Application of green tea residue-derived carbon dots in the detection of Fe3+ ions and imaging of Caco-2 cells

In this study, we successfully synthesized green luminescent carbon dots by using green tea residue as the precursor of carbon source. Based on the internal filter effect (IFE), the fluorescence emission intensity of the probe decreased significantly with the increase of Fe 3 + concentration. Based on this, a linear relationship between Fe 3 + concentration and the fluorescence emission intensity of the probe was established to semi-quantitatively detect Fe 3 + . The results showed that the linear range was 1–400 μM, and the detection limit was 3.58 μM. In addition, the probe was further applied to actual samples, and it was found that the recovery rate was between 97.75% and 104.59%, and the relative standard deviation was below 1.81%. These findings underscore the considerable potential of the carbon dots for practical Fe 3+ detection applications. In a further application, the fluorescent carbon dots were diluted and directly employed to stain Caco-2 cells. Remarkably, even after 10 and 20-fold dilutions, the Caco-2 cells displayed vivid fluorescence at the green excitation wavelength. This outcome suggests a promising avenue for the application of fluorescent carbon dots in the field of biology.