The oxidants found in living organisms are byproducts of metabolism and are essential for healing and immunity to the wounds. However, when their concentrations become too high, inflammation and damage to the tissue may occur. Engineers at the University of Illinois have developed and tested a new drug delivery system that feels high levels of oxidant and reacts by administering the right amount of antioxidant to restore this delicate balance.
The findings are published in the journal Small.
Many drugs include specialized polymers and particles that control the time or concentration of the released drug after administration, researchers say. However, these additives can inhibit crystallization during the production phase of some antioxidants as drugs – causing their dissolution in the body in an uncontrolled manner.
"Here we saw an opportunity to develop a different kind of drug delivery system that could feel the level of oxidant in the system and respond with the administration of an antioxidant as needed," said Professor of Chemical and Biomolecular Engineering and study co-author Hyunong Kong.
Kong and his team have found a way to collect catechin crystals – a light green antioxidant found in green tea – using a polymer that can think when the concentrations of oxidants become too high. The researchers tested the reaction of the resulting polymer containing catechin crystals in the common planktonic Cancer Daphnia magna, a waterfall.
"Heart rate is an indicator of the extent to which potentially toxic chemicals affect the physiology of aquatic fleas," Kong said. "Daphnids are often used to monitor environmental impacts on environmental systems, and because their hearts are similar to those of 'vertebrates, they are also used to assess the effectiveness of cardioprotective drugs.'
The researchers exposed dafnidas in water contaminated with sublethal concentrations of the natural oxidant hydrogen peroxide, while monitoring their cardiac frequency. They found that the median heart rate of Daphni had dropped from 348 to 290 and 277 beats per minute, depending on the hydrogen peroxide concentration that was used.
When the team added the new catechin crystal composed of the polymer of the experiment, the water repellent eventually renewed the heart toxins close to normal.
Beyond potential pharmaceutical use for the new polymer, the Cong group is reviewing its use to reduce the impact of highly oxidizing chemicals on natural waterways.
"Hydrogen peroxide is often used for pure water contaminated by excessive algae, and it raises concerns about how the oxidant can affect living organisms in water," he said. "We think that this new antioxidant system can be used to solve the problem of excessively oxidized natural waters."
The researchers plan to continue the development of a polymer for pharmaceutical and environmental purposes. "This study proved to be a concept, but we need to do more work," Kong said. "There is concern about the safety of the specific polymer we used – polyethyleneamine diselenide – but we are approaching finding a viable substitute."
Materials provided by University of Illinois at Urbana-Champaign. Note: The content can be edited for style and length.