Surface plasmon resonance characterization of photoswitchable antigen-antibody interactions

Photostimulated association and dissociation of anti-dinitrophenyl antibody, anti-DNP-Ab, to and from a dinitrospiropyran photoisomerizable monolayer is probed by surface plasmon resonance (SPR). The anti-DNP-Ab binds to a dinitrospiropyran antigen monolayer, whereas the DNP-Ab dissociates from the protonated dinitromerocyanine monolayer. Reversible binding and dissociation of anti-DNP-Ab to and from the photoisomerizable monolayer was assayed by SPR spectroscopy. Analysis of the SPR data indicates that the average thickness of the antibody layer is ca. 70 angstroms which corresponds to a surface coverage of ca. 4.4×10^-9 mol·cm^-2.