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Aggregation behavior of lipid IVA in aqueous solutions at physiological pH. 1: Simple buffer solutions

M Hofer1, R Y Hampton, C R Raetz

  • 1Joanneum Research, Optical Sensor Institute, Graz, Austria.

Chemistry and Physics of Lipids
|September 1, 1991
PubMed

Insights

Lipid IVA forms stable vesicles in aqueous solutions across physiological pH. These small unilamellar vesicles exhibit a rigid surface structure, influencing their stability and aggregation behavior.

Area of Science:

  • Biochemistry
  • Biophysics
  • Materials Science

Background:

  • Lipid IVA is a bioactive precursor to lipid A and the lipid anchor of lipopolysaccharide.
  • Understanding lipid aggregation is crucial for biological and pharmaceutical applications.

Purpose of the Study:

  • To investigate the aggregation behavior of lipid IVA in aqueous solutions.
  • To determine the stability and structural characteristics of lipid IVA aggregates.
  • To explore the influence of pH and ionic strength on vesicle formation.

Main Methods:

  • Dynamic light scattering (DLS)
  • Nuclear magnetic resonance (NMR) spectroscopy
  • Fluorescence spectroscopy
  • Surface pressure measurements
  • Electron microscopy
  • Force field simulations

Main Results:

  • Sonication of lipid IVA yields stable vesicles in the concentration range of 10(-3) - 10(-7) M.
  • Vesicle size is primarily dependent on pH and ionic strength, not buffer type.
  • Small unilamellar vesicles demonstrate long-term stability attributed to a rigid surface structure, supported by NMR and simulations.
  • Evidence suggests coexistence of micelles and/or other aggregates with bilayered vesicles at higher concentrations.

Conclusions:

  • Lipid IVA forms stable, small unilamellar vesicles with a rigid surface structure in aqueous solutions within the physiological pH range.
  • pH and ionic strength are key factors controlling vesicle size and stability.
  • The findings provide insights into the self-assembly of lipid IVA and its potential biological implications.

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