A bifunctional sensitive fluorescence probe based on pyrene for the detection of pH and viscosity in lysosome.

Lysosome is one of the important organelles in intracellular transport. It plays a significant role in the physiological process. The lysosomal microenvironment affects the functions of lysosome. When the original acidic environment of lysozyme is destroyed or the fluid viscosity increases gradually, various diseases are easily induced. However, most fluorescent probes can only locate in cells. The fewer probes of subcellular organelles were found and their functions are often single. So, it is of great importance to design multifunctional fluorescent probes with the capable of localizing in lysosome. In this study, a novel lysosome probe, 4-(4-Pyren-1-yl-but-3-enyl)-morpholine (PIM), was synthesized using pyrene as a fluorescent group and morpholine as a target group. The introduction of morpholine group made PIM localize in lysosome with high selectivity. The fluorescence will be enhanced with the increased viscosity because of restricting the rotation of CC bond and CN in PIM, and the detecting linear range is from 4.05 cP to 393.48 cP, which qualified the requirement of the viscosity monitoring in body. Meanwhile, the fluorescence intensity of PIM declines with the decrease of pH because the Schiff base of PIM is hydrolyzed, which was affirmed by 1H NMR, LC-MS and fluorescence spectra. Moreover, cell imaging and MTT experiments confirmed that PIM as a novel bifunctional probe can be used to detect pH and endogenous viscosity in lysosome.

Thermo-sensitivity of hybrid nanogels for specific endogenous hydrogen sulfide detection and efficient flash chill treatment.

Thermo-responsive nanogels, poly(NIPAM-AAM) were prepared by a facile method of free radical one-pot precipitation based on monomeric N-isopropylacrylamide (NIPAM). At the same time, surface carboxyl group-modified fluorescent conjugated polymer nanoparticles (PNPs-COOH) were immobilized in the nanogel networks by hydrogen bonding to show bright green photoluminescence and outstanding thermo-responsive properties with a typical two-phase Tai Chi structure. Poly(NIPAM-AAm)-PNPs-COOH displays a larger change of hydrodynamic diameter (Dh) and a reversible volume transition from ∼150 nm at 40 °C to ∼1.0 µm at 4 °C. The change will cause apoptosis of cells to finish flash chill treatment. Meanwhile, the fluorescence of poly(NIPAM-AAm)-PNPs-COOH demonstrates reversible quenching and recovery with the expansion and collapse of the nanogel network induced by temperature changes. In addition, when adding Fe3+, the fluorescence of poly(NIPAM-AAm)-PNPs-COOH can be quenched due to the chelation between the PNPs-COOH and Fe3+ and then recovered in the presence of hydrogen sulfide because the chelate is broken; this was attributed to the stronger affinity between Fe3+ and S2-. Therefore, the fluorescence nanoplatform, Fe3+/poly(NIPAM-AAm)-PNPs-COOH, was successfully used to detect endogenous hydrogen sulfide in living A549 cells.