When a foreign material is put inside the human body, you will always get an inflammatory response to some degree, says Guillermo Ameer, professor of biomedical engineering in McCormick School of Engineering and Applied Science and professor of surgery in the Feinberg School of Medicine at Northwestern University (Chicago). "A problem with commonly used plastic materials, in particular, is that in addition to that inflammatory response, oxidation occurs," he adds. This can lead to an imbalance in the amount of oxygen in the body and contribute to chronic disease, chronic inflammation, and other complications that may cause the implant to fail. Ameer and his team have created what they describe as the world's first biodegradable biomaterial that is inherently antioxidant. The material can be used to create elastomers, liquids that turn into gels, or solids for building devices that are more compatible with cells and tissues.
The biomaterial is a citric acid–based polyester, in which vitamin C is integrated into the building blocks. "In the past, people have added antioxidant vitamins to a polymer and blended it in," says Ameer in a press release posted on the Northwestern University website. "That can affect the mechanical properties of the material and limit how much antioxidant you can add, so it doesn't work well. What we're doing is different. We're building a material that is already inherently, intrinsically antioxidant."
In preliminary experiments, vascular grafts were coated with the antioxidant biomaterial and evaluated in animals. Grafts typically tend to inflame nearby cells and slowly scar over time, which eventually leads to failure. When the antioxidant vascular graft was implanted, however, scarring was significantly reduced. Ameer's team also found that a water-soluble, thermoreversible version of the material accelerated the healing of diabetic ulcers. Because the material is biodegradable, it is absorbed by the body over time.
The new biomaterial could be used to create scaffolds for tissue engineering; coat or build safer medical devices; promote healing in regenerative medicine; and protect cells, genes, and viruses during drug delivery. Ameer adds that the new biomaterial is easy to make and inexpensive, since citric acid is readily available and affordable.
The research is described in the June 26 issue of Biomaterials.