Retention filter's in general

Several concepts, products, manufactures exist for upstream cell retention purposes. The use of mammalian cell expression of mAbs is huge and in general serving the same purpose - lower the cost of product. Two methods are well established:

• Alternating Flow Filtration (AFF) involves broth alternating along the surface of the membrane. 
• Tangential Flow Filtration (TFF) involves recirculation the broth across the surface of the membrane. 

Cross-Flow-Filter (CFF) is a membrane device which allow selectable components under some pressure to pass from one liquid volume into another liquid volume crossing a “membrane” eliminating other components to pass the membrane.

Hollow-Fiber-Filter (HFF) modules is a specific popular membrane product based on a number of parallel arranged extruded hollow straw, lumen arranged inside a plastic tube.

 

An important parameter is the Trans-Membrane-Pressure (TMP) - the force that drives liquid through, across the membrane. During filtration, the feed, broth side of the membrane is under pressure higher than the permeate side. This pressure difference forces liquid and the desired particles, proteins through the membrane.