Chemistry: analytical and immunological testing – Involving diffusion or migration of antigen or antibody
Reexamination Certificate
2000-04-04
2002-11-05
Nguyen, Bao-Thuy L. (Department: 1641)
Chemistry: analytical and immunological testing
Involving diffusion or migration of antigen or antibody
C422S051000, C422S051000, C422S187000, C422S186220, C422S105000, C422S110000, C422S287000, C435S007100, C435S007200, C435S007800, C435S007920, C435S007940, C435S007950, C435S174000, C435S287300, C435S970000, C435S971000, C435S007930, C436S518000, C436S524000, C436S538000, C436S535000, C436S810000, C436S807000
Reexamination Certificate
active
06475805
ABSTRACT:
BACKGROUND OF THE INVENTION
There are numerous patents and publications which describe various lateral-flow or immunochromatographic test kits and methods for the detection of the presence or concentration of chemical residues or analytes or classes thereof from liquid samples. One publication includes “A SHORT GUIDE—developing Immunochromatographic Test Strips” by Millipore Corporation, Bedford, Mass., while U.S. patents would include U.S. Pat. No. 4,703,017, issued Oct. 27, 1987; U.S. Pat. No. 5,591,645, issued Jan. 7, 1997; U.S. Pat. No. 5,266,497, issued Nov. 30, 1993; U.S. Pat. No 4,999,285, issued Mar. 12, 1991; U.S. Pat. No. 5,238,652 issued Aug. 24, 1993; and U.S. Pat. No. 5,622,871, issued Aug. 22, 1997 (all hereby incorporated by reference).
U.S. Pat. No. 5,622,871 describes analytical test devices for biological fluids which include elongated, rectangular, hollow casings to contain a test strip, and which casings have an aperture to permit visual observation of the test results on the test strip. The casings include a protective, removable cap to protect and enclose the application end of the casing. The internal constructional details of the housing are not a significant feature of the invention, but are employed to provide a housing for the particular test strip (column 12, lines 20-26).
It is desired to provide a new and improved analyte test device and method based on test strips in which the housing of the test strip is designed to promote the absorption, flow and efficiency of the test device and the tests carried out.
SUMMARY OF THE INVENTION
The invention relates to an analyte or chemical residue test device and method employing a lateral-flow test strip for the detection of the analyte or residue within a housing and a method therefor.
The invention comprises an analyte test device for detecting, in the general horizontal position, an analyte in a liquid sample by capillary lateral flow in an inmunochromatographic test strip, which device comprises an elongated housing defining an elongated strip cavity having a one open application aperture at one end and having another end, the cavity adapted to receive and hold a test strip therein, and having a transparent top cover section, to permit the observation of test results on the test strip, the housing characterized by an enlarged application cavity extending outwardly from the top cover and having or adapted to have an open end at the application end. The test device includes a test strip positioned in the strip cavity.
The test strip comprises a support strip with a plurality of sequential, contacting, liquid-sample, permeable zones extending from the first to the second ends, which zones permit the lateral capillary flow of the liquid sample from the first to the second end. The zones include a sample-absorbing and filtering zone composed of an expandable, porous, compressed-material layer which moves, on contact with the liquid sample, between a nonexpanded state and an expanded state on absorption of a preselected amount of the liquid sample, and a releasing zone having a mobile-phase layer thereon with a receptor for the analyte of the liquid sample thereon, typically a visible area, for example, of colored beads. The zones include also a reaction zone having at least one stationary-layer analyte reference or test line, or generally a test and a separate control line thereon for observation, to detect the presence of analytes in the liquid sample, and optionally a disposal zone of a layer of liquid-sample absorbent material for the liquid sample and to induce capillary flow to the second end. The sample-absorbing zone with the compressed material layer is positioned adjacent the application cavity, the compressed-material layer and the application cavity designed to provide the compressed-material layer to absorb a selected amount of liquid sample to be tested and sufficient to carry out the test and to expand from a dry, nonexpanded to a wet, expanded state, and to provide for the said material layer in the wet, expanded state to fill substantially the application cavity and to cause sufficient pressure on the housing walls of the expansion cavity to drive capillary flow of the liquid sample toward the disposal zone in said strip in a selected time period and to restrict flow of the liquid sample in the application cavity to a selected volume, when the open application end of the test device is inserted into a liquid to obtain the liquid sample.
In the invention, one preferred embodiment is the employment of a housing, such as a one-piece, integral, injection-molded, all-transparent, plastic material, with the plastic material selected or designed to be subject to incubator temperatures of 50° C. or more for incubation times; for example, of 2 to 10-15 minutes, depending on the particular test.
The preferred embodiment includes a generally toothbrush-type housing shape, with the enlarged, generally rectangular, toothbrush-type head at the open application end of the housing, with a dry, inert, porous, expandable, liquid-permeable, absorbing material in a generally rectangular layer as an absorbing zone in the test strip; for example, of cellulose or nitrocellulose, positioned beneath the open bottom of the application cavity or chamber. The absorbing layer on contact, such as immersion of the application end of the housing of the test device in a liquid, will absorb a preselected amount of the liquid sample required for the test. The absorbing-layer material will expand; for example, in 1 to 30 seconds, to fill or substantially fill the expansion cavity and contact the surrounding walls of the expansion-cavity housing, to cause sufficient pressure within the expansion cavity and in the expanded state of the material to drive capillary flow laterally in the underlying test strip toward the end of the elongated housing where the test strip is positioned. Thus, proper selection and dimensioning of the expansion cavity and underlying absorbing-layer material which generally mimics two dimensions of the expansion cavity, permits absorbing and filtering of the selected amount of liquid sample for the test strip, and aids in driving the lateral flow of the liquid sample in the test strip in the housing toward the end of the test strip; for example, the disposal zone, to receive the liquid sample where employed. If the absorbing layer does not expand sufficiently to fill or substantially fill the expansion cavity, then lateral or capillary flow rates and times are unsatisfactory; that is, flow rate too slow and time period too long. Where the absorbing layer is used in excess, then excess pressure occurs in the expansion cavity, and the expanded absorbing layer tends to retard the desired lateral flow of the liquid sample.
The housing with the toothbrush-shaped design may comprise a separate, injection-molded housing with an optional end cover, to protect the exposed application end before sampling and after sampling, and in the incubation chamber, to prevent cross-contamination from other sources. The test device with the molded housing enables the user to handle the handle end of the housing and to obtain a liquid sample merely by dipping the open application cavity into a liquid.
The housing also may comprise a toothbrush-shaped design, wherein the expansion cavity is formed in a plastic, usually transparent, blister-type package which is sealed against a flat support, such as a paper strip or another plastic strip, and which encompasses within the blister package the selected test strip. The blister package includes a removable seal strip at the one application end of the enclosed test strip, for peeling or removal prior to use and for the introduction of a selected volume of the liquid to the application-absorbing zone of the test strip while in the blister package. The blister package with the liquid sample and test strip may be incubated in the incubator and the test results observed or read.
In a further embodiment, it has been discovered to be desirable to provide one or more apertures in the housing
Charm Stanley E.
Markovsky Robert J.
Saul Steven J.
Skiffington Richard
Zomer Eliezer
Charm Sciences Inc.
IP Legal Strategies Group P.C.
Meyer-Leon Esq. Leslie
Nguyen Bao-Thuy L.
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