UNDER BUFFER SFM OBSERVATION OF IMMUNOSPECIES ADSORBED ON A CYANO GRAFTED SILICON SUBSTRATE1

Scanning force microscopy (SFM) in contact mode and in liquid medium h as been employed to study immunospecies layers adsorbed on a silicon w afer. The silicon wafer has been grafted with a cyanosilane monolayer in order to create a surface with strong adhesive properties which pre vent proteins being swept by the scan of the SFM tip. The force curves reveal that the adhesive force has been increased by a factor six wit hout roughness modification (<1 nm). After the incubation of the surfa ce in a monoclonal antibody (mouse anti-human alpha-fetoprotein IgG) s olution, SFM surface images suggest an homogeneous layer composed by e llipsoidal objects (40-60 nm in diameter, 6-13 nm in height), The subs trate was moreover incubated in an antigenic solution (human alpha-fet oprotein): SFM images reveal that proteins have been added onto the an tibody layer.