An overview is given of a stimulating Meeting held at the University of Nottingham in June 2003 focusing on molecular interactions occurring in membranes or ‘2D’ and those occurring in aqueous solution or ‘3D’. It was held jointly between the Biochemical Society and the British Biophysical Society. The 80 or so delegates who attended benefitted from an exciting exchange of ideas between researchers from a wide spectrum of backgrounds. It is hoped the collection of papers which follow this Introductory paper will provide a useful summary of the state of the art and help stimulate collaboration across the wide range of disciplines represented.
The adhesive properties of certain types of biopolymer can be used to increase the residence time of orally or nasally administered drugs. A fuller understanding of the molecular processes underpinning such ‘mucoadhesive’ phenomena will help in the optimal design of delivery systems. The interactions involved are, however, less well defined compared with those often encountered in protein-recognition phenomena: mucoadhesive interaction products can be very large and polydisperse, so to probe them we need to adopt a different strategy to those used by protein biochemists. Reviewed herein is some of the recent work at physiological or near-physiological solution conditions involving molecular hydrodynamics – with analytical ultracentrifugation and SEC-MALLs (size-exclusion chromatography coupled to multi-angle laser light scattering) as the cornerstones – reinforced by viscometry and the imaging probes of electron microscopy and atomic force microscopy. These clearly demonstrate the mucoadhesive properties of both an unusual cationic protein [Deacon, Davis, Waite and Harding (1998) Biochemistry 37 , 14108–14112] and more significantly chitosan polysaccharides of varying degrees of charge/acetylation as a function of solution conditions, and are providing the platform for the construction of stable formulations.