Qichao Yao

A fluorescent probe for H2S in vivo with fast response and high sensitivity

In this work, we design and synthesize a new near-infrared (NIR) ratiometric fluorescent probe FD-H2S for the highly sensitive (DL 68.2 nM) detection of H2S with fast response (15 s), large emission shift (220 nm) and excellent enhancement (168-fold in ratiometric value). The probe could be applied for monitoring and imaging of exogenous or endogenous H2S in live MCF-7 cells and in live mice with the fastest response.

A NIR fluorescent chemodosimeter for imaging endogenous hydrogen polysulfides via the CSE enzymatic pathway

Sodium polysulfides (Na2Sn, n > 1) as important raw materials in the chemical industry can afford hydrogen polysulfides (H2Sn, n > 1) under physiological conditions. Hydrogen polysulfides are important reactive sulfide species that play crucial roles in biological systems. The simple detection of H2Sn in solution and biosystems becomes very important as a consequence of the foregoing applications. Herein, we report a NIR fluorescent chemodosimeter, Cy-Sn, displaying turn-on fluorescence after reaction with H2Sn, which exhibits good selectivity and sensitivity in solution and biosystems. Moreover, it was applied successfully to monitor endogenous hydrogen polysulfides via the cystathionine γ-lyase (CSE) enzymatic pathway during inflammation and anti-inflammation in living RAW 264.7 cells. Mouse experiments indicated that this chemodosimeter has good potential to be employed in the imaging of living biosystems.

A two-photon NIR-to-NIR fluorescent probe for imaging hydrogen peroxide in living cells

Hydrogen peroxide (H2O2), one of the reactive oxygen species (ROS), plays vital roles in diverse physiological processes. Imbalance of the H2O2 is concerned with serious diseases such as cardiovascular disorders, neurodegenerative diseases, Alzheimers disease and cancer. Therefore, it is critical to develop efficient methods for monitoring H2O2 in vivo. In this work, a two-photon excitation (860nm) NIR fluorescent turn-on probe TPNR-H2O2 for H2O2 based on Dicyanomethylene-4H-pyran fluorophore is reported, which can be used in solution detection with 13.2-fold NIR fluorescence enhancement, fast response (completed within 40min), excellent sensitivity (DL 72.48nM), and lower cellular auto-fluorescence interference. Importantly, the perfect photostability of TPNR-H2O2 clearly demonstrated that the probe could be applied to imaging intracellular H2O2 for a long time without photobleaching. In addition, through two-photon imaging, this probe was cell permeable and used to monitor the level of endogenous and exogenous H2O2 with promising biological application.

A NIR fluorescent probe: imaging endogenous hydrogen peroxide during an autophagy process induced by rapamycin

In this work, a near-infrared probe (Cy-B) with high sensitivity, and good specificity as well as photo-stability has been developed for monitoring both exogenous and endogenous H2O2 in living cells. To the best of our knowledge, it was applied successfully for the first time to monitor spontaneous hydrogen peroxide in an autophagy process induced by the stimulation of rapamycin. The mice imaging experiments indicate that the probe has a good potential to be employed in the imaging of living biological systems.

Recognition of Exogenous and Endogenous Nitroxyl in Living Cells via a Two-photon Fluorescent Probe

Nitroxyl (HNO), one electron reduced and protonated form of nitric oxide (NO), plays vital in various biological functions and pharmacological activities, such as mediating β-agonist dobutamine, inhibiting the activity of enzyme and treating cardiovascular diseases. However, the accurate mechanism of HNO in living cells is not thoroughly understood due to lacking of effective methods. In this work, a novel two-photon fluorescent probe TP-HNO was designed and synthesized based on 6-hydroxyl-quinonline-2-benzothiazole derivatives through introducing 2-(diphenylphosphino)benzoate as the ideal HNO recognition unit, which demonstrated the merits of outstanding selectivity, excellent sensitivity (DL 0.19 μM) and rapid response (20 min). In addition, owing to the high cell permeability and low biotoxicity of probe TP-HNO, it was successfully used for the qualitative and bioimaging of exogenous and endogenous nitroxyl concentration fluctuations in living cells via a two-photon laser confocal fluorescence microscopy, respectively, which is of importance for revealing the biological of HNO in the further.

Differentiating RNA from DNA by a molecular fluorescent probe based on the “door-bolt” mechanism biomaterials

Although excellent florescent probes have been developed for DNA, good probes for RNA remain lacking. The shortage of reported and commercial RNA probes is attributable to their severe interference from DNA. As DNA and RNA have similar structures but different functions, it has been an imperative challenge to develop RNA probes that differentiate from DNA. In this study, an NIR fluorescent probe, NBE, is described, which contains a bulky julolidine group that can fit in a spacious RNA pocket and emit intense fluorescence. However, NBE has no response to DNA, as it cannot intercalate into the double strands or even in the DNA minor groove. The sensing mechanism is similar to the effect of a door-bolt. NBE shows excellent performance in RNA sensing (outstanding photostability, high selectivity and fast response), whether in aqueous buffers, fixed cells or living cells. These findings might provide not only a potential imaging tool but also a new design strategy for the recognition of RNA while avoiding interference from DNA.