Fundamental studies

Lipids and surfactants may self-assemble into a variety of liquid crystalline phases. Many of these can be dispersed in excess water to yield nanosized particles. By inclusion of components that offer electrostatic or steric protection the longevity of the particles can be substantially increased, and such stabilized lipid/surfactant aggregates have found important pharmaceutical, biotechnical, and analytical applications. Dispersed particles of lamellar and bicontinous cubic liquid crystalline phase are, for instance, widely employed as vehicles for drug delivery and as vaccine adjuvants.

The structures formed in dilute lipid/surfactant systems are interesting, however, also from a more fundamental point of view. Thorough investigations of the formation, stability and transformation of liposomes and related lipid aggregates have, for example, increased our basal knowledge about many of the important events taking place in, and at the surface of, biological membranes.

Figure 1. Sequence of aggregate structures formed in the classical DMPC/DHPC ”bicelle” system.

We utilize a combination of experimental techniques to retrieve information concerning structure, dynamics, and phase behaviour in dilute lipid/surfactant systems. Systematic physico-chemical investigations are carried out by means of various, primarily scattering and photo physical techniques. Direct structural information is collected by means of cryo-transmission electron microscopy (cryo-TEM), which offers unique possibilities for visualization of micelles, liposomes, and other labile microstructures built from lipids, surfactants and/or polymers.

The research is focused on fundamental aspects of phase- and structural behaviour, but issues and problems of biological and/or pharmaceutical relevance often inspire the different projects. Examples of recent projects include

investigations of phase- and structural behaviour in the classical DMPC/DHPC ”bicelle system”
studies to learn more about how the lipid component ubiquinone-10 (Q10), affects and modulates the mechanical properties and stability of biological membranes
investigations to reveal the effect of antimicrobial peptides on the aggregation behaviour of bacterial lipopolysaccharides
Further, via collaborations with pharmaceutically/medically and biologically oriented research groups, the knowledge gained from the fundamental investigations is utilised in more applied projects.

Figure 2. Cryo-TEM image showing aggregated lipopolysaccharides in the precense of antimicrobial peptide.