Adriana Rovers/University Photography
Researchers involved in inventing a novel class of biomaterials having biological activities for repairing
damaged human tissue and organs, are, from left to right, Jack H. Freed, professor of chemistry; Keun Ho Lee,
doctoral student in textiles and apparel; and C.C. Chu, professor of fiber science.
By Susan Lang
A Cornell fiber/biomedical material scientist has made two breakthroughs, both recently approved by the U.S. Patent Office, to help the health care industry and medical patients: a non-toxic method for sterilizing biodegradable medical materials and devices, and an innovative chemical process that could make im plants "biologically active" to help promote healing and fight off disease.
These inventions are the work of C.C. Chu, professor of fiber science in the Department of Textiles and Apparel in the College of Human Ecol ogy. Chu is an expert in polymer science and biomaterials.
The first involves modifying the currently used gamma irradiation steriliza tion process with extremely low temperatures (-192 degrees C) and a very strong vacuum. This method could replace the current ethylene oxide gas method of sterilizing biodegradable materials and devices, which is tedious, time -consuming and toxic to workers.
Currently, biodegradable biomaterials, such as surgical thread, staples, clips and surgical meshes, must be sterilized by ethylene oxide gas, a highly toxic substance that poses serious risk to workers. Other methods of sterilization de s
troy the properties of these biodegradable sensitive biomaterials.
By modifying the existing, convenient and efficient gamma irradiation process, however, Chu has successfully sterilized biodegradable biomaterials without any deterioration of the materials' mechanical properties.
"Extremely low temperatures -- those used for liquid nitrogen -- in a strong vacuum somehow retards the breakdown of the biomaterial's properties by gamma rays," Chu said.
Adapting existing gamma sterilization equipment would be relatively inex pensive, Chu said, and easy for the industry to accept. With K.H. Lee, a doctoral candidate in textiles and apparel, Chu has tested the new method using standard protocols of sterility.
The second invention, in collaboration with Lee and Jack Freed, Cornell professor of chemistry, is a new chemical process to attach nitric oxide and its de rivatives -- molecules that play important roles in blood clotting, blood pressure, neurotransmission and anti-tumor functions, among others -- onto biomaterials.
"Nitric oxide, named the Molecule of the Year by Science magazine, is a very small but highly reactive and unstable free radical biomolecule with expanding known biological functions," Chu ex p
lained. To date, artificial delivery of this "wonder" biochemical and its de rivatives into humans at a controlled rate for therapeutic purposes has been diffi cult because of the molecule's extreme instability and short shelf life.
By devising a successful method of attaching these messenger molecules onto synthetic biomaterial substrates, implants could become "biologically alive." In other words, nitric oxide and its derivatives could be delivered to any living tissue at any desirable concentration, and the rate of their release could be con trolled for performing biological functions. In addition, biologically active sur gical implants could be developed that reduce inflammatory and foreign-body reactions, Chu said.
"This new process has the potential to trigger the development of a new class of biomaterials, from anti-cancer drugs, surgical implants and wound closure biomaterials with improved healing and anti-microbial capabilities to innovative drug control/release devices for fortifying the immune system against cancer and synthetic vascular grafts that would not clot for the reconstruction of injured, dis eased or aged blood vessels," Chu said.
Each of the projects was supported with about $50,000 from the College of Human Ecology.