Preparation of metallocarbonyl–gold-antibody bioconjugates for mid-IR optical immunosensing

Metallocarbonyl-labeled gold nanoparticles (displaying specific and intense absorption bands assigned to the stretching vibrations of the carbonyl ligands in IR spectroscopy) were derivatized with an anti-mouse IgG antibody to provide IR reporter immunoprobes that were characterized by several analytical techniques like ELISA, IR and transmission electron microscopy (TEM). These immunoprobes were able to detect a mouse monoclonal anti-staphylococcal enterotoxin A (SEA) antibody chemisorbed to a planar gold-coated glass sensor. The formation of the immune complex between metallocarbonyl–gold nanoparticle-antibody bioconjugate and anti-SEA antibody was assessed by mid-IR surface and atomic force microscopy (AFM) analysis.