Colorimetric phospholipid determination with erythrosin B

Area of Science:

• Biophysical Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Phospholipid vesicles are crucial in drug delivery and biological systems.
• Accurate quantification of phospholipid vesicles is essential for research and development.

Purpose of the Study:

• To develop a simple, rapid, and sensitive method for quantifying unilaminar phospholipid vesicles.
• To utilize the spectral shift of erythrosin B upon binding to phospholipids.

Main Methods:

• Spectrophotometric analysis of erythrosin B dye.
• Binding studies with unilaminar phospholipid vesicles at varying pH and concentrations.
• Determination of binding constants (Kd) and maximal binding ratios.

Main Results:

• Erythrosin B shows a spectral shift from 528 to 549 nm upon binding to phospholipid vesicles.
• Optimal binding and assay conditions determined at pH 4.5 with a Kd of 3.6 µg/ml.
• High sensitivity observed for zwitterionic phospholipids, dependent on vesicle surface area.

Conclusions:

• The developed method offers a sensitive and rapid approach for phospholipid vesicle quantification.
• The assay's dependence on vesicle size highlights the role of surface area in dye binding.
• This technique provides a valuable tool for characterizing phospholipid-based systems.