Large-scale centrifugal separations of nanoparticles
Density gradient centrifugation using swinging-bucket rotors is an efficient method for isolation and purification of biological particles ranging from whole cells down to serum proteins. Already in the 1960s, a program was launched at the Oak Ridge National Laboratory that came up with hollow rotors capable of hosting density gradients and therefore allowing large-scale separations. From then on, the technique was solely used for biological separations. In its original field the technique is nowadays widely superseded by chromatographic techniques and threatens to fall into oblivion. We will demonstrate that waking this “sleeping beauty” opens up exciting perspectives apart from biology, namely in sorting mixtures of synthetic nanoparticles.
Clusters built from variable numbers of spherical particles are referred to as “colloidal molecules” because they share configurations with true molecules. Such supraparticles are an ideal testing system to probe fractionation of multimodal nanoparticles using zonal rotor centrifugation. Here zonal rotor ultracentrifugation is helping to solve a major bottleneck regarding the application of shape-tailored nanoparticles as elementary units for hierarchically organized materials.