Microspheres biological distribution

Biological samples such as bacteria and viruses have been studied by SdFFF as well as FIFFF. These two techniques provided bacterial number, density, size, and mass distributions of bacterial cells of diverse shapes and sizes, molecular weights, sizes, densities, and diffusivities of viruses. SdFFF has been used to analyze protein particles, including casein derived from nonfat dry milk, albumin microspheres, and particles in cataractous lenses originating from the aggregation of lens proteins. 

As pointed out in Chapter 8, the forces of centrifugation are too weak to influence the distribution of small molecules. The molecular weight M of species must be 106 in order to generate the necessary force in SdFFF. However for M > 106, there are many important separation problems involving polymers, biological macromolecules (such as DNAs), subcellular particles, emulsions, and a great variety of natural and industrial colloids. SdFFF has been applied to many such systems [10-12,16]. An example of the separation of colloidal polystyrene latex microspheres is shown in Figure 9.9,. 

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