A low speed rotor for the separation of whole cells
Applications of a low-speed centrifuge rotor designed to separate whole cells at very low g-forces in partially reoriented, shallow density gradients are presented. The particle separation chamber was fabricated using Lucite so that gradient behavior and particle sedimentation could be monitored visually during rotor operation by using stroboscopic illumination. Runs were recorded on videotape for later study and frame-by-frame analysis. Rotor performance was tested using a model system consisting of polystyrene microspheres of known sizes and densities. The resolution obtained exceeded that of previously reported centrifugal separations. Cells from an ascites-grown tumor were separated into three discrete subpopulations. Cells comprising each subpopulation were characterized in terms of size distributions and sedimentation rates. Experimental results are discussed in relation to theoretical considerations about the behavior of particles in partially reoriented density gradients.