Effect of varying molecular weight of dextran on acrylic-derivatized dextran and concanavalin A glucose-responsive materials for closed-loop insulin delivery.
OBJECTIVE
Dextran methacrylate (dex-MA) and concanavalin A (con A)-methacrylamide were photopolymerized to produce covalently cross-linked glucose-sensitive gels for the basis of an implantable closed-loop insulin delivery device.


METHODS
The viscoelastic properties of these polymerized gels were tested rheologically in the non-destructive oscillatory mode within the linear viscoelastic range at glucose concentrations between 0 and 5% (w/w).


RESULTS
For each cross-linked gel, as the glucose concentration was raised, a decrease in storage modulus, loss modulus and complex viscosity (compared at 1 Hz) was observed, indicating that these materials were glucose responsive. The higher molecular weight acrylic-derivatized dextrans [degree of substitution (DS) 3 and 8%] produced higher complex viscosities across the glucose concentration range.


CONCLUSIONS
These studies coupled with in vitro diffusion experiments show that dex-MA of 70 kDa and DS (3%) was the optimum mass average molar mass to produce gels that show reduced component leach, glucose responsiveness, and insulin transport useful as part of a self-regulating insulin delivery device.
De Montfort University, The Gateway, Leicester, UK.
Tarsem
T
Sahota
Kirsty
K
Sawicka
Joan
J
Taylor
Sangeeta
S
Tanna
D000178:Acrylamides / Q000737:chemistry*; D003208:Concanavalin A / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D004058:Diffusion; D016503:Drug Delivery Systems; D025461:Feedback, Physiological; D005782:Gels; D005947:Glucose / Q000032:analysis; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000737:chemistry* / Q000494:pharmacology; D015918:Infusion Pumps, Implantable; D007328:Insulin / Q000008:administration & dosage* / Q000737:chemistry*; D008689:Methacrylates; D008970:Molecular Weight; D013696:Temperature; D014783:Viscosity
D000178:Acrylamides; D003911:Dextrans; D005782:Gels; D007004:Hypoglycemic Agents; D007328:Insulin; D008689:Methacrylates; C514458:methacrylated dextran; D003208:Concanavalin A; D005947:Glucose; C045985:methacrylamide