Authors: D. Griffiths, P. Hole, J. Smith, A. Malloy, B. Carr
Affilation: NanoSight, United States
Pages: 176 - 179
Keywords: count, concentration, virus, protein, aggregate
A new analytical system is described which provides total particle count and high-resolution size measurements for biological structures such as virus and protein aggregates. This system builds on the Nanoparticle Tracking and Analysis (NTA) technique for the simultaneous visualization and individual sizing of nanoparticles based on their Brownian motion. Virus production and purification processes rely on overall measurements of concentration such as optical density, a low accuracy method, and infectivity assays which may take days to obtain results. The NTA method provides a result in minutes and the total particle count, in combination with the infectivity assay values, provides a clearer picture of how the sample has been attenuated or killed by the purification process. For non-lytic virus or virus-like particles (VLP), this provides the only measure of concentration for the final product. Much attention has been paid of late to sub-visible (<10 micron) particles in therapeutic protein preparations. While numerous options exist for sizing and counting above one micron, NTA provides the only alternative for concentration and sizing of the polydisperse aggregates formed in this range. By studying the early stages of the aggregation process, much greater insight can be gained into the aggregation dynamics.