Cationic cyanine chromophore-assembled upconversion nanoparticles for sensing and imaging H2S in living cells and zebrafish

Elevated hydrogen sulfide (H2S) level is closely associated with various diseases. So the sensing of H2S is noteworthy for divulging its role in diagnosing these diseases. Herein, we proposed poly(acrylic acid)-modified upconversion nanoparticles assembled with cationic near-infrared cyanine chromophores (Cy7-Cl) as the nanoprobe (Cy7-UCNPs) for monitoring H2S based on thiolation reactions. The presence of H2S resulted into about five-fold enhancement in the luminescence intensity of Cy7-UCNPs and the nanoprobe showed a good linearity (R-2 = 0.9952) over the range of 1.0 - 90 mu M. Furthermore, Cy7-UCNPs were successfully employed in sensing and imaging of exogenous and endogenous H2S in live cells and zebrafish. The system shows great potential in the field of nanobiomedicine because of the many excellent properties including high sensitivity, good selectivity, and low cytotoxicity.