W. Lukosz, INTEGRATED-OPTICAL AND SURFACE-PLASMON SENSORS FOR DIRECT AFFINITY SENSING .2. ANISOTROPY OF ADSORBED OR BOUND PROTEIN ADLAYERS, Biosensors & bioelectronics, 12(3), 1997, pp. 175-184
The theory of sensitivities of integrated-optical (IO) and of surface-
plasmon resonance sensors used for real-time analysis of adsorption pr
ocesses or of binding reactions in affinity sensing given previously f
or an optically isotropic adlayer formed by the adsorbed or bound mole
cules (Lukosz, 1991) is extended to anisotropic adlayers. The anisotro
py of a (sub-)monomolecular adlayer of (protein) molecules on the sens
or surface, caused by their nonspherical (e.g., ellipsoidal) shape and
preferential orientation, is described by Maxwell-Garnett theory. The
analyses of adsorption or binding processes monitored with IO grating
-coupler sensors, not only yield results for the thickness and refract
ive indices and the surface mass density of the adlayer, but can also
give some information about the shape and orientation of the adsorbed
or bound molecules. (C) 1997 Elsevier Science Limited.