Dithiothreitol monolayers on Gold for supported bilayer membranes

MARÍA ANTONIETA DAZA MILLONE; GUILLERMO BENÍTEZ; MARÍA ELENA VELA; ROBERTO C. SALVAREZZA; MAXIMILIANO LUIS MUNFORD; VÂNIA RODRIGUES DE LIMA; TÂNIA BEATRIZ CRECZYNSKI-PASA; ANDRÉ AVELINO PASA

Montevideo (Uruguay)

Conferencia; 6th International Conference of Biological Physics; 2007

Supported lipid membranes on the surface of gold gives relevant information related to phase transition, stability and morphology of the layers and are promising structures for the development of biosensors. The modification of gold with organic molecules that act as spacers to link macromolecules such as phospholipids provides a biomimetic system where hydrophilic domains can accommodate proteins and makes available studies of charge transport through this complex layers (1-3).In this work we have studied the structure and electrochemical properties of a well order Au(111) surface modified with dithiothreitol (DTT) at room temperature and at 60° C in order to elucidate the possible configurations of this layer to prepare lipidic bilayers by vesicle fusion.XPS and electrochemical measurements made at room temperature allow us to infer that DTT forms a monolayer in an up-right position with one of the two sulfur atoms bound to the Au through one S-Au bound and the terminal S-H group facing the interface. The STM images show a flat surface with a disorder layer on it. At 60° C the DTT layer has been partially oxidized to sulfonate groups. In this experimental condition the vesicle fusion produce the formation of phospholipidic bilayer membranes as has been extensively characterized by in-situ AFM measurements.[1]   Lingler S., Rubinstein, I., Knoll, W., Offenhausser, A., Langmuir, 1997, 13, 7085-7091. [2]  Tyrrell, M., Kokkoli, E., Biesalski, M., Surf. Science, 2002, 61-83.[3]   Biosensors, B.Eggins, John Wiley & Sons, England, 1999Acknowledgments: Financial support from CONICET, ANPCyT (PICT 02-11111), CIC BsAs, and FAPESC, PROSUL-CNPq and CAPES are greatly acknowledged.