11 min

Nanocellulose paper filters catch nasty viruses

Nano-sized cellulose fibers can help to create new and effective materials for important medical applications. Albert Mihranyan’s research team is designing customized composite materials capable of replacing body tissue, and filters able to catch viruses and antibodies.

Albert Mihranyan

Associate Professor

Wallenberg Academy Fellow 2013

Institution:
Uppsala University

Research field:
The use of nanocellulose in biomedical applications

Albert takes out a couple of round filter papers in his laboratory. They are specially-made nanocellulose membranes that can trap undesirable virus particles, he explains. There is a great need for effective filters capable of removing airborne viruses in schools and hospitals, for example, to reduce the risk of epidemics.

“And in all biotech processes involving the production of proteins and vaccines there is a risk of virus contamination. The problem is that size-wise, there is not much difference between proteins and viruses. This means that the size of the pores in the membrane must be very carefully controlled.”

In collaboration with researchers at the Swedish University of Agricultural Sciences (SLU) the membrane has been tested on the swine flu virus with good results. An article describing the virus filter was published in Advanced Healthcare Materials October 2014.
“For the first time we can show that membranes made solely of natural cellulose nanofibers can be used to filter out viruses. Removing viruses becomes nearly as easy as brewing coffee.”

From pharmacist to materials researcher

Albert was born and grew up in Armenia, and graduated from the Faculty of Pharmacy at Yerevan State Medical University. He moved to Sweden and Uppsala University having been awarded a research scholarship by the Swedish Institute in 2000 to study cellulose, with a view of developing new materials for pharmaceutical applications. His assistant supervisor during his PhD studies was Professor Maria Strømme, who leads a successful research team in the field of nanotechnology and functional materials at the Ångström Laboratory. Later on Albert joined her team to work more broadly in materials science.

With the help of a grant from the Knut and Alice Wallenberg Foundation he has now set up his own research team. Just as before, their focus is interdisciplinary basic research, with applications being involved right from the outset.

“I see this as a fantastic opportunity to achieve my goals and dreams – to become the researcher I have always wanted to be. Now I have the freedom to build up my own research team, and our aim is to conduct research at the highest international level.”

“We are working with a pool of materials we know well, focusing on various types of nanocellulose. But our work is not based on the material; it is based on a need we have identified. You might say we are trying to tailor the material to fit the application.”

Several of Albert’s discoveries have resulted in media attention, patents and business start-ups. The latest example is Upsalite, an absorbent material with enormous potential.

“The company set up to commercialize Upsalite is doing really well. But I have left that venture in favor of my Wallenberg Academy Fellow project. It is a major undertaking and so important to me that I want to commit 100 percent to it. I see my admission as a Fellow as recognition for all the hard work I have done in the past and also for what I intend to achieve in the future.”

Alga in conductive nano paper

Some years before Upsalite he invented a new, non-metallic electrode material for storing energy based on nanocellulose from the green filamentous Cladophora alga. The “algae battery” is now being further developed by Maria Strømme’s team for use in various commercial applications.

“My original idea was to use this porous conductive paper material in a new membrane system for filtering toxins accumulated in blood of patients with impaired kidney function, similar to hemodialysis but electrochemically controlled. I have been working on that idea in parallel with the algae battery because the removal of toxins could be externally controlled by applying electric current to the electrode. In collaboration with doctors at Uppsala University Hospital I am developing a nanocellulose membrane to remove harmful autoimmune antibodies from the blood.”

Antibodies normally serve the purpose of protecting our bodies from external harmful objects, e.g. microorganisms, but sometimes become overprotective and attack our own tissues and organs causing various autoimmune diseases. The membrane that Albert’s group develops is decorated with molecules known as ligands, with the ability of binding incorrectly oriented antibodies from blood or plasma passing through the membrane outside the body. Lupus, or systemic lupus erythematosus (SLE), an autoimmune disease, is used as the model system in the project and the ligand is DNA.

“Sometimes we need alternatives to the drugs that are typically used to suppress the immune system in a medical emergency or during pregnancy when the use of drugs can be contradicted. The advantage of our system is that nanocellulose is biocompatible, and it has a very large surface area, which renders it highly effective.”

Hydrogel replacing tissue

A number of other interesting projects are in progress at the lab. Albert holds up a tiny lens on his finger that looks like a standard contact lens. He explains that the lens is a molded gel of polyvinyl alcohol reinforced with cellulose nanofibers. More than 90 percent of the gel is water.

“Polyvinyl alcohol hydrogels, which are highly biocompatible, are commonly used for medical applications but they often lack mechanical stiffness. Nanocellulose is strong and very good for improving the mechanical properties of other materials.”

The team hopes it will be possible to use the reinforced hydrogel to replace soft body tissue. Lenses to repair the cornea are one application they believe in.

“We also hope to utilize the strength and elasticity of this material in orthopedic applications, such as in implants to replace worn intervertebral discs. This is a very exciting prospect, but there is a long way to go before we can begin testing the material on animals and humans.”

Text Susanne Rosén
Translation Maxwell Arding
Photo Magnus Bergström

 

Facts

The prefix “nano-” means a millionth part. Nanostructures are thus very small (an atom is approximately 0.2 nanometers).

Advanced electron microscopes are needed to study and manufacture new nanomaterials.

Nanocellulose is really a wide-ranging family of materials whose common feature is that they consist of cellulose that has been processed in a special way to produce nanofibers or nanostructures that are strong and have a large surface area.
Their properties can vary a great deal depending on how the nanocellulose is produced and the source from which it has been extracted; the surface charge, the molecular groups that are grafted on, and the length and thickness of the fibers can differ.

The cellulose comes from Swedish forests or algae harvested in the Baltic Sea. Another source is cellulose produced bacterially. Major initiatives are under way in Sweden to develop applications for nanocellulose.

One center for these initiatives is the Wallenberg Wood Science Center at KTH Royal Institute of Technology, and Chalmers University of Technology.