Whole blood collected for medical tests has to be centrifuged to separate the cells from the plasma. The tests generally use only the plasma (also called serum), which is the least dense and remains on top.
A gel designed to reversibly liquefy is usually added to the blood sample tube before blood is drawn into the tube. The gel has a density between the cells and the plasma. Therefore, during centrifugation, the gel forms a barrier that separates the plasma from the cells. The barrier remains between the plasma and the cell layers after centrifugation. But because the barrier is soft, the layers can leak together and contaminate a sample while it is being transported or stored.
The new gel depends on density as well but reduces the contamination risk because it can be solidified immediately after centrifugation. Thomas explains how it works:
The separator gel is composed of a sorbitol-based gelator in a diacrylate oligomer, which initially has the consistency of ketchup. After UV exposure, it converts to the consistency of stiff rubber owing to the formation of chemical crosslinks.
Researchers Jane Emerson at the University of Southern California and Srinivasa Raghavan at the University of Maryland, and colleagues developed the new gel. They wrote in a journal article that it “is a significant advance in the practice of blood analysis for medical purposes.”
The gel may also ease separations on larger scales. Emerson told Chemistry World:
The technology has potential in industrial applications for any situation in which a permanent barrier is desired in the primary container so that pouring off into additional containers is not required for further processing, storage or testing.
Source: “Blood barrier gel aids medical analysis,” Chemistry World, 1/6/12
Source: “A new method for centrifugal separation of blood components: Creating a rigid barrier between density-stratified layers using a UV-curable thixotropic gel,” Journal of Materials Chemistry, 12/22/11
Image by Wheeler Cowperthwaite, used under its Creative Commons license.
Rachel Petkewich is a freelance science writer and editor. She has worked as a research scientist in the chemical industry and spent eight years as a staff writer and editor at various science journals and magazines, including Chemical & Engineering News.