Molecular recognition on fluidic lipid bilayer microarray corralled by well-defined polymer brushes

Abstract

We have developed a new method for creating phospholipid bilayer microarrays (PLBMAs) via site-specific adsorption of phospholipid vesicles on a silicon surface bearing prepatterned, well-defined poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) brushes prepared by surface-initiated atom transfer radical polymerization. The monolayer of 3-(2-bromoisobutyryl) propyl dimethylchlorosilane (BDCS), which acts as an initiator for ATRP, was selectively decomposed with UV light irradiation through a photomask. The formation of PMPC brushes was well controlled on the remaining region of the BDCS on the surface. The adsorption of phospholipid bilayers on the PMPC brushes was completely obstructed, whereas planar bilayers were formed on the bare silicon surface. That is, the PLBMAs were perfectly formed on the prepatterned PMPC brush surface after being in contact with the phospholipid vesicles. The fluidity of the adsorbed lipid bilayer was determined by fluorescence recovery after photobleaching. Furthermore, on both the phospholipid bilayer and the PMPC brush surfaces, nonspecific interaction with proteins was effectively reduced. To demonstrate molecular recognition on the PLBMAs, phospholipid vesicles containing ganglioside GM₁ or biotin-capped lipids were allowed to contact the prepatterned PMPC brush surface. Specific bindings of GM₁/cholera toxin B and biotin/NeutrAvidin were quantitatively observed. PLBMAs are applicable for a variety of microarrays for determining protein/lipid and protein/protein interactions because the different compositions of phospholipid vesicles can be transferred. PLBMA-corralled PMPC brushes will be useful as matrices for use in the diagnostic and pharmaceutical fields.