Cyanine-modified near-infrared upconversion nanoprobe for ratiometric sensing of NH in living cells.

Although being as an important chemical material in industry, hydrazine (NH) is highly toxic to the humans and animals. The development of sensitive methods for the detection of hydrazine is meaningful. Herein, we develop a new organic-inorganic hybrid nanoprobe for the detection of NH based on luminescent resonance energy transfer (LRET) process. The nanoprobe contains NH-responsive NIR cyanine dye (CQM1) and α-cyclodextrin (CD) anchored on the surface of lanthanide-doped upconversion nanophosphors (UCNPs). In the presence of hydrazine, the hybrid materials (CQM1-UCNPs) showed the a large ratiometric luminescent signal change with high sensitivity and selectivity. More importantly, by taking advantage of ratiometric Upconversion luminescent (UCL) signal and the features of NIR emission/excitation, the nanoprobe was successfully applied for visualization of hydrazine in living cells for the first time.