GB2261949A

GB2261949A - Detection of analyte species in gaseous media

Info

Publication number: GB2261949A
Application number: GB9224898A
Authority: GB
Inventors: Ramadan Arbi Abuknesha; Mark Philip Byfield
Original assignee: GEC Marconi Ltd; Marconi Co Ltd
Current assignee: BAE Systems Electronics Ltd
Priority date: 1991-11-27
Filing date: 1992-11-27
Publication date: 1993-06-02
Also published as: GB9224898D0

Abstract

The present invention relates to the detection of an analyte species. The invention provides, inter alia, apparatus suitable for use in the immunological detection of an analyte species in a gaseous medium, or the detection of a particulate species in a gaseous medium, which apparatus includes means for applying a sample containing analyte species to a carrier means (12) the carrier means being such that, in operation, the sample may be applied to a portion thereof and such that the portion may be presented to a detector (27) for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive analysis of samples for analyte species. The apparatus may also include means (21, 22, 23) for obtaining from the gaseous medium a sample containing analyte species, for application to the carrier. The analyte species may be, for example, an airborne species such as a drug or an environmental pollutant.

Description

Detection The present invention relates to the detection of an analyte species.

According to one aspect of the present invention there is provided an apparatus suitable for use in the immunological detection of an analyte species in a gaseous medium (as hereinafter defined) which apparatus includes a carrier means said carrier means being such that, in operation, a sample may be applied to a portion thereof and such that the portion may be presented to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive immunological analysis of samples for analyte species.

It is to be understood that immunological analysis is analysis which may utilise immunological detection (i.e. detection in which immunological interaction may take place).

According to another aspect of the present invention there is provided an apparatus suitable for use in the detection of a particulate analyte species in a gaseous medium (as hereinafter defined), which apparatus includes a carrier means said carrier means being such that, in operation, a sample may be applied to a portion thereof and such that the portion may be presented to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive analysis of samples for analyte species.

The term "particulate analyte species" as used in this Specification indicates an analyte species which is initially in particulate form and not that the analyte species is necessarily in particulate form when it is subjected to analysis.

Thus, for example, a particulate analyte species may be formed into a sample (e.g. by incorporation into a solvent) suitable for subjecting to analysis.

By way of example, a reagent or reagents may be carried by the carrier means, or a reagent or reagents may be incorporated into a sample before introduction of a sample to the carrier means. Thus, for example1 the apparatus may include means for incorporating a reagent or reagents into a sample before introduction of a sample to the carrier means.

Apparatus in accordance with the present invention optionally may also, for example, include a means for obtaining from the gaseous medium a sample, containing analyte species, for application to the carrier means.

The means for obtaining a sample may be, for example, a means for forming, from the gaseous medium, a liquid sample containing analyte species (e.g. an aqueous solution containing analyte species) for application to the carrier means. For example, the means for forming a liquid sample may comprise means for spraying a solvent (e.g. water) into a flow of gaseous medium thereby to form a sample containing analyte species; by way of further example the means for forming a liquid sample may comprise means for passing gaseous medium through a solvent (e.g. water), for example, by bubbling gaseous medium through the solvent, thereby to form a sample containing analyte species.

From the foregoing disclosure, it will be understood that the present invention embraces, for example, circumstances where a liquid sample is obtained from a gaseous medium and that accordingly "detection of an analyte species in a gaseous medium" and "detection of a particulate analyte species in a gaseous medium" as used in this Specification embraces, inter alia, circumstances where an analyte species from a gaseous medium is formed into a sample suitable for application to the carrier means.

The gaseous medium may be any suitable gaseous medium. The term "gaseous medium" as used in this Specification embraces, for example, a gas as such, a vapour, a mixture of gases, a mixture of vapours, a mixture containing a gas or gases and a vapour or vapours, an aerosol, and any suitable gaseous medium such as a dispersion or suspension of solid particles or liquid droplets in, for example, a gas, a mixture of gases, a vapour or a mixture of vapours or any suitable combination thereof. Thus, for example, the present invention may find application in the detection of analyte species in any suitable gaseous medium. Ambient air or ambient atmosphere are examples of gaseous media.

A gaseous medium may be, for example, a pre-existing gaseous medium such as may be present, for example, in any given environment or location which it is desired to investigate or test for an analyte species.

Alternatively, for example, a gaseous medium may be formed deliberately to facilitate detection in accordance with the present invention.

Thus, for example, the present invention may optionally include means for forming a gaseous medium.

For example, a particulate analyte species may be formed into a gaseous medium by incorporation into a suitable medium. Thus, for example, a dispersing means, which may operate in the manner of a vacuum cleaner, may be employed to disperse a particulate analyte species in a medium (e.g. a gas, a mixture of gases, a vapour, a mixture of vapours or a mixture containing a gas or gases and a vapour or vapours) thereby to form a gaseous medium.

Where a reagent or reagents is/are to be incorporated into the sample before introduction of the sample to the carrier means, apparatus in accordance with the present invention may include means for incorporating a reagent or reagents into the sample.

In an embodiment of the present invention the carrier means may be such that, in operation, the carrier means may be moved relatively to an application means for applying a sample to a portion of the carrier means, and relatively to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive analysis of samples for analyte species.

For example, the carrier means may be such that in operation the carrier means may be moved relatively to an application means for applying a sample to a portion of the carrier means such that the sample may be brought into contact with a reagent or reagents carried by the carrier means, and relatively to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents carried by the carrier means so as to permit successive analysis of samples for analyte species.

According to a further aspect of the present invention there is provided a sensor, suitable for use in the immunological detection of an analyte species in a gaseous medium (as hereinbefore defined), comprising a carrier means, application means for applying a sample, which may contain analyte species, to a portion of the carrier means, and detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents, the arrangement being such that, in operation, the carrier means may be moved relatively to the application means and to the detection means to permit successive immunological analysis of samples for analyte species.

According to yet a further aspect of the present invention there is provided a sensor, suitable for use in the detection of a particulate analyte species in a gaseous medium (as hereinbefore defined), comprising a carrier means, application means for applying a sample, which may contain analyte species, to a portion of the carrier means, and detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents, the arrangement being such that, in operation, the carrier means may be moved relatively to the application means and to the detection means to permit successive analysis of samples for analyte species.

As hereinbefore disclosed, a reagent or reagents may, for example, be carried by the carrier means or a reagent or reagents may be incorporated into the sample before introduction of the sample to the carrier means.

Thus, for example, the sensor may include a means for incorporating a reagent, or reagents, into a sample before introduction of the sample to the carrier means.

A sensor in accordance with the present invention optionally may, for example, include a means for obtaining from a gaseous medium, a sample containing analyte species.

A sensor in accordance with the present invention optionally may also, for example, include means for forming a gaseous medium.

In accordance with the present invention, the successive analysis of samples may be carried out in any desired manner, for example continuously or, for example, in a stepwise manner. For example, the present invention may find application in the sequential monitoring of samples for analyte species.

The arrangement may be such that, for example, the rate of detection of an analyte species may be determined by controlling the rate at which the portion of carrier means to which a sample has been applied is presented to the detection means.

Thus, for example, the rate of detection of an analyte species may be determined by controlling the rate of movement of the portion of carrier means to which a sample has been applied from the application means to the detection means.

The carrier means may be any suitable form; thus the carrier means may be in the form of a tape, or a strip, or a belt.

Where the carrier means is in the form of a tape, or a strip, or a belt, it may be stored for use in the form of a reel from which it may be unwound as required and moved past an application means and then to a detection means; for example a carrier means in the form of a tape, or a strip, or a belt may be housed in a replaceable cassette and technology similar to that used in relation to video tapes may be utilised in moving the tape, or strip, or belt past an application means and to a detection means.

The carrier means may carry one or more reagents as desired (e.g. in a layer, bi-layer, or multilayer arrangement).

Where a reagent or reagents is/are carried by the carrier means, a reagent or reagents may be carried by the carrier means in any suitable manner. For example, the carrier means may itself provide a reagent or reagents, or a reagent or reagents may be covalently linked to a carrier means, or a reagent or reagents may be sorbed onto a carrier means.

By way of further example, the carrier means may be a composite structure comprising a support material carrying an immobilised or sorbed reagent or reagents.

Further, by way of example, it will be appreciated that the carrier means may be suitable for receiving a reagent or reagents.

Also, by way of example, the carrier means (which may be, for example, in the form of a tape, strip or belt) may be such that it can be arranged to allow for the sequential release of a reagent, or reagents, carried thereon into an active liquid phase (e.g. an aqueous phase) associated with the carrier means. The reagent, or reagents, may therefore, for example, be transformed from an inactive, dehydrated form into an active liquid phase by the introduction of a sample in a liquid (e.g.

aqueous form) or by pre-wetting with a suitable solution (e.g. a buffer solution) prior to introduction of the sample to the carrier means.

Examples of carrier means are support materials such as nitrocellulose, nylon (which may be pre-treated, for example, by O-alkylation, partial depolymerisation by acid hydrolysis, non-hydrolytic depolymerisation or Nalkylation to form polyisonitrile-nylon), cellulose (which may be pre-treated, for example, by s-triazinyl derivatives, cyanuric chloride, cyanogen bromide, modification by transition metal salts, modification to hydrazides, or modification by isoxazolium salts), polyamides (which may be pre-treated by alkaline hydrolysis to carboxylic groups (deamidation), preparation of hydrazide derivatives, preparation of aminoethyl derivatives, also extension of flexible arms by means of further modification of hydrazide derivatives (e.g. by glutarylhydrazide derivatisation or bromoacetamidocaproyl-hydrazide derivatisation)), inorganic support materials (which may be pre-treated by silanisation, cyanogen bromide treatment (e.g. of glass) or diazonium reagent treatment (e.g. of glass)), polystyrene (which may be pre-treated with glutaraldehyde, polycationic materials (e.g. poly-1 lysine) or conversion to amino derivatives by nitration and reduction) and any suitable plastics material.

The application means and detection means may be in the form of windows which allow one portion of the carrier means to receive a sample through an application window whilst another portion of the carrier means (which has previously received a sample through the application window) may be observed through a detection window.

The present invention may be utilised in, for example, the detection of analyte species which are airborne materials (e.g. airborne organic species).

Thus, the invention provides, for example, an apparatus or a sensor suitable for use such that an airborne species may be detected as an analyte species.

By way of example, an analyte species may be present in a gaseous medium in any suitable form; thus, for example, an analyte species may be in the form of particles or droplets or may be in the form of a gas or a vapour. It will be appreciated that the analyte species may be considered to form part of the gaseous medium.

Examples of analyte species which may be detected in accordance with the present invention are airborne species such as particles of drugs, environmental pollutants in the atmosphere, chemical species in chemical work areas and chemical species in the proximity of chemical plant. By way of example, an analyte species which exists initially in particulate form may be treated so as to form a sample which may be subjected to analysis by any suitable method (e.g. an immunological method or a non-immunological method). For example, a particulate analyte species may be dissolved in a solvent to produce a solution for analysis.By way of further example, where immunological detection is utilised in accordance with the present invention, it is to be understood that, in principle, any species which can take part in an immunochemical interaction (e.g. any species which can act as a ligand) may be detected in accordance with the present invention.

The present invention may also find application in, for example, ex-vivo monitoring (e.g. of clinical samples), on-line continuous measurement in industrial processes or continuous and/or discontinuous monitoring (e.g. of organic pollutants).

The present invention may be utilised, for example, in uninterrupted analysis of analyte species in which there is no time period in which a new sample cannot be received. Thus, for example, the carrier means may move continuously from an application means (where a sample may be introduced to the carrier means) to a detection means, such interaction as necessary between a sample, or a constituent thereof, and a reagent or reagents taking place to a satisfactory extent in the time taken to move between the application means and the detection means so as to present a detectable signal at the detection means.

By way of example, a reagent or reagents may be carried by the carrier means, or a reagent or reagents may be incorporated into the sample before introduction of the sample to the carrier means.

It is to be understood that, in accordance with the present invention, airborne species (i.e. airborne analyte species) may be dissolved (e.g. by a continuous stream of solvent (such as water) supplied, for example, through one or more fine sprays).

By way of example, a reagent, or reagents may be applied to a carrier means in any suitable manner and at any suitable time.

Thus, for example, a reagent or reagents may be incorporated into a sample, before introduction of the sample to the carrier means.

Alternatively, by way of example, in one embodiment, a carrier means may be treated so as to carry a reagent or reagents, to form a reagent carrier means, and then stored ready for use; in such an embodiment the reagent or reagents may need to be activated prior to receiving a sample. This may be achieved in any convenient manner; for example, if the reagent or reagents have been dehydrated the introduction of water (e.g. by mixing with the sample) may serve to activate the reagent or reagents.

Alternatively, by way of further example, a reagent or reagents may be introduced to a carrier means just prior to introducing a sample thereto. Thus, for example, a carrier means may be moved sequentially past a reagent introduction means, an application means and a detection means.

By way of further example, a reagent or reagents may be applied to a carrier means after introduction of a sample and before the carrier means is presented to a detection means.

If desired, by way of example, a reagent or reagents may be carried by the carrier means and a further reagent or reagents may be incorporated into a sample before introduction of the sample to the carrier means.

By way of further example, a carrier means may carry a reagent or reagents and a further reagent or reagents may be added before and/or after a sample has been applied to the carrier means.

From the foregoing disclosure it will be appreciated that a reagent or reagents may be, for example, introduced to a carrier means at any suitable time, in any suitable manner. Also, it will be appreciated that reagents may be introduced to the carrier means in any suitable combination.

Also, by way of example, it may be convenient to incorporate a reagent in a solvent (e.g. water) which solvent is used to form a sample. Thus, for example, where water is used wetting and addition of a reagent may be achieved at the same time.

It will be appreciated that the reagent or reagents used in accordance with the present invention will depend, inter alia, upon the analyte species to be detected and the manner in which an analyte species is to be detected. By way of example, a reagent or reagents in accordance with the present invention may include species capable of taking part in an immunological detection procedure. Also, by way of example, any suitable immunological procedure may find application in accordance with the present invention.

Thus, for example, a labelled binder (e.g. antibody) dispiacement immunoassay may be used in accordance with the present invention; where such an assay is to be utilised the carrier means may carry a ligand (e.g. a hapten covalently bonded to the carrier means) and a binder for the ligand (e.g. an antibody thereto) labelled with tracer species (also known as a signal species).

It is to be understood that in order to achieve a given (e.g. optimum) detection sensitivity for an analyte species a ratio of ligand concentration to binder concentration may be determined, in accordance with known procedures (e.g. titration) in the field of immunochemical analysis, using analyte species standards, prior to detecting a concentration of analyte species in a sample.

The ligand is an authentic analyte species (i.e. a species (e.g. an antigen) which will bind to a binder (e.g. an antibody) to be used in an assay in substantially the same manner as an analyte species to be detected).

The tracer species may be, for example, any suitable signal species such as those known in the art (e.g.

fluorophores (e.g. fluoresceins, coumarins or rhodamine) chemiluminescent compounds, bioluminescent compounds, radioisotopes, dyes and enzymes).

(The carrier means carrying the ligand and labelled binder may be dehydrated and stored ready for use or used immediately or utilised in any other suitable manner.

Where it has been dehydrated the carrier means carrying the ligand and the labelled binder generally will need to be "activated" by rehydration before interaction with a sample. This may be achieved, for example, by introducing a sample as an aqueous sample.) A portion of the carrier means carrying the ligand and labelled binder may be subjected to the introduction of an analyte species (e.g. in aqueous conditions) such that some of the labelled binder is displaced from the carrier means by binding with the analyte species.

By use of standard samples of analyte species a calibration curve may be prepared and thereafter samples containing unknown amounts of analyte species may be detected by detection of either bound or unbound labelled binder. By arranging for bound and unbound labelled binder to display different properties from each other (e.g. by fluorescence quenching or polarisation) the need for a separation step may be avoided.

By way of further example, a labelled ligand (e.g.

hapten) displacement immunoassay may be used in accordance with the present invention; where such an assay is to be utilised the carrier means may carry a binder (e.g. an antibody covalently bound to the carrier means) and a ligand for the binder (e.g. a hapten) labelled with a tracer species (as hereinbefore disclosed).

The labelled ligand may be added at non-saturating concentrations such that it will bind to only some of the binder carried by the carrier means. The ligand is an authentic analyte species (i.e. a species (e.g. an antigen) which will bind to a binder (e.g. an antibody) to be used in an assay in substantially the same manner as an analyte species to be detected).

(The carrier means comprising the binder and labelled ligand may or may not be dehydrated as hereinbefore disclosed.) A portion of the carrier means carrying the binder and labelled ligand may be subjected to the introduction of an analyte species (e.g. in aqueous conditions) such that some of the labelled ligand is displaced from the carrier means by binding of some of the analyte species with the binder.

By use of standard samples of analyte species a calibration curve may be prepared and thereafter samples containing unknown amounts of analyte species may be detected, by detection of bound or unbound labelled ligand.

By arranging for bound and unbound labelled ligand to display different properties from each other (e.g. by fluorescence quenching or polarisation) the need for a separation step may be avoided.

By way of further example, a labelled binder (e.g.

antibody) competitive immunoassay may be used in accordance with the present invention; where such an assay is to be utilised in accordance with the present invention the carrier means may carry a ligand (e.g. a hapten) covalently bound to the carrier means.

A binder for the ligand (e.g. an antibody to the ligand), labelled with a tracer species (as hereinbefore disclosed) is maintained in proximity to the ligand on the carrier means (e.g. by means of a membrane on the carrier means); the ligand and the binder are held in a form such that they do not bind (e.g. by maintaining in a dehydrated state). The ligand is an authentic analyte species (as hereinbefore disclosed).

A portion of the carrier means may be subjected to the introduction of an analyte species under conditions such that competitive binding between the ligand and the labelled binder and the analyte species and the labelled binder takes place; where the ligand and labelled binders have been maintained in a dehydrated state this may be achieved, for example, by introducing the analyte species in aqueous conditions.

As a result of the competitive binding a portion of the labelled binder will be bound to the carrier means by being bound to the ligand and a portion of the labelled binder will be unbound (i.e. not bound to the carrier means) by being bound to the analyte species.

By use of standard samples of analyte species a calibration curve may be prepared and thereafter samples containing unknown amounts of analyte species may be detected by detection of bound or unbound labelled binder.

By arranging for bound and unbound labelled binder to display different properties from each other (e.g. by fluorescence quenching or polarisation) the need for a separation step may be avoided.

By way of further example, a labelled ligand (e.g.

hapten) competitive immunoassay may be used in accordance with the present invention; where such an assay is to be utilised in accordance with the present invention the carrier means may carry a binder (e.g. an antibody) bound to the carrier means.

A ligand for the binder (e.g. a hapten), labelled with a tracer species (as hereinbefore disclosed) is maintained in proximity to the binder on the carrier means (e.g. by means of a membrane on the carrier means).

The ligand is an authentic analyte species (as hereinbefore disclosed). The binder and ligand are held in a form such that they do not bind (e.g. by maintaining in a dehydrated state).

A portion of the carrier means may be subjected to the introduction of an analyte species under conditions such that competitive binding between the binder and the labelled ligand and the analyte species and the binder takes place; where the binder and labelled ligand has been maintained in a dehydrated state this may be achieved, for example, by introducing the analyte species under aqueous conditions.

As a result of the competitive binding a portion of the labelled ligand will be bound to the carrier means by being bound to the binder and a portion of the labelled ligand will be unbound.

By use of standard samples of analyte species a calibration curve may be prepared and thereafter samples containing unknown amounts of analyte species may be detected by detection of bound and unbound labelled ligand.

By arranging for bound and unbound labelled ligand to display different properties (e.g. by fluorescence quenching or polarisation) the need for a separation step may be avoided, However, if desired, a separation step may be utilised in accordance with the present invention; where a separation step is utilised, this may be effected in any suitable manner.

By way of further example, if required, postreaction binding to the carrier means may be utilised.

(It is to be understood that "post-reaction'2 as used in this Specification means "post-primary binding reaction".) Thus, for example, if required any suitable means for effecting post-reaction binding to the carrier means may be utilised.

By way of further example, auxiliary species (e.g.

auxiliary ligand and auxiliary binder) may be used in accordance with the present invention.

For example, an immunoassay method which involves one form of post-reaction binding to the carrier means may be used in accordance with the present invention; where such an assay is to be utilised in accordance with the present invention an auxiliary ligand (e.g. a hapten), may be carried by the carrier means (e.g. by covalent linkage thereto).

A binder (e.g. an antibody) for an analyte species or an authentic analyte species (as hereinbefore disclosed) is maintained in proximity to the auxiliary ligand on the carrier means (e.g. by means of a membrane on the carrier means). The binder is labelled with a tracer species (as hereinbefore disclosed).Also there is maintained in proximity to the auxiliary ligand and binder (e.g. by means of a membrane on the carrier means) an auxiliary binder (i.e. a binder for the auxiliary ligand (e.g. an antibody)); the auxiliary binder is associated with an authentic analyte species. (It will be appreciated that the authentic analyte species associated with the auxiliary binder may be considered to be a "conjugated analyte species".) The auxiliary ligand, labelled binder and auxiliary binder associated with the authentic analyte species are held in such a form that they do not bind (e.g. by maintaining in a dehydrated state).

A portion of the carrier means may be subjected to the introduction of an analyte species under conditions (e.g. hydration) such that analyte species and authentic analyte species (conjugated to the auxiliary binder) compete for binding to the labelled binder; also binding takes place between the auxiliary binder and the auxiliary ligand such that some of the labelled binder becomes bound to the carrier means (via the authentic analyte species and the auxiliary binder).

By use of standard samples of analyte species a calibration curve may be prepared and used in the detection of analyte species in samples containing unknown amounts of analyte species as hereinbefore disclosed.

By way of further example, an immunoassay method which involves another form of post-reaction binding to the carrier means may be used in accordance with the present invention; where such an assay is to be utilised in accordance with the present invention an auxiliary ligand (e.g. a hapten) may be carried by the carrier means (e.g. by covalent linkage thereto).

An auxiliary binder (i.e. a binder for the auxiliary ligand (e.g. an antibody)) linked to a binder (e.g. an antibody) for the analyte species is maintained in proximity to the auxiliary ligand (e.g. by means of a membrane on the carrier means).

Also authentic analyte species (e.g. a hapten) labelled with a tracer species (as hereinbefore disclosed) is maintained in proximity to the auxiliary ligand and the auxiliary binder linked to the binder for the analyte species (e.g. by means of a membrane on the carrier means).

The auxiliary ligand, auxiliary binder, binder for the analyte species, authentic analyte species and tracer species are held in such form that they do not bind (e.g.

by maintaining in a dehydrated state).

A portion of the carrier means may be subjected to the introduction of an analyte species under conditions (e.g. hydration) such that analyte species and authentic analyte species carrying the tracer species compete for binding to the binder attached to the auxiliary binder; also binding takes place between the auxiliary binder and the auxiliary ligand on the carrier means such that some of the labelled authentic analyte species becomes bound to the carrier means.

By use of standard samples of analyte species a calibration curve may be prepared and subsequently used in the detection of analyte species in samples containing unknown amounts of analyte species as hereinbefore disclosed.

It will be appreciated that, by way of example, any suitable variation of the use of auxiliary species may be utilised. Thus, for example, an auxiliary binder, rather than an auxiliary ligand, may be provided on a carrier means and other species for effecting detection may be varied accordingly.

An auxiliary species is a species which is not itself capable of taking part in a primary binding reaction with an analyte species (or an authentic analyte species).

An auxiliary species may be, for example, provided on a carrier means in any suitable manner. Thus, for example, the carrier means itself, or a part of the carrier means itself, may provide an auxiliary species (e.g. an auxiliary ligand); thus, for example, chemical groups or units of the carrier means itself, or of a part of the carrier means itself, may provide an auxiliary species.

Alternatively, by way of example, the carrier means may carry an auxiliary species (e.g. an auxiliary ligand or an auxiliary binder). An auxiliary species may be carried by a carrier means in any suitable manner (e.g.

by covalent attachment or any other suitable means).

Examples of auxiliary ligands are 2,4 dinitrophenol, fluorescein, digitoxin, coumarin and cibacron blue and examples of auxiliary binders are anti-2,4 dinitrophenol antibody, anti-fluorescein antibody, anti-digitoxin antibody, anti-coumarin antibody and anti-cibacron blue antibody.

The term "antibody" as used in this Specification embraces whole antibody and antibody fragments such as Fab and (Fab)2, and, accordingly, the term "antibodies" as used herein embraces whole antibodies and antibody fragments.

It will be appreciated that antibodies such as those immediately hereinbefore disclosed may be prepared by any suitable method, for example those known for the raising of polyclonal or monoclonal antibodies; thus, antibodies may be raised, for example, by immunising animals with conjugate made of suitable derivatives of a ligand and an immunogenic carrier partner such as bovine serum albumin or keyhole limpet haemocyanin; the product obtained by immunising animals may be purified as desired (e.g. by the use of affinity chromatography) to obtain the required antibodies.

By way of example, a primary immune specific binding reaction (which may also be called a primary immune binding reaction or primary binding reaction) is one in which an analyte species undergoes, or an authentic analyte species undergoes, a specific binding reaction, or an analyte species and an authentic analyte species undergo specific binding reactions. (It will be appreciated that the analyte species and the authentic analyte species undergo specific binding reactions with other species and not with each other.) It is to be understood that an authentic analyte species is a species which is capable of reaction in a substantially similar manner as an analyte species to be detected under substantially similar conditions.

A species capable of taking part in a primary immune reaction may be considered to be a primary species. A primary species may be, for example, a primary antibody or a ligand (e.g. an antigen). It is also to be understood that, for example, a primary species may be an antibody to an analyte species or an antibody to an authentic analyte species; it will be appreciated that, for a given immunoassay, the antibody to the analyte species and the antibody to the authentic analyte species will be the same antibody. It is also to be understood that a primary species may be, for example, an analyte species or an authentic analyte species.

By way of further example, post-reaction binding to the carrier may be effected, if desired, by use of a "mixed" primary/auxiliary species (i.e. a species which has a part which provides a species capable of interaction with an auxiliary species and a part which provides a primary species being a binder for a primary species; an example of such a mixed primary/auxiliary species is an antibody having more than one function (e.g. a bifunctional antibody). It is to be understood that the part of a mixed primary/auxiliary species which provides a species for interaction with an auxiliary species may be regarded as an "auxiliary function" in that it may interact with an auxiliary species.

Thus, for example, post-reaction separation may be effected by binding of an auxiliary function of a mixed primary/auxiliary species with an auxiliary species carried by the carrier means.

In view of the foregoing disclosure regarding the time at which a reagent or reagents may be applied to the carrier means, it will be appreciated that, in the foregoing examples of immunoassays, where appropriate, one or more of the reagents used may be incorporated into the sample rather than being carried by the carrier means.

It will be appreciated that the detection means used may depend upon the type of signal that is generated by interaction between the sample, or a constituent thereof, and a reagent or reagents carried by the reagent carrier means.

Thus, for example, the detection means may be a fluorescence detector, or a luminescence detector or a detector capable of detecting a colour change According to yet a further aspect of the present invention there is provided a method suitable for use in the immunological detection of an analyte species in a gaseous medium (as hereinbefore defined) which includes successively applying samples, which may contain analyte species, to portions of a carrier means and presenting the portions to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to effect successive immunological analysis of samples for analyte species.

According to yet a further aspect of the present invention there is provided a method suitable for use in the detection of a particulate analyte species in a gaseous medium (as hereinbefore defined) which includes successively applying samples, which may contain analyte species, to portions of a carrier means and presenting the portions to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to effect successive analysis of samples for analyte species.

(It will be appreciated that the present invention may be utilised in qualitative detection, or quantitative detection (i.e. measurement) of an analyte species.) Also, it will be appreciated that the present invention may be utilised with samples which contain analyte species and with samples which contain substantially no analyte species (e.g. a "standard" sample containing substantially no analyte species or an "unknown" sample which, upon subjecting to detection in accordance with the present invention, is found to contain substantially no analyte species).

The present invention may, for example, find application in the detection of one kind of analyte species, or in the detection of more than one kind of analyte species. Thus, for example, by appropriate choice of reagent or reagents, a single kind of analyte species may be probed for in a given sample.

Alternatively, by way of further example, if desired, by appropriate choice of reagent or reagents more than one kind of analyte species may be probed for in a given sample. Thus, the present invention may find application in the detection of two or more analyte species and may find application in multi-analyte species detection (which may also be considered to be multianalyte species detection).

By way of example, multi-analyte analysis may be used, if desired, to probe for two or more analytes at the same time.

The present invention may find application in, for example, ratiometric detection (e.g. in ratiometric immunological detection methods) in which more than one detectable species is used.

The present invention will now be further described, by way of example only, by reference to the Figures of the accompanying Drawings in which: Figure 1 is a diagrammatic representation of one form of apparatus in accordance with the present invention, and Figure 2 is a diagrammatic representation of one form of sensor in accordance with the present invention.

Referring now to Figure 1 of the Drawings, there is shown an apparatus 1 having a carrier means 2 comprising a tape carrying a reagent or reagents, and/or suitable for receiving a reagent or reagents, for interaction with a sample or a constituent thereof. It will be appreciated that only a part of carrier means 2 is shown in Figure 1. The apparatus 1 also comprises a sample window 3 (by means of which a sample may be applied to a portion of the carrier means 2) and a detection window 4.

In operation the carrier means 2 is moved in the direction of the arrow 5 and a sample is applied to a portion of the carrier means 2 by means of sample window 3. (It will be appreciated that the size of the window 3 may be used to define the size cf the portion of carrier means 2 to which a sample is applied. Also it will be appreciated that sample window 3 may be associated with, or regarded as, an application means.) The sample or a constituent thereof (e.g. an analyte species) may interact with a reagent, or reagents, carried by the carrier means 2, or a reagent or reagents incorporated in the sample, such that by the time that the portion of the carrier means 2 to which the sample has been introduced reaches the detection window 4 a signal is provided which may be detected through the detection window 4 by means of a suitable detector (not shown).

Referring now to Figure 2 of the accompanying Drawings there is shown a sensor 10, suitable for use in the detection of airborne analyte species (which is, it will be appreciated, one example of an analyte species in a gaseous medium), having a spool 11 of carrier means 12, said carrier means 12 being in the form of-a tape and carrying a reagent or reagents in inactive form. The arrangement is such that in operation carrier means 12 is fed from spool 11 around spindles 13 and 14 and is wound onto a take-up spool 15. The direction of movement of carrier means 12 is shown by the arrows 16.

The sensor 10 also has an activating agent reservoir 17, an activating agent control valve 18 and an inlet means 19 for delivering an activating agent to an application chamber 20.

Application chamber 20 has sample application means 21, a means 22 for introducing a fine aqueous spray and an air intake 23.

The sensor 10 also has a chamber 24 for providing a temperature-controlled reaction zone 25. Chamber 24 also has a light source 26 and detection means 27 comprising a photodetector. The detection means 27 is connected to a signal processing means 28 which, in operation, may transfer output to a display means represented as 29 and/or to an alarm system represented as 30.

It is to be understood that features 11, 12, 13, 14, and 15 may be, for example, in the form of a disposable cassette which may be located in, or removed from, the rest of the sensor 10 as required.

In operation, an activating agent is introduced to carrier means 12 from reservoir 17 via control valve 18 and inlet means 19 and air is introduced through the air intake 23 in the direction indicated by arrow 31.

A fine aqueous spray is introduced by use of means 22 and the sample thus formed with any airborne analyte species is introduced to a portion of carrier means 12 via sample application means 21.

The carrier means 12 moves in the direction of arrows 16 being paid-out from spool 11 and moved via spindles 13 and 14 to take-up spool 15.

Thus, a reagent, or reagents, carried by the carrier means 12 is activated and a sample is introduced to a portion of the carrier means 12 by sample application means 21.

The carrier means 12 then moves into chamber 24 and zone 25 where any analyte species in the sample interacts, or continues to interact, with the reagent or reagents carried by the carrier means 12 such that by the time that the portion of the carrier means 12 to which a sample has been applied reaches the light source 26 and the detection means 27 the presence or absence of analyte species in the sample (and thus the presence or absence of analyte species in air introduced through the air intake 23) may be detected by the detection means 27 by means of an optical signal.

Output from the detection means 27 is passed to the signal processing means 28 and output from the signal processing means 28 may be passed to the display means 29 and/or to an alarm system 30.

The carrier means 12 may be moved from the spool 11 to the spool 15 (via the spindles 13 and 14) at any velocity which is convenient for the analysis to be performed. For example, the carrier means 12 may be moved at a uniform velocity or may be moved in a stepwise manner as required.

Thus, by way of example, it will be understood that by continuous or stepwise movement of the carrier means 12, monitoring of samples introduced through the sample application means 21 may be effected (for example continuous monitoring of air introduced by means of the air intake 23 may be effected).

It will be appreciated that in an alternative arrangement, given by way of example, the carrier means 12 may not carry all of the reagents required for effecting the detection of an airborne analyte species, and means may be provided for introducing another reagent or reagents required to effect the detection. For example, another reagent or reagents may be introduced by use of means 22.

Claims

1. An apparatus suitable for use in the immunological detection of an analyte species in a gaseous medium (as hereinbefore defined) which apparatus includes a carrier means said carrier means being such that, in operation, a sample may be applied to a portion thereof and such that the portion may be presented to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive immunological analysis of samples for analyte species.

2. An apparatus suitable for use in the detection of a particulate analyte species in a gaseous medium (as hereinbefore defined), which apparatus includes a carrier means said carrier means being such that, in operation, a sample may be applied to a portion thereof and such that the portion may be presented to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive analysis of samples for analyte species.

3. An apparatus suitable as claimed in Claim 1 or Claim 2 wherein a reagent is, or reagents are, carried by the carrier means.

4. An apparatus as claimed in Claim 1 or Claim 2 wherein a reagent is, or reagents are, incorporated into a sample before introduction of the sample to the carrier means.

5. An apparatus as claimed in any one of Claims 1 to 4 which includes means for obtaining from the gaseous medium a sample, containing analyte species, for application to the carrier means.

6. An apparatus as claimed in Claim 4 which includes means for incorporating a reagent or reagents into a sample.

7. An apparatus as claimed in any one of the preceding Claims which includes means for forming a gaseous medium.

8 An apparatus as claimed in any one of Claims 1 to 7 wherein the carrier means is such that,.in operation, the carrier means may be moved relatively to an application means for applying a sample to a portion of the carrier means, and relatively to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to permit successive analysis of samples for analyte species.

9. An apparatus as claimed in any one of Claims 1 to 8 wherein the carrier means is such that in operation the carrier means may be moved relatively to an application means for applying a sample to a portion of the carrier means such that the sample may be brought into contact with a reagent or reagents carried by the carrier means, and relatively to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents carried by the carrier means so as to permit successive analysis of samples for analyte species.

10. A sensor, suitable for use in the immunological detection of an analyte species in a gaseous medium (as hereinbefore defined), comprising a carrier means, application means for applying a sample, which may contain analyte species, to a portion of the carrier means, and detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents, the arrangement being such that, in operation, the carrier means may be moved relatively to the application means and to the detection means to permit successive immunological analysis of samples for analyte species.

11. A sensor, suitable for use in the detection of a particulate analyte species in a gaseous medium (as hereinbefore defined), comprising a carrier means, application means for applying a sample, which may contain analyte species, to a portion of the carrier means, and detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents, the arrangement being such that, in operation, the carrier means may be moved relatively to the application means and to the detection means to permit successive analysis of samples for analyte species.

12. A sensor as claimed in Claim 10 or Claim 11 wherein a reagent is, or reagents are, carried by the carrier means.

13. A sensor as claimed in Claim 10 or Claim 11 which includes means for incorporating a reagent, or reagents, into a sample before introduction of the sample to the carrier means.

14. A sensor as claimed in any one of Claims 10 to 13 which includes means for obtaining, from the gaseous medium, a sample containing analyte species.

15. A sensor as claimed in any one of Claims 10 to 14 which includes means for forming a gaseous medium.

16. An apparatus or a sensor as claimed in any one of the preceding claims wherein samples are analysed continuously.

17. An apparatus or a sensor as claimed in any one of Claims 1 to 15 wherein samples are analysed in a stepwise manner.

18. An apparatus or a sensor as claimed in any one of the preceding Claims wherein the carrier means is a support material comprising nitrocellulose, nylon, cellulose, a polyamide, an inorganic support material, polystyrene or a suitable plastics material.

19. An apparatus or a sensor as claimed in any one of the preceding Claims wherein the carrier means is in the form of a tape, or a strip, or a belt.

20. An apparatus or a sensor as claimed in any one of the preceding Claims wherein the carrier means itself provides a reagent or reagents, or has a reagent, or reagents, covalently linked thereto, or sorbed thereon.

21. An apparatus or a sensor as claimed in any one of the preceding Claims wherein the carrier means carries more than one layer of reagents.

22. An apparatus or a sensor as claimed in any one of the preceding Claims wherein the carrier means is a composite structure.

23. An apparatus or a sensor as claimed in any one of the preceding Claims suitable for use such that an airborne species may be detected as an analyte species.

24. An apparatus or a sensor as claimed in Claim 23 wherein the airborne species is a drug or an environmental pollutant.

25. An apparatus or a sensor as claimed in Claim 23 wherein the airborne species is an organic species.

26. An apparatus or a sensor as claimed in any one of Claims 23 to 25 wherein an airborne species is dissolved before being applied to a carrier means.

27. An apparatus or a sensor as claimed in any one of the preceding Claims wherein a detection means is a fluorescent detector, a luminescence detector or a detector capable of detecting a colour change.

28. An apparatus or a sensor as claimed in any one of the preceding Claims wherein a reagent is, or reagents are, such that post-reaction binding (as hereinbefore defined) to the carrier means may be effected.

29. An apparatus or a sensor as claimed in Claim 28 wherein an auxiliary species or a mixed primary/auxiliary species is provided to participate in post-reaction binding to the carrier means.

30. A method suitable for use in the immunological detection of an analyte species in a gaseous medium (as hereinbefore defined) which includes successively applying samples, which may contain analyte species, to portions of a carrier means and presenting the portions to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to effect successive immunological analysis of samples for analyte species.

31. A method suitable for use in the detection of a particulate analyte species in a gaseous medium (as hereinbefore defined) which includes successively applying samples, which may contain analyte species, to portions of a carrier means and presenting the portions to a detection means for detecting interaction of the sample, or a constituent thereof, with a reagent or reagents so as to effect successive analysis of samples for analyte species.

32. A method as claimed in Claim 30 or Claim 31 wherein an airborne species is detected as an analyte species.

33. A method as claimed in Claim 32 wherein the airborne species is a drug, or an environmental pollutant.

34. A method as claimed in Claim 33 wherein the airborne species is an organic species.

35. A method as claimed in any one of Claims 30 to 34 wherein samples are monitored sequentially.

36. An apparatus substantially as hereinbefore described with reference to Figure 1 of the accompanying Drawings.

37. A sensor substantially as hereinbefore described witch reference to Figure 2 of the accompanying Drawings.

38. A method substantially as hereinbefore described with reference to Figure 1 or Figure 2 of the accompanying Drawings.