R. Ballerstadt et R. Ehwald, SUITABILITY OF AQUEOUS DISPERSIONS OF DEXTRAN AND CONCANAVALIN-A FOR GLUCOSE SENSING IN DIFFERENT VARIANTS OF THE AFFINITY SENSOR, Biosensors & bioelectronics, 9(8), 1994, pp. 557-567
Aqueous dispersions of dextran and Concanvalin A (Con A) were investig
ated for possible application as the essential part of a glucose affin
ity sensor. The considered variants of signal formation were based on
the sugar-dependent dissociation of Con A and dextran, which were encl
osed in a small dialysis chamber with a membrane permeable to sugars b
ut not to macromolecules. Two alternative proposals were investigated:
(a) determination of the concentration of dissolved labelled lectin i
n equilibrium with a lectin fraction bound to cross-linked dextran or
(b) determination of the viscosity of an homogeneous dextran-lectin di
spersion. For both approaches, suitable conditions were established to
give a strong dependence of the measured parameter on the glucose con
centration in a concentration range relevant for blood sugar sensing.
Both glucose-dependent Con A distribution and glucose-dependent viscos
ity changes of the dextran/Con A solution showed a sufficiently fast r
esponse (<2 min) to a change in the glucose concentration. The long te
rm stability of the lectin, with respect to binding to dextran and its
influence on the viscosity of a concentrated solution of high molecul
ar weight dextran, was remarkable.