Planar supported lipid bilayer polymers formed by vesicle fusion. 2. Adsorption of bovine serum albumin

Planar supported lipid bilayers (PSLBs) composed of phosphorylcholine (PC) lipids are known to be highly resistant to nonspecific adsorption of soluble proteins. However, these structures lack the stability desired for implementation in molecular devices (e.g., biosensors). In part 1 of this report [Ross, E. E.; Spratt, T.; Liu, S.; Rozanski, L. J.; O'Brien, D. F.; Saavedra, S. S. Langmuir 2003, 19, 1752-1765], we described preparation and characterization of (poly)PSLBs composed of diene-functionalized lipids. Here we have examined nonspecific adsorption of bovine serum albumin (BSA) to these (poly)PSLBs and several reference surfaces, using total internal reflection fluorescence and atomic force microscopy. The results show that the protein resistance of a cross-linked (poly)PSLB composed of bis-sorbyl phosphatidylcholine (bis-SorbPC) is equivalent to that of a fluid PSLB composed of 1-palmitoyl-2-oleoylphosphatidylcholine, even after the former has been dried and rehydrated. Since the lipids in a (poly)bis-SorbPC PSLB are laterally immobile, these results also demonstrate that fluidity is not required for a PC lipid bilayer to resist nonspecific protein adsorption. Relative to (poly)bis-SorbPC, BSA adsorption to other types of (poly)-PSLBs was significantly greater, including PSLBs formed from a diacetylene-functionalized lipid. The increased protein adsorption is attributed to a higher density of structural defects.