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Project ID: G5RD-CT-2000-00282
Finanziato nell'ambito di: FP5-GROWTH
Paese: United Kingdom

Development of non-destructive sterilisation protocol for macroporous scaffolds

Gamma irradiation was found to irreversibly damage the polymer components of tissue engineering scaffolds resulting in increased degradation rates and increased rate of loss of mechanical strength when degraded. Ethylene oxide sterilised scaffolds showed less damage and a slower rate of loss of mechanical strength when degraded similar to that of virgin scaffolds. In vitro tests with and without serum and/or cells showed significant differences in degradation and mechanical behaviour. Data has been obtained that will enable degradation and mechanical behaviour to be calculated for the bioreactor and in vivo studies. With this data candidate the PLGA/CaP scaffolds degradation and mechanical state can be controlled by pre-treatment with an in vitro post sterilisation technique, optimising it for implantation.

A purpose built plasma sterilisation test rig was constructed. Plasma characteristics for plasma sterilisation were found to proportional to the gas flow rates and the power intensity used. Increased amounts of hard UV were observed when lower percentages of oxygen were used in a nitrogen plasma. Plasma sterilisation in the glow was found to kill bacterial spores but at the same time result in thermal degradation of polymer scaffolds. Using the afterglow of the plasma was found to result in the destruction in bacterial spores without thermal damage to PLGA based scaffolds.

Therefore two important outcomes have come from this work that will be of interest to the scientific and industrial community:
- Data on suitable characterisation profiles of a degradable polymer scaffolds for use through bioreactors to an implant allowing prediction of a polymer (in this case PLGA) state of degradation and mechanical performance at key time points in its delivery.

- The potential to sterilize a 3-D porous polymer construct or composite using plasma sterilisation rather than EtO sterilisation which has a temperature c.a. 50?C which is too close to the Tg of some of the key degradable polymers. Plasma sterilisation effectiveness is strongly dependent on the interconnectivity and dimensions of the construct.

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