Published online by Cambridge University Press: 15 February 2011
We report a method using vesicle fusion techniques that result in long-standing hydrophilic and protein-resistant PDMS surfaces. The PDMS was oxidized in plasma followed by treatment with various concentrations of phospholipid vesicles to form planar bilayer membranes in the microchannels. Contact angle measurements showed that a freshly oxidized hydrophilic surface began hydrophobic recovery immediately, but PC (phosphatidylcholine) treated surfaces exhibited prolonged hydrophilic properties up to two hours after bilayer modification, and cationic DOPC+ treated surfaces had a contact angle of ∼70. FRAP experiments confirmed fusion of vesicles to form bilayers with lateral mobility. Protein adsorption studies in microchannels showed 2-3 orders of magnitude decrease in fluorescence from non-specific adsorption of dye-conjugated avidin and BSA. Coulombic interaction was found to play an important role in determining the amount of non-specific adsorption. Dehydration of the membranes resulted in increased protein adsorption after rehydration for PC but not for the synthetic lipid DOPC+, which has a positively charged headgroup.