Smart particles release insulin into diabetics' bloodstream

Researchers in the US have developed a type of nanoparticle that automatically releases insulin into the blood when glucose levels get too high, and have demonstrated that its effects last for 10 days in mice.

 Regular injections of the particles could mean type 1 diabetics wouldn’t have to check their blood sugar levels several times a day, or inject the exact right amount of insulin when needed, which can result in too high or low doses being administered, with further health problems following.

 ‘We’ve created a ‘smart’ system that is injected into the body and responds to changes in blood sugar by releasing insulin, effectively controlling blood-sugar levels,’ said Dr Zhen Gu, an assistant professor in the joint biomedical engineering program at North Carolina State University and the University of North Carolina.

 ‘This technology effectively creates a ‘closed-loop’ system that mimics the activity of the pancreas in a healthy person, releasing insulin in response to glucose level changes. This has the potential to improve the health and quality of life of diabetes patients.’

 The nanoparticles have a solid core of insulin surrounded by a layer of a modified glucose-based material known as dextran and another of glucose oxidase enzymes.

 When the enzymes are exposed to high glucose levels they effectively convert the sugar into gluconic acid, which breaks down the modified dextran and releases the insulin.

 The insulin then brings the glucose levels under control. The gluconic acid and dextran are biocompatible and dissolve in the body.

 The nanoparticle cores are given a biocompatible coating that makes them positively or negatively charged, causing them to form a network that prevents them from dispersing throughout the body.

 The positively charged coatings are made of chitosan (a material normally found in shrimp shells), abnd the negatively charged coatings are made of alginate (a material normally found in seaweed).

 When the solution of coated nanoparticles is mixed together, the positively and negatively charged coatings are attracted to each other to form a “nano-network.”

 Once injected into the subcutaneous layer of the skin, the nano-network holds the nanoparticles together. Both the nano-network and the coatings are porous, allowing blood - and blood sugar - to reach the nanoparticle cores.

 Gu’s research team is now in discussions to move the technology into clinical trials for use in humans.

 A paper on the research has been published in the scientific journal ACS Nano.