nystatin-a1 and pyrene

Mitochondria play central roles in plenty of biological processes, such as apoptosis, signaling, and cell differentiation. Mitochondrial depolarization is a significant sign of deterioration of intracellular status. Although many fluorescent probes for visualizing mitochondria have been delivered, two-photon red-emitting mitochondrial probes capable of detecting mitochondrial depolarization remain rare. In this work, by linking a pyrene moiety to a quinoline salt, we have constructed two-photon red-emitting mitochondrial probes, MVQ and HVQ. Between them, HVQ with a longer side chain exhibits higher hydrophobic properties, and can image mitochondria with high-fidelity due to the aggregation caused quenching effect. In cooperation with MTDR, a commercialized mitochondrial probe, HVQ, could be used to image the depolarization of mitochondria induced by a protonophore and hydrogen peroxide. We believe that HVQ can serve as a powerful tool for the investigation of mitochondria and mitochondrial membrane potential in fundamental biological research.

Topics: Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Hep G2 Cells; Humans; Hydrogen Peroxide; Membrane Potential, Mitochondrial; Mitochondria; Models, Molecular; Molecular Conformation; Nystatin; Photons; Pyrenes; Quinolines

The properties of liquid-ordered, solid-ordered, and liquid-disordered phases were investigated by steady-state fluorescence spectroscopy in liposomes composed of mixtures of dipalmitoylphosphatidylcholine and cholesterol (0-40 mol %) as a function of temperature (24-51 degrees C). The fluorescent probes used (bis-pyrene, nystatin, prodan, and merocyanine) were chosen because they differ in the location they occupy in the membrane and in the types of properties they sense. Comparison of phase diagrams with contour plots of the fluorescence data suggested that bis-pyrene is sensitive primarily to lipid order. In contrast, nystatin fluorescence intensity responded to changes in lipid fluidity. The shape of the prodan emission spectrum detected both liquid-solid and order-disorder transitions in the phase diagram. Merocyanine's behavior was more complex. First, it was more sensitive than any of the other probes to the membrane pretransition that occurs in the absence of cholesterol. Second, regardless of whether emission intensity, anisotropy, or spectral shape was observed, the probe appeared to distinguish two types of liquid-ordered phases, one with tightly packed lipids and one in which the apparent spacing among lipids was increased. The prodan data supported these results by displaying modest versions of these two observations. Together, the results identify eight regions within the phase diagram of distinguishable combinations of these physical properties. As an example of how this combined analysis can be applied to biological membranes, human erythrocytes were treated similarly. Temperature variation at constant cholesterol content revealed three of the eight combinations identified in our analysis of liposomes.

Topics: 1,2-Dipalmitoylphosphatidylcholine; 2-Naphthylamine; Anisotropy; Biophysics; Cholesterol; Fluorescent Dyes; Lipids; Microscopy, Fluorescence; Nystatin; Phospholipids; Pyrenes; Pyrimidinones; Spectrometry, Fluorescence; Temperature