Researchers at the Division of Nanotechnology and Functional Materials at Uppsala University in Sweden have developed a paper filter which can remove virus particles with an efficiency that is said to match that of the best industrial virus filters. The paper filter consists of 100% high purity cellulose nanofibres, directly derived from nature.
The research was carried out with virologists from the Swedish University of Agricultural Sciences/Swedish National Veterinary Institute and is published in the Advanced Healthcare Materials journal.
Virus particles are tiny (about thousand times thinner than a human hair) and can only replicate in living cells but once the cells become infected they can turn out to be extremely pathogenic. They can actively cause diseases on their own or even transform healthy cells into malignant tumours.
Inexpensive and robust virus removal filters are highly demanded
‘Viral contamination of biotechnological products is a serious challenge for production of therapeutic proteins and vaccines. Because of the small size, virus removal is a non-trivial task, and, therefore, inexpensive and robust virus removal filters are highly demanded’, says Albert Mihranyan, Associate Professor at the Division of Nanotechnology and Functional Materials, who led the study.
Cellulose is one of the most common materials used 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 sterilisation e.g. by autoclaving. The pores in normal filter paper, used for chemistry, are too large to remove viruses.
The new paper filter discovery is a result of a decade of research into the properties of high surface area nanocellulose materials, which enabled the scientists to tailor the pore size distribution of their paper precisely in the range desirable for virus filtration.
Previously described virus removal paper filters relied heavily on the interception of viruses through 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 laborious multistep phase-inversion processing involving hazardous solvents and rigorous pore annealing processing.
