Unique Vibrational Features as a Direct Probe of Specific Antigen–Antibody Recognition at the Surface of a Solid-Supported Hybrid Lipid Bilayer

Here, we demonstrate how sum frequency generation (SFG), a vibrational spectroscopy based on a nonlinear three-photon mixing process, may provide a direct and unique fingerprint of bio-recognition; This latter can be detected with an intrinsically discriminating unspecific adsorption, thanks to the high sensitivity of the second-order nonlinear optical (NLO) response to preferential molecular orientation and symmetry properties. As a proof of concept, we have detected the biological event at the solid/liquid interface of a model bio-active antigen platform, based on a solid-supported hybrid lipid bilayer (ss-HLB) of a 2,4-dinitrophenyl (DNP) lipid, towards a monoclonal mouse anti-DNP complementary antibody.