Characterization of Self Assembled Phospholipid Bilayers on Dithiothreitol and Dithioerythritol Treated Gold Surfaces

MAXIMILIANO LUIS MUNFORD; TIAGO OPALA VIEIRA; VÂNIA RODRIGUES DE LIMA; MARÍA ANTONIETA DAZA MILLONE; MARÍA ELENA VELA; ANDRÉ AVELINO PASA; TÂNIA BEATRIZ CRECZYNSKI-PASA

Florianópolis (Brasil)

Congreso; 5th Brazilian MRS (Materials Research Society) Meeting; 2006

This work presents the characterization of self-assembled lipid bilayers on dithiothreitol (DTT) and dithioerythritol (DTE) treated gold thin films, evaporated on silicon. The interest on gold surfaces is to preserve this substrate as an electrode for detection of charge transfer processes for fundamental studies and biosensor applications. The isomers DTT and DTE were used in a tentative to elucidate the mechanism of the molecules binding on gold substrate. To obtain the lipid bilayers dimyristoylphosphatidylcholine (DMPC) was supported on gold by vesicle fusion. The morphology of the structures obtained were analyzed by in-situ atomic force microscopy inside a fluid cell with HEPES buffer (pH = 7.4), under contact mode with controlled cantilever forces. It was possible to observe the formation of large surface areas covered with lipid in the presence of both HS- molecules. No differences between bilayers on DTT or DTE were observed. The measured height of the lipid coverage was ~6 nm, which corresponds to the formation of a DMPC bilayer. The membranes obtained are softly supported on the Au treated substrates and can be easily scratched away by slightly increasing the force of AFM tip. This feature also opens the possibility of employing nanolithography methods with such systems. Additional electrochemical measurements were employed to evaluate the coverage of gold surfaces with DTE and DTE. The possible mechanisms of DTT and DTE binding onto gold surfaces were discussed.