A biocompatible ratiometric fluorescent nanoprobe for intracellular hydrogen sulfide accurate detection based on rare...

Hydrogen sulfide (H₂S) is an important signal molecule involved in intracellular activities. To understand the role of H₂S in cellular physiological and pathological process, the development of sensitive and selective methods, especially biocompatible assays, for efficient monitoring the level of H₂S is necessary. Herein, we modified novel rare earth element europium (EU) based fluorescent nanospheres with azide (-N₃) based sensor to construct an ingenious ratiometric fluorescent nanoprobe EU-N3. This nanoprobe showed excellent water solubility and high biocompatibility for intracellular H₂S accurate detection. Nanoprobe EU-N3 had two obvious emission peaks, the green fluorescence peak at 540 nm increased according to the increasing of H₂S concentration and the red fluorescence peak at 616 nm was stable as ratiometric reference. The fluorescence intensity ratio (I₅₄₀/I₆₁₆) displayed good linear response (R = 0.99136) in H₂S range of 0.5 ∼ 30 μM. The analytes response assay demonstrated that the nanoprobe EU-N3 possessed a better specificity for H₂S, compared with other 9 anions and 3 cations. The cell viability assay indicated the nanoprobe EU-N3 had an excellent biocompatibility. The cell imaging showed that the proposed nanoprobe could be applied for detecting the intracellular H₂S changes accurately in live cells. Such nanoprobe provided a safe and accurate strategy for intracellular H₂S detection, which is helpful for the real-time H₂S visualization in the live cell activities.