Glucose-responsive Hydrogel Research Articles

Preparation of reversibly glucose-responsive hydrogels by covalent immobilization of lectin in polymer networks having pendant glucose

Glucose-responsive hydrogels were prepared by copolymerization of a monomer having a pendant glucose with modified lectin (concanavalin A (ConA)) having vinyl groups. Swelling behavior of ConA-copolymerized glucosyloxyethyl methacrylate (GEMA) hydrogels was discussed from the viewpoint of their synthetic condition and structures. The swelling ratio of the ConAcopolymerized GEMA hydrogels was strongly dependent on the glucose concentration in a buffer solution. As free glucose resulted in the dissociation of the complex between ConA and pendant glucose in the networks and the cross-linking density in the hydrogel decreased, the hydrogels swelled gradually in the presence of free glucose. Leak of ConA from the ConA-entrapment hydrogel and ConA-copolymerized hydrogel was examined in order to discuss the reversible changes of their glucose-responsive behavior. During swelling in the presence of free glucose, ConA leaked out of the ConA-entrapment GEMA hydrogel but did not out of the ConA-copolymerized GEMA hydrogel. As a result, the ConA-copolymerized GEMA hydrogel showed the reversible swelling changes in response to a stepwise change in the glucose concentration. This study revealed that covalent immobilization of ConA in the GEMA networks is very important for development of reversibly glucose-responsive hydrogels.

A sulfonamide based glucose-responsive hydrogel with covalently immobilized glucose oxidase and catalase

A new glucose-sensitive hydrogel, based on sulfonamide chemistry with covalently conjugated glucose oxidase and catalase, was synthesized and tested. The pH-induced full swelling transition of the gel occurred in the range of pH 6.5∼7.5. In a glucose concentration range of 0–300 mg/dl in an isotonic phosphate buffered saline solution (pH 7.4), the pH inside the gel varied from pH 7.4 to 7.2. At the same glucose concentration range, the gel showed reversible glucose dependent swelling without hysteresis from 12 to 8, expressed in water (g)/polymer (g).

A Chemically Synthesized Artificial Pancreas: Release of Insulin from Glucose-Responsive Hydrogels

A Chemically Synthesized Artificial Pancreas: Release of Insulin from Glucose-Responsive Hydrogels

A Photopaiterned Glucose Responsive Hydrogel for Use in a Conductimetric Sensor

AbstractThe glucose responsive hydrogels developed by Horbett et al. [1, 2] are potentially useful as materials for constructing glucose sensors. The construction of microsensors presents challenges in developing processes for preparing these gels that are compatible with semiconductor fabrication technology.We have lithographically patterned a pH-sensitive copolymer (poly-(2-hydroxyethyl methacrylate-co-dimethyl aminoethyl methacrylate) 90:10 (mole ratio) (HEMA/DMA) from a prepolymer solution of monomers, crosslinker, solvent, and a viscosity agent (p(HEMA)). Varying the spin speed and p(HEMA) concentration resulted in reproducible thicknesses between 5 and 25 μm. pH sensors produced by this method showed sensitivity ranging from 20 to 50%/pH and a response time (10%–90%) of 6.8 minutes. Sensitivity dropped by a factor of two over a 24 day testing period. The limited lifetime is thought to be due to loss of adhesion of the polymer to the substrate.Derivatizing glucose oxidase with a photoactivatible crosslinker allowed it to be covalently immobilized onto the surface of the gel layer in a spatially specific manner. After immobilization, GOX specific staining showed that enzyme activity was preserved, however the amount of enzyme immobilized was insufficient to create a working glucose sensor.