Chemistry: analytical and immunological testing – Peptide – protein or amino acid
Reexamination Certificate
2001-02-02
2003-04-22
Warden, Jill (Department: 1743)
Chemistry: analytical and immunological testing
Peptide, protein or amino acid
C436S056000, C436S800000, C422S051000, C422S067000
Reexamination Certificate
active
06551834
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the field of contamination testing, particularly including the field of testing for biological contaminants.
This description is provided solely to assist the understanding of the reader, and does not constitute an admission that the cited references are prior art to the present invention.
In the processing of food materials and in the preparation of food products, as well as in other fields, it is advantageous to test for the presence of particular substances, often substances that would be regarded as contaminants. Materials detected as indicators of contamination include, for example, viable bacterial cells and ATP. For many substances, however, the commonly used detection methods involve a number of different procedural steps, such as reagent preparation, reagent mixing, sample transfer, and sample/reagent mixing. As an example, current methods for protein determination, which can serve as an indicator of a contaminated surface, often involve on-site reagent preparation due to stability problems, along with multiple transfer steps, and/or involve highly subjective color changes which make interpretation difficult, and/or require the use of complex instrumentation. Examples of common protein determination methods are described in Stoscheck,
Quantitation of Protein
, in METHODS IN ENZYMOLOGY Vol. 182, pp.50-68, 1990. Among the variants of basic protein detection methods are methods using colloidal forms of Coomassie® blue stain to detect proteins in gels such as polyacrylamide electrophoresis gels. Such methods are described, for example, in Neuhoff et al., 1985,
Electrophoresis
6:427-488 and Neuhoff et al., 1988,
Electrophoresis
9:255-262.
In addition, for tests performed in food processing facilities, contamination of food by assay reagents is a concern and the individuals performing the tests may lack significant experience preparing chemical formulations, potentially introducing significant test error. Therefore, the use of detection methods which require the preparation or transfers of assay chemicals is undesirable in many testing environments.
In addition to the conventional protein assay methods referenced above, a combination cleaning and protein staining composition is described in Winicov et al., U.S. Pat. No. 5,424,000, entitled ACID CLEANINGS AND STAINING COMPOSITIONS, issued Jun. 13, 1995. The solutions preferably include phosphoric, sulfuric, and nitric acids, and Acid Violet 19 dye.
A number of different self-contained sampling/testing devices employing certain assays have been described. Examples of such assays include sampling for bacterial contaminants in food processing plants, the sampling for contamination of the environment by heavy metals such as lead, and the collection of specimens from a patient to test for microorganism infection.
Specific examples of self-contained sampling/testing devices include Nason, U.S. Pat. No. 5,266,266, issued Nov. 30, 1993, and Nason, U.S. Pat. No. 4,978,504, issued Dec. 18, 1990, both entitled SPECIMEN TEST UNIT; Nason, U.S. Pat. No. 4,707,450, issued Nov. 17, 1987, entitled SPECIMEN COLLECTION AND TEST UNIT; and Tobin, U.S. Pat. No. 3,792,699, issued Feb. 19, 1974, all of which are hereby incorporated by reference in their entireties including drawings.
SUMMARY OF THE INVENTION
The need for, and utility of on site, immediate feedback to cleaning and audit personnel on the presence of residual contaminating substances in a variety of environments is well-established. For example, the need for contaminant monitoring has a well documented role in food safety programs when residual food residues can result in bacterial contamination and allergic responses in some individuals. Effective cleaning also reduces the risk of pathogens contaminating subsequent food products. A variety of devices and methods have been utilized for contaminant testing.
Particularly advantageous devices for the purpose of evaluating the presence of specific materials require no secondary reagents or steps, have easily detected changes in the presence of target material, give immediate results, and allow integrated collection of sample into the device. The present inventor shows that such a self-contained sampling/testing device can be constructed in which the presence of target material in a sample is detected colorimetrically through use of a dye which binds the target material. As indicated above, this device is particularly advantageous for routine sanitation testing procedures.
In a first aspect, the present invention concerns a self-contained device having a sampler for collecting a sample which may contain a target material, a signal generator having a contactable dye that binds to the collected target material, and a sampler washer having a wash solution for washing the collected target material and/or free dye from or on the sampler to facilitate measurement of a signal produced from the interaction of dye and target material. The sample collection surface or portion of the sampler is in communication with or can be placed in communication with the sampler washer. In preferred embodiments, the sampler collection surface is also in communication with or can be placed in communication with an absorbent material able to take up liquid from a wetting agent and/or dye solution and/or wash solution. The device may be constructed with any of many possible structural configurations, depending on the requirements of the particular application, e.g., depending on the specific type of dye used and the type of target material to be tested.
The term “in communication” refers to a contact or channel or other means that allows fluid contact between the referenced components. Thus, for example, a sampler washer and an absorbent material are in communication if fluid transport can occur from the sampler washer into the absorbent material. The term does not imply that fluid is actually present, but only that such fluid contact could occur if fluid were present.
In preferred embodiments, the device incorporates a target material precipitating dye, preferably a protein precipitating dye, for example, Ponceau-S dye. Such a dye binds to and precipitates, or assists in precipitating or keeping out of solution a target material. The sample collection surface of the sampler can be contacted with the dye ( in solution or dry) in a manner such that a quantity sufficient to dye target material in a sample is taken up by the sampler. In using such dyes, it is generally advantageous to separate bound dye from unbound dye to provide convenient detection of the presence of target material. Thus, preferred embodiments using such dyes employ an arrangement where the collected sample (which may contain target material) is or can be disposed between reservoirs such that wash solution can pass through or over a solid matrix carrying the collected sample. For example, the collected sample can be disposed between an absorbent material able to absorb wash solution and an absorbent material or other reservoir containing a wash solution. The saturation differential between these reservoirs provides for a directional transport of dye and wash solution across the collection pad surface. Preferably the wash solution is drawn through or over a matrix bearing a collected sample by capillary action. In embodiments where the collection surface and dry absorbent material are in direct contact, the dry absorbent material should have at least enough capacity to absorb sufficient dye and wash solution to wash one sample collection surface. In other embodiments, rather than involving capillary action in an absorbent material to draw wash solution through a sample-bearing matrix, a wash utilizes user-applied pressure that pushes wash solution through the sample bearing matrix.
The term “matrix” refers to a solid material suitable for retaining dye/target material complexes. In the context of this invention, a matrix is preferably, but not necessarily a porous matrix or porous material, meaning that the matrix is penetrated by a large n
Carpenter Charles
Clark Genevieve
Eckenroth Brian
Ehrenfeld Elizabeth
Pierson Mark W.
BioControl Systems, Inc.
Cole Monique T.
Seed Intellectual Property Law Group PLLC
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