WO1992016842A1

WO1992016842A1 - Saliva testing and fingerprint identification method and device

Info

Publication number: WO1992016842A1
Application number: PCT/US1992/001793
Authority: WO
Inventors: Raouf A. Guirguis
Original assignee: La Mina Ltd.
Priority date: 1991-03-12
Filing date: 1992-03-12
Publication date: 1992-10-01
Also published as: EP0637383A1; EP0637383A4; CA2062900A1; AU1589092A

Abstract

A method and device for testing for the presence of substances such as drugs in the saliva of a test subject while simultaneously positively identifying the test subject comprising obtaining a saliva sample on a swab (20), adding labelled antibodies to the swab, covering the finger of the test subject with the mixture of saliva and labelled antibodies and pressing the finger onto the membrane of the test device. The device comprises a membrane (38) containing a plurality of separated areas provided with different immobilized antibodies, each of the antibodies having a specific binding site for specific antigens which correspond to the substances to indicate the presence of those substances in the saliva sample. The device further comprises a base area without immobilized antibodies to record the fingerprint of the test subject.

Description

SALIVA TESTING AND FINGERPRINT IDENTIFICATION METHOD AND DEVICE

BACKGROUND OF INVENTION

The present invention is directed to an individual testing method and device and more specifically to a method and device for detecting the presence of specific antigens or specific antibodies produced by drugs in a biological fluid such as saliva and using the device to also positively identify the individual tested by reproducing the fingerprint of the person being tested. Previously drug testing has been accomplished by testing individual fluid samples such as urine or blood to determine the presence of drugs in the body. Such testing procedures are very common in the athletic world, prisons, courts of law, and in the general workplace and are many times proscribed by contracts between the individual and his/her employer or labor union which represents the individual or group. A problem which has occurred during such testing is that test fluids are obtained from persons other than the person to be tested or that test fluids become mixed, lost, or cannot be specifically identified with that person after the test comes back with positive results. Another problem is that the time for testing is generally too long to obtain results which are timely.

Saliva is a transcellular fluid produced by several paired salivary glands, particularly the parotid, the submaxillary, the sublingual glands and some other small glands.

The present invention attempts to overcome the problems which are inherit in the prior art through the use of a specifically designed fingerprint pad device which tests for the presence of drugs or other specified agents in the saliva as well as providing a fingerprint of the person giving the test so that positive identification of the fluid donor is irrefutably obtained. It is known that there is a correlation between cocaine levels in blood and levels of cocaine in saliva (Vol. 11, Journal of Analytical Toxicology, p. 36, January/February 1987) and that cocaine can be found in saliva after cocaine administration in concentrations equal to or greater than those in plasma allowing for the possibility of a relatively noninvasive means of chain detection and monitoring (Vol. 34, Clinical Chemistry, p. 150B, No. 7, 1988). It is also known that detection of cocaine in saliva and urine is successful through the first 24 hours of collection for saliva and 4-5 days for urine (Vol. 13, Journal of Analytical Toxicology, p. 65, March/April 1989.

Furthermore, it has been proposed that morphine and codeine usage can be found in testing human hair long after drug levels in urine, plasma and saliva are not detectable and a comparison of same with drug levels in biofluids is found in Vol. 14, Journal of Analytical Toxicology, p. 1, January/February 1990.

Medium dosages of heroin in the range of 5-10 mg per 70 kg has been found detectable in saliva 1 to 2 hours after use as was dextromethorphan, while morphine has been found detectable for 3 to 4 hours after the last morphine dose. (Vol. 15, Clinical Pharmacology and Therapeutics, p. 579, No. 6, 1974).

A saliva collection device for the quantitative determination of endogenous substances and therapeutic drugs in disclosed in Vol. 37, Clinical Chemistry, pp. 114-115, No. 1, 1991. The saliva is collected in the buccal cavity by a specially designed device comprising an osmotically active substance enclosed in a pouch consisting of a semipermeable membrane to form a disc of about 35 mm diameter.

The family of immunoassays works upon the single principle that is the specific recognition of an antigen by an antibody. The specific antigen detection and quantification requires an antibody which recognizes the uniqueness of an antigen. One unique binding site serves as an identifying marker for that protein.

Thus detection can be direct where the antigen- specific antibody is purified, labelled and used to bind directly to the antigen or indirect where the antigen- specific antibody is unlabelled and need not be purified. In indirect detection the binding to the antigen is detected by a secondary reagent such as labelled anti- immunoglobulin antibodies or labelled protein A. A variation that uses aspects of both the direct and indirect methods modifies the primary antibody by coupling to it a small chemical group such as biotin or dinitrophenol (DNP) so that the modified primary antibody can then be detected by labelled reagents such as a biotin binding protein or haptene-specific antibodies such as an i-DNP antibodies.

Antibodies which are immobilized (irreversibly bound) on a membrane are well known in the art and such antibodies are designed to have binding sites which have high affinity for the epitopes of the antigens carried in the saliva and vice versa. Covalent binding of protein to the membrane surface offers a permanent bond which is irreversible, so that once a protein like an antibody is bound, it will not be desorbed during an assay. The principle of affinity chromatography requires that a successful separation of a biospecific ligand is available and that it can be chemically immobilized to a chromatographic bed material, the matrix. Numbers of methods well known in the art have been used to couple or immobilize the ligand to a variety of activated resins. Examples of immobilization techniques which exhibit variable linkage are those formed by the reaction of the reactive groups on the support with amino, thiol, hydroxyl, and carboxyl groups on the protein ligand. The selection of the ligand is influenced by two factors. First, the ligand should exhibit specific and reversible binding affinity for the substance to be purified and secondly it should have chemically modifiable groups which allow it to be attached to the matrix without destroying its binding activity. (Examples of such are Protein G manufactured by Pharmacia, Hydrazide AvidGel Ax manufactured by BioProbe International, and Actigel-ALD manufactured by Sterogene Bioseparation Inc.)

When a definitive antibody for a given antigen is available, it is used to identify the antigen in the sample mixture. Once the antibody combines with the antigen, a means is needed to recognize the complex. This has been accomplished in the past by providing a labelled antibody, such as an enzyme, enzyme link immunosorbent (ELISA) -type assay so that the site is incubated with a chromogenic substrate and a color is developed whose intensity is proportional to the enzyme label present.

It is known in the prior art to use membranes in immunoassay testing and also to use such membranes in connection with an absorbent pad to permit the creation of a self-contained package, which is easily disposable.(American Clinical Products Review, June 1987). Such membrane structures have been developed by Millipore Corp. and other manufacturers. Various problems have occurred with the use of such membranes which are primarily used in strip testing due to different plastics which have been used and the degradation for absorption of the protein from the affinity membrane.

It is therefore desirable to provide an easy to handle disposable testing pad which holds a saliva sample taken from under the tongue of the test patient with the saliva then being finger pressed on a membrane substrate having a specific immobilized antibody or antigen bed to capture a concentrated amount of specified antigen or labelled antibody from the saliva while simultaneously providing the fingerprint indentation of the user to be recorded for positive identification. BRIEF SUMMARY OF THE INVENTION

The invention is directed toward a saliva antigen collection device for testing and identification. The device is in the form of a support member with an absorbent section having a permeable membrane test pad mounted thereon which is coded with specific antibodies. The membrane bed antibodies capture specific antigens carried by the saliva to determine the presence in the body of specific drugs or substances. It is, of course, apparent that antigens and antibodies can be switched and either immobilized to capture the other.

It is an object of the invention to collect antigen and/or antibodies from saliva samples removed from the body for testing and simultaneously use the fingerprint pattern obtained from pressing the finger of the test subject against the saliva coated pad to positively identify the donor of the sample. Previously such testing has been accomplished by a series of tests which may involve shifting of the fluid being tested to different containers and removal of the fluid from the person being tested to a place distant from the person which allows fluid misplacement and substitution and questions as to the chain of title of the tested fluid.

It is also an object of the invention to segregate various areas of the pad and provide specific immobilized antibodies which react to specific drugs or substances on different predetermined separated areas so that a multiple drug test can be given to the test subject with one fingerprinting using the test subject's saliva.

In the accompanying drawings there is shown an illustrated embodiment of the invention from which these and other objectives, novel features and advantages will be readily apparent.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic exploded view of the test kit components of the invention; Figure 2 is a schematic view of a swab being placed under the tongue of the user;

Figure 3 is a schematic view of the saliva soaked swab being placed on the support member of the invention;

Figure 4 is a schematic view of the saliva soaked swab placed on the support member and solution carrying labelled antibodies being added to the swab;

Figure 5 is a schematic view of the finger of the test subject engaging the swab so that the finger is covered with a thin film of mixed saliva and solution complex before touching the testing pad;

Figure 6 is a schematic view of the solution complex covered finger of Figure 5 pressed against the test pad;

Figure 7 is a top plan view of the finger pad surface shown in Figure 1 having the capacity to test for multiple drugs used with the present invention;

Figure 8 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing a negative test;

Figure 9 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing bad reagents;

Figure 10 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing cocaine positive test results;

Figure 11 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing opiates positive test results;

Figure 12 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing PCP positive test results;

Figure 13 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing THC positive test results; Figure 14 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing methamphetamine positive test results; and

Figure 15 is a top plan view of the surface of the pad of Figure 7 after a fingerprint has developed on the surface showing alcohol positive test results.

DETAILED DESCRIPTION OF THE DRAWINGS

The preferred embodiment and best mode of the invention is shown in Figures 1-15. In the invention, a swab 20 is removed from a sterile swab package 22 which is packaged with or attached to support member 30. The swab is is placed under the tongue 101 of the test subject 100 to obtain a saliva specimen as is shown in Figure 2. The swab after it is soaked with saliva is then placed in an incubation channel 31 and basin 32 cut in support member 30. The support member 30 has an absorbent section 34 which includes an absorbent pad 36 upon which is mounted a membrane 38 impregnated with specified antibody or antigen which will capture specific antigen or antibodies produced in the human body by a drug, biological agent or substance which has been taken by the individual. The swab 20 and subsequently membrane 38 is then incubated with a chromogenic substrate solution 40 as shown carried in bottle 42 and a color fingerprint 44 is developed whose intensity is proportional to the enzyme present. The addition of the chromogenic substrate to the saliva soaked swab eliminates the need to add another liquid to develop the color on the membrane surface. Thus when the membrane 38 is incubated with a chromogenic substrate pressed into it by the coated finger a reverse fingerprint will be developed by the deposit of colloidal gold particles.

Many of commonly used substrates for binding antibodies or enzymes are large and/or have a large number of charged groups. A secondary antibody is premixed in the solution added to the saliva and complexes with the antigen in the saliva prior to applying the fingertip to the membrane to produce the fingerprint. This secondary antibody is provided with microsome labelling which colors the fingerprint in negative or reverse order of a normal print in that the valleys contain a majority of colloidal particles. The enzyme in the conjugate serves as an indicator that upon reaction with substrate demonstrates the presence of unknown in the sample. The chromogenic substrate provides a detection for the conjugate enzyme and the color produced is proportional to the amount of the unknown in the sample.

The preferred substrate used in the present invention is that of colloidal gold. Gold is biologically inert and has very good charge distribution. It is now becoming widely available in many useful forms. Its detection can be enhanced using several silver deposition methods available commercially. Colloidal gold also can be detected easily in electron microscopy applications and can be prepared in discrete and uniform size ranges, permitting double-labelling experiments. Several commercial companies have introduced silver enhancement kits that do not require using a darkroom, permitting development to be monitored under the microscope or by the naked eye. Colloidal gold particles bind tightly but not covalently to proteins at pH values around the protein's pi. Colloidal gold particles conjugated with a wide range of anti-immunoglobulin antibodies, protein A or streptavidin are available commercially. Because some of the bound protein may slowly dissociate from the gold particles, the colloid can be washed if desired before use to remove free protein.

Gold labels give higher resolution than enzyme- based methods and avoid the problems of substrate preparation and endogenous enzyme activity. Until recently the gold labels lacked sensitivity at the level of light microscopy, but the recent development of the photochemical silver method of amplification has overcome this problem.

With the silver enhancement method, the gold particles become coated in metallic silver and yield a black-brown label, best visualized by bright-field optics. Gold labelling methods are compatible with many histoche ical strains. Gold labelling reactions are very readily controlled, as the appearance of staining can be monitored directly and continuously under the microscope or with the naked eye.

The membrane 38 which is preferably of latex has a surface 50 which as shown in Figure 7 is divided up into separate segment test areas which are provided immobilized ligands such as antibodies or antigens which attach to predetermined labelled ligands carrying specific substances. The test segment areas are shown reacting or holding cocaine molecules 51, opiates 52, PCP 53, THC 54, methamphetamine 55 and alcohol 56 although other substances can be substituted. Presence of one or more of the aforenoted drugs or predetermined substance in the saliva provides the corresponding segment with a negative no color or inhibition assay. A control center 57 and outer ring 58 are provided to provide backup accuracy. The central control area is porous to prevent fluid entrapment on the surface of the membrane.

A chromogenic substrate provides a sensitive detection method for the enzyme. The following tables I and II set forth chromogenic substrates yielding water- insoluble products and water-soluble products that can be used in the invention in place of the colloidal gold substrate previously noted. TABLE I Chroao enic Substrates Yieldin Water-Insoluble Products

B-GalactosidaseNaphthol AS-BI-B- NABG Clear Red d-galactopyrano- side

SABLE II Chroao enic Substrates Yieldin Water-Soluble Products

B-GalactosidaseO-Nitrophenyl-B- ONPG Clear Yellow d-galactophyran- oside Generally, the color produced is proportional to the amount of unknown in the sample, providing the unknown is the limiting component of the system. The BCIP,NBT Phosphates Substrate System generates a dark purple stain on membrane sites bearing phosphatose. Alkaline phosphatase catalyze the dephosphorylation of 5-bromo-4- chloro-3 indolyl phosphate which initiates a reaction cascade resulting in intense color formation.

Binding of an antibody can be detected by a variety of reagent systems as is the case for antigen bound to the antibodies of the membrane. For instance, I- labelled antimouse immunoglobulin or I-labelled protein A may be used. Antimouse immunoglobulin conjugated directly to alkaline phosphatase or to peroxidase may be used, together with appropriate chromogenic substrates. The biotin-avidin peroxidase system together with appropriate chromogenic substrates. The biotin-avidin peroxidase system (for example, the Vectaβtain ABC system supplied by Vector Laboratories) is particularly sensitive.

The solid phase membranes eliminate handling, allow the product configuration to be cut in the desired shape or format for placement on a base, and provides faster kinetics and increased protein binding. Protein binding to solid plastic substrates has been found to be a non-stoichiometric process and varies greatly by the type of plastic used. Binding is not specific and generally occurs through electrostatic and hydrophobic interreactions between plastic and proteins. Membrane substrates overcome many of the problems inherent in solid phase immunoassays as they combine the qualities of a solid substrate with a range of expanded capabilities and, due to their porosity and consequential large surface area, have a high protein binding capacity. A protein binding capacity is increased by using smaller pore sized membranes whose total binding surface increases for an equivalent frontal surface. Membranes which can be used in the present invention in addition to the noted latex can be constructed of nitrocellulose, nylon, cellulose or IAM produced by Millipore Inc. The choice of adsorbing matrix depends on the physical properties such as sensitivity, binding capacity, stability or bound molecules and compatibility with the assay system.

The preferred membrane used is polystyrene latex because the fingerprint color is retained. In adsorption of protein to polystyrene latex, the reaction tube is prepared with 25 mg of washed latex, 1.0 mg/ml antibody and lOmM Tris Buffer, pH 7.8 Q.S. to 2.0 ml total volume. The reaction tube is incubated for 2 hours at 37°C with rotation. The tube is then (a) spun at 2,000-4,000 XG (depending on size of latex) to remove unbound antibody and (b) the beads are resuspended in 3.0 ml of deionized water and the latex is washed three times repeating steps (a) and (b) above and the washed latex is resuspended in 500 ul of PBS (pH 7.4) plus 1.0% BSA plus 4% sucrose and .05% azide, and the sonicate is bathed if necessary to disperse the latex. Membranes, such as nylon and cellulose, can be modified to create surface sites for covalent binding of proteins. Nitrocellulose is one of the most commonly used membranes due to it's high affinity for proteins and cellular macromolecules. In IAM, polyvinylidenedifluoride (PVDF), the base polymer of IAM is hydrophobic and binds proteins. IAM permits a high degree of control over the extent of protein binding and the user can reproducibly immobilize nanogram to microgram quantities of protein on the surface to suit various assay requirements. Binding the protein to IAM surfaces occurs primarily though the epsilon amino group of lysine, which contrasts the binding proteins to nitrocellulose, nylon or plastic where the bonding is ionic or hydrophobic.

Another type of membrane which can be used in the invention which has previously been noted is nitrocellulose which provides an excellent matrix for blotting proteins and nucleic acids. The nitrocellulose may be cut into whatever shape is required and has the useful characteristic that the amount of protein in a fingerprint will be clearly visible. Pure nitrocellulose adsorbs proteins, nucleic acids and other cellular antigens. These adsorbed substances often retain antigen- antibody binding activity and can be visualized using ultrasensitive, enzyme amplified immunostaining methods so that a chromogenic stain marks the location of the adsorbed materials. This approach uses a technique called Dot ELISA, (which also can be utilized with the Nylon, IAM, plastic membranes) whereby nanogram amounts of protein are directly applied to nitrocellulose. One important advantage of Dot ELISA is the ability to perform multiple enzyme immunoassays in a single test procedure using as little as one microliter of antigen or capture antibody solution. Nanogram amounts of capture antibodies dotted onto a single membrane can be used to screen simultaneously for a variety of antigens. In a Dot ELISA procedure the reactant is diluted in coating^' solution and dotted onto the damp membrane. While the optimal concentration will vary from reactant to reactant, for complex antigens 0.1 - 1.0 mg/ml is suitable. Following membrane blotting excess binding sites are blocked by thoroughly soaking both sides of the membrane in Diluent/Blocking Solution. Any of a variety of reservoirs can be used. The Diluent/Blocking Solution contains 1% bovine serum albumin (BSA) in phosphate buffered saline which protects adsorbed protein from surface denaturation. Following the blocking step, membranes can be stored dry at refrigeration temperatures for several months without loss of activity. The adsorption of an antigen or capture antibody onto the nitrocellulose membrane can be accomplished by Antigen Detection ELISA, which is the simplest method for detection of antigen. Indirect Antibody ELISA which is capable of detecting either antibody or antigen, depending on which is defined as the unknown or Antibody Sandwich ELISA which is accomplished by adsorption of an antigen or capture antibody, washing each reagent of any free or unattached reactant and adding another reagent to build step by step a molecular sandwich on the membrane surface which is completed by the addition of an enzyme-antibody conjugate. The construction of such membrane surfaces is clearly shown by a bulletin of Kirkegaard & Perry Laboratories, Inc. 1985 entitled ELISAmate (TM) Enzymne Immunoassay Test System for Detection of Antigens or Antibodies on Membranes which is incorporated in this application by reference.

In operation of the test device, a swab 20 is removed from its sterile pack 22 which may be attached to or included with the test kit. The swab 20 is placed under the tongue 101 of the test subject 100 for one minute. The swab 20 is placed in the incubation channel 31 and basin 32 which forms the swab holder of the support member 30. Three drops of solution 40 provided with a microsome gold label or silver treated gold label are added to the saliva swab and one minute is allowed for absorption and mixing. The index finger 110 or thumb of the test subject is pressed against the swab in its swab holder as shown in Figure 5 for 10 seconds and the finger or thumb is lifted off the swab and immediately pressed and held on the test pad 36 for 30 seconds. The finger or thumb is lifted off the test pad and after two minutes the result is read on membrane surface 50.

In the foregoing description, the invention has been described with reference to a particular preferred embodiment, although it is to be understood that specific details shown are merely illustrative and the invention may be carried out in other ways without departing from the true spirit and scope of the following claims:

Claims

WHAT IS CLAIMED IS;

1. A device for testing for the presence of substances in humans and identifying specifically the human tested with a saliva sample taken from the human being; comprising a support member, swab holder means formed in said support member, a membrane means mounted to said support member, said membrane means being constructed to contain immobilized antibodies having a specific receptor site for antigens produced in the saliva by at least one predetermined substance which captures antigen in direct proportion to the concentration of the substance in the saliva sample placed on the membrane and present a fingerprint of the human tested.

2. A device as claimed in claim 1 wherein said substance is a drug.

3. A device as claimed in claim 2 wherein said drug is cocaine.

4. A device as claimed in claim 2 wherein said drug is PCP.

5. A device as claimed in claim 2 wherein said drug is THC.

6. A device as claimed in claim 2 wherein said drug is methamphetamine.

7. A device as claimed in claim 2 wherein said drug is alcohol.

8. A device as claimed in claim 2 wherein said drugs are opiates.

9. A device as claimed in claim 1 wherein said membrane means is a plastic membrane which retains a negative fingerprint imprint on its surface.

10. A device as claimed in claim 1 wherein said membrane means is a membrane which is provided with a plurality of different sector areas, each of which contains immobilized antibodies which attach to different predetermined substances to present an inhibition assay for each predetermined substance in the saliva sample while retaining a fingerprint imprint on its surface.

11. A device for testing for the presence of different drugs in humans and identifying specifically the human test subject through the use of the human test subject's saliva comprising a support member with an absorbent pad section and a swab holder means, a membrane mounted to said absorbent pad section, said membrane being provided with a plurality of separated areas, each area being provided with different immobilized antibody, each antibody having a specific receptor site for specific antigens produced by different predetermined drugs.

12. A device for testing for the presence of different drugs in human beings and identifying specifically the human being through the use of saliva as claimed in claim 11 wherein said swab holder means comprises a channel and basin formed in said support member to hold and incubate a swab.

13. A device for testing for the presence of different drugs in human beings and identifying specifically the human being through the use of saliva as claimed in claim 11 including a swab removably mounted to said support member.

14. A method for testing for substances in the saliva of a test subject while simultaneously positively identifying the test subject comprising the steps of: (a) obtaining a quantity of saliva of a test subject in an absorbent holder; (b) adding a solution containing labelled antibodies against specific substance molecules of interest to the saliva to form a saliva solution composite; (c) covering the finger with the saliva solution composite; and (d) placing the finger on a membrane so that saliva composite is deposited from the finger on the membrane to form a fingerprint and identify specific substance molecules of interest contained in the saliva.

15. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 14 wherein said solution antibodies are attached to microspheres which allow visualization of antibody reaction.

16. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 15 wherein said solution antibodies are attached to gold particles microspheres.

17. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 15 wherein said specific substance molecules are at least one drug.

18. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 17 wherein said drug is cocaine.

19. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 17 wherein said drug is PCP.

20. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 17 wherein said drug is THC.

21. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 17 wherein said drug is methamphetamine.

22. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 17 wherein said drug is alcohol.

23. A method for testing for substances in the saliva while simultaneously positively identifying the test subject as claimed in claim 17 wherein said drugs are opiates.

24. A method for testing for drugs in the saliva and positively identifying the test subject 18

comprising the steps of: (a) covering the finger of the test subject with a thin film of saliva taken from the test subject premixed with a labelled antibody solution containing antibodies against specific substance molecules of interest, the antibodies attached to microsome means which present a color; (b) pressing the finger against a membrane mounted on an absorbent pad to deposit saliva antibody solution on the surface of the membrane to form a fingerprint, the membrane being provided with specific ligands which bind predetermined biological ligands produced in response to the substance molecules of interest, said biological ligands being carried in the saliva bringing out a coloration of the test subjects fingerprint and inhibition assay of any specific substance of interest.

25. A method of testing as claimed in claim 24 wherein said saliva is mixed with labelled antibodies having receptor sites for specific antigens produced by the body in reaction to specific drugs.

26. A method of testing as claimed in claim 24 wherein said membrane has receptor sites for specific ligands present in the saliva, the membrane being provided with a specific activated chemical groups which bind predetermined biological ligands, said biological ligands being carried in the saliva.

27. A method of testing as claimed in claim 24 wherein said microsome means are colloidal gold.

28. A method of testing as claimed in claim 24 wherein said microsome means are gold particles coated with silver.