Langmuir, Vol.19, No.5, 1752-1765, 2003
Planar supported lipid bilayer polymers formed by vesicle fusion. 1. Influence of diene monomer structure and polymerization method on film properties
Although fluid lipid films have been used widely in biosensing devices, they lack the high stability desired for technological implementation because the noncovalent forces between the constituent lipids are relatively weak. In this work, polymerized, planar supported lipid bilayers ((poly)PSLBs) composed of diene-functionalized lipids have been prepared and characterized. Several parameters relating (poly)-PSLB structure and stability to observations made in studies of polymerized bilayer vesicles were examined, including a comparison of UV photopolymerization and redox-initiated radical polymerization, the number and location of the polymerizable moieties in the lipid monomer, and a comparison to PSLBs produced with diacetylene lipids. Redox-initiated polymerization of films composed of bis-substituted diene lipids with at least one polymerizable moiety located near the acyl terminus produced dried PSLBs that were highly uniform and stable. All other conditions yielded PSLBs that contained a high density of defects after drying, including those formed from diacetylene lipids. In most cases, defect formation is attributed to desorption of unreacted monomers or low molecular weight polymers when the film was passed through the air/water interface. Studies on highly stable (poly)PSLBs doped with nonpolymerizable lipids showed that 40-80% of the dopants are retained when the film is dried. Thus to ensure quantitative lipid retention upon PSLB removal from water., all of the lipid monomers must be covalently anchored to the polymer network.