13 May 2013

Diabetes: is one injection enough for a week?

The injected nanoset monitors blood sugar levels for 10 days

NanoNewsNet based on materials from NC State University: Injectable Nano-Network Controls Blood Sugar in Diabetes for Days at a TimeScientists from the University of North Carolina (North Carolina State University), the University of North Carolina at Chapel Hill (University of North Carolina at Chapel Hill), the Massachusetts Institute of Technology (Massachusetts Institute of Technology) and the Boston Children's Hospital (Children's Hospital Boston) have constructed a network of nanoscale particles that, while in a living organism, releases insulin in response to an increase in blood glucose levels.

The system, so far tested on laboratory animals with a type 1 diabetes model, is able to maintain glucose levels within the normal range for more than a week.

The body of patients with type 1 diabetes does not produce enough insulin, a hormone that transports glucose from the blood to the cells, as a result of which the energy production process is disrupted. Today, in order for the glucose concentration to remain in the normal range, patients must constantly monitor their blood sugar levels and inject themselves with insulin. However, such injections are painful, and it is quite difficult to calculate the exact dose of insulin. The introduction of too large or, conversely, insufficient dose of the drug itself is fraught with significant health risks.

The new injected nanoset consists of a mixture containing nanoparticles from a solid core of insulin, the enzyme glucose oxidase and modified dextran. Both the nanoset as a whole and the coating of nanoparticles have a porous structure, which allows blood – and glucose contained in it – to reach the nuclei of nanoparticles. When exposed to high concentrations of glucose, the enzyme effectively converts glucose into gluconic acid, which breaks down the modified dextran and releases insulin. Insulin, in turn, takes control of blood glucose levels. Gluconic acid and dextran are completely biocompatible and decomposed by the body.

The coating of nanoparticles has either a positive or negative charge. Positively charged shells are made of chitosan (an amino sugar contained in the shells of crustaceans), and negatively charged shells are made of alginate (a substance obtained from seaweed). When mixing solutions of such particles, the differently charged coatings are attracted to each other, forming a nanoset. When injected under the skin, the resulting network holds the nanoparticles together, preventing them from spreading through the body.

Under hyperglycemic conditions, the nanocomposite porous architecture formed by the electrostatic interaction between oppositely charged dextran nanoparticles loaded with insulin and glucose-specific enzymes decomposes due to the catalytic conversion of glucose into gluconic acid, which cleaves dextran, and releases insulin. (Fig. ACS Nano)

"This technology creates an effective feedback system that, by releasing insulin in response to changes in glucose levels, mimics the function of the pancreas of a healthy person," comments the head of the research group, Dr. Zhen Gu, on the essence of the development. "It can improve the health and quality of life of diabetic patients."

Currently, Dr. Gu is negotiating to start clinical trials of his technology.

The article Injectable Nano-Network for Glucose-Mediated Insulin Delivery is published in the journal ACS Nano

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