Presidential Green Chemistry Challenge: 2007 Small Business Award
Environmentally Benign Medical Sterilization Using Supercritical Carbon Dioxide
Innovation and Benefits: Sterilizing biological tissue for transplant is critical to safety and success in medical treatment. Common existing sterilization techniques use ethylene oxide or gamma radiation, which are toxic or have safety problems. NovaSterilis invented a technology that uses carbon dioxide and a form of peroxide to sterilize a wide variety of delicate biological materials such as graft tissue, vaccines, and biopolymers. Their Nova 2200TM sterilizer requires neither hazardous ethylene oxide nor gamma radiation.
Summary of Technology: None of the common methods for medical sterilization is well-suited to sterilizing delicate biological materials. The sterility of these materials is critical. Distribution of contaminated donor tissues by tissue banks has resulted in serious infections and illnesses in transplant patients. The two most widely used sterilants (ethylene oxide and gamma radiation) also raise toxicity and safety concerns. Ethylene oxide is a mutagenic, carcinogenic, volatile, flammable, reactive gas. Residues of ethylene oxide remain in the sterilized material, increasing the risk of toxic side effects. Gamma radiation is highly penetrating and is lethal to all cells. Neither ethylene oxide nor gamma radiation can sterilize packaged biological products without eroding their physical integrity.
NovaSterilis, a privately held biotechnology company in Ithaca, NY, has successfully developed and commercialized a highly effective and environmentally benign technique for sterilizing delicate biological materials using supercritical carbon dioxide (CO2). NovaSterilis licensed a patent for bacterial inactivation in biodegradable polymers that was issued to Professor Robert S. Langer and his team at the Massachusetts Institute of Technology. NovaSterilis then enhanced, expanded, and optimized the technology to kill bacterial endospores. Their supercritical CO2 technology uses low temperature and cycles of moderate pressure along with a peroxide (peracetic acid) and small amounts of water. Their Nova 2200TM sterilizer consistently achieves rapid (less than one hour) and total inactivation of a wide range of microbes, including bacterial endospores. The mechanism of bacterial inactivation is not well-understood, but does not appear to involve bacterial cell lysis or wholesale degradation of bacterial proteins.
The new technology is compatible with sensitive biological materials and is effective for a wide range of important biomedical materials including: (a) musculoskeletal allograft tissue (e.g., human bone, tendons, dermis, and heart valves) for transplantation; (b) biodegradable polymers and related materials used in medical devices, instruments, and drugs; (c) drug delivery systems; and (d) whole-cell vaccines that retain high antigenicity. Besides being a green chemical technology, supercritical CO2 sterilization achieves "terminal" sterilization, that is, sterilization of the final packaged product. Terminal sterilization provides greater assurance of sterility than traditional methods of aseptic processing. Sterilization of double-bagged tissue allows tissue banks to ship terminally sterilized musculoskeletal tissues in packages that can be opened in operating rooms by surgical teams immediately prior to use. NovaSterilis's patented technology addresses the market need in tissue banks as well as other needs in the biomedical, biologics, medical device, pharmaceutical, and vaccine industries. By the end of 2006, NovaSterilis had sold several units to tissue banks.