Single Particle Measurements of Viral Surface Chemistry for Separations and Stability

Viruses have extremely complex surfaces, making their study at a molecular level extremely difficult. We have developed a single particle method to study viral surface chemistry, thus filling the void between molecular and bulk measurements. Chemical force microscopy (CFM) measures the adhesion force between a particle, in this case a virus particle, and a functionalized atomic force microscopy (AFM) tip. CFM reduces many of the difficulties of bulk characterization techniques by measuring adhesion of individual virus particles. This will reduce the effects of purity on the virus suspension, as individual virus particles are targeted and not a measurement of the bulk liquid. We have characterized virus charge and hydrophobicity with CFM. We have used our understanding of virus surface chemistry to explain, and in the future to develop new methods, to purify and stabilize viral particles. CFM is allowing us to better understand the fundamental thermodynamics in virus purification and stabilization, thus bringing greater process understanding into vaccine and gene therapy manufacturing.