Surface engineering: optimization of antigen presentation in self-assembled monolayers

The formation of self-assembled monolayers (SAMs) on gold surfaces contg. an antigenic peptide (NANP)6 and HS(CH2)11OH, and the specific binding of a monoclonal antibody to these layers were investigated by surface plasmon resonance (SPR). Peptides were synthesized by solid-state phase synthesis and were linked either to cysteine or to an alkyl-thiol to allow covalent attachment to gold. The content of the peptide in the SAMs was systematically varied, and the binding properties of the monoclonal antibody were compared with those measured by microcalorimetry in soln. At a crit. peptide concn. in the SAM an optimal antibody binding and complete surface coverage was attained. At lower peptide concns., the amt. of adsorbed antibody decreased: at higher peptide concns., the binding const. decreased. These effects can be explained if the accessibility of the antigenic epitopes depends on the peptide d. Addn. of free antigen induced the desorption of bound antibodies and allowed accurate measurements of the dissocn. rate const. Binding consts. obtained from steady-state measurements and from measurements of the kinetic rate consts. were compared. [on SciFinder (R)