GB2560967A - Technique for developing skin-prints on an absorbent substrate - Google Patents

Technique for developing skin-prints on an absorbent substrate Download PDF

Info

Publication number
GB2560967A
GB2560967A GB1705131.9A GB201705131A GB2560967A GB 2560967 A GB2560967 A GB 2560967A GB 201705131 A GB201705131 A GB 201705131A GB 2560967 A GB2560967 A GB 2560967A
Authority
GB
United Kingdom
Prior art keywords
silver
substrate
skin
containing compound
lateral flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB1705131.9A
Other versions
GB201705131D0 (en
Inventor
J Atkinson Samuel
K Wilson Paul
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Intelligent Fingerprinting Ltd
Original Assignee
Intelligent Fingerprinting Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Intelligent Fingerprinting Ltd filed Critical Intelligent Fingerprinting Ltd
Priority to GB1705131.9A priority Critical patent/GB2560967A/en
Publication of GB201705131D0 publication Critical patent/GB201705131D0/en
Priority to PCT/GB2018/000052 priority patent/WO2018178615A2/en
Publication of GB2560967A publication Critical patent/GB2560967A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54366—Apparatus specially adapted for solid-phase testing
    • G01N33/54386—Analytical elements
    • G01N33/54387—Immunochromatographic test strips
    • G01N33/54388—Immunochromatographic test strips based on lateral flow
    • 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
    • G01N33/558—Immunoassay; Biospecific binding assay; Materials therefor using diffusion or migration of antigen or antibody
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/117—Identification of persons
    • A61B5/1171—Identification of persons based on the shapes or appearances of their bodies or parts thereof
    • A61B5/1172—Identification of persons based on the shapes or appearances of their bodies or parts thereof using fingerprinting
    • 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
    • G01N33/483—Physical analysis of biological material
    • G01N33/487—Physical analysis of biological material of liquid biological material
    • G01N33/48707—Physical analysis of biological material of liquid biological material by electrical means
    • G01N33/48714—Physical analysis of biological material of liquid biological material by electrical means for determining substances foreign to the organism, e.g. drugs or heavy metals
    • 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
    • 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
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54306—Solid-phase reaction mechanisms
    • 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
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54366—Apparatus specially adapted for solid-phase testing
    • G01N33/54386—Analytical elements
    • 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
    • G01N33/94—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving narcotics or drugs or pharmaceuticals, neurotransmitters or associated receptors
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Immunology (AREA)
  • Biomedical Technology (AREA)
  • Molecular Biology (AREA)
  • Chemical & Material Sciences (AREA)
  • Urology & Nephrology (AREA)
  • Hematology (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Biochemistry (AREA)
  • Analytical Chemistry (AREA)
  • Food Science & Technology (AREA)
  • Cell Biology (AREA)
  • Microbiology (AREA)
  • Biotechnology (AREA)
  • Theoretical Computer Science (AREA)
  • Biophysics (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Multimedia (AREA)
  • Human Computer Interaction (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Pharmacology & Pharmacy (AREA)
  • Medical Informatics (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)

Abstract

A method of obtaining an optical image of a skin-print on an absorbent substrate having a skin-print receiving region comprises: depositing a solution of a silver-containing compound having a solubility in water of at least 10 g/l on the skin-print receiving region of the absorbent substrate such that between 25 µg and 300 µg per cm2 of the silver-containing compound is deposited, and allowing the substrate to dry. The method further comprises depositing a skin-print on a skin-print receiving region of the substrate such that sodium chloride and water in the skin-print react with the silver-containing compound to form silver chloride; exposing the substrate to electromagnetic radiation, e.g. UV radiation, such that the silver chloride decomposes to form metallic silver; taking an optical image of the pattern of the metallic silver; and releasing a buffer solution onto the substrate. The buffer solution comprises a counterion for silver, which reacts with the silver-containing compound to form a compound of silver having a solubility in water of less than 1 g/I. The absorbent substrate may form part of a lateral flow immunoassay device 1 that has a skin-print receiving region 42, and analysis region 44.

Description

(71) Applicant(s):
Intelligent Fingerprinting Limited 14-17 Evolution Business Park, Milton Road, Impington, Cambridge, Cambridgeshire, CB24 9NG, United Kingdom (72) Inventor(s):
Samuel J Atkinson Paul K Wilson (56) Documents Cited:
GB 1497791 A WO 2016/012812 A1
WO 2011/008581 A2 (58) Field of Search:
INT CL A61B, B01L, C12Q, G01N, G06K Other: WPI, EPODOC, Patent Fulltext, INSPEC, XPESP, Springer (74) Agent and/or Address for Service:
Boult Wade Tennant LLP
Verulam Gardens, 70 Gray's Inn Road, LONDON, WC1X 8BT, United Kingdom (54) Title of the Invention: Technique for developing skin-prints on an absorbent substrate Abstract Title: Technique for developing skin-prints on an absorbent substrate (57) A method of obtaining an optical image of a skin-print on an absorbent substrate having a skin-print receiving region comprises: depositing a solution of a silver-containing compound having a solubility in water of at least 10 g/l on the skin-print receiving region of the absorbent substrate such that between 25 pg and 300 pg per cm2 of the silver-containing compound is deposited, and allowing the substrate to dry. The method further comprises depositing a skin-print on a skin-print receiving region of the substrate such that sodium chloride and water in the skin-print react with the silver-containing compound to form silver chloride; exposing the substrate to electromagnetic radiation, e.g. UV radiation, such that the silver chloride decomposes to form metallic silver; taking an optical image of the pattern of the metallic silver; and releasing a buffer solution onto the substrate. The buffer solution comprises a counterion for silver, which reacts with the silver-containing compound to form a compound of silver having a solubility in water of less than 1 g/l. The absorbent substrate may form part of a lateral flow immunoassay device 1 that has a skin-print receiving region 42, and analysis region 44.
Figure GB2560967A_D0001
Figure GB2560967A_D0002
Figure GB2560967A_D0003
3/3 <?4 χ
π τ
4$ 46
Figure GB2560967A_D0004
Technique for developing skin-prints on an absorbent substrate
BACKGROUND
An impression left by the friction ridges of human skin, such as the skin of a human finger, contains information regarding the identity of the human. It is widely known that the appearance of the impression of the human finger, known as a fingerprint, is unique to each human and may be used to confirm the identity of the human. The appearance of the impression of the skin of other human body parts may also be unique to each human and so may also be used to confirm the identity of the human. Such impressions of human skin, when not specific to the skin of the human finger, may be called skin-prints.
In addition to the appearance of the impression left by human skin, the impression may contain chemical species which themselves may be detected in order to obtain further information.
For example, when a human intakes a substance (e.g. by ingestion, inhalation or injection) the substance may be metabolised by the human body giving rise to secondary substances known as metabolites. The presence of a particular metabolite can be indicative of a specific intake substance. The intake substance and/or metabolites may be present in sweat and, as such, may be left behind in a skin-print, e.g. a fingerprint. Detection of such metabolites in a skin-print can be used as a non-invasive method of testing for recent lifestyle activity such as (but not limited to) drug use, or compliance with a pharmaceutical or therapeutic treatment regime.
Importantly, the taking of a skin-print is much simpler than obtaining other body fluids such as blood, saliva and urine, and is more feasible in a wider range of situations. Not only this but since the appearance of the skin-print itself provides confirmation of the identity of the person providing the skin-print, there can be greater certainty that the substance or substances in the skin-print are associated with the individual. This is because substitution of a skin-print, particularly a fingerprint, is immediately identifiable from appearance whereas substitution of, for example, urine, is not immediately identifiable from appearance. As such, testing for one or more substances in a skin-print provides a direct link between the one or more substances and the identity of the human providing the skinprint.
The applicant has demonstrated various techniques for analysing skin-prints, including the use of mass spectrometry, for example paper spray mass spectrometry. The applicant has also developed a lateral flow skin-print analysis technique as described in
WO 2016/012812, published 28 January 2016.
In order to confirm the identity of a person providing the skin-print, an image of the skinprint may be obtained. This image may be compared with one or more previously obtained images of skin-prints, which may form part of a database of skin-prints. Absorbent substrates (such as those used in lateral flow and paper spray techniques) may not be as suitable as non-absorbent substrates (such as glass or PET) to conventional optics-based imaging techniques. In order to obtain an image of a skin-print that provides sufficient contrast to enable maximum detail of the features of the skin-print to be observed, it may be appropriate to develop the skin-print in order to increase image contrast.
At the same time, it is vital that any development of the skin-print to enable enhanced optical analysis of the skin-print does not prejudice subsequent analysis of one or more chemical constituents of the skin-print.
STATEMENTS OF INVENTION
Against this background, in a first aspect of the disclosure there is provided method of obtaining an optical image of a skin-print on an absorbent substrate having a skin-print receiving region, the method comprising:
depositing a solution of a silver-containing compound having a solubility in water of at least 10 g/l on the skin-print receiving region of the absorbent substrate such that between 25 pg and 300 pg per cm2 of the silver-containing compound is deposited;
allowing the substrate to dry;
depositing a skin-print on a skin-print receiving region of the substrate such that sodium chloride and water in the skin-print react with the silver-containing compound to form silver chloride;
-3exposing the substrate to electromagnetic radiation such that the silver chloride decomposes to form metallic silver;
taking an optical image of the pattern of the metallic silver;
releasing a buffer solution onto the substrate, wherein the buffer solution comprises a counterion for silver which reacts with the silver-containing compound to form an compound of silver having a solubility in water of less than 1 g/l.
Advantageously, this allows a skin-print to be developed using the silver-containing compound to assist in optical analysis of the skin-print whilst not compromising chemical analytes that might be the subject of a subsequent chemical analysis.
It may be that between 50 pg and 200 pg per cm2 of the silver-containing compound is deposited.
It may be that between 50 pg and 100 pg per cm2 of the silver-containing compound is deposited.
The solution of silver-containing compound may have a solubility in water of at least 100 g/l.
The solution of silver-containing compound may have a solubility in water of at least 1,000 g/l.
The silver-containing compound may comprise one or more of silver nitrate, silver fluoride and silver acetate.
The silver-containing compound may comprise silver nitrate and may have a solubility in water of at least 1,000 g/l.
The silver-containing compound may comprise silver nitrate and may have a solubility in water of at least 2,500 g/l.
The silver-containing compound may be silver nitrate.
-4The absorbent substrate may further comprise a downstream region and a silver trap, wherein the silver trap is situated between the skin-print receiving region and the downstream region and prevents silver compounds from moving from the skin-print receiving region to the downstream region.
The step of depositing may comprise one or more of the following: spraying; dipping; stamping; and roller printing.
The absorbent substrate may comprise one or more of: porous paper, microstructured polymer, and sintered polymer.
The absorbent substrate may be or may forms part of a lateral flow immunoassay substrate.
The downstream region may comprise a conjugate pad and one or more immunoassay result regions.
The electromagnetic radiation may be or may comprise UV radiation.
The substrate may be exposed to UV radiation for between 10 and 120 seconds, preferably between 10 and 60 seconds, more preferably between 20 and 40 seconds, more preferably approximately 30 seconds.
The counterion may be one or more of the following:
acetate; permanganate; sulphate; nitrite; bromate; salicylate; iodate; dichromate;
chromate; carbonate; citrate; phosphate; chloride; stearate; oxide; sulphide; bromide; iodide; cyanide; arsenate; azide; benzoate; oxalate; sulphite; and thiocyanide.
The trap may comprise a chemical trap, the chemical trap optionally comprising glucose.
Alternatively, the trap may comprise an optical trap providing electromagnetic radiation having a maximum wavelength of between 200 nm and 500 nm which causes
-5decomposition of silver compounds resulting from reactions between the counterion for silver and the silver-containing compound.
In a further alternative, the trap may comprise a mechanical trap.
The mechanical trap may comprise one or more of: a small particle filter; and iron wool.
The absorbent substrate may be pre-treated with a surfactant.
The absorbent substrate may be pre-treated with an adhesive.
The absorbent substrate may be pre-treated with one or more of the following: polyvinyl alcohol (PVA); polyethylene glycol (PEG);
PVA/PEG copolymer; polyethylene oxide (PEO); polyoxyethylene (POE);
PEG acrylate;
PEG maleimide;
PEG-COOH (carboxylic acid);
PEG-NH2;
PEG-SH; and polylactic acid.
In a second aspect of the disclosure, there is provided a lateral flow immunoassay substrate comprising a skin-print receiving region, a conjugate pad and one or more immunoassay result regions, wherein the skin-print receiving region comprises 25 pg and 300 pg per cm2 of a silver-containing compound having a solubility in water of at least 10 g/l.
Advantageously, this allows a skin-print to be developed using the silver-containing compound to assist in optical analysis of the skin-print whilst not compromising the lateral
-6flow immunoassay technique that may be used subsequently to test for the presence of one or more analytes.
The skin-print receiving region may comprise between 50 pg and 200 pg per cm2 of the silver-containing compound.
The skin-print receiving region may comprise between 50 pg and 100 pg per cm2 of the silver-containing compound.
The solution of silver-containing compound may have a solubility in water of at least 100 g/l.
The solution of silver-containing compound may have a solubility in water of at least 1,000 g/l.
The solution of the silver-containing compound may comprise one or more of silver nitrate, silver fluoride and silver acetate.
The silver-containing compound may comprise silver nitrate and may have a solubility in water of at least 1,000 g/l.
The silver-containing compound may comprise silver nitrate and may have a solubility in water of at least 2,500 g/l.
The silver-containing compound may be silver nitrate.
The substrate may comprise one or more of: porous paper, microstructured polymer, sintered polymer, single-layer matrix (e.g. GE Healthcare Fusion 5™).
The lateral flow immunoassay substrate may comprise a silver trap situated between the skin-print receiving region and the conjugate pad that prevents or substantially restricts silver compounds from moving from the skin-print receiving region to the conjugate pad.
The trap may comprise a chemical trap, the chemical trap optionally comprising glucose.
-7 The trap may comprise a mechanical trap.
The mechanical trap may comprise one or more of: a small particle filter; and iron wool.
The lateral flow immunoassay substrate may be pre-treated with a surfactant.
The lateral flow immunoassay substrate may be pre-treated with an adhesive.
The lateral flow immunoassay substrate may be pre-treated with one or more of the following:
polyvinyl alcohol (PVA); polyethylene glycol (PEG);
PVA/PEG copolymer; polyethylene oxide (PEO); polyoxyethylene (POE);
PEG acrylate;
PEG maleimide;
PEG-COOH (carboxylic acid);
PEG-NH2;
PEG-SH; and polylactic acid.
The lateral flow immunoassay may comprise a buffer reservoir containing a buffer comprising a counterion for silver which reacts with the silver-containing compound to form an compound of silver having a solubility in water of less than 1 g/l.
The counterion may be or may comprise one or more of the following:
acetate; permanganate; sulphate; nitrite; bromate; salicylate; iodate; dichromate;
chromate; carbonate; citrate; phosphate; chloride; stearate; oxide; sulphide; bromide; iodide; cyanide; arsenate; azide; benzoate; oxalate; sulphite; and thiocyanide.
-8BRIEF DESCRIPTION OF THE DRAWINGS
Specific embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 shows a lateral flow test device that uses the skin-print development technique in accordance with the present disclosure;
Figure 2 shows an exploded view of the lateral flow test device of Figure 1; and
Figure 3 shows the lateral flow immunoassay substrate of Figures 1 and 2 in isolation.
SPECIFIC DESCRIPTION
The technique for developing a skin-print on an absorbent substrate without compromising analytes that may subsequently be tested may be applicable to a lateral flow immunoassay analysis (also known as a lateral flow test).
Figures 1 and 2 show an example of a device 1 for performing a lateral flow immunoassay analysis that is compatible with the skin-print development technique of the present disclosure.
The device comprises a housing 2 and a sample receiving material in the form of a substrate 4 that is located within the housing 2. The housing 2 comprises a body 3 having an upper portion 31 and a lower portion 32. The housing 2 also comprises a solution capsule assembly 50 comprising a solution capsule 5 containing a buffer solution. The housing 2 further comprises a sample window 6 that bounds a skin-print receiving region 42 of the substrate 4. The dimensions of the sample window 6 may be configured to allow receipt of at least a part of an area of a skin-print, such as a fingerprint. The housing 2 further comprises a result window 7 and a shutter 10 that is slidable relative to the body 3.
The solution capsule 5 comprises a frangible enclosing member (not visible in the Figures) of a laminar material comprising a layer of polypropylene and a layer of aluminium allowing release of a buffer solution onto the substrate 4 beneath.
-9The substrate 4, shown in isolation in Figure 3, comprises the skin-print receiving region 42, a solution-receiving region 43 and an analysis region 44. The analysis region 44 comprises a conjugate pad 48, a result line 45 and a control line 46, both of which are located within the result window 7. The conjugate pad 48 is located downstream of the skin-print receiving region 42 and upstream of the result line 45 and control line 46. The analysis region 44 further comprises an absorbent solution sink 47, downstream of the result line 45 and control line 46, which simply acts to soak up fluid that has already passed through the previous parts of the lateral flow test. The solution-receiving region 43 of the substrate 4 may comprise an aperture 435.
The solution receiving region 43 of the substrate 4 is of variable width. In the vicinity of the aperture 435 the solution receiving region 43 is at its narrowest. With distance towards the skin-print receiving region 42, the width of the solution-receiving region 43 increases.
The solution-receiving region 43 may have a portion of constant width and a portion of narrowing width towards the analysis region 44. The analysis region 44 may be of constant width. The width of the absorbent sink 47 may again be wider.
The substrate 4 is of a porous, wicking material. The substrate 4 may be one or more of porous paper, microstructured polymer, sintered polymer, single-layer matrix (e.g. GE Healthcare Fusion 5™).
Further details of the lateral flow technique developed by the applicant may be found in WO 2016/012812, published 28 January 2016.
The technique of the present disclosure for optical development of the skin-print without compromising the lateral flow is now described.
The skin-print receiving region 42 of the substrate 4 comprises between 50 pg and 100 pg per cm2 of a silver-containing compound having a solubility in water of at least 10 g/l, preferably at least 100 g/l, more preferably at least 1,000 g/l. In a preferred embodiment, the silver-containing compound is or comprises silver nitrate having a solubility in water of at least 2,500 g/l.
- 10In one embodiment, the substrate 4 may comprise a silver trap (not shown). The silver trap may comprise a chemical trap or a mechanical trap or a combination of both. The silver trap may be located downstream of the skin-print receiving region 42 of the substrate 4 and upstream of the analysis region 44. The silver trap prevents or substantially restricts silver compounds from moving from the skin-print receiving region 42 to the conjugate pad 48. In an alternative technique, an optical process may be employed to trap the silver onto the skin-print receiving region 42 and thereby prevent it from travelling into the analysis region 44 of the substrate 4.
The lateral flow immunoassay substrate is pre-treated with a surfactant and/or an adhesive which may include one or more of the following:
polyvinyl alcohol (PVA); polyethylene glycol (PEG);
PVA/PEG copolymer; polyethylene oxide (PEO); polyoxyethylene (POE);
PEG acrylate;
PEG maleimide;
PEG-COOH (carboxylic acid):
PEG-NH2;
PEG-SH; and polylactic acid.
The buffer reservoir 5 contains a buffer solution comprising fluid that is suitable not only for the immunoassay analysis (and which may be dependent upon the analyte to be detected by the immunoassay) but also a counterion for silver which reacts with the silver-containing compound to form a compound of silver having a solubility in water of less than 1 g/l. In a preferred embodiment, the counterion may be one or more of the following: acetate; permanganate; sulphate; nitrite; bromate; salicylate; iodate; dichromate; chromate; carbonate; citrate; phosphate; chloride; stearate; oxide; sulphide; bromide; iodide; cyanide; arsenate; azide; benzoate; oxalate; sulphite; and thiocyanide.
The process of using the substrate of a preferred embodiment directed to a lateral flow immunoassay substrate is now described.
- 11 The device 1 is provided to a user in the configuration shown in Figure 1 wherein the shutter does not obscure the sample window 6 that bounds a skin-print receiving region 42 of the substrate 4. The solution capsule 5 is supplied with a precise volume of a buffer solution. A user applies a skin-print (most likely a fingerprint) to the skin-print receiving region 42, perhaps under the guidance of another party.
The shutter 10 may be used to cover the sample window 6 and hence the skin-print receiving region 42 of the substrate 4 for protection between depositing of the skin-print and analysis of the skin-print. This is discussed further in WO 2016/012812.
The process of analysis begins with facilitating a chemical reaction between the skin-print and the silver-containing compound.
In the preferred embodiment where the silver containing compound is silver nitrate, the reaction may constitute the following:
AgNO3(aq) + NaCI(aq) = AgCI(s) + NaNO3(aq)
In this way, the salt (in its aqueous form) in the sweat reacts with the silver nitrate (in its aqueous form) in order to produce silver chloride (in solid form) and sodium nitrate (in aqueous form). In this way, silver chloride is produced in the regions of the substrate where a skin-print is present. Where the sweat deposition is greatest (e.g. on the ridges of the print), the quantity of silver chloride will be greatest. In any regions of substrate where no skin-print is deposited, the reaction will not take place and silver chloride will not be formed. Thus, the location and quantity of silver chloride produced will mirror the pattern of the skin-print.
Exposure to UV light for a period of 30 to 120 seconds to causes development of the image of the skin-print by causing the silver chloride to decompose leaving metallic silver in the pattern of the skin-print. (Alternatively, exposure to broad spectrum visible light for a longer period may be used to cause development of the image of the skin-print.)
This metallic silver pattern of the skin-print that is produced in this way may then be recorded optically using a conventional camera or other optical recording equipment.
- 12 Unreacted silver nitrate (e.g. in areas of the skin-print receiving region 42 where less or no skin-print is present) remains on the skin-print receiving region 42 after this process.
The purpose of the counterion in the buffer is to mitigate the effect this silver nitrate on the subsequent lateral flow immunoassay procedure.
After exposure to the UV light, the buffer capsule 5 is actuated which releases buffer solution onto the solution-receiving region 43 of the substrate 4. The buffer solution is drawn down the substrate from the solution-receiving region 43 to the skin-print receiving region 42. The widening of the substrate 4 with distance away from the source of the solution acts to draw the solution towards the skin-print receiving region 42 since the skinprint receiving region 42 has a greater capacity to absorb solution by virtue of being wider. The solution acts to dissolve chemical species that may be present in the skin-print off the skin-print receiving region 42.
The counterion in the buffer solution is selected to react with silver nitrate in order to produce an insoluble compound such as chloride or phosphate.
Since small particles of the insoluble compound may still travel along the substrate 6 as the buffer flows laterally, a silver trap is provided in order to prevent the silver from proceeding as far as the analysis region of the substrate 4. In this way, silver is prevented from affecting the preferential binding/non-binding processes that are configured in the lateral flow immunoassay to take place in the event that the analyte of interest is present.
The buffer solution, together with the dissolved chemical species (but without the silver), is the drawn further down the substrate 4 towards the analysis region 44. Where the substrate becomes thinner, between the skin-print receiving region 42 and the analysis region 44, the solution becomes concentrated into a smaller area.
If the analyte of interest is present in the skin-print and is dissolved and carried with the solution to the analysis region 44, the analyte will bind with the labelled competitive binding assay in the conjugate pad 48 downstream of the skin-print receiving region 42 but upstream of the result line 45. The labelled competitive binding assay is drawn further down the substrate 4 as the solution is drawn down.
- 13If the labelled competitive binding assay has bound to the analyte (because the analyte is present), when the solution reaches the result line 45 its binding sites will be occupied and it will not bind to the protein-analyte conjugate that is immobilised on the result line 45. Hence, the labelled conjugate will pass through the result line (and the control line) towards the absorbent sink 47.
If, on the other hand, the labelled competitive binding assay has not bound to analyte (because the analyte is not present), when the solution reaches the result line 45 its binding sites will be available to bind with the protein-analyte conjugate that is immobilised on the result line 45. Hence, the labelled conjugate will become visible at the result line.
Whatever happens at the result line, a control assay (also labelled) that is present in the buffer solution will bind with an immobilised conjugate at the control line 46. Hence, the labelled control assay will become visible at the control line 46. This provides a user with confidence that the test has been successful, whether the result line 45 shows a positive or negative result.
Alternatives
While the specific embodiment has been introduced in the context of a lateral flow immunoassay, the skilled person will appreciate that the scope of the disclosure is not so limited. In particular, the technique for using a silver-containing compound in order to develop an image of a skin-print and then use of a counterion to prevent the results of the silver reaction from compromising a chemical analysis of the skin-print is applicable to a wide variety of different analyses. For example, the technique may be applicable to a skinprint analysis technique that uses mass spectrometry.

Claims (40)

  1. CLAIMS:
    1. A method of obtaining an optical image of a skin-print on an absorbent substrate having a skin-print receiving region, the method comprising:
    depositing a solution of a silver-containing compound having a solubility in water of at least 10 g/l on the skin-print receiving region of the absorbent substrate such that between 25 pg and 300 pg per cm2 of the silver-containing compound is deposited;
    allowing the substrate to dry;
    depositing a skin-print on a skin-print receiving region of the substrate such that sodium chloride and water in the skin-print react with the silver-containing compound to form silver chloride;
    exposing the substrate to electromagnetic radiation such that the silver chloride decomposes to form metallic silver;
    taking an optical image of the pattern of the metallic silver;
    releasing a buffer solution onto the substrate, wherein the buffer solution comprises a counterion for silver which reacts with the silver-containing compound to form an compound of silver having a solubility in water of less than 1 g/l.
  2. 2. The method of claim 1 wherein the step of depositing a solution of a silvercontaining compound having a solubility in water of at least 10 g/l on the skin-print receiving region of the absorbent substrate is performed such that between 50 pg and 200 pg per cm2 of the silver-containing compound is deposited.
  3. 3. The method of claim 2 wherein the step of depositing a solution of a silvercontaining compound having a solubility in water of at least 10 g/l on the skin-print receiving region of the absorbent substrate is performed such that between 50 pg and 100 pg per cm2 of the silver-containing compound is deposited.
  4. 4. The method of any preceding claim wherein the solution of silver-containing compound has a solubility in water of at least 100 g/l.
  5. 5. The method of claim 4 wherein the solution of silver-containing compound has a solubility in water of at least 1,000 g/l.
    - 156. The method of any preceding claim wherein the solution of the silver-containing compound comprises one or more of silver nitrate, silver fluoride and silver acetate.
  6. 7. The method of any preceding claim wherein the silver-containing compound comprises silver nitrate and has a solubility in water of at least 1,000 g/l.
  7. 8. The method of claim 7 wherein the silver-containing compound comprises silver nitrate and has a solubility in water of at least 2,500 g/l.
  8. 9. The method of claim 8 wherein the silver-containing compound is silver nitrate.
  9. 10. The method of any preceding claim wherein the absorbent substrate further comprises a downstream region and a silver trap, wherein the silver trap is situated between the skin-print receiving region and the downstream region and prevents silver compounds from moving from the skin-print receiving region to the downstream region.
  10. 11. The method of any preceding claim wherein the step of depositing comprises one or more of the following:
    spraying; dipping; stamping; and roller printing.
  11. 12. The method of any preceding claim wherein the absorbent substrate comprises one or more of: porous paper, microstructured polymer, and sintered polymer.
  12. 13. The method of any preceding claim wherein the absorbent substrate is or forms part of a lateral flow immunoassay substrate.
  13. 14. The method of claim 13 wherein the downstream region comprises a conjugate pad and one or more immunoassay result regions.
  14. 15. The method of any preceding claim wherein the electromagnetic radiation is or comprises UV radiation.
    - 1616. The method of claim 15 wherein the substrate is exposed to UV radiation for between 10 and 120 seconds, preferably between 10 and 60 seconds, more preferably between 20 and 40 seconds, more preferably approximately 30 seconds.
  15. 17. The method of any preceding claim wherein the counterion is one or more of the following:
    acetate; permanganate; sulphate; nitrite; bromate; salicylate; iodate; dichromate; chromate; carbonate; citrate; phosphate; chloride; stearate; oxide; sulphide; bromide; iodide; cyanide; arsenate; azide; benzoate; oxalate; sulphite; and thiocyanide.
  16. 18. The method of any preceding claim wherein the trap comprises a chemical trap, the chemical trap optionally comprising glucose.
  17. 19. The method of any of claims 1 to 17 wherein the trap comprises an optical trap providing electromagnetic radiation having a maximum wavelength of between 200 nm and 500 nm which causes decomposition of silver compounds resulting from reactions between the counterion for silver and the silver-containing compound.
  18. 20. The method of any preceding claim wherein the trap comprises a mechanical trap.
  19. 21. The method of claim 18 wherein the mechanical trap comprises one or more of: a small particle filter; and iron wool.
  20. 22. The method of any preceding claim wherein the absorbent substrate is pre-treated with a surfactant.
  21. 23. The method of any preceding claim wherein the absorbent substrate is pre-treated with an adhesive.
  22. 24. The method of any preceding claim wherein the absorbent substrate is pre-treated with one or more of the following:
    polyvinyl alcohol (PVA); polyethylene glycol (PEG);
    PVA/PEG copolymer;
    - 17polyethylene oxide (PEO); polyoxyethylene (POE);
    PEG acrylate;
    PEG maleimide;
    PEG-COOH (carboxylic acid);
    PEG-NH2;
    PEG-SH; and polylactic acid.
  23. 25. A lateral flow immunoassay substrate comprising a skin-print receiving region, a conjugate pad and one or more immunoassay result regions, wherein the skin-print receiving region comprises between 25 pg and 300 pg per cm2 of a silver-containing compound having a solubility in water of at least 10 g/l.
  24. 26. The lateral flow immunoassay substrate of claim 25 wherein the skin-print receiving region comprises between 50 pg and 200 pg per cm2 of the silver-containing compound.
  25. 27. The lateral flow immunoassay substrate of claim 26 wherein the skin-print receiving region comprises between 50 pg and 100 pg per cm2 of the silver-containing compound.
  26. 28. The lateral flow immunoassay substrate of any of claims 25 to 27 wherein the solution of silver-containing compound has a solubility in water of at least 100 g/l.
  27. 29. The lateral flow immunoassay substrate of any of claims 25 to 27 wherein the solution of silver-containing compound has a solubility in water of at least 1,000 g/l.
  28. 30. The lateral flow immunoassay substrate of any of claims 25 to 29 wherein the solution of the silver-containing compound comprises one or more of silver nitrate, silver fluoride and silver acetate.
  29. 31. The lateral flow immunoassay substrate of any of claims 25 to 30 wherein the silvercontaining compound comprises silver nitrate and has a solubility in water of at least
    1,000 g/l.
    - 1832. The lateral flow immunoassay substrate of claim 31 wherein the silver-containing compound comprises silver nitrate and has a solubility in water of at least 2,500 g/l.
  30. 33. The lateral flow immunoassay substrate of claim 32 wherein the silver-containing compound is silver nitrate.
  31. 34. The lateral flow immunoassay substrate of any of claims 25 to 33 wherein the substrate comprises one or more of: porous paper, microstructured polymer, sintered polymer, single-layer matrix (e.g. GE Healthcare Fusion 5™).
  32. 35. The lateral flow immunoassay substrate of any of claims 25 to 34 further comprising a silver trap situated between the skin-print receiving region and the conjugate pad that prevents or substantially restricts silver compounds from moving from the skin-print receiving region to the conjugate pad.
  33. 36. The lateral flow immunoassay substrate of claim 35 wherein the trap comprises a chemical trap, the chemical trap optionally comprising glucose.
  34. 37. The lateral flow immunoassay substrate of claim 35 or claim 36 wherein the trap comprises a mechanical trap.
  35. 38. The lateral flow immunoassay substrate of claim 37 wherein the mechanical trap comprises one or more of:
    a small particle filter; and iron wool.
  36. 39. The lateral flow immunoassay substrate of any of claims 25 to 38 wherein the lateral flow immunoassay substrate is pre-treated with a surfactant.
  37. 40. The lateral flow immunoassay substrate of any of claims 25 to 39 wherein the lateral flow immunoassay substrate is pre-treated with an adhesive.
  38. 41. The lateral flow immunoassay substrate of any of claims 25 to 40 wherein the lateral flow immunoassay substrate is pre-treated with one or more of the following:
    polyvinyl alcohol (PVA);
    - 19polyethylene glycol (PEG);
    PVA/PEG copolymer; polyethylene oxide (PEO); polyoxyethylene (POE);
    5 PEG acrylate;
    PEG maleimide;
    PEG-COOH (carboxylic acid);
    PEG-NH2;
    PEG-SH; and
    10 polylactic acid.
  39. 42. A lateral flow immunoassay device comprising the lateral flow immunoassay of any of claims 25 to 41 and a buffer reservoir containing a buffer comprising a counterion for silver which reacts with the silver-containing compound to form an compound of silver
    15 having a solubility in water of less than 1 g/l.
  40. 43. The lateral flow immunoassay device of claim 42 wherein the counterion is or comprises one or more of the following:
    acetate; permanganate; sulphate; nitrite; bromate; salicylate; iodate; dichromate;
    20 chromate; carbonate; citrate; phosphate; chloride; stearate; oxide; sulphide; bromide; iodide; cyanide; arsenate; azide; benzoate; oxalate; sulphite; and thiocyanide.
    Intellectual
    Property
    Office
    Application No: GB1705131.9 Examiner: Gareth Prothero
GB1705131.9A 2017-03-30 2017-03-30 Technique for developing skin-prints on an absorbent substrate Withdrawn GB2560967A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB1705131.9A GB2560967A (en) 2017-03-30 2017-03-30 Technique for developing skin-prints on an absorbent substrate
PCT/GB2018/000052 WO2018178615A2 (en) 2017-03-30 2018-03-27 Technique for developing skin-prints on an absorbent substrate

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1705131.9A GB2560967A (en) 2017-03-30 2017-03-30 Technique for developing skin-prints on an absorbent substrate

Publications (2)

Publication Number Publication Date
GB201705131D0 GB201705131D0 (en) 2017-05-17
GB2560967A true GB2560967A (en) 2018-10-03

Family

ID=58682695

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1705131.9A Withdrawn GB2560967A (en) 2017-03-30 2017-03-30 Technique for developing skin-prints on an absorbent substrate

Country Status (2)

Country Link
GB (1) GB2560967A (en)
WO (1) WO2018178615A2 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1497791A (en) * 1975-07-14 1978-01-12 Secr Defence Fingerprint detection
WO2011008581A2 (en) * 2009-07-13 2011-01-20 Freelance Corporation Devices, methods, and kits for determining analyte concentrations
WO2016012812A1 (en) * 2014-07-24 2016-01-28 Intelligent Fingerprinting Limited Sample analysing device

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5438984A (en) * 1988-09-08 1995-08-08 Sudor Partners Apparatus and method for the collection of analytes on a dermal patch
US5244815A (en) * 1990-01-19 1993-09-14 Lamina Ltd. Fingerprint test pad and method for fingerprinting using particle based immunoassay
ATE419592T1 (en) * 2003-09-11 2009-01-15 Nxp Bv FINGERPRINT RECOGNITION BY USING A SWEEP-TYPE IMAGGER WITH OPTOELECTRONIC SPEED SENSOR
US7879623B2 (en) * 2006-03-31 2011-02-01 Guirguis Raouf A Integrated device for analyte, testing, confirmation, and donor identity verification
US20140072781A1 (en) * 2012-09-12 2014-03-13 Ana Holc Skin print products
GB2535998A (en) * 2015-02-27 2016-09-07 Intelligent Fingerprinting Ltd A device for receiving and analysing a sample

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1497791A (en) * 1975-07-14 1978-01-12 Secr Defence Fingerprint detection
WO2011008581A2 (en) * 2009-07-13 2011-01-20 Freelance Corporation Devices, methods, and kits for determining analyte concentrations
WO2016012812A1 (en) * 2014-07-24 2016-01-28 Intelligent Fingerprinting Limited Sample analysing device

Also Published As

Publication number Publication date
GB201705131D0 (en) 2017-05-17
WO2018178615A3 (en) 2018-11-29
WO2018178615A2 (en) 2018-10-04

Similar Documents

Publication Publication Date Title
US10871486B2 (en) Device and method for performing a diagnostic test
US20070003115A1 (en) Remote diagnostic device for medical testing
Worley et al. Detection of visible and latent fingerprints using micro‐x‐ray fluorescence elemental imaging
CA3053125A1 (en) Qmax assay and applications (ii)
US20130006068A1 (en) Method and apparatus for screening drug offenders
CA2977891C (en) A device for receiving and analysing a sample
JP2018532998A (en) Apparatus and system for analyzing samples, in particular blood, and methods of their use
JP2002519641A (en) Non-invasive transdermal detection of analytes
Yang et al. HIV, syphilis, hepatitis C and risk behaviours among commercial sex male clients in Sichuan province, China
Spinelli et al. Low tenofovir level in urine by a novel immunoassay is associated with seroconversion in a preexposure prophylaxis demonstration project
Gordon et al. Molecular imaging: a novel tool to visualize pathogenesis of infections in situ
Jang et al. On the relevance of cocaine detection in a fingerprint
JP2023522357A (en) Mask-based diagnostic system using exhaled breath condensate
Smith et al. Common interferences in drug testing
Hassan et al. Testing the sensitivity and specificity of the fluorescence microscope (Cyscope®) for malaria diagnosis
Gilkey et al. Physicians’ rhetorical strategies for motivating HPV vaccination
Poulladofonou et al. Wearable electronic finger for date rape drugs screening: from “do-it-yourself” fabrication to self-testing
Jurewicz et al. Exposure to pesticides and childhood cancer risk: has there been any progress in epidemiological studies?
GB2560967A (en) Technique for developing skin-prints on an absorbent substrate
Bedi et al. Evaluation of pesticide residues in human blood samples from Punjab (India)
Trabaris et al. Effects of temperature, surfactants and skin location on the dermal penetration of haloacetonitriles and chloral hydrate
US20110244589A1 (en) In-vivo platelet function test by online bleeding volume measurement
WO2020000598A1 (en) Mercury ion detection product and method and smart phone imaging analysis system
US20220091119A1 (en) Methods for the Diagnosis and Detection of Viral Analytes
US20120288442A1 (en) Nuclear Imaging Method Using Molecular Target Detection Agent for Liver Fibrosis

Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)