Director, Filtration R&D
EMD Millipore Corporation
Abstract: Microporous and ultrafiltration membranes made by phase inversion processes have been used for decades to improve the safety of drugs by removal of bacteria and viruses from process streams in biopharmaceutical manufacturing. Until recently, no alternative technology existed to form filtration materials for these critical applications.
Recent availability of commercial electrospinning equipment greatly improved the ease of producing nanofiber mats with fiber diameters down to few tens of nanometers. This enabled preparation of highly porous fiber mats for liquid filtration exhibiting very high fluxes. In this work, it was demonstrated that highly consistent electrospun nanofiber mats could be produced and successfully used for reliable and complete retention of microorganisms. Nanofiber mats optimized for removal of bacteria and viruses were generated and permeability and retention performance were compared to model predictions. A relationship between structural parameters of nanofiber-based filters (fiber diameter, mat thickness, and porosity) and their permeabilities and retention characteristics was established. It was found that with optimal combinations of structural parameters, nanofiber membranes can offer as much as 3 times higher permeability - with similar retention performance - compared to conventional cast microfiltration and virus removal membranes