Myricetin-derived carbon dots for ratio-metric pH and Al3+ sensing via rational hydrazone engineering

Myricetin-derived carbon dots enable ratio-metric pH sensing with pH from 7.2 to 9.6. • Hydrazone structures confer highly sensitive and selective Al 3+ recognition. • Confocal imaging validates dual-function intracellular pH and Al 3+ monitoring. Sensitive analysis of intracellular pH and Al 3+ is essential for biological and environmental accessment. And traditional fluorescent nanomaterials often contain heavy metal components, whereas carbon dots (CDs) are metal-free with excellent biocompatibility, making them attractive candidates for probe construction. However, most CDs-based fluorescent probes have been developed empirically, with rational design strategies remaining relatively limited. Therefore, hydrazone functionalized carbon dots (N 2 H 4 @CDs) are fabricated by combining natural myricetin precursor with hydrazine-assisted post-functionalization strategy, establishing a structure-guided design that enables both ratio-metric pH sensing and selective Al 3+ analysis. Notably, N 2 H 4 @CDs showed dual emissions at 495 and 570 nm, with the peak at 570 nm increasing under higher pH. This ratio-metric response enabled accurate self-calibrated analyzing, showing a great linear correlation between the ratio I 495 / I 570 and pH from 7.2 to 9.6. As for Al 3+ analysis, fluorescence spectra show a pronounced enhancement of the emission intensity at 495 nm upon addition of Al 3+ , reflecting specific coordination with surface functional groups. The N 2 H 4 @CDs platform enable sensitive analysis of Al 3+ , with a linear range of 2–18 μmol/L and a detection limit of 0.125 μmol/L (3.37 μg/L). The spiked recovery experiments in lake water yielded satisfactory results, indicating its potential application in environmental exposure analysis. Confocal imaging in L929 fibroblasts confirmed that N 2 H 4 @CDs enable imaging of intracellular pH and Al 3+ . This strategy propses a rational hydrazone engineering strategy to realize ratiometric pH imaging as well as selective Al 3+ sensing. Download: Download high-res image (100KB) Download: Download full-size image