One‐step hydrothermal process of carbon dots derived from lemon and ginger juice: synthesis and characterizations

Abstract BACKGROUND This study aimed to develop a simple and eco‐friendly method for synthesizing fluorescent and stable carbon dots (CDs) using natural precursors. A one‐step hydrothermal approach was employed using a mixture of lemon and ginger juice as the carbon source. The resulting CDs were characterized to evaluate their structural, optical, and biocompatibility properties for potential biomedical and sensing applications. RESULTS Transmission electron microscopy (TEM) analysis revealed that the CDs had a quasi‐spherical morphology with an average particle size of 9.797 ± 1.87 nm. The CDs exhibited a fluorescence quantum yield of 27.7% and an excitation‐dependent emission, with maximum excitation and emission wavelengths at 400 and 480 nm, respectively. X‐ray diffraction (XRD) confirmed the amorphous nature of the CDs, showing a characteristic peak at 28.61°. Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS) identified abundant hydroxyl, carboxyl, and carbonyl functional groups on the surface of CDs. Dynamic light scattering (DLS) analysis determined a hydrodynamic size of 47.7 ± 15.57 nm and a zeta potential of −13.88 ± 1.73 mV, indicating good dispersion and surface charge stability in aqueous solutions. The thermal and structural characterization of the synthesized CDs using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Brunauer–Emmett–Teller (BET) confirmed their stability, phase transition behavior, and mesoporous nature. The CDs demonstrated excellent stability for several months under ambient conditions without showing turbidity or precipitation. Cytotoxicity assay on HeLa and MCF‐7 cell lines confirmed high cell viability ≥86%, indicating low toxicity and good biocompatibility. CONCLUSION The successful synthesis of fluorescent CDs from a mixture of lemon and ginger juices provides a green and sustainable approach to nanomaterial development. Their stability, low toxicity, and favorable optical properties make them promising candidates for bioimaging, drug delivery, and biosensing applications. © 2025 Society of Chemical Industry (SCI).