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

• Synthesis of novel fluorescent N-CDs from Boerhavia diffusa leaves. • The optical, and structural properties and their elemental composition are examined. • It shows good anti-bacterial activity against E. coli and S. aureus. • It is a promising candidate for cytotoxic effects against human breast cancer cells (MDA MB231 cell line) and in-vitro imaging. • It has the potential for anti-counterfeiting applications. 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.