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Nano-paper filter can remove viruses

Last Updated Aug 2015
By: Michael Nystås

Researchers at the Division of Nanotechnology and Functional Materials, Uppsala University, have developed a paper filter, which can remove virus particles with an efficiency matching that of the best industrial virus filters. Viral contamination of biotechnological products is a serious challenge for production of therapeutic proteins and vaccines, but because of the small size, virus removal is a non-trivial task. Previously described virus removal paper filters relied heavily on interception of viruses via electrostatic interactions, which are sensitive to pH and salt concentrations, whereas the virus removal filters made from synthetic polymers and which rely on size-exclusion are produced through tedious multistep phase-inversion processing involving hazardous solvents and rigorous pore annealing processing. The new filter consists of 100 percent high purity cellulose nanofibers, directly derived from nature. Cellulose is one of the most common materials to produce various types of filters because it is inexpensive, disposable, inert and non-toxic. It is also mechanically strong, hydrophyllic, stable in a wide range of pH, and can withstand sterilization e.g. by autoclaving. Normal filter paper, used for chemistry, has too large pores to remove viruses. As a result of a decade long research on the properties of high surface area nanocellulose materials, the scientists have been able to tailor the pore size distribution of their paper precisely in the range desirable for virus filtration.

Metreveli, G. ; Wågberg, L. ; Emmoth, E. ; Belák, S. ; Strømme, M. ; and Mihranyan, A., A Size-Exclusion Nanocellulose Filter Paper for Virus Removal (2014). Advanced Healthcare Materials, 3: 1546–1550 (2014); DOI: 10.1002/adhm.201300641.


Caption: SEM images of PS latex beads and SIV particles following filtration on Cladophora cellulose membrane: a) 500 nm beads; b) 100 nm beads; c) 30 nm beads; and d) SIV particles.