Gelatin added in certain concentration into the density gradient mixtures allows to solidify and melt the gradient reversibly. Such a method was applied to separation of partially disintegrated Escherichia coli VKM B-125 cells in discontinuous sucrose gradient which was optimized to obtain small round "nano-cells" free from other cell components. Gelatin added to the sucrose solutions had the advantages: i) accurate gradient layers were formed, ii) gelatin did not interfere with the cells and sub-particles during centrifugation, iii) solidified gelatin allowed to cut out the separated cell components, and iv) gelatin allowed to prepare ready-made solidified gradient centrifugation tubes into storage.
Keywords: Density gradient; differential centrifugation; separation of cells and particles; solidifying gradients.
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