Safer gas filter cuts fire risk in bioproduction

Pall has launched a new gas filter that should increase safety in the production of biologic drugs that need to be made in an oxygen-enriched environment, writes Phil Taylor.

An increasing number of life-saving protein-based therapies are produced from cells that are grown in bioreactors using oxygen enriched air for aeration. But while oxygen enrichment improves production yields and lowers overall processing costs, it can increase potential fire risks for sterilising gas filtration operations.

Pall's Emflon CPFR sterilising grade gas filter - just launched at the at the PDA 2005 annual meeting - has been specifically designed for this type of fermenter or bioreactor applications by enabling manufacturers to use oxygen enrichment more safely.

Oxygen enrichment techniques, while highly productive, can lead to safety challenges because elevated levels of oxygen in bioreactor airflows can increase the risk of spontaneous ignition of conventional air sterilising filter materials.

But as worldwide demand for fermentation and biotechnology products continues to rise, manufacturers are increasingly turning to oxygen enrichment to maximise the levels of oxygen that reach cells, thereby promoting growth and raising the yield of their proteins.

At the same time, traditional technologies to boost cell growth - such as mechanical agitation or airlifting - can be inefficient or not appropriate for certain types of cells, including mammalian cells used for biotech drug products, because they are sensitive to shear.

The Emflon CPFR filter membrane is constructed of PTFE material, a widely used material that does not readily ignite. Additionally, the filter's support and drainage layers are designed using special materials to minimise combustibility, compared to polypropylene, a common material of construction in other gas filters.

"This is the first filter for the oxygen-enriched aeration of mammalian cell culture and microbial fermentation operations that gives manufacturers a higher degree of safety," said Christian Martin, product manager at Pall Life Sciences, who presented data on the new filter yesterday at the PDA meeting.

"It enables drug producers to use modern aeration techniques safely, boosting cell culture yields and enabling a faster level of biotech drug production," added Dr Martin.

The Emflon CPFR filter was evaluated by the Federal Institute for Material Research and Testing in Germany, which routinely tests materials for usage in gaseous oxygen.

After subjecting the filter materials to pressure shock tests with 100 per cent gaseous oxygen at 10-bar g (145psi) pressure at 60 degrees C (140 Farenheit), the Institute concluded that the filter's materials had a high combustion resistance.