Intelligent polymer containing antioxidants reacts to body chemistry and the environment

Oxidants in living organisms are byproducts of metabolism and are essential for healing and immunity. However, when their concentrations become too high, inflammation and tissue damage may occur. Engineers at the University of Illinois have developed and tested a new drug delivery system that detects high levels of oxidants and responds by administering the proper amount of antioxidants required to restore this delicate balance.

The results are published in the journal Small.

Many pharmaceuticals include polymers and specialized particles that control the timing or concentration of the drug released once administered, the researchers said. However, these additives can hinder crystallization during the manufacturing phase of certain drugs, such as antioxidants, which dissolve them uncontrollably in the body.

"We have seen here an opportunity to develop a different type of drug delivery system that can detect the level of oxidant in a system and respond by administering an antioxidant as needed," Hyunjoon said. Kong, professor of chemical and biomolecular engineering and co-author of the study.

Kong and his team have found a way to assemble catechin crystals – the bright green antioxidant found in green tea – by using a polymer that can detect too much oxidant concentration. The researchers tested the reactivity of the resulting polymer containing catechin crystals in the planktonic freshwater crustacean Daphnia magna, the water chip.

"The heart rate is an indication of the extent to which potentially toxic chemicals are affecting the physiology of water fleas," Kong said. "Daphnids are often used to monitor environmental impacts on ecological systems, and since their hearts are similar to those of vertebrates, they are also used to evaluate the effectiveness of cardioprotective drugs."

The researchers exposed the daphnids to water contaminated with sublethal concentrations of natural hydrogen peroxide while monitoring their heart rate. They found that the average heart rates of Daphnia increased from 348 to 290 and 277 beats per minute, depending on the concentration of hydrogen peroxide used.

When the team added to the experiment the new catechin crystal assembled with a polymer, the water chips eventually found a heart rate close to normal.

Beyond the potential pharmaceutical uses of the new polymer, Kong Group is currently studying its use to reduce the impact of highly oxidative chemicals in natural water courses.

"Hydrogen peroxide is often used to clean water fouled by excess algae, which raises concerns about the possibility that the oxidant affects living organisms in the water." 39, water, "he said. "We believe that this new system of release of antioxidants could be used to solve the problem of over-oxidized natural waters."

The researchers plan to continue the development of the polymer for pharmaceutical and environmental purposes. "This study proved that it was a concept, but we still have work to do," Kong said. "We are concerned about the safety of the specific polymer we have used, polyethylenimine diselenide – but we are on the verge of finding a viable replacement."