Surface plasmon microscopy measurements of lipid vesicle adsorption on a micropatterned self-assembled monolayer

This paper presents a novel method of measuring the adsorption of egg-phosphatidylcholine (egg-PC) vesicles onto a micropatterned heterogeneous self-assembled monolayer (SAM). Microcontact printing (mu CP) was used to make an array of mercaptoethanol patches surrounded by an octadecanethiol (ODT) SAM. Surface plasmon microscopy (SPM) followed the change in the different plasmon minima of the mercaptoethanol and ODT SAMs with respect to lipid adsorption time. Gray scale analysis (GSA) of the two domains showed clear differences in the kinetics of lipid adsorption, which were equated to a very different mechanism of lipid vesicle fusion on microcontact printed (mu CP) SAMs compared with homogeneous SAMs. Surface plasmon microscopy combined with GSA has allowed us to spatially deconvolute the adsorption of lipid on a patterned surface, giving a unique insight into the lipid adsorption process. Conventional surface plasmon resonance measurements were made on the homogeneous SAM moieties in order to quantify the gray scale analysis in terms of adsorbed lipid thickness.