Phase-selective staining of model and cell membranes, lipid droplets and lipoproteins with fluorescent solvatochromic pyrene probes

The push-pull solvatochromic pyrene derivatives PA and PK have been applied to the study of model membrane vesicles, cells purified human serum lipoproteins, using both confocal fluorescence microscopy spectroscopy. These polarity-sensitive probes provide information similar that obtained by Laurdan or Prodan, i.e. mainly lipid order in biomembranes, but they essential advantage being excitable a standard 405 nm laser light, bypassing use multiphoton excitation. In addition, are brighter much more photostable than those dimethylamino naphthalene derivatives. Our results with spectroscopy (multilamellar vesicles) (giant unilamellar showed capacity report differently on liquid-disordered, liquid-ordered gel phase bilayers. Moreover, ratiometric parameter, Red/Blue Intensity Ratio (RBIR) could be used for inter-domain, inter-vesicle even inter-technique comparison, appropriate microscopy-spectroscopy conversion coefficients estimated. studies at cellular level, probe stained almost exclusively plasma red blood cells, revealing its high degree order. Using Chinese Hamster Ovary was shown an excellent detection cytoplasmic droplets, superior Nile Red provides simultaneously detailed whole cell, which droplets appear very good contrast. spectrofluorometric data PA-stained lipoproteins indicated essentially identical value RBIR high-density lipoproteins.