Mint leaf derived carbon dots for dual analyte detection of Fe(iii) and ascorbic acid

Highly luminescent carbon dots (CDs) are obtained from mint leaves adopting a simple and cost effective route devoid of additional chemical reagents and functionalization. The as-synthesized CDs are characterized by TEM, FE-SEM, XRD analysis, FTIR, Raman, UV-visible and photoluminescence spectral studies. The results reveal that the CDs have an average diameter of 4 nm with a hydroxyl-rich surface. The luminescence of the dots was excitation dependent and was stable towards variation in the medium. The system could perform as a promising on-off-on fluorescent sensor for the selective and sensitive dual analyte recognition of Fe³⁺ and AA with a detection limit of 374 nM and 79 nM, respectively. The mechanism of ascorbic acid sensing by the CD-Fe³⁺ unit is established by identifying the binding sites of the biomolecule with the metal ion by examining the behaviour of the sensor in the presence of ascorbic acid derivatives.