Purdue research points to improved drug delivery

Scientists at Purdue University are creating a biological sensor for glucose in research that may help to design intelligent drug delivery devices.

Scientists at Purdue University are creating a biological sensor for glucose in research that may help to design ‘intelligent drug delivery’ devices that could be implanted in the body to administer medications such as insulin.

The researchers formed a mesh-like ‘biomimetic’ gel containing glucose molecules and then used a slightly acidic chemical to remove the glucose, leaving behind spaces where the glucose used to be.

If placed in a liquid such as blood, glucose in the liquid diffuses into the gel and binds to the empty spaces.

The gel is said to be ‘imprinted’ for glucose molecules. Similar materials might be used in future medical devices to sense the presence of glucose, perhaps signalling an action to release insulin or other medications for diabetics, said chemical engineering doctoral student Mark Byrne.

The approach attempts to mimic how some molecules attach to ‘binding sites’ on other molecules. Such binding is critical to various biological processes. Each binding site, however, must possess the proper shape and other characteristics for it to bind to a specific molecule.

The biomimetic gel contains numerous binding sites for glucose.

‘Essentially, we are trying to design what nature has done so well, and that’s a difficult thing to do,’ Byrne said. ‘We are creating artificial binding sites.’

Artificial sensing mechanisms might one day be incorporated into medical devices implanted inside the body.

The sensing mechanism would be part of a meshwork containing medications inside numerous microscopic cavities. Sensing glucose in the blood would automatically trigger the meshwork to expand, opening pores and releasing insulin or a medication that would enable the body to more efficiently absorb insulin.

‘Ultimately, it would be nice to design something of this sort that would provide therapy for type one diabetes,’ Byrne said. ‘It would automatically sense when the glucose level was high, and then it would release an appropriate level of insulin. Then, whenever the glucose level went down again, the polymer gel would intelligently stop the release of insulin.’

The gels might be incorporated into a drug-dispensing system that receives signals from the sensors and then commands the meshwork to expand, releasing insulin. Another possibility is that the sensors themselves might directly command the meshwork to expand.

‘The system would be sensitive to what is in the blood, and then, depending on what it sensed in the blood, would administer the right amount of drug,’ Byrne said.

Such applications probably will be at least five years in the future, researchers said.

An important aspect of the Purdue research is that the scientists have been able to make the gel with a non-toxic solvent and in water, meaning it would be compatible with the human body.

The gel is created by ultraviolet light, which causes molecules surrounding the glucose to form the binding sites. The glucose is then removed with an acidic chemical, leaving the empty, synthetic binding sites.