X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), UV–visible spectroscopy, and Transmission Electron Microscopy (TEM). These analyses verified the amorphous and graphitic carbon structure, uniform spherical distribution, and elemental composition, highlighting the surface functionalities of the N-CDs. They demonstrated strong antibacterial activity against E. coli and S. aureus. Additionally, MDA-MB-231 cells were clearly visible after 24 h at an N-CD concentration of 512 µg/mL, confirming non-toxicity. The N-CDs promise as fluorescent bioimaging probes for MDA-MB-231 cells and as anti-counterfeit agents.