U.S. patent application number 12/982452 was filed with the patent office on 2011-04-28 for swab-based diagnostic systems.
This patent application is currently assigned to KIMBERLY-CLARK WORLDWIDE, INC.. Invention is credited to Naveen Agarwal, Jeffrey Eldon Fish, Lei Huang, Rosann Marie Matthews Kaylor, Robert John Lyng, John Albert Shuty.
Application Number | 20110097820 12/982452 |
Document ID | / |
Family ID | 34678912 |
Filed Date | 2011-04-28 |
United States Patent
Application |
20110097820 |
Kind Code |
A1 |
Lyng; Robert John ; et
al. |
April 28, 2011 |
Swab-Based Diagnostic Systems
Abstract
A diagnostic test system for detecting the presence or absence
of an analyte within a test sample is provided. For instance, the
system may include a swab and a detection unit. The detection unit
includes a first component that is capable of receiving the swab,
the first component defining an insertion chamber within which a
fluid is capable of being retained. The detection unit also
includes a second component that defines a detection chamber within
which an assay for detecting the presence or absence of the analyte
is capable of being contained. The first component is rotatable
relative to the second component from an inactive position to an
active position. In the inactive position, the fluid remains
substantially contained within the insertion chamber. In the active
position, the fluid may flow from the insertion chamber to the
detection chamber and contact the assay.
Inventors: |
Lyng; Robert John;
(Norcross, GA) ; Fish; Jeffrey Eldon; (Dacula,
GA) ; Kaylor; Rosann Marie Matthews; (Cumming,
GA) ; Agarwal; Naveen; (Evansville, IN) ;
Huang; Lei; (Duluth, GA) ; Shuty; John Albert;
(Alpharetta, GA) |
Assignee: |
KIMBERLY-CLARK WORLDWIDE,
INC.
Neenah
WI
|
Family ID: |
34678912 |
Appl. No.: |
12/982452 |
Filed: |
December 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10744607 |
Dec 23, 2003 |
7863053 |
|
|
12982452 |
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Current U.S.
Class: |
436/518 ;
436/174; 436/175 |
Current CPC
Class: |
Y10T 436/25 20150115;
A61B 10/0051 20130101; A61B 5/150358 20130101; A61B 5/14546
20130101; A61B 5/150022 20130101; A61B 5/150305 20130101; A61B
5/150343 20130101; A61B 5/150015 20130101; A61B 5/150251 20130101;
Y10T 436/25125 20150115; A61B 2010/0009 20130101; A61B 5/157
20130101 |
Class at
Publication: |
436/518 ;
436/174; 436/175 |
International
Class: |
G01N 33/543 20060101
G01N033/543; G01N 1/28 20060101 G01N001/28 |
Claims
1-20. (canceled)
21. A method for detecting the presence or absence of an analyte
within a test sample, said method comprising: i) providing a
diagnostic test system, said system comprising a swab and a
detection unit, said detection unit comprising: a) a first
component that is capable of receiving said swab, said first
component defining an insertion chamber within which a fluid is
retained; and b) a second component that defines a detection
chamber within which an assay for detecting the presence or absence
of the analyte is contained; ii) contacting said swab with the test
sample; iii) inserting said swab into said insertion chamber of
said first component so that said swab contacts said fluid; and iv)
rotating said first component relative to said second component so
that said fluid flows from said insertion chamber to said detection
chamber and contacts said assay.
22. A method as defined in claim 21, wherein said first component
defines a sample port through which said swab is inserted.
23. A method as defined in claim 22, wherein said detection unit
further comprises a hydraulic seal that forms a sealing fit between
said sample port and said swab.
24. A method as defined in claim 21, wherein a flexible packet is
contained within said insertion chamber that retains said fluid,
said swab rupturing said flexible packet when inserted into said
insertion chamber.
25. A method as defined in claim 21, further comprising determining
the intensity of a detection signal generated at a detection zone
of said assay, wherein the amount of the analyte within the test
sample is determined from said detection signal.
26. A method as defined in claim 25, further comprising calibrating
said detection signal with a calibration signal generated at a
calibration zone of said assay, wherein the amount of the analyte
within the test sample is determined from said detection signal as
calibrated by said calibration signal.
Description
BACKGROUND OF THE INVENTION
[0001] Medical swabs are commonly used to collect biological
specimens from a patient. Such medical swabs generally include a
fibrous tip at one end of an elongated stick or shaft. Once a
sample is collected, it may be transferred from the tip to a
testing medium for performance of an immunoassay to determine the
presence or absence of an analyte of interest. Some systems, known
as "all-in-one" swab systems, have been developed that provide both
the reagents for the immunoassay and the swab in a single,
self-contained apparatus. However, one problem with such
"all-in-one" systems is that the fluid contained within the
apparatus often leaks out of the apparatus prior to use. In
addition, the method for using such devices typically involves
several complicated steps that may lower the real-time efficacy of
the device in detecting the presence or absence of the analyte.
[0002] As such a need currently exits for a swab-based device that
is effective in detecting the presence of an analyte in a simple
manner.
SUMMARY OF THE INVENTION
[0003] In accordance with one embodiment of the present invention,
a diagnostic test system is disclosed for detecting the presence or
absence of an analyte within a test sample. The system comprises a
swab and a detection unit. The detection unit comprises a first
component that is capable of receiving the swab. In one embodiment,
the first component defines a sample port through which the swab is
capable of being inserted. A hydraulic seal (e.g., o-ring) may form
a sealing fit between the sample port and the swab. The first
component defines an insertion chamber within which a fluid is
capable of being retained. In one embodiment, a flexible packet is
contained within the insertion chamber, the flexible packet being
configured to retain the fluid. For example, the flexible packet
may be formed from a film, metallic foil, or combinations thereof.
The flexible packet may have a thickness of less than about 0.05
inches, and in some embodiments, from about 0.0007 inches to about
0.02 inches.
[0004] The diagnostic test system also comprises a second component
that defines a detection chamber within which an assay for
detecting the presence or absence of the analyte is capable of
being contained. The first component is rotatable relative to the
second component from an inactive position to an active position.
In the inactive position, the fluid remains substantially retained
within the insertion chamber. In the active position, the fluid may
flow from the insertion chamber to the detection chamber and
contact the assay. In one embodiment, for instance, the system
further comprises a delivery channel that is also rotatable
relative to the second component. The second component may comprise
a connection channel, wherein the delivery channel is capable of
rotation into fluid communication with the connection channel so
that the fluid flows from the insertion chamber, through the
delivery channel, and into the connection channel. The connection
channel may be in fluid communication with the detection
chamber.
[0005] In accordance with another embodiment of the present
invention, a method is disclosed for detecting the presence or
absence of an analyte within a test sample. The method
comprises:
[0006] i) providing a diagnostic test system, the system comprising
a swab and a detection unit, the detection unit comprising: [0007]
a) a first component that is capable of receiving the swab, the
first component defining an insertion chamber within which a fluid
is retained; and [0008] b) a second component defining a detection
chamber within which an assay for detecting the presence or absence
of the analyte is capable of being contained;
[0009] ii) contacting the swab with the test sample;
[0010] iii) inserting the swab into the insertion chamber of the
first component so that the swab contacts the fluid; and
[0011] iv) rotating the first component relative to the second
component so that the fluid flows from the insertion chamber to the
detection chamber and contacts the assay. The method may further
comprise determining the intensity of a detection signal generated
at a detection zone of the assay, wherein the amount of the analyte
within the test sample is determined from the detection signal. In
addition, the detection signal may be calibrated by a calibration
signal generated at a calibration zone of the assay, wherein the
amount of the analyte within the test sample is determined from the
detection signal as calibrated by the calibration signal.
[0012] Other features and aspects of the present invention are
discussed in greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth more particularly in the remainder of the
specification, which makes reference to the appended figures in
which:
[0014] FIG. 1 is a perspective view of one embodiment of a
diagnostic system of the present invention contained within a
sealed package;
[0015] FIG. 2 is a perspective view of one embodiment of a
diagnostic system of the present invention with the swab and test
unit shown separately;
[0016] FIG. 3 is a perspective view depicting insertion of a swab
into the test unit shown in FIG. 2;
[0017] FIG. 4 is a perspective view depicting rotation of the test
unit shown in FIG. 2;
[0018] FIG. 5 is a cross-sectional view of the rotated test unit
depicted in FIG. 4; and
[0019] FIG. 6 is a perspective view of an assay that may be
utilized in one embodiment of the present invention.
[0020] Repeat use of reference characters in the present
specification and drawings is intended to represent same or
analogous features or elements of the invention.
DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS
Definitions
[0021] As used herein, the term "analyte" generally refers to a
substance to be detected. For instance, analytes may include
antigenic substances, haptens, antibodies, and combinations
thereof. Analytes include, but are not limited to, toxins, organic
compounds, proteins, peptides, microorganisms, amino acids, nucleic
acids, hormones, steroids, vitamins, drugs (including those
administered for therapeutic purposes as well as those administered
for illicit purposes), drug intermediaries or byproducts, bacteria,
virus particles and metabolites of or antibodies to any of the
above substances. Specific examples of some analytes include
ferritin; creatinine kinase MB (CK-MB); digoxin; phenytoin;
phenobarbitol; carbamazepine; vancomycin; gentamycin; theophylline;
valproic acid; quinidine; luteinizing hormone (LH); follicle
stimulating hormone (FSH); estradiol, progesterone; C-reactive
protein; lipocalins; IgE antibodies; cytokines; vitamin B2
micro-globulin; glycated hemoglobin (Gly. Hb); cortisol; digitoxin;
N-acetylprocainamide (NAPA); procainamide; antibodies to rubella,
such as rubella-IgG and rubella IgM; antibodies to toxoplasmosis,
such as toxoplasmosis IgG (Toxo-IgG) and toxoplasmosis IgM
(Toxo-IgM); testosterone; salicylates; acetaminophen; hepatitis B
virus surface antigen (HBsAg); antibodies to hepatitis B core
antigen, such as anti-hepatitis B core antigen IgG and IgM
(Anti-HBC); human immune deficiency virus 1 and 2 (HIV 1 and 2);
human T-cell leukemia virus 1 and 2 (HTLV); hepatitis B e antigen
(HBeAg); antibodies to hepatitis B e antigen (Anti-HBe); influenza
virus; thyroid stimulating hormone (TSH); thyroxine (T4); total
triiodothyronine (Total T3); free triiodothyronine (Free T3);
carcinoembryoic antigen (CEA); lipoproteins, cholesterol, and
triglycerides; and alpha fetoprotein (AFP). Drugs of abuse and
controlled substances include, but are not intended to be limited
to, amphetamine; methamphetamine; barbiturates, such as
amobarbital, secobarbital, pentobarbital, phenobarbital, and
barbital; benzodiazepines, such as librium and valium;
cannabinoids, such as hashish and marijuana; cocaine; fentanyl;
LSD; methaqualone; opiates, such as heroin, morphine, codeine,
hydromorphone, hydrocodone, methadone, oxycodone, oxymorphone and
opium; phencyclidine; and propoxyhene. Other potential analytes may
be described in U.S. Pat. No. 6,436,651 to Everhart, et al. and
U.S. Pat. No. 4,366,241 to Tom et al.
[0022] As used herein, the term "test sample" generally refers to a
material suspected of containing the analyte. The test sample may
be used directly as obtained from the source or following a
pretreatment to modify the character of the sample. The test sample
may be derived from any biological source, such as a physiological
fluid, including, blood, interstitial fluid, saliva, ocular lens
fluid, cerebral spinal fluid, sweat, urine, milk, ascites fluid,
mucous, synovial fluid, peritoneal fluid, vaginal fluid, amniotic
fluid or the like. The test sample may be pretreated prior to use,
such as preparing plasma from blood, diluting viscous fluids, and
the like. Methods of treatment may involve filtration,
precipitation, dilution, distillation, mixing, concentration,
inactivation of interfering components, and the addition of
reagents. Besides physiological fluids, other liquid samples may be
used such as water, food products and the like for the performance
of environmental or food production assays. In addition, a solid
material suspected of containing the analyte may be used as the
test sample. In some instances it may be beneficial to modify a
solid test sample to form a liquid medium or to release the
analyte.
DETAILED DESCRIPTION
[0023] Reference now will be made in detail to various embodiments
of the invention, one or more examples of which are set forth
below. Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that various modifications and
variations may be made in the present invention without departing
from the scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment, may be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0024] Referring to FIGS. 1-2, for instance, one embodiment of a
diagnostic test system 10 that may be formed according to the
present invention will now be described in more detail. As shown,
the system 10 includes a swab 20 and a detection unit 30 into which
the swab 20 may be inserted. The swab 20 and/or detection unit 30
may optionally be sealed within a package 40. The configuration of
the swab 20 (e.g., shape, size, materials, etc.) may generally vary
as is well known in the art. For example, in the illustrated
embodiment, the swab 20 includes an elongated shaft 22 having a tip
24 of an absorbent material, such as cotton or rayon, at one end.
It should be understood that the tip 24 may also be formed from any
other absorbent material known in the art, and may possess any
desired shape and/or size. Further, any other swab construction, as
well as any other type of test sample collection device, may also
be used in the present invention. For example, other types of test
sample collection devices are described in U.S. Pat. No. 6,541,194
to DiCesare and U.S. Pat. No. 6,548,018 to DiCesare, et al., which
are incorporated herein in their entirety by reference thereto for
all purposes.
[0025] The detection unit 30 is generally of a size and shape to
enable easy manual handling during use. In the illustrated
embodiment, for example, the detection unit 30 is substantially
cylindrical in shape and is formed from at least two components,
i.e., a first component 32 in fluid communication with a second
component 34. The first and second components 32 and 34 may be made
from any of a variety of materials, such as molded or blown
plastic. In addition, the first and second components 32 and 34 may
also have a variety of different shapes and/or sizes. In the
illustrated embodiment, for instance, the first component 32 has a
generally cylindrical shape defined by an enclosure 80 that begins
at a generally circular lower portion 82 and ends at the sample
port 72, wherein the width (e.g., diameter) of the component 32 is
greater at the lower portion 82 than at the port 72. Similarly, the
second component 34 also has a generally cylindrical shape defined
by an enclosure 84 that begins at a generally rectangular upper
portion 86 and ends at the bottom end 88 of the detection unit 30,
wherein the width of the component 34 is greater at the upper
portion 86 than at the bottom end 88. The detection unit 30 has a
length that allows the swab absorbent tip 24 to be fully immersed
in the reagents involved, which may be determined by the amount of
reagent that is required. Example volumes of the reagents are from
about 50 to about 1000 microliters of fluid, with a typical amount
being from about 100 to about 200 microliters.
[0026] The first component 32 defines a hollow insertion chamber 70
into which the swab 20 may be easily inserted via a sample port 72.
The insertion chamber 70 may be provided with a fluid for mixing
with a test sample contained on the swab 20. For example, the fluid
may be a buffer fluid, such as phosphate-buffered saline (PBS)
(e.g., pH of 7.2) or 2-(N-morpholino) ethane sulfonic acid (MES)
(e.g., pH of 5.3). Other types of fluids that may be contained
within the device include detergents, salts, lysing agents (such as
for detection of microbes, e.g., Strep bacteria or yeasts),
blocking agents (e.g., bovine serum albumin), other proteins, and
so forth. Still other optional materials that may be present within
the fluid include labeled microparticles, detection probes, dyes,
electrochemically-active agents (e.g., redox mediators), or other
reagents used to create a signal for detection.
[0027] To inhibit leaking of the fluid from the sample port 72,
various mechanisms may be employed. For example, prior to insertion
of the swab 20, a top or cap may cover the sample port 72. In
addition, the fluid within the insertion chamber 70 may also be
retained within a thin, flexible packet (not shown) that is
relatively resistant to diffusion of the fluid therethrough. The
packet may be formed from a variety of different materials, such as
nonporous films, metallic seals (e.g., aluminum foil), etc. Some
suitable materials used in the fabrication of films for forming the
packet may include thermoplastic polymers, such as polyolefins
(e.g., polyethylene, polypropylene, etc.), including homopolymers,
copolymers, terpolymers and blends thereof; ethylene vinyl acetate;
ethylene ethyl acrylate; ethylene acrylic acid; ethylene methyl
acrylate; ethylene normal butyl acrylate; polyurethane;
poly(ether-ester); poly(amid-ether) block copolymers; and the like.
Other suitable materials may include non-thermoplastic materials,
silicone-based materials, other elastomeric materials, and so
forth. In some embodiments, it is desired to minimize the thickness
of the packet so that a user may easily rupture it with the swab
20. In such instances, the thickness of the packet may be less than
about 0.05 inches, in some embodiments between about 0.0003 inches
to about 0.01 inches, and in some embodiments, between about 0.0007
inches to about 0.02 inches.
[0028] In addition, mechanisms may also be employed to inhibit
fluid leakage from the sample port 72 after insertion of the swab
20 into the insertion chamber 70. For example, as shown in FIG. 2,
the first component 32 may utilize a hydraulic seal, such as
o-rings 33 and 44. As is well known in the art, the o-rings 33 and
44 provide a sealing fit between the outer surface of the swab 20
and the inner surface of the sample port 72. Other known hydraulic
seals, such as t-rings, B-rings, v-rings, etc., may also be used in
the present invention. Using such seals, unwanted leakage from the
sample port 72 may be inhibited.
[0029] As indicated above, the first component 32 is in fluid
communication with a second component 34. In this embodiment, for
example, the first component 32 generally rotates about a vertical
axis A relative to the second component 34. Rotation may be
accomplished manually, or through any well known automated device
known in the art, including well known electronics, timing
circuitry, etc. Due to the relative rotation of the components 32
and 34, a user may easily manipulate the components as desired so
that they are placed in direct engagement. Namely, the detection
unit 30 contains a delivery channel 38 that is also capable of
rotation about a vertical axis A, which is formed integral with or
separate from the first component 32. In the illustrated
embodiment, for example, the delivery channel 38 is connected to
the lower portion 82 of the first component 32.
[0030] When not in use, the first component 32 and delivery channel
38 are positioned so that fluid within the insertion chamber 70
does not flow to a detection chamber 73 of the second component 34,
i.e., inactive position. In one embodiment, for instance, this
prohibitive function is accomplished by a barrier 36, which may
have any suitable size and/or shape, and be formed from any
suitable material known in the art. For example, in one embodiment,
the barrier 36 is formed from a liquid-impermeable polymeric
material. To engage the first component 32 with the second
component 34, the first component 32 is rotated so that the
delivery channel 38 is positioned adjacent to a connection channel
42 of the second component 34, i.e., active position. Consequently,
fluid is capable of flowing from the chamber 70, through the
delivery channel 38 and connection channel 42, and finally into the
detection chamber 73.
[0031] Referring to FIGS. 3-5, the operation of the diagnostic test
system 10 will now be described in more detail. Initially, the tip
24 of the swab 20 is contacted with a test sample suspected of
containing the analyte of interest. Thereafter, as represented by
the directional arrows of FIG. 3, the tip 24 is inserted through
the sample port 72. Upon insertion, the o-rings 33 and 44 form a
fitting seal around the elongated shaft 22 of the swab 20. As
described above, insertion of the tip 24 may also cause a thin,
flexible packet (not shown) within the insertion chamber 70 to
rupture, thereby releasing a fluid retained therein to mix with the
test sample. Once the swab 20 is inserted and optionally allowed to
mix with a fluid within the insertion chamber 70, the first
component 32 may then be placed into engagement with the second
component 34. The engagement of the two components is illustrated
in FIG. 4. Specifically, in this embodiment, the first component 32
is rotated in a counter-clockwise direction so that the delivery
channel 38 is placed into communication with the connection channel
42. In this manner, fluid may flow from the insertion chamber 70
into a detection chamber 73 of the second component 34. Once in the
detection chamber 73, the fluid is allowed to contact an assay 60
for detecting the presence or absence of the analyte of
interest.
[0032] For purposes of illustration only, various examples of an
assay 60 that may be used in conjunction with the diagnostic test
system 10 will now be described in more detail. It should be
understood, however, that other assays are also contemplated by the
present invention. In fact, the present invention is not limited to
any particular assay configuration. In this regard, referring to
FIG. 6, one embodiment of an assay 60 is illustrated that is an
immunoassay. Immunoassays utilize mechanisms of the immune systems,
wherein antibodies are produced in response to the presence of
antigens that are pathogenic or foreign to the organisms. These
antibodies and antigens, i.e., immunoreactants, are capable of
binding with one another, thereby causing a highly specific
reaction mechanism that may be used to determine the presence or
concentration of that particular antigen in a biological
sample.
[0033] In the illustrated embodiment, the assay 60 contains a
porous membrane 63 optionally supported by a rigid material 61. In
general, the porous membrane 63 may be made from any of a variety
of materials through which a fluid is capable of passing. For
example, the materials used to form the porous membrane 63 may
include, but are not limited to, natural, synthetic, or naturally
occurring materials that are synthetically modified, such as
polysaccharides (e.g., cellulose materials such as paper and
cellulose derivatives, such as cellulose acetate and
nitrocellulose); polyether sulfone; polyethylene; nylon;
polyvinylidene fluoride (PVDF); polyester; polypropylene; silica;
inorganic materials, such as deactivated alumina, diatomaceous
earth, MgSO.sub.4, or other inorganic finely divided material
uniformly dispersed in a porous polymer matrix, with polymers such
as vinyl chloride, vinyl chloride-propylene copolymer, and vinyl
chloride-vinyl acetate copolymer; cloth, both naturally occurring
(e.g., cotton) and synthetic (e.g., nylon or rayon); porous gels,
such as silica gel, agarose, dextran, and gelatin; polymeric films,
such as polyacrylamide; and the like. In one particular embodiment,
the porous membrane 63 is formed from nitrocellulose and/or
polyether sulfone materials. It should be understood that the term
"nitrocellulose" refers to nitric acid esters of cellulose, which
may be nitrocellulose alone, or a mixed ester of nitric acid and
other acids, such as aliphatic carboxylic acids having from 1 to 7
carbon atoms.
[0034] The assay 60 may also contain an absorbent pad 68. The
absorbent pad 68 generally receives fluid that has migrated through
the entire porous membrane 63. As is well known in the art, the
absorbent pad 68 may assist in promoting capillary action and fluid
flow through the membrane 63. In some embodiments, the fluid from
the connection channel 42 (see FIGS. 1-5) may first contact a
sample pad (not shown) that is in fluid communication with the
porous membrane 63. Some suitable materials that may be used to
form the sample pad include, but are not limited to,
nitrocellulose, cellulose, porous polyethylene pads, and glass
fiber filter paper. If desired, the sample pad may also contain one
or more assay pretreatment reagents, either diffusively or
non-diffusively attached thereto.
[0035] In the illustrated embodiment, the test sample travels from
the sample pad (not shown) to a conjugate pad 62 that is placed in
communication with one end of the sampling pad. The conjugate pad
62 is formed from a material through which a fluid is capable of
passing. For example, in one embodiment, the conjugate pad 62 is
formed from glass fibers. Although only one conjugate pad 62 is
shown, it should be understood that other conjugate pads may also
be used in the present invention.
[0036] To facilitate detection of the presence or absence of an
analyte within the test sample, various detection probes may be
applied to the conjugate pad 62. While contained on the conjugate
pad 62, these detection probes remain available for binding with
the analyte as it passes from the sampling pad through the
conjugate pad 62 (or optionally in diluent). Upon binding with the
analyte, the detection probes may later serve to identify the
presence or absence of the analyte. The detection probes may be
used for both detection and calibration of the assay 60. In
alternative embodiments, however, separate calibration probes may
be applied to the conjugate pad 62 for use in conjunction with the
detection probes to facilitate simultaneous calibration and
detection, thereby eliminating inaccuracies often created by
conventional assay calibration systems. It should be understood,
however, that the detection probes and/or the calibration probes
may be applied together or separately at any location of the assay
60, and need not be applied to the conjugate pad 62. Further, it
should also be understood that the detection probes and/or the
calibration probes may be applied to the same or different
conjugate pads.
[0037] In some instances, it is desired to modify the detection
probes in some manner so that they are more readily able to bind to
the analyte. In such instances, the detection probes may be
modified with certain specific binding members that are adhered
thereto to form conjugated probes. Specific binding members
generally refer to a member of a specific binding pair, i.e., two
different molecules where one of the molecules chemically and/or
physically binds to the second molecule. For instance,
immunoreactive specific binding members may include antigens,
haptens, aptamers, antibodies (primary or secondary), and complexes
thereof, including those formed by recombinant DNA methods or
peptide synthesis. An antibody may be a monoclonal or polyclonal
antibody, a recombinant protein or a mixture(s) or fragment(s)
thereof, as well as a mixture of an antibody and other specific
binding members. The details of the preparation of such antibodies
and their suitability for use as specific binding members are well
known to those skilled in the art. Other common specific binding
pairs include but are not limited to, biotin and avidin (or
derivatives thereof), biotin and streptavidin, carbohydrates and
lectins, complementary nucleotide sequences (including probe and
capture nucleic acid sequences used in DNA hybridization assays to
detect a target nucleic acid sequence), complementary peptide
sequences including those formed by recombinant methods, effector
and receptor molecules, hormone and hormone binding protein, enzyme
cofactors and enzymes, enzyme inhibitors and enzymes, and so forth.
Furthermore, specific binding pairs may include members that are
analogs of the original specific binding member. For example, a
derivative or fragment of the analyte, i.e., an analyte-analog, may
be used so long as it has at least one epitope in common with the
analyte.
[0038] The specific binding members may generally be attached to
the detection probes using any of a variety of well-known
techniques. For instance, covalent attachment of the specific
binding members to the detection probes (e.g., particles) may be
accomplished using carboxylic, amino, aldehyde, bromoacetyl,
iodoacetyl, thiol, epoxy and other reactive or linking functional
groups, as well as residual free radicals and radical cations,
through which a protein coupling reaction may be accomplished. A
surface functional group may also be incorporated as a
functionalized co-monomer because the surface of the detection
probe may contain a relatively high surface concentration of polar
groups. In addition, although detection probes are often
functionalized after synthesis, in certain cases, such as
poly(thiophenol), the probes are capable of direct covalent linking
with a protein without the need for further modification. Besides
covalent bonding, other attachment techniques, such as physical
adsorption, may also be utilized.
[0039] In one embodiment, for instance, the fluid containing the
test sample travels to the conjugate pad 62, where the analyte
mixes with detection probes modified with a specific binding member
to form analyte complexes. Because the conjugate pad 62 is in fluid
communication with the porous membrane 63, the complexes may
migrate from the conjugate pad 62 to a detection zone 65 present on
the porous membrane 63. The detection zone 65 may contain an
immobilized receptive material that is generally capable of forming
a chemical or physical bond with the analyte and/or complexes
thereof (e.g., complexes of the analyte with the detection probes).
In some embodiments, the receptive material may be a biological
receptive material. Such biological receptive materials are well
known in the art and may include, but are not limited to, antigens,
haptens, antibodies, protein A or G, avidin, streptavidin, and
complexes thereof. In some cases, it is desired that these
biological receptive materials are capable of binding to the
analyte and/or the complexes of the analyte with the detection
probes.
[0040] These receptive materials serve as stationary binding sites
for the detection probe/analyte complexes. In some instances, the
analytes, such as antibodies, antigens, etc., have two binding
sites. Upon reaching the detection zone 65, one of these binding
sites is occupied by the specific binding member of the complexed
probes. However, the free binding site of the analyte may bind to
the immobilized receptive material. Upon being bound to the
immobilized receptive material, the complexed probes form a new
ternary sandwich complex.
[0041] The detection zone 65 may generally provide any number of
distinct detection regions so that a user may better determine the
concentration of a particular analyte within a test sample. Each
region may contain the same receptive materials, or may contain
different receptive materials for capturing multiple analytes. For
example, the detection zone 65 may include two or more distinct
detection regions (e.g., lines, dots, etc.). The detection regions
may be disposed in the form of lines in a direction that is
substantially perpendicular to the flow of the test sample through
the assay 60. Likewise, in some embodiments, the detection regions
may be disposed in the form of lines in a direction that is
substantially parallel to the flow of the test sample through the
assay device.
[0042] Although the detection zone 65 may indicate the presence of
an analyte, it is often difficult to determine the relative
concentration of the analyte within the test sample using solely a
detection zone 65. Thus, the assay 60 may also include a
calibration zone 64. In this embodiment, the calibration zone 64 is
formed on the porous membrane 63 and is positioned downstream from
the detection zone 65. The calibration zone 64 is provided with a
receptive material that is capable of binding to any remaining
uncaptured detection probes and/or calibration probes that pass
through the length of the membrane 63. In particular, upon being
contacted with the test sample, any uncaptured probes that do not
bind to the analyte migrate through the detection zone 65 and enter
the calibration zone 64 of the porous membrane 63. At the
calibration zone 64, these uncaptured probes then bind to the
receptive materials.
[0043] The receptive materials utilized in the calibration zone 64
may be the same or different than the receptive materials used in
the detection zone 65. For instance, in some embodiments, the
receptive material may include a polyelectrolyte that may bind to
the uncaptured probes. The polyelectrolytes may have a net positive
or negative charge, as well as a net charge that is generally
neutral. For instance, some suitable examples of polyelectrolytes
having a net positive charge include, but are not limited to,
polylysine (commercially available from Sigma-Aldrich Chemical Co.,
Inc. of St. Louis, Mo.), polyethylenimine;
epichlorohydrin-functionalized polyamines and/or polyamidoamines,
such as poly(dimethylamine-co-epichlorohydrin);
polydiallyldimethyl-ammonium chloride; cationic cellulose
derivatives, such as cellulose copolymers or cellulose derivatives
grafted with a quaternary ammonium water-soluble monomer; and the
like. In one particular embodiment, CelQuat.RTM. SC-230M or H-100
(available from National Starch & Chemical, Inc.), which are
cellulosic derivatives containing a quaternary ammonium
water-soluble monomer, may be utilized. Moreover, some suitable
examples of polyelectrolytes having a net negative charge include,
but are not limited to, polyacrylic acids, such as
poly(ethylene-co-methacrylic acid, sodium salt), and the like. It
should also be understood that other polyelectrolytes may also be
utilized in the present invention, such as amphiphilic
polyelectrolytes (i.e., having polar and non-polar portions). For
instance, some examples of suitable amphiphilic polyelectrolytes
include, but are not limited to, poly(styryl-b-N-methyl 2-vinyl
pyridinium iodide) and poly(styryl-b-acrylic acid), both of which
are available from Polymer Source, Inc. of Dorval, Canada.
[0044] Similar to the detection zone 65, the calibration zone 64
may also provide any number of distinct calibration regions in any
direction so that a user may better determine the concentration of
a particular analyte within a test sample. The calibration regions
may be pre-loaded on the porous membrane 63 with different amounts
of the binder so that a different signal intensity is generated by
each calibration region upon migration of the uncaptured probes.
The overall amount of receptive material within each calibration
region may be varied by utilizing calibration regions of different
sizes and/or by varying the concentration or volume of the binder
in each calibration region. If desired, an excess of probe
molecules may be employed in the assay 60 so that each calibration
region reaches its full and predetermined potential for signal
intensity. That is, the amount of uncaptured probes that are
deposited upon calibration regions are predetermined because the
amount of the binder employed on the calibration regions is set at
a predetermined and known level. Once captured, the signal of the
probes at the detection and calibration zones 65 and 64 may be
measured visually or through other methods of detection (e.g.,
instruments). When determined visually, for instance, a portion of
the enclosure 84 of the second component 34 may optionally be
provided with a window or other viewing area (not shown) as is well
known in the art so that a user may readily observe the assay
60.
[0045] In some cases, the membrane 63 may also define a control
zone (not shown) that gives a signal to the user that the assay is
performing properly. For instance, the control zone (not shown) may
contain an immobilized receptive material that is generally capable
of forming a chemical and/or physical bond with probes or with the
receptive material immobilized on the probes. Some examples of such
receptive materials include, but are not limited to, antigens,
haptens, antibodies, protein A or G, avidin, streptavidin,
secondary antibodies, and complexes thereof. In addition, it may
also be desired to utilize various non-biological materials for the
control zone receptive material. For instance, in some embodiments,
the control zone receptive material may also include a
polyelectrolyte, such as described above, that may bind to
uncaptured probes. Because the receptive material at the control
zone is only specific for probes, a signal forms regardless of
whether the analyte is present. The control zone may be positioned
at any location along the membrane 63, but is preferably positioned
upstream from the detection zone 65.
[0046] Various formats may be used to test for the presence or
absence of an analyte using the assay 60. For instance, in the
embodiment described above, a "sandwich" format is utilized. Other
examples of such sandwich-type assays are described by U.S. Pat.
No. 4,168,146 to Grubb, et al. and U.S. Pat. No. 4,366,241 to Tom,
et al., which are incorporated herein in their entirety by
reference thereto for all purposes. In addition, other formats,
such as "competitive" formats, may also be utilized. In a
competitive assay, the labeled probe is generally conjugated with a
molecule that is identical to, or an analogue of, the analyte.
Thus, the labeled probe competes with the analyte of interest for
the available receptive material. Competitive assays are typically
used for detection of analytes such as haptens, each hapten being
monovalent and capable of binding only one antibody molecule.
Examples of competitive immunoassay devices are described in U.S.
Pat. No. 4,235,601 to Deutsch, et al., U.S. Pat. No. 4,442,204 to
Liotta, and U.S. Pat. No. 5,208,535 to Buechler, et al., which are
incorporated herein in their entirety by reference thereto for all
purposes. Various other device configurations and/or assay formats
are also described in U.S. Pat. No. 5,395,754 to Lambotte, et al.;
U.S. Pat. No. 5,670,381 to Jou, et al.; and U.S. Pat. No. 6,194,220
to Malick, et al., which are incorporated herein in their entirety
by reference thereto for all purposes.
[0047] In addition, it should be understood that any known
detection technique may be utilized in the present invention. For
example, as is well known in the art, the assay 60 may also be an
electrochemical affinity assay, which detects an electrochemical
reaction between an analyte (or complex thereof) and a capture
ligand on an electrode strip. For example, various electrochemical
assays are described in U.S. Pat. No. 5,508,171 to Walling, et al.;
U.S. Pat. No. 5,534,132 to Vreeke, et al; U.S. Pat. No. 6,241,863
to Monbouquette; U.S. Pat. No. 6,270,637 to Crismore, et al.; U.S.
Pat. No. 6,281,006 to Heller, et al.; and U.S. Pat. No. 6,461,496
to Feldman, et al., which are incorporated herein in their entirety
by reference thereto for all purposes.
[0048] It has been discovered that the system of the present
invention provides a relatively simple, compact and cost-efficient
device for facilitated collecting and substantially immediate
on-site testing of analytes. The system enables quick and easy
specimen collection with a swab, followed by prompt placement of
the collected specimen into a test unit that is substantially
closed and sealed to minimize risk of direct personnel contact with
the collected organism. Thereafter, the test unit may be
manipulated to analyze the collected specimen and provide a visible
test result. This visible test result may be readily observed by
the person performing the test in a prompt manner and under test
conditions conducive to highly reliable and consistent test
results. After initial specimen collection, human contact with the
specimen is thus substantially precluded throughout the test
protocol, and the entire device with the collected specimen safely
contained therein may be discarded as a unit when the test is
concluded.
[0049] While the invention has been described in detail with
respect to the specific embodiments thereof, it will be appreciated
that those skilled in the art, upon attaining an understanding of
the foregoing, may readily conceive of alterations to, variations
of, and equivalents to these embodiments. Accordingly, the scope of
the present invention should be assessed as that of the appended
claims and any equivalents thereto.
* * * * *