Kiwifruit-derived carbon dots for sensitive detection of Fe³⁺ ions

Fluorescent carbon dots (CDs) have been receiving much attention from researchers because of their properties such as excellent photostability and low toxicity. In this work, water-soluble fluorescent carbon dots were prepared from kiwifruits through a one-step, low-cost hydrothermal process. The as-prepared CDs had average sizes of 2.3±0.6 nm, and they emitted blue photoluminescence (PL). The surface functional group and structures of the CDs were investigated via Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The blue fluorescence of the as-prepared CDs was effectively quenched by Fe³⁺ ions, whereas it was poorly quenched by other competing metal ions. Therefore, these CDs can serve as effective fluorescent probes for sensitive and selective detection of Fe³⁺ ions. Moreover, a linear relationship was obtained between the relative fluorescence intensity and the concentration of Fe³⁺ ions with a limit of detection of 0.37 nM and a linear detection range of 0 to 20 μM.