Development of Green Synthesized Novel Carbon Dots from <i>Ruta Graveolens L</i>. for Fluorescent and Intracellular Sensing of Mercury Ions in Pico‐molar (p<scp>m</scp>) Concentration

Abstract Green nanotechnology, which uses carbon nanomaterials for environmental remediation, is the pioneer among the prevailing approaches for the production and characterization. In the present study, highly fluorescent carbon dots (CDs) from Ruta Graveolens ( ARH‐CD ) is developed, and its efficacy as a fluorescent sensor and biomarker is investigated. They act as a fluorescence sensor for Hg 2+ over an extensive concentration range of 1 picomolar (p m ) to 1 molar ( m ), with a detection limit as low as 26.75 p m . The studies reveal ARH‐CD as an effective biomarker for intracellular toxicity analysis and a fluorescent probe for multi‐colored (blue, green, and red) imaging of HEK293 cell lines. After 24 h of incubation, it is found that the ARH material reveals noticeable biocompatibility and visible fluorescence, with a viability of 98.88% at 5 µg mL −1 and over 78.33% even at a concentration of 100 µg mL −1 . The IC50 value for the MTT assay for cell viability results is calculated to be 224.56 ± 4.67 µg, which further confirms the appreciable biocompatibility of the ARH‐CD. The obtained samples are effective in being inspected for the intracellular detection of Hg 2+ and serve as a possible candidate for cell imaging.