Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
  • B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
  • B01L3/5023—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures with a sample being transported to, and subsequently stored in an absorbent for analysis
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/5302—Apparatus specially adapted for immunological test procedures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2200/00—Solutions for specific problems relating to chemical or physical laboratory apparatus
  • B01L2200/12—Specific details about manufacturing devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2300/00—Additional constructional details
  • B01L2300/08—Geometry, shape and general structure
  • B01L2300/0809—Geometry, shape and general structure rectangular shaped
  • B01L2300/0825—Test strips
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2300/00—Additional constructional details
  • B01L2300/08—Geometry, shape and general structure
  • B01L2300/0861—Configuration of multiple channels and/or chambers in a single devices
  • B01L2300/087—Multiple sequential chambers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2400/00—Moving or stopping fluids
  • B01L2400/04—Moving fluids with specific forces or mechanical means
  • B01L2400/0403—Moving fluids with specific forces or mechanical means specific forces
  • B01L2400/0406—Moving fluids with specific forces or mechanical means specific forces capillary forces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2400/00—Moving or stopping fluids
  • B01L2400/08—Regulating or influencing the flow resistance
  • B01L2400/084—Passive control of flow resistance
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/25—Chemistry: analytical and immunological testing including sample preparation
  • Y10T436/2575—Volumetric liquid transfer

Definitions

• the invention concerns analytical devices for use in assay procedures.
• the analysis to be carried out in such assay procedures is generally in respect of an analyte in the form of an antigen within a body fluid sample, such as a sample of blood or urine.
• a body fluid sample such as a sample of blood or urine.
• the antigen will first be specifically bound with antibody held at an analytical site.
• a first reagent for example a labelling reagent, is then delivered to the analytical site, followed by a second reagent, for example a label detection reagent to provide a signal for the user.
• the signal may for example be a colorimetric change, the colour or intensity of colour produced providing information for the user.
• first and second liquid flow channels of porous materials lead from a respective pair of channel ends to a common site, the channels being operable to transfer liquid by capillary flow to the common site in sequentially timed manner following simultaneous application of the liquid to the pair of channel ends.
• the first and second reagents are delivered to the analytical site by a liquid, such as a buffer solution. This solubilises and entrains the reagents to carry them onwards and thereby deliver them to the analytical site.
• a liquid such as a buffer solution.
• This speed at which a reagent is carried is dependent on the length of the column of liquid, and a typical relationship may be represented as follows:
• T k L R
• L length of liquid column
• k and n are positive constants specific to the material of the device.
• the first reagent travels considerably faster than the second (see the equation above).
• the second reagent is an enzymic reagent (which is often provided in excess)
• the first reagent is usually involved in an antibody/antigen reaction. For such a reaction it is most important that the time of contact between the reagents, or incubation period, is sufficient. With currently available devices this is not always the case and there is therefore a need to improve the effectiveness of this incubation stage.
• the need to provide a sufficient incubation period is not of course restricted solely to sequential delivery analytical devices featuring two or more reagents, but can arise more generally with liquid transfer analytical devices.
• an analytical device for use in assay procedures, comprising at least one liquid flow channel of porous material leading from a channel end to an analytical site via a localised reagent site, in which channel a flow path is provided to transport liquid which passes from the channel end through the reagent site, wherein a permanent liquid-impermeable barrier is provided adjacent to the reagent site and intercepting said flow path.
• the liquid-impermeable barrier is arranged in such a way that it provides an obstacle to the transport of a reagent from the reagent site and therefore slows the transport of the reagent relative to the overall rate of transport of the liquid.
• the liquid-impermeable barrier is preferably located on the upstream side of the reagent site, but for certain applications may be on the downstream side.
• barrier Different forms of barrier are envisaged, the flow characteristics within the flow channel depending on the form selected.
• the method may also include controlling the form of the relatively stagnant zone by selecting the flow characteristics within the flow channel.
• the device and method according to the invention provide elongation of the flow of solubiused reagent such as to extend the incubation period for the reaction between the reagent and analyte at the analytical site.
• the incubation period can be varied as required by selecting an appropriate form of barrier.
• Figure 2 illustrates the operation of the device of Figure 1 ;
• FIGS 3-6 illustrate further embodiments of the device according to the invention.
• an analytical test strip is represented by reference 1. This is formed from a sheet of porous material appropriate for capillary liquid flow and a material such as that supplied under the trade name MiHipore AP25 is suitable for such application.
• the test strip shown features a single liquid flow channel in which there is an analytical site 2 where an analyte can be immobilised.
• the analyte is, for example, an antigen within a sample of body fluid such as blood or urine.
• the antigen is immobilised by being specifically bound with antibody held at the analytical site.
• the test strip has a reagent site 3 where a reagent is impregnated into a specific zone in the porous material .
• test strip may feature a plurality of channels, a plurality of reagent sites, and/or even a plurality of analytical sites within the same device. Only a single reagent site 3 and a single analytical site 2 are represented in Figure 1 to illustrate the invention. Moreover the test strip need not be of simple sheet form but may be, for example, of multi-layer construction.
• a liquid such as an appropriate buffer solution
• a liquid is introduced to an end of the test strip 1 such that capillary action causes it to flow along the strip in the direction of the arrow 5 in Figure 1.
• the reagent is solubiused and entrained such that it is carried by the channel flow towards the analytical site 2.
• the reaction between the reagent and the antibody-bound antigen takes place. The flow continues washing unbound serum and any other waste material onwards to downstream area 4 which serves as a waste reservoir.
• a further step may then take place wherein a second reagent is carried to the analytical site.
• this sequential delivery of reagents to the analytical site can be realised by a single test strip featuring multiple flow channels determining the relative times of delivery to the analytical site.
• Figure 1 also shows a liquid-impermeable barrier 6 in the form of a rectangular zone, or bar, extending at right angles to the direction of liquid flow and arranged centrally of the strip and immediately upstream of the reagent site 3.
• a liquid-impermeable barrier 6 in the form of a rectangular zone, or bar, extending at right angles to the direction of liquid flow and arranged centrally of the strip and immediately upstream of the reagent site 3.
• the liquid flow approaches the barrier 6 and then separates around its edges, the reagent site being located in the wake of the barrier.
• the result of this is that there is produced a relatively stagnant zone downstream of the barrier.
• the liquid will gradually flow Into this zone to solubilise and entrain the reagent in the direction of the analytical site, but the reagent will be carried at a slower speed than that of the advancing flow front 11 of the liquid and effectively the moving reagent will be elongated as shown by reference 10.
• the reagent site may be directly adjacent or abutting the liquid-impermeable barrier 6, or may be located at a short distance from the barrier, and the separation between the two influences the degree of elongation of the entrained reagent. The closer they are together, the more will be the elongation.
• liquid-impermeable barrier 6 forms an obstruction to the flow of any subsequent reagent carried along the test strip
• the initial liquid flow establishes two streambands, one on either side of the barrier, which rejoin one another beyond the barrier.
• Any solubilised reagent carried along the test strip therefore flows past the relatively stagnant zone and merges again beyond the barrier, without being slowed in the same way as the flow of the first reagent.
• any reagent will flow around the sides of the barrier and rejoin on the other side.
• FIG. 3 shows an alternative embodiment of a device according to the invention.
• the liquid-impermeable barrier takes the form of a shallow 'V 12, the apex of the 'V being directed upstream and the reagent site 3 being located between the arms of the 'V. This has the effect of increasing the elongation of the entrained reagent and can provide an initial wash at the analytical site 2 to remove unfixed material from the site before delivery of the reagent to the site commences. Conversely, an inverted 'V shaped liquid-impermeable barrier reduces elongation and wash.
• a form of barrier as shown in Figure 4 can be used, featuring a rectangular barrier 13 with two 'V-form recesses on the downstream side of the barrier and two reagent sites, one in the hollow of each of the recesses.
• Liquid under capillary action flows around both sides of the barrier and down into the recesses, entraining the reagent and carrying it onwards to the downstream apex 14 between the two 'V-form recesses where the liquid stream bands rejoin one another. Because the liquid flow 15 sweeps through the hollow of the V-form recesses there is no danger of forming an unwanted stagnation region therein.
• barrier shown in Figure 4 is very effective for such a technique, as each of the two 'V-form recesses may contain a different reagent, kept apart on the test strip until the two liquid stream bands respectively entrain the two reagents and bring them together at the point where the liquid stream bands join one another, before the common flow carries the reaction product downstream towards the analytical site 2.
• FIG. 5 illustrates yet another embodiment of a device according to the invention.
• the liquid-impermeable barrier in this case is of triangular form 16 with an apex d-irected downstream and with the reagent site 3 being located on the upstream side of and adjacent to the barrier.
• the flow of the solubilised first reagent is still elongated as it has to take a longer route around the barrier than the advancing front of the liquid flow.
• the triangular form of the barrier encourages the two strea bands on either side to rejoin downstream of the barrier as quickly as possible, both in the case of the solubilised first reagent and in that of subsequently delivered reagents.
• One result of the elongation of the solubilised reagent may be the narrowing of its flowpath. If it narrows such that it becomes narrower than the analytical site the positive result in the case of a subsequent colour change may be indicated by a thin line rather than a comprehensive colour change at the analytical site.
• the width of the flowpath of the reagent may be increased immediately downstream of the reagent site to widen the elongated reagent flow.
• a necked section 17 of the porous channel in the region of or just downstream of the liquid-impermeable barrier may be provided, as shown in Figure 6. The narrowing of the porous channel at this necked section 17 results in a widening elongated reagent flow 18.
• liquid- impermeable barriers other than those described above are possible, the specific design being selected as appropriate to vary the incubation period and generally to influence the flow of the reagent as desired.
• a plurality of liquid-impermeable barriers may also be used.
• the liquid-impermeable barrier may be formed by excision or omission of material as a stage in the manufacturing of the test strip, for example, by stamping.
• an agent, such as wax can be applied to the strip to render it impermeable in the appropriate region.
• the barrier may be physically or chemically etched on to the strip, for example by laser etching techniques.

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• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Immunology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Hematology (AREA)
• Engineering & Computer Science (AREA)
• Molecular Biology (AREA)
• General Health & Medical Sciences (AREA)
• Analytical Chemistry (AREA)
• Urology & Nephrology (AREA)
• Biomedical Technology (AREA)
• Clinical Laboratory Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Food Science & Technology (AREA)
• Physics & Mathematics (AREA)
• Medicinal Chemistry (AREA)
• Biochemistry (AREA)
• Microbiology (AREA)
• General Physics & Mathematics (AREA)
• Pathology (AREA)
• Cell Biology (AREA)
• Biotechnology (AREA)
• Automatic Analysis And Handling Materials Therefor (AREA)
• Spectrometry And Color Measurement (AREA)
• Devices For Use In Laboratory Experiments (AREA)

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Publications (1)

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Citations (4)

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• 1993
  • 1993-03-04 GB GB939304452A patent/GB9304452D0/en active Pending
• 1994
  • 1994-02-23 WO PCT/GB1994/000356 patent/WO1994020215A1/en not_active Ceased
  • 1994-02-23 CA CA002153788A patent/CA2153788A1/en not_active Abandoned
  • 1994-02-23 KR KR1019950703813A patent/KR960700815A/ko not_active Withdrawn
  • 1994-02-23 AU AU61122/94A patent/AU6112294A/en not_active Abandoned
  • 1994-02-23 GB GB9403414A patent/GB2276002B/en not_active Revoked
  • 1994-02-23 JP JP6519689A patent/JPH08507605A/ja active Pending
  • 1994-02-23 CN CN94191369A patent/CN1118998A/zh active Pending
  • 1994-02-23 DE DE69404859T patent/DE69404859T2/de not_active Expired - Fee Related
  • 1994-02-23 US US08/495,539 patent/US5705397A/en not_active Expired - Fee Related
  • 1994-02-23 EP EP94907620A patent/EP0731731B1/en not_active Expired - Lifetime
  • 1994-02-28 TW TW083101688A patent/TW258788B/zh active

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