A Ratiometric and Colorimetric Hemicyanine Fluorescent Probe for Detection of SO2 Derivatives and Its Applications in Bioimaging.

Based upon the intramolecular charge transfer (ICT) mechanism, a novel ratiometric fluorescent probe EB was developed to detect SO32-/HSO3-. The probe displayed both colorimetric and ratiometric responses toward SO32-/HSO3-. It displayed a quick response (within 60 s), good selectivity and high sensitivity (a detection limit of 28 nM) towards SO32-/HSO3-. The SO32-/HSO3- sensing mechanism was confirmed as the Michael addition reaction by ESI-MS. Moreover, the probe could be applied to measure the level of sulfite in real samples, like sugar and chrysanthemum, and it could also be used to detect SO32-/HSO3- in HepG2 cells through confocal fluorescence microscopy, which proved its practical application in clinical diagnosis.

Simultaneous determination of canonical purine metabolism using a newly developed HILIC-MS/MS in cultured cells.

Purine metabolism acts as the core role in human metabolic network. It offers purine metabolites as raw material for building blocks in cell survival and proliferation. Purine metabolites are the most abundant metabolic substrates in organisms. There are few reports to simultaneously quantify canonical purine metabolism in cells. A novel hydrophilic interaction liquid chromatography coupled with mass spectrometry (HILIC-MS/MS) method was developed to simultaneously determine purines profile in biological samples. Chromatographic separation was achieved using a HILIC (Waters Xbridge™ Amide) column. Different optimizing chromatographic conditions and mass spectrometric parameters were tested in order to provide the best separation and the lowest limit of quantification (LLOQ) values for targeted metabolites. The validation was evaluated according to the Food and Drug Administration guidelines. The limit of determination (LOD) and the LOQ values were in the range of 0.02-8.33 ng mL-1 and 0.1-24.5 ng mL-1, respectively. All calibration curves displayed good linear relationship of with excellent correlation coefficient (r) ranging from 0.9943 to 0.9999. Both intra-day and inter-day variability were below 15 %, respectively. Trueness, expressed as relative error, was always within ±15 %. In addition, no derivatization procedure and ion-pair reagents are in need. The innovated approach demonstrates high sensitivity, strong specificity, and good repeatability, making it suitable for absolute quantitative studies of canonical purine metabolism in cultured cells.

Rational modulation of coumarin-hemicyanine platform based on OH substitution for higher selective detection of hypochlorite.

To monitor delicate changes of biological HOCl in vivo, a new probe (OH-substituted coumarin-hemicyanine, probe 2) was synthesized for NIR and ratiometric HOCl detection. Selectivity studies indicated that the electron-donating group (OH) substituted on the indolium moiety enhanced the selectivity to detect HOCl. With HOCl, the probe showed a ratiometric fluorescence (I500/I650) with a low detection limit (49.1 nM) and a rapid response (within 2 min). In addition, probe 2 was successfully applied to visualize exogenous and endogenous HOCl in living cells and animals and exhibited a perfect mitochondria target ability. This probe has been further studied as a potential and powerful tool to probe HOCl in arthritis models.