Enzyme-Induced Staining of Biomembranes with Voltage-Sensitive Fluorescent Dyes
摘要:
We consider the physicochemical basis for enzyme-induced staining of cell membranes by fluorescent voltage-sensitive dyes, a method that may lead to selective labeling of genetically encoded nerve cells in brain for studies of neuronal signal processing. The approach relies on the induction of membrane binding by enzymatic conversion of a water-soluble precursor dye. We synthesized an amphiphilic hemicyanine dye with and without an additional phosphate appendix at its polar headgroup. The fluorescence of these dyes is negligible in water but high when bound to lipid membranes. By fluorescence titration with lipid vesicles it was shown that the phosphate group lowers the partition coefficient from water to membrane by more than an order of magnitude. By isothermal titration calorimetry, we showed that the dye phosphate was a substrate for a water-soluble alkaline phosphatase following Michaelis-Menten kinetics. In a suspension of lipid vesicles, the enzyme reaction led to a fluorescence increase due to enhanced membrane binding of the product dye in accord with the Michaelis-Menten kinetics of the reaction and the partition coefficients of substrate and product. We successfully tested the staining method by fluorescence microscopy with individual giant lipid vesicles and with individual red blood cells. In both systems, the membrane fluorescence due to bound hemicyanine was enhanced by an order of magnitude, proving the feasibility of enzyme-induced staining with voltage-sensitive dyes.
Two fluorescent hemicyanine type compounds, 1 and 2 have been developed for membrane staining, and their photophysical properties were investigated in various solvents. The demonstrated 2-photon-microscopy-biological-imaging application indicates the usefulness of 1 as a fluorescent probe.
Amphiphilic cationic polyenic pushâpull chromophores
which offer interesting supramolecular possibilities for second harmonic
generation have been synthesised and their optical non-linearities studied
for the first time by electric field induced second harmonic (EFISH)
generation in solution.
Ionogels encapsulating Pd(OAc)2 were successfully used as catalysts in HeckâMizoroki coupling reactions. Reaction rates were compared to homogeneous systems showing no significant difference. Leaching tests showed that catalysis actually took place in the ionic liquid phase confined within the silica matrix. The absence of leaching of palladium, the trapping of salt by-product in ionogels and the ability to produce convenient ready-to-use catalyst doses open interesting potential applications.
Selective staining of biomembranes using voltage-sensitive dyes
申请人:Max-Planck-Gesellschaft zur Förderung
der Wissenschaften e.V.
公开号:EP1553396A2
公开(公告)日:2005-07-13
The present invention relates to a method for staining membranes, in particular, a method for selective staining of cells using voltage-sensitive dyes.
本发明涉及一种对膜进行染色的方法,特别是使用电压敏感染料对细胞进行选择性染色的方法。
HASSNER, A.;BIRNBAUM, D.;LOEW, L. M., J. ORG. CHEM., 1984, 49, N 14, 2546-2551