Physics Demos Simulating Density Gradient Centrifugation Isolating Peripheral Blood Mononuclear-cells

Gravity, buoyancy, Stoke's drag, Brownian motion, centrifugal force, density, viscosity and temperature factor in isolating Mononuclear-cells from whole blood by Density Gradient Centrifugation. Add 15 mL of density gradient medium, Ficoll-Paque (TM), in a 50 mL conical tube. Carefully layer 35 mL of diluted blood over the F-P. Centrifuge 30 minutes at 400g's. Acceleration from rest takes 2 minutes, while deacceleration to rest is 15 minutes. Centrifugation and sedimentation generate a self-made density gradient - rearranged with increasing density (top to bottom). Blood components separate at neutral buoyancy locations: plasma, white blood cells (Peripheral Blood Mononuclear-Cells), F-P (powdered hydrophilic polysaccharide Ficoll, mixed with sodium diatrizoate to 1.077 g/mL), and red blood cells. Pipette to remove PBMCs. The centrifugation demo uses discrete layers of sucrose-water concentrations, (50,40,...,10%) for the density gradient and a suspension layer of polystyrene colored microspheres (several densities) illustrating separation.