Finding use from a lack of symmetry in filtering; Sterlitech Polyethersulfone takes an advantage

May 09, 2016

Filtering difficult biological solutions? Normally, using a thin membrane filter can pose serious questions:

“How much liquid can I get through the filter?”
“When will it clog?”
“What if my solution is very critical to the project?"

Sterlitech Polyethersulfone (PES) membrane filters have a unique asymmetric pore structure that allows the user to take advantage of this feature; PES can be its own pre-filter and dynamically increase throughput!

Hold a sample piece of this material up to the light at an oblique angle, and you will see a glossy/shiny side, and a more matte/dull side. This sided-ness feature (see Figure 1) is helpful in that the more open area (matte side) has larger entry pores compared to the glossy side; and it should face into the incoming liquid stream for the best results with particulate-heavy liquids. If you were to view an SEM image of the matte side, you may quickly notice the pores seem much larger than the stated pore size, this is normal! Each pore’s ability to capture particulates is not only a function of the outer diameter, but of the entire pore pathway through the filter. Each pathway constricts in diameter, turns sharp curves, and makes multiple intersections with other pore pathways. This feature is what gives PES its high level of water flow and particulate loading compared to many other absolute-rated filters of the same pore size.

This is especially helpful when filtering liquids from cell lysates, cell culture media, plasma, serum, sputum, surface water, seawater, river/pond water, and other liquids from a biological or pharmaceutical source. PES membranes bind very little protein and have a high degree of open area to facilitate fast filtering, even with most challenging particulate loads. If sterile filtering is needed, this is easily accomplished with the 0.2 µm pore size. This material was tested against ASTM method F838-05 for the removal of B. diminuta for a minimum 7-log reduction, and it passed very well.

Sterlitech offers PES filter discs, sheets, and roll stock in 0.03, 0.1, 0.2, 0.45, 0.65, 0.8, 1.2, and 5.0 micron pore sizes. Syringe filters for smaller volumes are also available in 0.2 and 0.45 micron and pre-sterilized syringe filters in 0.2, 0.45, and 0.8 microns. Not sure what pore size is needed or if your solution will work with PES? Get in touch with a Sterlitech technical representative at [email protected] for an informative and fast reply. Stay tuned for next month’s article on pore geometry as exposed by SEM imagery! Sterlitech PES membrane filters can be seen here.