LIQUID TESTING SYSTEM, DEVICES, AND METHODS

Abstract

A testing system and test cartridge for analyzing a sample of water from a water source for specific analyte levels. The test cartridge including a membrane filter that captures a target analyte while allowing a labelled conjugate to permeate through the membrane. The conjugate includes an analyte-specific labelled binding reagent to bind with the target analyte for optical detection. The direct membrane interrogation (i.e., on-filter detection), determines analyte levels without elution of the analyte from a filter thereby improving analyte recovering and assay sensitivity.

Claims

1. A method for testing a fluid source for a target analyte using a fluid analyte level assay device, the method comprising: passing a sample of fluid from the fluid source through a filter membrane for the testing; passing a conjugate of labels and analyte-specific binding reagents through the sample-passed filter membrane to bind with a target analyte captured on the filter membrane; and interrogating the sample-passed filter membrane for the labels bound to the target analyte to determine a level of the target analyte in the sample.

2. The method of claim 1, further comprising: loading a test cartridge including the filter membrane.

3. The method of claim 1, further comprising: preparing the sample-passed filter membrane by washing the sample-passed filter membrane with solution.

4. The method of claim 3, wherein preparing the sample-passed filter membrane further comprising: drying of the washed sample-passed filter membrane prior to interrogation.

5. The method of claim 1, wherein the sample is collected from a cooling tower.

6. The method of claim 1, wherein the labels are up-converting nanoparticles.

7. The method of claim 1, wherein determining the level of the target analyte includes exciting the labels and optically detecting the excited labels to determine the level of the target analyte.

8. The method of claim 1, wherein the target analyte is a bacteria or virus.

9. The method of claim 1, wherein the interrogation includes: exciting the labels bound to the target analyte with a laser; and optically detecting a fluorescence of the excited labels.

10. The method of claim 9, further comprising: determining a level of the target analyte based upon an intensity of the optically detected fluorescence of the excited labels.

11. A fluid assay testing device configured to test a sample of fluid from a fluid source for analyte levels, the device comprising: a fluid flow path to provide the sample of fluid to a test cartridge containing a filter membrane, and to provide a conjugate of analyte-specific binding reagents with labels to the test cartridge, wherein the conjugate collects on a filter membrane by specifically binding to a target analyte captured on the filter membrane of the test cartridge, wherein the fluid flow path includes a pump and a valve; a translational base to position a test cartridge for analysis; an excitation mechanism to excite the labels for optical analysis; and an optical detector to detect optical frequencies of the excited labels to determine a target analyte level.

12. The device of claim 11, further comprising: a drying mechanism to dry the sample-passed test cartridge.

13. A fluid analyte testing system configured to test fluids for target analyte levels, the system comprising: a test cartridge, wherein the test cartridge includes a filter membrane to collect the target analyte and one or more labels; and a fluid analyte assay device to filter a sample of fluid from a fluid source through the test cartridge and directly detect the target analyte level based on the labels remaining on a filter membrane of the test cartridge.

14. The system of claim 13, wherein the test cartridge includes a plurality of testing sites to allow a plurality of tests of the fluid source from the same test cartridge.

15. The system of claim 13, wherein the labels are conjugated with analyte-specific binding reagents for reacting to the target analyte, wherein the labels absorb energy to emit light.

16. The system of claim 15, wherein the labels are selected from the group consisting of colorimetric elements, phosphor molecules, and up-converting nanoparticles.

17. The system of claim 13, wherein the assay device includes gated fluidic paths for water, conjugates, or reagents to be filtered through the test cartridge.

18. The system of claim 13, wherein the assay device directly detects the target analyte captured on the filter membrane using an optical reader.

19. The system of claim 13, wherein the fluid analyte testing system is a water testing system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 shows a fluid flow diagram of a testing system in accordance with the invention.

[0018] FIG. 2 shows a system diagram of a testing system with a testing cartridge in accordance with the invention.

[0019] FIG. 3 shows a side view of a testing system using a testing cartridge for water analyte testing in accordance with the invention.

[0020] FIG. 4A shows conjugated labels passed through a filter membrane due to the lack of a target analyte captured on a filter membrane in accordance with the invention.

[0021] FIG. 4B shows a filter membrane with conjugate bound to targeted analytes in accordance with the invention.

[0022] FIG. 4C shows a filter membrane with conjugate bound to targeted analytes during optical analysis in accordance with the invention.

[0023] FIG. 5 shows a filter membrane with conjugate bound to targeted analytes in accordance with the invention.

[0024] FIG. 6A shows a perspective view of a loader/storage of testing cartridges in a testing device in accordance with the invention.

[0025] FIG. 6B shows a top view of testing cartridges in a loader in accordance with the invention.

[0026] FIG. 7 shows a perspective view of a testing device with testing cartridge positioning in accordance with the invention.

[0027] FIG. 8 describes a method of using a testing device in accordance with the invention.

DETAILED DESCRIPTION

[0028] The assays of the invention provide a way to test liquids for target analytes.

[0029] As shown in FIG. 1, a testing system 100 includes fluid flow paths of a testing device 101 configured to accept a testing cartridge 103 to determine analyte levels in a water source. One device 101 includes pumps 105a and 105b and valves 107a-107d configured to be controlled by a processor and regulate flow through the testing system 100. The pumps 105a and 105b may be any type of pump that can accurately provide the fluid needed in the system. In some embodiments, the pumps are peristaltic pumps.

[0030] In one embodiment, the testing device 101 includes containers which provide the water sample, such as from water source 109. Container(s) 111, wash container 113, and waste container 115 with a drain 117 are also included in the device 101. Each container includes different solutions for introduction to the filter membrane. These solutions may include analyte-specific binding reagents (i.e., antibody, nucleic acids, aptamers, nanobodies, streptavidin, avidin, proteins, lipoproteins, lectins, carbohydrates, polypeptide ligands of cellular receptors, polynucleotide probes, drugs, antigens, toxins, and the like) and/or other wash solutions, e.g., a solution or buffer with salt or detergent to prevent the conjugate from sticking to the filter membrane. Each container is connected to a valve which may open or close as each fluid from each container is needed. For example, when a sample is needed from water source 109, valve 107a opens, and the sample of water is collected for testing using pump 105a. Similarly, valve 107b is opened for conjugate in the reagent container 111, and pump 105b may be used to pump a wash from wash container 113 throughout the system 100. Further, valve 107c may be opened to provide fluids to the testing cartridge 103, and valve 107d may be opened to provide direct access to the waste container 115. Waste container 115 may include a drain 117 to easily dump waste from the system.

[0031] As shown in FIGS. 1 and 2, the testing systems 100 include a water source 109 from which a sample is taken. The sample is introduced into the testing systems 100 through a fluidic pathing 201. The fluidic path, including valves and pumps, provide various fluids to testing cartridges 103 and/or waste output 203. The systems 100 provide the water sample to the testing cartridges 103. The water sample and conjugate may be introduced to the membrane filter 207 of the testing cartridges 103. The testing cartridges 103 may be positioned in the assay for analysis 211 to test for the target analyte. Additionally, the testing cartridges 103 may be disposed through a disposable handler 213 and results and notification of disposal provided to users through a communication protocol 215.

[0032] As shown in FIG. 3, the testing systems 100 include providing a wash (e.g., water, wash solution, or other reagent to prevent remaining conjugates from sticking to the membrane filter) through a reagent flow path 301 sealed, with a gasket 303, to the testing cartridges 103 to prevent waste. The testing cartridges 103 include a sealed conjugate packet 305, filter membrane 307, and in some embodiments may include a check valve 309 to create a volume for adsorption, binding, and/or reactions to take place. The conjugate packet 305 (e.g., labelled antibody packet) stores the analyte-specific conjugate in a form and manner that preserves functionality until use (e.g., as a liquid in stabilization buffer, dried or lyophilized), to provide for proper test function and results throughout the shelf-life of the product. The conjugate packet 305 may include a seal for release into the filter membrane 307. The conjugate packet 305 seal is broken with a piston or other piercing mechanism to allow the conjugate to mix with the target analyte for binding. The filter membrane 307 includes pores smaller than the target analyte, but larger than the conjugate. In other embodiments, the conjugate is introduced from a separate reagent container which flows to the testing cartridge 103 through the flow path 301. The bound labels (on the target analyte) may be excited to optically detect analyte levels on the filter membrane 307. The target analyte is collected on the filter membrane prior to introduction of the labelled conjugate. The labelled conjugate reacts/binds to the target analyte remaining on the filter membrane and the amount of remaining conjugate is used to determine the amount of target analyte in the water sample.

[0033] In one embodiment, the labelled conjugate may be bound with the sample-passed filter membrane 307 by mixing of the conjugate with the sample-passed filter membrane. The mixing may be through directing flow of the conjugate forward and reverse through the sample-passed filter membrane multiple times to ensure more binding of the conjugate to the target analyte. For example, E. coli or Legionella pneumophila bacteria in a water sample filtered through the filter membrane 307 may bind to labelled antibodies by repeated mixing with a sufficient amount of the labelled antibodies. The testing cartridges 103 may then be washed with water, wash solution, or other reagent to remove excess conjugate in the filter membrane 307 and to remove other chemicals or biologics which may adulterate the test. The testing cartridges 103 may then be purged of fluids with air.

[0034] In other embodiments, the water samples are provided to the filter membranes 307 through flow paths 301, to filter and collect targeted analytes. The conjugates may be provided by either the packets 305 or the flow paths 301. The target analytes on the filter membranes 307 react to the conjugate, e.g., labelled antibodies bind to the E. coli or Legionella pneumophila bacteria and that are captured by the filter membranes. The filter membranes 307 are then washed to remove any excess conjugate and set to dry for optical analysis.

[0035] In some embodiments, the testing cartridges 103 may then be placed in a dry position to allow drying of the concentrated analytes, e.g., when using up-converting nanoparticles. Drying may aid in optical analysis of the up-converting nanoparticles. In one embodiment, the drying position may include drying mechanisms, such as heaters and fans which do not affect and/or denature the labelled analytes. Once dry, the testing cartridges 103 may be positioned for analysis and disposal. A laser 311 is used to excite the captured labels bound to the analytes and optical analysis through optical detection 313 of the excited nanoparticles provides a concentration level of the target analyte.

[0036] As shown in FIGS. 4A-4C, the optically detectable labels 401 and analyte-specific binding reagents 403, e.g., antibodies are captured on a filter membrane 307 after binding to the target analyte. Those antibodies that do not bind to the target analyte pass through the filter membrane 307. Prior to introduction of the conjugate, when a water sample is introduced if the sample does not contain the targeted analyte, such as in FIG. 4A, the conjugate, e.g., labels 401 with analyte-specific binding reagents 403, have not reacted to a target analyte captured by the filter membrane 307 and simply pass through the filter membrane 307. Washing with a water, wash solution, or reagent further confirms that little to no reaction has occurred between target analyte and the conjugate, since the conjugate is unable to be collected by the filter membrane 307 which includes larger pores than the conjugate.

[0037] In FIG. 4B, the labels 401 and analyte-specific binding reagents 403 bind to a target analyte 409 in the water sample and remain trapped on the filter membrane 307. Additionally, as shown in FIG. 5, in one embodiment, the labels 401 are 0.02 μm, the antibodies are 0.012 μm, the target analyte 409 (i.e., bacterium cell) is 1 μm, and the filter membrane 307 has a pore size of 0.22 μm. As shown, many compounds of the conjugate binds with the captured target analyte. The conjugate is able to pass through the filter if unbound, but when bound to the target analyte, the conjugate remains captured to the filter membrane. With more bacterium, the concentration of labels is greater and thus produce an optically brighter target when excited. Finally, in FIG. 4C, the remaining labels 401 (i.e., the labels bound to target analyte 409) are excited by laser 411 and fluorescence from the labels 401 is captured by an optical detector 413. The optical detector 413 may then detect optical frequencies of the excited labels to determine concentration level of the target analyte directly from the membrane filter (i.e., direct membrane interrogation).

[0038] As shown in FIGS. 6A and 6B, testing cartridges 103, e.g., a puck containing a filter membrane, may include a notch 601 for storage, conjugate packet 305, membrane filter 307, and cone-shaped gasket 605 for mating with fluid paths 301. The notch 601 aids in preventing testing cartridges from tilting and binding to the side of the storage chute 609, i.e., puck loader. The conjugate packet 305, i.e., labelled antibodies, is positioned near a side wall to allow penetration by a piston from the side of the testing cartridge 103 for release of the conjugate into the membrane filter 307. The cone-shaped gasket 605 allows sealed capture of fluids from fluid paths 301.

[0039] As shown in FIG. 7, in one embodiment of the invention, the testing cartridges 103 are moved from position to position by a rotating base 701. The rotating base 701 includes positions for testing cartridge storage drop position 703, fluid path position 705, optional drying position 707, excitation position 709, direct membrane interrogation position 711, and testing cartridge disposal position 713. At each position, the testing device 101 provides various actions which use the testing cartridges 103 to determine analyte levels in the water. A processor of the testing device 101 rotates base 701 to move to the next position in the rotation.

[0040] A method of using the testing device 101 with a testing cartridge 103 is shown in blocks 801-807 of FIG. 8. As described in block 801, the testing device 101, loads a test cartridge into a rotating base for positioning to pass fluids through the testing cartridge. The test cartridge may be dropped from a storage chute into a loaded position on the base. In block 803, the testing device 101 passes a sample of fluid from the fluid source through the filter membrane of the test cartridge. The cartridge may include a filter membrane that is configured to capture the targeted analyte, but allow passage of the conjugate. In block 805, the testing device 101 passes the conjugate of labels 401 and analyte-specific binding reagents 403 through the sample-passed filter membrane to bind with target analyte remaining on the filter membrane. In other words, in one embodiment, the labelled antibodies (i.e., conjugate), binds specifically with the target bacteria remaining on the filter membrane for later interrogation. In block 807, the testing device 101 directly interrogates the filter membrane for the remaining labels to determine a level of the target analyte in the sample. The testing device 101 provides the labels bound to the target analyte on the filter membrane with energy. By exciting the labels using a laser, based on the optical frequency of the excited labels, an optical detector of the testing device 101 may determine a level of target analyte in the sample directly from the membrane filter.

[0041] In one embodiment, the testing device 101 measures the level of Legionella pneumophila cells in tap water by using up-converting nanoparticles conjugated with anti-L. pneumophila antibodies. The water and conjugate are passed through a 25 mm thick PVDF filter membrane with 0.22 μm pores at 30 mL/min. Once the Legionella pneumophila and conjugate are captured on the filter membrane, the filter membrane is washed and may be dried prior to optical analysis.

[0042] The invention addresses design and ease of use difficulties of many previously available water testing systems. The invention provides an economical and easy to use platform when performing tests of water samples for analyte levels.