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 di nitrospiropyran antigen monolayer, whereas the DNP-AI, dissociates from the protonated dinitromerocyanine monolayer. Reversible binding and dissociati on of anti-DNP-Ab to and from the photoisomerizable monolayer was assayed b y SPR spectroscopy. Analysis of the SPR data indicates that the average thi ckness of the antibody layer is ca. 70 Angstrom which corresponds to a surf ace coverage of ca. 4.4 x 10(-9) mol.cm(-2).