Hybrid Nanoparticles Separated by Buoyant Density in a Large‐Scale Centrifugal Process

Abstract

In isopycnic centrifugations carried out in a density gradient, the separation of macromolecules and polymer nanoparticles is contingent on their respective densities alone. The influence of size on the velocity of the particles is only operative until the particles reach a zone within the gradient where their density is equivalent to that of the surrounding fluid. The advent of bowl‐shaped zonal rotors has marked a substantial advancement, obviating the necessity for centrifugal separations within centrifuge tubes. Notably, this study is the first to investigate the separation of mixtures of synthetic nanoparticles carried out in a zonal rotor by two different scenarios. Initially, the separation of colloidal dimers, composed of two distinct polymer types, from particles of pure polymers is explored. The study is then extended to protein‐loaded polymer particles that are separated from unloaded particles. The efficacy of the separation process is benchmarked against separations on a smaller scale using swing‐out rotors. In both instances, the manifestation of a conspicuously sharp band formation can be observed, thereby enabling the determination of the buoyant densities of the individual particle populations through precise measurement of band positions. This opens up a new framework for the sorting of particle mixtures based exclusively on their buoyant densities, irrespective of their sizes or shapes.