Hydrogels, materials that can absorb and retain large quantities of water, could revolutionise medicine. Our bodies contain up to 60% water, but hydrogels can hold up to 90%. It is this similarity to human tissue that has led researchers to examine if these materials could be used to improve the treatment of a range of medical conditions including heart disease and cancer.
These days hydrogels can be found in many everyday products, from disposable nappies and soft contact lenses to plant-water crystals. But the history of hydrogels for medical applications started in the 1960s. Scientists developed artificial materials with the ambitious goal of using them in permanent contact applications – ones that are implanted in the body permanently.
One of the most exciting clinical applications being tested is in drug delivery. People with type 1 diabetes need to constantly inject themselves with insulin in order to control their blood sugar levels. But hydrogels could dispense with that need.
Researchers are working on hydrogels that contain insulin which can be injected under the skin. This creates a deposit of insulin within the body. Because these materials contains a large amount of water, the insulin can move from the interior of the hydrogel to the exterior producing a slow release of the hormone. When all the insulin is released, the hydrogel is naturally disposed of by the body. In this way, multiple insulin injections can be replaced with a single hydrogel injection.
Others have sought to get rid of the need for insulin injections by trying to develop a tablet containing insulin which can be taken orally. One of the main challenges is that insulin tends to be destroyed in the stomach before it can reach the intestines to be absorbed into the body. Scientists are using hydrogels to try to solve this problem. By creating hydrogels which can protect the insulin from the stomach acids and adhere temporarily to the walls of the intestine, the insulin can be safely absorbed into the body, removing the need for an injection.
The treatment of cancer can also be improved through the use of hydrogels. Chemotherapy generally involves patients attending a hospital for treatment with the medicine administered either via injection or a drip. Researchers are attempting to reduce the cost of chemotherapy and improve patients’ quality of life by exploring the use of hydrogels as a means of delivering this treatment too. Similar to diabetes, researchers are investigating whether these medicines can be delivered orally. This would reduce the need for patients to attend hospital for treatment and lessen the cost of providing chemotherapy. However, as anti-cancer drugs cannot be easily dissolved in water, researchers need to find a way to improve the ability of the body to absorb these drugs when they are taken orally.
The uses of hydrogels are not limited to drug delivery. Recently, a group of researchers from the University of Pennsylvania demonstrated how hydrogels can be used to help prevent damage to the heart. People are at a greater risk of experiencing heart damage after a heart attack as the organ becomes enlarged and its walls tend to narrow and become scarred. Injecting hydrogels into the heart’s walls after an attack provide mechanical support and stabilises the damaged area.
Hydrogels can also be used to improve tissue healing and tissue regeneration by delivering stem cells or proteins – inside a wound or broken bone – to stimulate tissue regrowth.
At Queen’s University Belfast, we are also working on several different medical applications of hydrogels including hydrogel microneedle patches, for the delivery of medicines through the skin, and a hydrogel capable of destroying hospital superbugs by preventing bacteria to form colonies. There seems to be no end to the versatility of this wonderful substance.