Research

            Removal of viruses from drinking water:  The World Health Organization estimates that 1.7 million people die each year due to infectious diarrhea that is transmitted through the drinking water supply, most commonly caused by bacteria and viruses. Bacteria can be removed by filtration, but the small size of viruses requires that more sophisticated methods be used. The objective of this NSF-BRIGE grant was to create functionalized membranes from nanofibers produced by electrospinning. We wanted to create large pore sized membranes that will allow a large amount of water to easily pass through them while having a high virus removal capacity. We were able to create an electrospun membrane that can remove viruses from water. We created a membrane that contains fibers that are about 200 nm in diameter. The pores are on the size of microns, which would allow viruses to pass by size. However, the viruses stick to the fibers due to the high positive charge that has been added through chemical means. We were able to remove 3.7 log reduction value of a non-enveloped virus (PPV, porcine parvovirus) and > 4 log reduction value of an enveloped virus (Sindbis virus). This is close to or exceeds the EPA regulation that a virus reduction mechanism must accomplish at least 4 log reduction value, which is equivalent to 99.99% removal of virus. From this positive result, we suggest that this positive charge material, which comes naturally from shrimp shells, be studied further for its ability to create membranes that could purify drinking water.

 

Images from Mi, X. et al. (2014). Carbohydrate Research, 387: 24-29

This project was funded by an NSF BRIGE award (CBET-1125585) and has produced 3 papers.

            Design of virus removal techniques through understanding of viral surface chemistry:  Biotherapeutics have revolutionized the treatment of many diseases, ranging from cancer to rheumatoid arthritis. As new biotherapeutics become available, the steep costs of biotherapeutic production significantly limit access to these lifesaving treatments. The most expensive step in biotherapeutic production is the FDA required virus removal step, which is most often nanofiltration. Researchers are trying to create new membrane surface chemistries that will reduce the cost of nanofiltration membranes, but large screening methods are inefficient, time consuming, and costly. This project proposes a shift in the design and creation of next-generation virus removal and detection technologies. Instead of screening large libraries of chemistries to determine the ones that will most efficiently remove viruses, this project will first examine the surface chemistry of the viruses. This will lead to targeted chemistries that will attract viruses and exponentially increase the efficiency of screening processes. 

This project is funded by an NSF CAREER award (CBET-1451959).

            Purification of viruses for vaccine manufacturing:  Many biomanufacturing companies are attempting to find platform approaches for the purification of monoclonal antibodies.  We would like to find platform approaches for virus purification for a quicker turn around if a new virus pandemic requires quick vaccine production.  

Vaccine technology has revolutionized the prevention of communicable diseases.  In order to improve the speed and efficiency of viral therapeutic manufacturing, there needs to be an improvement in current virus purification processes.  Chromatography resins are acceptable for proteins, but not for large biomolecules, such as virus particles.  In tangential flow filtration, the capacity of the membrane can be affected by fouling of large biomolecules, leading to low flux and high transmembrane pressures.  We have focused on virus flocculation in the presence of osmolytes, followed by microfiltration.  Osmolytes are natural compounds that stabilize intracellular proteins against environmental stresses.  We are currently working with a non-enveloped virus, porcine parvovirus (PPV), and an enveloped virus, Sindbis virus (SINV).  We have discovered several protecting osmolytes that flocculate PPV and SINV and demonstrate a >80% removal with a 0.20 μm filter without flocculating other model proteins.  This micropore filter is usually used to retain bacteria, not small virus particles.  A 0.20 μm micropore filter improves the flux and reduces the fouling that is typically experienced with nanopore filters used for virus retention.  
Images from Gencoglu et al. (2014) Journal of Biotechnology. 186, 83-90 and Gencoglu and Heldt (2015) Journal of Biotechnology. 206, 8-11.

This project is funded by NSF (CBET-1159425) and has currently produced 2 papers.


            Sensor development for protein and pathogen detection:  In collaboration with XG Sciences, a manufacturer of

graphene nanoplatelets, and several Michigan Tech faculty, we are exploring the use of graphene paper as a protein detection platform.  We have currently determined that a graphene-cellulose blend changes electrical conductivity in response to protein concentration and functions over a wide pH and conductivity range.  Our next steps are to study the attachment of specific antibodies to detect the binding of specific proteins in solution.  

This project is funded by the Michigan Space Grant Consortium and NSF GOALI award (CBET-1510006) and has currently produced 3 papers.

Image from Heldt, C. L. et al. (2013). Sensors and Actuators B: Chemical 181, 92-98. 

 

            Antiviral compounds:  We have discovered that osmolytes, natural compounds that stabilize proteins, have antiviral activity against a nonenveloped virus.  Nonenveloped viruses are difficult to inhibit with compounds that do not have cellular toxicity.  These compounds have the potential to become future therapeutic antiviral agents.  We are exploring other antiviral compounds and molecules to find ways to limit viral infections in hospitals and the manufacturing of biotherapeutics.  This project has produced one paper.