FUSION OF SMALL UNILAMELLAR LIPID VESICLES TO ALKANETHIOL AND THIOLIPID SELF-ASSEMBLED MONOLAYERS ON GOLD

Adsorption of a monolayer of dimyristoyl-L-alpha-phosphatidylcholine f rom dispersions of small unilamellar vesicles onto hydrophobic surface s was investigated by means of a combined surface plasmon resonance sp ectroscopy/impedance spectroscopy/cyclic voltammetry setup. The hydrop hobic surfaces were prepared by assembling alkanethiols or a thiolipid onto gold surfaces. The kinetics of the monolayer formation were foll owed using time-dependent surface plasmon resonance spectroscopy in co mbination with time-dependent impedance spectroscopy and showed remark able differences depending on the composition of the proximal monolaye r. The formation of the lipid monolayer on these assemblies was comple te after an adsorption time of similar to 6000-10000 s. We observed di fferences in the thickness and capacitance of the lipid monolayer depe nding on the underlying thiol monolayer. The expected thickness and ca pacitance were obtained using long chain thiols or the thiolipid for t he proximal monolayer. Electrochemical measurements of electron transf er rates indicate that the lipid monolayer improves the blocking prope rties of the assembled alkanethiols and thiolipid.