Immobilization of Protein A on SAMs for the elaboration of immunosensors.
Binary mixtures of 11-mercaptoundecanoic acid (MUA) and other thiols of various lengths and terminal functions were chemisorbed on gold-coated surfaces via S-Au bonds to form mixed self-assembled monolayers (SAMs). Several values of the mole fraction of MUA in the thiol mixtures were tested and the structure and composition of the resulted thin films were characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The results made it clear that co-adsorption of MUA with thiols of similar chain length led to well-ordered monolayers whereas the co-adsorption of MUA with shorter thiols yielded less crystalline-like thin films, but with more reactive carboxylic acid terminal groups. This criterion appeared decisive for efficient covalent binding of Staphylococcus aureus Protein A (PrA), a protein that displays high affinity for the constant fragment (Fc) of antibodies of the IgG type from various mammal species. The ability of immobilized Protein A to recognize and bind a model IgG appeared to be optimal for the mixed SAM of MUA and the short-chain, omega-hydroxythiol 6-mercaptohexanol in the proportion 1-3.
Briand
Elisabeth
E
Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France.
Salmain
Michèle
M
Compère
Chantal
C
Pradier
Claire-Marie
CM
D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D006046:Gold / Q000737:chemistry*; D007074:Immunoglobulin G / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D013205:Staphylococcal Protein A / Q000737:chemistry / Q000378:metabolism*; D013211:Staphylococcus aureus; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism*
C505222:11-mercaptoundecanoic acid; D005227:Fatty Acids; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D013438:Sulfhydryl Compounds; D006046:Gold