Biomimetic membranes and biomolecule immobilisation strategies for nanobiotechnology applications

Byline: Agnes P. Girard-Egrot, Christophe A. Marquette, Loic J. Blum Biological membranes constitute a source of inspiration for making supramolecular assemblies which can be used in the design of biomimetic sensors. At the same time, the concept of using biomolecules as an elementary structure to develop self-assembled entities has received considerable attention. More particularly, the ability of amphiphilic molecules like lipids, to spontaneously organise into bilayers, is suitable to achieve biomimetic membrane models. The potential of two-dimensional molecular self-assemblies is clearly illustrated by Langmuir monolayers of lipids formed at an air/water interface, which can be used as models to acquire knowledge about the molecular recognition process occurring in biological membranes. Langmuir-Blodgett (LB) technology, based on the transfer of this interfacial monomolecular film onto a solid support, allows building up lamellar lipid stack, with an accurate control of thickness and molecular organisation. This technique offers the possibility to prepare ultrathin layers suitable for biomolecule immobilisation. We are presenting herein an overview of work performed in our group that sheds light on the formation of biomimetic LB membranes associating protein in a well-defined orientation. Two points will be addressed: investigations of protein/lipid interactions using lipid monolayers as membrane models and biosensing applications. The objectives are to highlight advantages of interfacial Langmuir monolayers and supported Langmuir-Blodgett films to investigate molecular interactions between biomolecules and lipid membrane components or to elaborate biomimetic membranes as sensing layers, respectively. The present paper also draws a general picture of non-conventional methods for biomolecule immobilisation and their applications for biochip developments. The technologies presented are based either on original solid supports or on innovative immobilisation processes. First, 'Macromolecules to PDMS transfer' technique relying on the direct entrapment of macromolecules spots during PDMS polymerisation is proposed as an alternative for the easy and simple PDMS surface modification. Then, the electro-addressing of biomolecule-aryl diazonium adducts at the surface of conducting biochips will be presented and shown to be an interesting alternative to immobilisation processes based on surface functionalisation.