Two quinoline-based two-photon fluorescent probes for imaging of viscosity in subcellular organelles of living HeLa cells.

Two viscosity-sensitive two-photon fluorescent probes (QL and QLS) were designed and synthesized, which can be localized in lysosome and mitochondria in living HeLa cells, respectively. As the increases of viscosity from 2.55 to 1150 cP, the fluorescence quantum yield (Φ) of QL and QLS was increased by 28-fold and 37-fold, respectively. At the same time, its effective two-photon absorption cross section (ΦδTPA) was enhanced by 15-fold and 16-fold, respectively. Fluorescence lifetime imaging (FLIM) of living HeLa cells stained with QL and QLS, revealed that lysosomal viscosity ranged from 100.76 to 254.74 cP and mitochondrial viscosity ranged from 92.21 to 286.79 cP. This type of fluorescent probe is helpful in the design and application of materials for monitoring diseases associated with abnormal viscosity.

4-{Phen-yl[4-(6-phenyl-2,2'-bipyridin-4-yl)phen-yl]amino}-benzaldehyde.

The title mol-ecule, C35H25N3O, is a tri-phenyl-amine derivative with the 4-position substituted by an aldehyde group, and the 4'-position substituted by a 6-phenyl-2,2'-bi-pyridine group. The whole mol-ecule is non-planar and the dihedral angle between the core benzene and pyridine rings is 36.96 (5)°. The dihedral angle between the phenyl and benzaldehyde groups bonded to the amine N atom is 70.86 (5)°.

Characterization of the aminated agarose nanoparticles labeled with fluorescein isothiocyanate.

Incorporating an organic fluorescence agent into nanoparticles can significantly promote its fluorescent efficiency. In this article, a novel fluorescein isothiocyanate labeling aminated agarose (FITC-AA) was synthesized and tested as an effective fluorescent labeling agent. FITC-AA could spontaneously form nanoparticles with a diameter less than 200 nm below 37°C due to gelling effect of the agarose. Cell culture experiments confirmed that 3T3 fibroblast cells could be marked by fluorescent FITC-AA nanoparticles and the labeling time sustained longer than by FITC alone. This finding demonstrates that the fluorescent labeling of cells can be enhanced when fluorescent nanoparticles are used as markers.