Sustainable synthesis and characterization of fluorescent nanoprobe based on unintentional heteroatom doped-carbon quantum dots for bioimaging of human neuroblastoma cancer cells and living organisms.

[Display omitted] • Biocompatible fluorescent N,K,Ca-doped CQDs derived from Chenopodium album. • Fluorescence quantum yield up to 48.12 % was achieved. • Bioimaging of SH-SY5Y human neuroblastoma cells, bacteria, fungal, and plant cells. • The cytotoxicity and cell viability have also been examined. This study demonstrated an economical, ecologically sustainable, and simple method for producing biocompatible fluorescent carbon quantum dots (CQDs) co-doped with N, K, and Ca from bathua (Chenopodium album), a popular medicinal herb leaf extract and nutritious vegetable. The nearly spherical shaped CQDs were discovered to be 3–5 nm in size in nature, with a quantum yield of around 48.12%, robust photo-stability, and excellent water solubility. Various morphological, compositional, physicochemical and optical characteristics were investigated. Additional factors affecting the photoluminescence of CQDs, such as hydrothermal process parameters, pH, and solvent sensitivity, were investigated further. Moreover, the newly synthesized N, K, Ca-doped CQDs were demonstrated to be a useful fluorescent nanoprobe for in vitro cellular imaging of SH-SY5Y human neuroblastoma cells, as well as other living organisms such as bacteria, fungal, and plant cells, as a cost-effective alternative to organic or synthetic fluorescent probes. Cell survival and cytotoxicity were found to be acceptable, with 95% of SH-SY5Y and HCT-116 cells surviving and other organisms able to withstand higher doses (10.9 mg/mL) for up to 4 days. [ABSTRACT FROM AUTHOR]