Researchers at North Carolina State University and the University of North Carolina at Chapel Hill have developed a new nanotechnology-based technique for regulating blood sugar in people with diabetes that allows them to control insulin release with an injectable nano-network and portable ultrasound device.
This technique may give patients the ability to release insulin painlessly using a small ultrasound device,in contrast to the current practice of multiple insulin injections each day.
In this technique biocompatible and biodegradable nanoparticles made of poly lactic-co-glycolic acid (PLGA) and filled with insulin are injected into a patient’s skin. Each of the PLGA nanoparticles is given either a positively charged coating made of chitosan (a biocompatible material normally found in shrimp shells), or a negatively charged coating made of alginate (a biocompatible material normally found in seaweed). When mixed together, the positively and negatively charged coatings are attracted to each other by electrostatic force to form a nano-network. Once injected into the subcutaneous layer of the skin, that nano-network holds the nanoparticles together and prevents them from dispersing throughout the body.
The coated PLGA nanoparticles are also porous. Once in the body, the insulin begins to diffuse from the nanoparticles . The electrostatic force of the nano-network keeps most of the insulin in the subcutaneous layer of the skin thereby creating a dose of insulin waiting to be transported into the bloodstream.
Using the new technology developed by Gu’s team, a person with diabetes can use a small, handheld device to apply focused ultrasound waves to the site of the nano-network that releases the insulin into the bloodstream.
The researchers believe the technique works because the ultrasound waves excite microscopic gas bubbles in the tissue, temporarily disrupting nano-network in the subcutaneous layer of the skin. The disruption pushes the nanoparticles apart, thus relaxing the electrostatic force being exerted on the store of insulin which in turn allows the insulin to begin entering the bloodstream. This process is accelerated by the effect of the ultrasound waves pushing on the insulin.
When the ultrasound is removed, the electrostatic force reasserts itself and pulls the nanoparticles in the nano-network back together. The nanoparticles then diffuse more insulin to replace the insulin.
Proof-of-concept testing in laboratory mice with type 1 diabetes shows that with this technique there isa quick release of insulin into the bloodstream, and that the nano-network contains enough insulin to regulate blood glucose levels for up to 10 days.
According to Jin Di, lead author and a graduate student in Gu’s research laboratory, when the insulin finishes, a new nano-network is injected and the earlier nano-network dissolves and is fully absorbed into the body in a few weeks.
“This advance will certainly give millions of people with diabetes worldwide hope that better days are ahead,” says Dr. John Buse, director of UNC-Chapel Hill’s Diabetes Care Center and deputy director of UNC-Chapel Hill’s NIH Clinical and Translational Sciences Award. “We must work to translate these exciting studies in the lab to clinical practice.”
The paper, “Ultrasound-Triggered Regulation of Blood Glucose Levels Using Injectable Nano-Network,” is published online in Advanced Healthcare Materials and was selected as a cover article. The paper was co-authored by Jennifer Price, an undergraduate in the joint biomedical engineering program; Dr. Xiao Gu, of Yangzhou University; and Dr. Xiaoning Jiang, an associate professor of mechanical engineering at NC State.
Source:
(http://news.ncsu.edu/)
North Carolina State Univ.
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