Fluidic temperature gradient focusing
AssigneeThe United States of America as represented by the Secretary of Commerce
InventorsDavid Ross, Laurie E. Locascio
Life of this patent
Estimating the term…
Abstract
A method and device are provided for concentrating and separating ionic species in solution within a fluidic device having a fluid conduit such as a channel or capillary. The concentration is achieved by balancing the electrophoretic velocity of an analyte against the bulk flow of solution in the presence of a temperature gradient. Using an appropriate buffer, the temperature gradient can generate a corresponding gradient in the electrophoretic velocity so that the electrophoretic and bulk velocities sum to zero at a unique point and the analyte will be focused at that point. The method and device may be adapted for use with a variety of analytes including fluorescent dyes, amino acids, proteins, DNA and to concentrate a dilute analyte.
Claims37
A method for directing ionic analytes contained in an ionic buffer solution, said ionic buffer solution having a temperature dependent property selected from the group consisting of ionic strength and pH, said method comprising the steps of:
- applying an electric field to an ionic buffer solution containing at least one species of ionic analyte to cause the analyte ions to have electrophoretic motion;
- establishing, in said buffer solution, a temperature gradient having a significant component substantially aligned with the electrophoretic motion of the analyte ions, which produces a gradient in the ionic strength or pH of said buffer solution, thereby generating a gradient of the electrophoretic velocity of the analytes;
- and
- producing a bulk flow of said buffer solution to have a significant component substantially aligned in the direction opposite the direction of the electrophoretic motion of one or more of the analytes so that at least one of said one or more analytes will accumulate or be focused at at least one point along said temperature gradient, the pH at said at least one point being unequal to the isoelectric point of said at least one of said one or more analytes that are focused at said at least one point.
A fluidic device, comprising:
- a fluid conduit;
- an ionic buffer solution with a temperature dependent property selected from the group consisting of ionic strength and pH disposed in said fluid conduit;
- an electric voltage source for providing an electric field within said fluid conduit, thereby causing one or more ionic analytes to have electrophoretic motion;
- at least one heat source or heat sink, thermally coupled to said fluid conduit, for providing a temperature gradient having a significant component substantially aligned with the electrophoretic motion of one or more ionic analytes so as to form an electrophoretic velocity gradient within said fluid conduit;
- and
- a source of bulk fluid flow for providing flow of said ionic buffer solution in said fluid conduit, in a direction opposite to the electrophoretic motion of at least one of said one or more ionic analytes;
- whereby said at least one of said one or more ionic analytes will accumulate or be focused at at least one point along said temperature gradient, the pH at said at least one point being unequal to the isoelectric point of said at least one of said one or more analytes that are focused at said at least one point.
Dependencies are inferred from the claim text.