(185d) New Diagnostic Paradigms Enabled By Hyperresolution Dielectrophoretic Separations

Our group is developing better separation methods for targets ranging from proteins to ten micron particles, including virtually all biological targets (proteins, organelles, bioparticles, cells, etc.) Using gradient techniques for separations of complex mixtures allows for the effects diffusion and other dispersive factors to be minimized. An especially attractive mix of forces for common biological samples is electrophoresis and dielectrophoresis. We have a closely related approach term electrophoretic exclusion which includes a flow field, which I will cover briefly, but the approach I will mostly focus on is one that sets electrophoretic forces to oppose dielectrophoretic ones across an open channel. In this channel, there are unique capture points for various values of electrophoretic and dielectrophoretic properties of the analytical targets, described by characteristic mobilities (u_EK and u_DEP, respectively). With this technique, very similar particles and biological materials can be efficiently separated. Under optimal conditions a one micron particle can be separated from one that varies by only one nanometer (one part in a 1000-2000). Other characteristic resolution factors include minimal resolvable u_DEP at 10^-26 m⁴/V²s (one part in 10⁹) and minimal resolvable Clausius-Mossotti factor at 10^-9. These are extraordinary figures of merit. We have already shown extremely positive results by separating gentamicin resistant Staphylococcus epidermidis and Staphylococcus aureus from susceptible strains, reflecting extremely subtle alterations in cellular structure or function. A theoretical framework and resulting predictions will be presented along with key data supporting the models.