Bifunctional Fluorescent Carbon Nanodots From Galangal as Sensors for Metal Ions and as a Nutrient Source for Peanut Growth.

This study demonstrates the bifunctionality of fluorescent carbon nanodots (C-dots) derived from galangal as both sensors for metal ions and a nutrient source for peanut growth. The C-dots were fabricated via a carbonization method at 200 °C for 30 min and exhibited blue fluorescence in ethanol and aqueous solutions. Characterization using absorption, photoluminescence (PL), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) confirmed successful formation. The C-dots showed absorption peaks at 275 nm (ethanol) and 270 nm (aqueous), with an average diameter of 5.74 nm and a standard deviation of 1.11 nm. PL intensity was significantly quenched upon interaction with Fe3⁺ and Mg2⁺ ions, enabling their detection with limits of detection of 2.98 µM and 3.3 µM, respectively. The application of C-dots enhanced peanut growth, as evidenced by increased chlorophyll content and biomass compared to untreated plants. These results indicate that galangal-derived C-dots function as effective nutrient sources for vegetative growth. Overall, this approach provides an economical and environmentally friendly strategy for developing bifunctional C-dots for metal ion sensing and agricultural applications.