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Medical sterilisation using supercritical CO2

Challenge

A new method for sterilisation of biological materials.

Problem

None of the common methods of medical sterilisation is well-suited to sterilising delicate biological materials. Distribution by tissue banks of contaminated donor tissues has resulted in serious infections and illnesses in transplant patients. The two most widely used sterilants (ethylene oxide and gamma radiation) also raise concerns about toxicity and safety. Ethylene oxide is a mutagenic, carcinogenic, volatile, flammable reactive gas. Residues of ethylene oxide remain in the sterilised 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 sterilise packaged biological products without eroding their physical integrity.

Solution

NovaSterilis and the Massachusetts Institute of Technology have successfully developed an environmentally benign technique for sterilising delicate biological materials using supercritical carbon dioxide. The technology uses low temperature and cycles of moderate pressure along with peracetic acid and small amounts of water to kill bacterial endospores.

Benefits

Rapid (less than one hour) and total inactivation of a wide range of microbes is achieved with the technique, compatible with sensitive biological materials and effective for a wide range of important biomedical materials including:
  • musculoskeletal allograft tissue (eg human bone, tendons, dermis and heart valves) for transplantation
  • biodegradable polymers and related materials used in medical devices, instruments, and drugs
  • drug delivery systems
  • whole-cell vaccines that retain high antigenicity.
Besides being a green chemical technology, supercritical CO₂ sterilization achieves terminal sterilisation – meaning sterilisation of the final packaged product – providing greater assurance of sterility than traditional methods of aseptic processing.
Sterilisation of double-bagged tissue allows tissue banks to provide terminally sterilised musculoskeletal tissues in packages that can be opened in operating rooms by surgical teams immediately prior to use.

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