title: Glucose-sensitive gel rheology of dextran-concanavalin A mixtures suitable for self-regulating insulin delivery.
abstract: Aqueous concentrated plain mixtures of dextran and concanavalin A (con A) were examined for their rheological response to glucose for comparison with previously studied partially photopolymerized acrylic derivatives. Non-destructive oscillatory tests were undertaken within the linear viscoelastic range to examine the relationship between the rheometry and the stoichiometry of the interactive materials and to examine rheological parameters as affected by molecular weight, component ratio, temperature and glucose concentrations between 0 and 1% w/w. These simple formulations were studied at 1 and 10 Hz at 0.5% strain at both 20 and 37 degrees C. A second simplified rheological test was undertaken to demonstrate gel-sol reversibility and to produce a measure of equilibria created between these gels and glucose solutions with which they are in contact. This mimics the conditions in which the gel acts as a responsive gateway in the insulin delivery device. It proved that the gels equilibrate with glucose solutions, rather than indiscriminately removing glucose. This is important in terms of producing a delivery device that can respond in a reversible, glucose concentration-dependent manner. The method used for this is capable of relative values only but provides information not obtainable from conventional rheometry.
authors.affiliation: The Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, The Gateway, Leicester, LE1 9BH, 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
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D003208:Concanavalin A / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D003920:Diabetes Mellitus / Q000188:drug therapy; D016503:Drug Delivery Systems; D005782:Gels; D005947:Glucose / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage*; D008970:Molecular Weight; D012212:Rheology; D013678:Technology, Pharmaceutical; D013696:Temperature; D014783:Viscosity
chemical_list: D001786:Blood Glucose; D003911:Dextrans; D005782:Gels; D007004:Hypoglycemic Agents; D007328:Insulin; D003208:Concanavalin A; D005947:Glucose