Laurdan|74515-25-6|安捷凯

Background

Laurdan is a membrane-permeable fluorescent probe that displays spectral sensitivity to the phospholipid phase of the cell membrane to which it is bound.[1] Quantitation of generalized polarization (GP) of laurdan can be used to identify phospholipid phase. When excited at 340 nm, GP values are 0.6 and -0.2 for gel phase and liquid crystalline phase, respectively. GP does not change with polar head group or pH (in the range 4-10); it changes only with phase state.

Laurdan 是一种可透过膜的荧光探针，显示出对其所结合的细胞膜磷脂相的光谱敏感性。[1] laurdan 的广义极化 (GP) 定量可用于鉴定磷脂相。当在 340 nm 激发时，凝胶相和液晶相的 GP 值分别为 0.6 和 -0.2。 GP 不随极性头基或 pH 值（在 4-10 范围内）而变化；它仅随相位状态变化。

Reference:
[1]. Parasassi, T., De Stasio, G., Ravagnan, G., et al. Quantitation of lipid phases in phospholipid vesicles by the generalized polarization of Laurdan fluorescence. Biophys. J. 60(1), 179-189 (1991).

Protocol

Samples

bacteria, cells, and liposomes.

Preparation method

1mg/ml in ethanol, 30mg/ml in DMSO & DMF. Stock solution can be stored below -20℃ for several months.

Reaction Conditions

The excitation wavelength is 360 nm, and emission wavelength is 440 nm and 490 nm. [1]

Applications

Measurements of laurdan generalized polarization (GP) Laurdan is an environment-sensitive fluorescent probe, which is conventionally used for monitoring phase state of lipid membranes. [1] For liposomes, using Laurdan-containing liposomes (Laurdan/lipid molar ratio is 1:200), the vesicle suspension was added to the vesicle suspension containing 40 mM KCl, 50 μM EGTA and 10 mM Tris / HCl (pH 7.5) buffer (final lipid concentration is 50μM), and laurdan fluorescence measured before and after adding various experiments.[1] For cell membranes, the erythrocyte plasma membrane was diluted to 3 ml in 0.01 M phosphate saline buffer. Then Laurdan was added to the membrane to a final concentration of 1 μM, and incubated at 37°C for 60 minutes to incorporate Laurdan into the red blood cell membrane. The steady-state fluorescence intensity of Laurdan was measured at 37°C by a spectrofluorometer. The fluorescence measured in the membrane without Laurdan is always subtracted from the data. Use FLWinLab software to normalize the spectrum. [2] Laurdan fluorescence is measured (λex = 360 nm) by a Cary Eclipse spectrofluorimeter. Emission wavelengths, corresponding to the blue and red peaks of laurdan, were 440 and 490 nm. The generalized polarization (GP) was defined as GP = (I440-I490)/ (I440 + I490), where I440 and I490 are the emission intensities at 440 and 490 nm, respectively. GP can theoretically assume values from +1 (being most ordered) and ? 1 (being least ordered).[1]

参考文献:

[1]. Mikhail V. Dubinina, Alena A. Semenovaa, Anna I. Ilzorkinaa, Irina B. Mikheevab, Valery A. Yashinc, Nikita V. Penkovc, Valentina A. Vydrinad, Gumer Yu. Ishmuratovd, Vyacheslav A. Sharapova, Ekaterina I. Khoroshavinaa, Sergey V. Gudkove, Konstantin N. Belosludtsev. Effect of betulin and betulonic acid on isolated rat liver mitochondria and liposomes. BBA – Biomembranes, 2020.1862:183383.

[2]. Vignini Arianna, Alia Sonila, Pugnaloni Sofia, Giulietti Alessia, Bacchetti Tiziana, Mazzanti Laura, Luzzi Simona, Fiorini Rosamaria. Erythrocyte membrane fluidity in mild cognitive impairment and Alzheimer's disease patients. Exp Gerontol. 2019.12;128:110754.

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Laurdan

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Background

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