Sponge like material developed to deliver insulin when it is needed

by Barbara Hewitt on July 23, 2013

Sponge like material developed to deliver insulin when it is needed

Sponge like material developed to deliver insulin when it is needed

Researchers have developed a sponge like material that expands and contracts in response to blood sugar levels and releases insulin as it is needed. The pioneering drug delivery technique could work well for diabetics who are insulin dependent and scientists believe it could also be used for targeted drug delivery to cancer cells.

The sponge like matrix surrounds a reservoir of insulin and mimics the function of healthy beta cells which produce insulin and control its release in a healthy body. The researchers in the United State created a spherical, sponge like matrix out of chitosan, a material found in shrimp and crab shells. Scattered throughout this matrix are smaller nanocapsules made of a porous polymer that contain glucose oxidase or catalase enzymes. The entire matrix sphere is approximately 250 micrometers in diameter and can be injected into a patient.

When a diabetic patient’s blood sugar rises, the glucose triggers a reaction that causes the nanocapsules’ enzymes to release hydrogen ions. Those ions bind to the molecular strands of the chitosan sponge, giving them a positive charge. The positively charged chitosan strands then push away from each other, creating larger gaps in the sponge’s pores that allow the insulin to escape into the bloodstream.

Quote from DiabetesForum.com : “Type 2 diabetes accounts for 90 % of cases of diabetes around the world, afflicting 2.5 million Canadians and costing over 15 billion dollars a year in Canada. It is a severe health condition which makes body cells incapable of taking up and using sugar. Dr. Alexey Pshezhetsky of the Sainte-Justine University Hospital Research Center, affiliated with the University of Montreal, has discovered that the resistance to insulin seen in type 2 diabetics is caused partly by the lack of a protein that has not previously been associated with diabetes. This breakthrough could potentially help to prevent diabetes.”

In type 1 and advanced type 2 diabetes, the body needs injections of insulin, a hormone that transports glucose, or blood sugar, from the bloodstream into the body’s cells. As the insulin is released, the body’s glucose levels begin to drop. This causes the chitosan to lose its positive charge, and the strands begin to come back together. This shrinks the size of the pores in the sponge, trapping the remaining insulin.

‘We can also adjust the size of the overall sponge matrix as needed, as small as 100 nanometers and the chitosan itself can be absorbed by the body, so there are no long term health effects,’ explained Dr. Zhen Gu, lead author of a paper describing the work and an assistant professor in the joint biomedical engineering programme at North Carolina State University and the University of North Carolina at Chapel Hill.

In tests using diabetic laboratory mice, the researchers found the sponge matrix was effective at reducing blood sugar for up to 48 hours. However, the researchers published a separate “smart system” for insulin delivery in May that maintained normal blood sugar levels for 10 days. ‘But we learned a lot from the promising sponge research and will further optimise it. Meanwhile, we are already exploring applications to combat cancer,’ Gu added.

The research team includes Daniel Anderson, the senior author and an associate professor of chemical engineering and member of the Koch Institute for Integrative Cancer Research at MIT, and researchers from the department of anaesthesiology at Boston Children’s Hospital.

The opinions expressed in this article do not necessarily reflect the views of the DiabetesForum.com Community and should not be interpreted as medical advice. Please see your doctor before making any changes to your diabetes management plan.

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