Separations and detection of particles/cells using stable stepwise density gradients and centrifugation
Aqueous Multiphase Polymer Systems (AMPS)
Gradient centrifugation is a widely used laboratory technique that overcomes the need for expensive ultra-centrifuges and allows the separation of cells, particles and small molecules based on size, weight or density. Important applications include the generation of a blood cell counts, cell separation for storage in blood or stem cell banks, detection of pathogens, viruses or circulating tumor cells, separation of tRNA and rRNA, and purification of DNA plasmids or recombinant proteins. Gradient centrifugation requires solutions with known density gradients, which are typically generated by careful layering of different density solutions or by centrifugation of heterogeneous solutions. The invention, AMPS, provides an easy, inexpensive and robust alternative for the generation of such density gradients. An example of an application is the diagnosis of malaria by demonstrating the presence of the less dense infected red blood cells.
Innovations and Advantages
If certain aqueous solutions of polymers are mixed, they do not form homogeneous solutions but separate into discrete layers with known density, so-called AMPS. The number of solutions determines the number of layers formed. Specifically, more than 81 two-phase, 73 three-phase, 38 four-phase, and 8 five-phase systems have been discovered. The density of each phase can be further adjusted by altering the salt concentrations and tuned for the specific application.
Because AMPS phase-separate spontaneously, they are very robust to package, which makes them ideal candidates for gradient centrifugation. Compared to non-equilibrium density gradients generated by centrifugation of heterogeneous solutions, AMPS are stable and do not require calibration procedures or special centrifuges. Compared to centrifugation systems that use a “frit” or polyester gel to separate two phases, AMPS can readily generate multi-layer systems to separate more than just two classes of cells, particles or molecules. The method is ideal for in-field use, Doctor’s offices and factory floor or in the developing world, as it requires no power, has no moving parts and provides results readily discernable by the naked eye.
Intellectual Property Status: Patent(s) pending
Akbulut Halatci, Ozge
Kumar, Ashok Ashwin
Mace, Charles R.
Patton, Matthew R.
Shapiro, Nathan D.
Whitesides, George M.
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Mick Sawka, Director of Business Development
Reference Harvard Case #3865