The patent's assignee for patent number 8617374 is
News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to capillary electrophoresis, and particularly an improved capillary tube for use to conduct capillary electrophoresis analysis.
"Synthetic fused silica capillary tubing is widely used in the separation sciences, including the popular fields of Gas Chromatography, Capillary Liquid Chromatography, and Capillary Electrophoresis (CE). From its advent in the late 1970's, steady advances in product quality have emerged. Light guiding fused silica capillary tubing by applying soft fluoropolymer coating is the latest step in this continuing development. [See,
"High-performance capillary electrophoresis (HPCE) now represents a set of powerful electromigration techniques whose impact has been felt in virtually all areas of biochemical analysis. [See, Novotny, M. V.; Sudor, J. Electrophoresis 1993, 14, 373-389; Novotny, M. V. High Performance Capillary Electrophoresis, Theory Techniques and Applications,
"The existing commercial CE systems with laser-induced fluorescence (LIF) detection mechanism that use multiple capillaries/channels for high-throughput applications are complicated in design and operation of the instrument. These systems utilize fused silica capillaries with polyimide coated jacket and a clear window area (i.e., with polyimide jacket removed at the window area) at the detection zone. Soft fluoropolymer coated capillaries have not been used in such multi-channel applications. The polyimide coating (jacket) provides strength and prevents the small OD glass capillaries from breakage. For fluorescence based detection, the polyimide jacket at the detection zone of the capillary must be removed. It is essential that the detection zone of the capillary tube to be completely free of any polyimide material or particulates to provide a clear optical path through the fused silica glass for excitation and direct emission detection/collection of fluorescence signal from the samples (bio-molecules) that are migrating or flowing inside the ID of the tubes.
"To remove the polyimide jacket to provide a clear optical widow at the detection zone of the capillary for fluorescence detection, the polyimide jacket could be burned off by applying heat (using hot electric coils), acid etching, mechanical type scraping or removal (e.g., using a razor blade), or the jacket could be removed by photo-etching or photo-ablation techniques using different wavelengths and/or types of lasers. This process is very labor intensive and requires a careful examination of the glass surface under high magnification after the removal process to make sure the window (glass surface) is completely free of the polyimide jacket or any other particulates. Polyimide also fluoresces under visible light, which introduces further complications in the detection path. The removal of the polyimide jacket at the detection zone (e.g., a 3-5 mm long section) also poses weak joint exposing the bare capillary for possible micro-cracks or complete breakage. Excessive heat or mechanical stresses applied at the detection zone during the removal of the coated materials/jacket also produces micro-cracks in the OD and ID of the fused silica tube, which are not visible or detectable under the high power magnification, which also can increase the background fluorescence affecting the overall Limit of Detection (LOD) in CE type instruments, such as DNA fragment analysis type CE instruments."
As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventor's summary information for this patent: "The present invention overcomes the drawbacks of polyimide coated capillaries for CE. The present invention provides a low cost, optically effective capillary tube having high structural integrity.
"One aspect of the present invention is directed to a hard coated, transparent or optically clear jacketed capillary tube. In one embodiment, the transparent or clear coated capillary tube comprises an external transparent or clear coating or cladding of hard-fluoropolymer. The hard-fluoropolymer coating bonds to the fused silica glass, providing higher strength and superior static fatigue performance resulting in vastly improved bending flexibility. The thin hard-fluoropolymer coating of capillaries provides higher initial tensile strength, longer lifetime (resistance to stress corrosion or static fatigue) and superior ability to transmit excitation light and emitted light directly through the jacket for fluorescence based detection. The hard polymer coated capillary is low in intrinsic fluorescence, which provides low background scattering and performs at least the same in signal-to-noise for DNA fragment gel capillary electrophoresis type applications, compared to prior art bare glass type capillaries with polyimide jacket removed. By using clear coated capillaries, there is no window burning required, which provides cost savings (less manual labor) and provides superior capillary strength within the detection zone for a reliable gel-cartridge assembly of electrophoresis type instruments. Since the detection zone (window) of the capillary tube is completely covered with the hard-fluoropolymer coated jacket, it also allows close fiber optic coupling (i.e., contacting the capillary exterior surface with greater optical coupling efficiency) to deliver excitation light or collect emission light from the separated samples at the center bore of the capillary, without cracking or breaking of the fragile glass capillary tubes. Another advantage is that one can cut the capillary tubes by diamond cleaving of the capillary tubes directly over the thin polymer coating, which provides clean cut glass surfaces without any carry over of the jacket at the distal (cut) ends. This further improves the manufacturing yield, which further reduces the overall assembly cost.
"Another aspect of the present invention is directed to a CE system and a method of conducting CE using the inventive clear coated capillary tubes."
For additional information on this patent, see: Amirkhanian, Varouj. Capillary Electrophoresis Using Clear Coated Capillary Tubes. U.S. Patent Number 8617374, filed
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