A colorimetric and fluorescent chemosensors based on synthesis of carbon dots from Cliptoria ternatea flowers for detecting Fe3+ions and their bioenvironmental applications

Biomass derived carbon dots (CDs) have attracted significant attraction as sustainable fluorescent nanomaterials. In this study, nitrogen-doped carbon dots (CtN-CDs) were synthesized through a one-pot hydrothermal method using Clitoria ternatea flowers as a carbon source and o-phenylenediamine as a nitrogen-dopant. The synthesized CtN-CDs were investigated by physicochemical evaluation characterization UV–Visible, fluorescence (FL), FTIR spectroscopy, XRD patter, TEM, and XPS analysis. The UV–Visible findings indicate that the absorption spectrum range 200–800 nm with excitation at 333 nm and emission at 458 nm exhibits a strong blue color. The as-prepared spherical CtN-CDs with an average size of 4.21 ± 0.17 nm and a quantum yield (QY) of 23.9 ± 1.26% is achieved. The metal sensing results indicate that CtN-CDs possess excellent selectivity toward Fe3+ ions over other metal ions, both colorimetrically and fluorometrically in aqueous medium. Introducing Fe3+ ions into an aqueous CtN-CDs solution caused the color to shift from yellow to colorless and resulted in significant FL quenching, demonstrating that CtN-CDs can serve as an efficient On–Off FL detection for Fe3+ ions. In aqueous solution of CtN-CDs/Fe3+, a linear detection range of 0–100 μM was achieved with limit of detection (LOD) with colorimetrically 0.11 μM and fluorimetrically 0.32 μM is lower than World Health Organization guideline in drinking water. Additionally, CtN-CDs/Fe3+ system also displayed good reversibility in the presence of EDTA and was successfully applied for Fe3+ detection in real water samples with recoveries ranging from 88.89% to 102.50%. Notably, the less cytotoxicity and high biocompatibility of the CtN-CDs make them promising candidates for cell imaging as well as for intracellular turn-Off Fe3+ and turn-On EDTA in HCT-116 cells.