KINETICS OF DISSOLUTION OF CONCANAVALIN-A DEXTRAN SOLS IN RESPONSE TOGLUCOSE MEASURED BY SURFACE-PLASMON RESONANCE

The dissolution of highly viscous dispersions composed of complexes of Concanavalin A (Con A) and high molecular-weight dextran (2000 kDa) i n response to glucose was studied by using surface plasmon resonance ( SPR). The viscous property of Con A/dextran sols is based on intermole cular affinity bonds between dextran and Con A. These receptor ligand cross-linkages call be reversibly cleaved by the competing analyte glu cose, resulting in a sol with a strongly reduced viscosity. Wr tested the concept of using the kinetics of sol dissolution as an analytical tool for glucose determination. Under this premise, a thin layer of th e Con A/dextran dispersion was placed on the gold surface of a novel S PR-probe. The sol's dissolution, when placed in contact with bulk solu tions of various glucose concentrations, was monitored by measuring th e shift of resonance angle. An increased rate of sol dissolution at in creasing levels of glucose concentration was found, presumably due to a decrease of the sol viscosity which led to a faster diffusion and ma ss transport of the sol components into the bulk solution. The thickne ss of the sol layer turned out to be the rate-limiting step of the dis solution kinetics. Other factors such as sugar specificity and tempera ture had a significant affect on the kinetics of sol dissolution also. However, matrix effects of the test solution effected the overall kin etics of the solution only to a minimal extent, rendering the method i nteresting for biosensing purposes. (C) 1998 Published by Elsevier Sci ence S.A. All rights reserved.