Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Calorimeter
Reexamination Certificate
1998-07-16
2001-11-20
Brumback, Brenda (Department: 1612)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Calorimeter
C422S051000, C422S051000, C422S067000, C422S187000, C422S186220, C436S514000, C436S524000, C436S525000
Reexamination Certificate
active
06319466
ABSTRACT:
BACKGROUND OF THE INVENTION
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 have been developed. An example of one such test kit includes a pregnancy test kit.
Particularly in the food safety area it has long been recognized that residue detection should be accurate, inexpensive and easily conducted. Consumers and governments are becoming increasingly aware of the necessity for testing foods for the presence of undesirable residues naturally occurring or otherwise.
Since a large portion of the consumers are children, food safety has long been critical in the dairy industry. Antibiotic residues used on a dairy farm occasionally appear in the milk supply. The hazards associated with these undesirable residues, include allergic reactions, assisting the propagation of new and sometimes drug resistant microorganisms and other long term health risks.
Government agencies have established in some cases legal limits for particular residues in foods, for example antibiotic residues in milk. Residues above the “legal” limit are considered unsafe for human consumption. Residue levels below the legal limit are considered “safe”. It is important, therefore, that detection methods, in addition to being inexpensive and easily conducted, do not give positive results when residues are below legal limits so that otherwise acceptable milk, or other foods, are not discarded or otherwise treated as containing residues above legal limits.
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 in a sample and a method therefor.
Often a liquid, such as milk, has one or more contaminants or analytes that are in trace amounts that need to be assayed. In order to detect the analyte, the present invention employs a labeled receptor that reacts with the analyte to form an analyte-receptor complex. The labeled receptor is positioned within or proximate to a membrane and when exposed to the liquid, lateral capillary flow occurs thereon. In the flow, the liquid carries the analyte-receptor complex, and any unbound labeled receptor with it. Positioned on the membrane in the flow path is a test zone. The test zone has a representative analyte conjugate attached to the membrane, to bind unbound receptor to form a first analyte conjugate receptor complex that, as a result of the label, has a signal visible to the eye or readable with an instrument.
Capillary flow of the liquid continues on the membrane to a control zone. The control zone includes a binder attached to the membrane that binds with the labeled receptor. Upon binding, the control zone changes to a signal that can be visible to the eye or readable with an instrument or visible under special light conditions, such as ultraviolet. If the signal in the test zone is more intense than the signal in the control zone, the test indicates that the analyte is not present in a sufficient amount (a negative test). If the test zone signal is less intense than the control zone signal, the test indicates that the analyte is present in an amount in excess of allowable levels (a positive test).
The receptor may bind a family of analytes (one or a plurality of analyte) which have similar structural binding sites. Members of an analyte family can have different detection level requirements and, therefore, additional analyte binders can be employed, for example, monoclonal or polyclonal antibodies, that bind a portion of the analyte in competition with the receptor, in the sample, thereby decreasing test sensitivity. The antibodies are mixed with the labeled receptor in an amount to adjust the sensitivity for a specific analyte or group of analytes. The sensitivity of the test is adjusted so that a positive test result is not given unless a certain threshold of analyte is present in the sample.
The test device includes a support strip and a sample-absorbing matrix attached to the support strip. The sample-absorbing matrix is a material for absorbing an amount of the sample for example a sponge. The test device also includes a mobile-phase support for holding a mobile-phase composition. The mobile-phase support is attached to the support strip and is in contact with the sample-absorbing matrix. A mobile-phase composition is disposed within or on the mobile-phase support and has a labeled receptor for binding with the analyte. The mobile-phase composition can be carried in the sample and flow together with the sample. A stationary-phase membrane is attached to the support strip and has a first membrane end in contact with the mobile-phase composition and a second membrane end in contact with the disposal zone. The membrane allows lateral capillary flow of the sample from the first membrane end to the second membrane end. A test zone is on the stationary-phase membrane between the first membrane end and second membrane end and has an analyte conjugate for binding with unbound labeled receptor. A control zone is on the stationary-phase membrane between the test zone and second membrane end and has a binder, for example an antibody to the particular receptor, for binding with analyte-bound receptor and excess unbound receptor.
The invention also includes an analyte test device for detecting, in a general horizontal position, an analyte in a liquid sample by capillary lateral flow in a chromatographic test strip. The device includes an elongated housing defining an elongated strip cavity having an open application aperture at one end and having another end. The cavity is adapted to receive and hold a test strip therein. The housing has a transparent top cover section to allow the observation of tests results on the test strip. The housing is 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 includes a support strip with a plurality of sequential contacting, liquid-sample, permeable zones extending from the first end to the second end. The zones allow the lateral capillary flow of the liquid sample from the first end to 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 to an expanded state on absorption of a preselected amount of the liquid sample, and a mobile phase support having a mobile-phase composition layer thereon or therein with a labeled receptor for binding the analyte in the liquid sample thereon, typically a visible area containing colored beads and a membrane generally of nitrocellulose which includes a reaction zone having at least one stationary analyte conjugate reference or test line, or generally a test and a separate control line thereon and optionally a disposal zone of liquid-sample absorbent material to absorb less liquid sample and to aid in 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 are designed to allow the compressed-material layer to absorb a selected amount of liquid sample for testing and in an amount sufficient to carry out the test and to expand from a dry, nonexpanded form to a wet, expanded state. The material layer in a wet, expanded state fills substantially the application cavity and causes sufficient pressure on the housing walls of the expansion cavity to drive capillary 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 or when a known amount of sample is pipetted into the application cavity.
In one embodiment, a housing is employed, such as a one-piece, integral, i
Boyer Cheryl A.
Charm Stanley E.
Donahue Paul R.
Glickman Yael Agi
Markovsky Robert J.
Brumback Brenda
Charm Sciences Inc.
IP Legal Strategies Group P.C.
Meyer-Leon Esq. Leslie
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