title: Rheological characterisation of dextran-concanavalin A mixtures as a basis for a self-regulated drug delivery device.
abstract: The rheological characterisation of glucose sensitive mixtures containing dextran and concanavalin A (con A) with and without glucose, was undertaken using oscillatory rheometry at 20 and 37 degrees C so that comparative data could be gathered in the linear viscoelastic (LVE) range. Measurements for a series of mixtures showed that complex viscosity is a function not only of the con A concentration but of the content and molecular weight of the dextran used. The extent of liquefaction on addition of glucose also depended on these factors. The tan delta profiles confirmed the change from semi-solid towards fluid behaviour. This occurs when glucose effects dismantling of the three-dimensional structure of the dextran-con A system by competitive binding to the glucose receptors in the protein. For the mixtures studied, the changes occurred between contents of 0 and 1% (w/w) glucose at 20 and 37 degrees C and form a useful basis for the formulation of a self-regulating delivery device for the control of hyper-and hypoglycaemia in diabetes.
authors.affiliation: The Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, Leicester, UK. mjt@dmu.ac.uk
authors.forename: M Joan
authors.initials: MJ
authors.lastname: Taylor
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Tanna
authors.forename: Tarsem S
authors.initials: TS
authors.lastname: Sahota
authors.forename: Barbara
authors.initials: B
authors.lastname: Voermans
mesh_terms: D003208:Concanavalin A / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D003920:Diabetes Mellitus / Q000188:drug therapy; D016503:Drug Delivery Systems; D004548:Elasticity; D005782:Gels; D005947:Glucose / Q000737:chemistry; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000737:chemistry; D012212:Rheology; D013696:Temperature; D014783:Viscosity
chemical_list: D003911:Dextrans; D005782:Gels; D007004:Hypoglycemic Agents; D003208:Concanavalin A; D005947:Glucose