Rhodia European PRIZE for Colloids
The Rhodia European prize for colloid and interfaces is given every year to a European scientist for a specific realization or experiment. Entries for the prize are nominated by a scientific committee. The prize in the amount of 3000 Euros is delivered by a senior scientist from Rhodia - an International company with a large amount of R&D based on colloid and interface science.
This year 2001, the prize will be given to Prof. Kåre Larsson, from Lund University and Camurus Lipid Research Foundation, for the discovery of cubosomes and hexosomes and explorative work on their applications.
Kåre Larsson started his research as X-ray crystallographer at Göteborg University, and in 1964 the first crystal structures of fatty acid mono-, di and triglycerides were reported in his PhD thesis. Then he worked as a post-doctoral fellow with V. Luzzatti group of in Gif sur Yvette. In Sweden he extended the crystal structure work on lipids to involve liquid-crystalline phases of lipid-water systems.
Kåre Larsson was then appointed as Professor of the Department of Food Technology at Lund University in 1975, and pioneered a new cross-disciplinary approach of modern colloid science in foods. An important contribution, besides food research, was the first demonstration that inverse cubic lipid-water phases are infinite periodic minimal surfaces (Chem. Phys. Lipid 1980, 27, 321 and Nature 1983, 304, 664). The formation and structure of cubosomes was first described in 1989 (J. Phys. Chem. 1989, 93, 7304). Between 1995 and 1997, a now classical series of papers, explaining how finely divided micronic aggregates are formed, were published. Such aggregates are composed of a liquid crystal (cubic or hexagonal) which is stabilized either by electrostatic or by multiplayer (Z. Kristallogr. 1995, 210, 315; Langmuir 1996, 12, 4611 and Langmuir 1997, 13, 6914). An electron microscopy of an individual cubosome is shown below.
Stable micronic dispersions can be obtained with moderate milling energy and are stable for months. The unit cell distance in the cubosome is about 20 nm, and the aggregate is around one micron. These dispersions are able to solubilise antibiotics or other pharmaceutical agents. Hence, gels for dental care could be formulated. These are injected between teeth and gingival, adhesion and viscosity are such that ultra-slow release of antibiotics is obtained. This is a very successful new method in dental care.
This success story of stable emulsions of lyotropic liquid crystals requires basic knowledge of phase diagrams, cubic structure, and general concepts in curvature of soft condensed material, together with extraordinary patience in characterization and formulation. The cubosome/hexosome discovery, understanding and use, is an exemplary study of how modern colloid science integrates basic research and application.