GB2297926A

GB2297926A - Diagnostic test-tube

Info

Publication number: GB2297926A
Application number: GB9603259A
Authority: GB
Inventors: Philip Monro
Original assignee: HATS Ltd
Current assignee: HATS Ltd
Priority date: 1995-02-17
Filing date: 1996-02-16
Publication date: 1996-08-21
Also published as: GB9503109D0; GB9603259D0

Abstract

A container for testing a potentially infectious, toxic or dangerous sample, comprises one or more primary chambers for the material, one or more secondary chambers linked to the primary chamber(s) via at least one common wall of at least partly formed by one or more semi-permeable membranes, whereby test reagent(s) in the secondary chamber(s) of lower MW or diameter than the cut-off point of the membrane, pass through the membrane(s) and react with the sample(s) within the primary chamber(s) whilst material of higher MW or diameter is retained within the primary chamber(s), or a lower MW fraction from the primary chamber(s) passes into the secondary chambers for reaction with reagents therein. The following features may be present : Primary chamber sealable by a lid and the secondary chamber open topped. Secondary chamber detachable. Device useable with a centrifuge or microscope (with clear-walled chambers) and volume-graduated. Substances affecting or influencing the reaction or diffusion rate, or indicators, included in the chambers and/or membrane. Single primary or secondary chamber associated with multiple secondary or primary chambers.

Description

Diagnostic test-tube Field of the invention This invention relates to a container for the analysis of potentially infectious or toxic material.

Background The increased incidence of highly infectious diseases, such as hepatitis, poses two separate but related problems for the pathology services: 1 How to minimise the risk to staff while detecting these highly infectious diseases that are present in biological fluids.

2 How to carry out other tests on biological fluids which may knowingly or unknowingly be concurrently infected with AIDS etc.

Similar problems apply to samples that may contain toxins, such as Botulinum toxins, or lectins such as Ricinus communis.

The object of the present invention is to reduce these problems.

For this, the invention provides a container with one or more primary chambers in which the infectious component of any material is contained.

These chambers are separated from one or more secondary chambers by a semipermeable membrane. This membrane will be permeable to a non-infections component of the material within the primary chamber as well as reagents present in the secondary chamber the movement of which 'will facilitate the identification and or quantification of material present in the primary chamber. As this membrane is impermeable to potentially infected material which is contained in the primary chambers this will allow tests to be performed on potentially infectious material with reduced risk to those carrying out these tests.

Existing technology Various containment systems are already in use for the analysis of potentially infectious material or for concurrent analysis of material that may be infected with such organisms. For example, membranes are used to separate and concentrate biological fluids and to provide a limited aseptic barrier in which case the typical minimum pore size is 0.22 microns. This provides a bacterial but not a viral screen. To produce a viral screen the pore size must be significantly reduced. With existing technology this results in a significantly reduced flow rate when used at normal pressure and a significant reduction of solute and solvent movement across these finer membranes which can only be overcome using high pressure or centrifugation.

In the majority of cases the forces used to move solutes and solvents through a membrane with a viral tight pore size are provided by the process of osmotically driven ultrafiltration, see our patent application WO 91/14466, or other physico-chemical means. These are not solely dependent on a significant hydrostatic or physical pressure difference between the regions on either side of the barrier across which the solutes and solvents move.

The result was a system for the analysis of biological fluids with a significant reduction in the risk of bacterial or viral infection to those carrying out the analysis.

In our patent application WO 91/14466, we introduced the concept of using an ultra-fine membrane barrier to provide a viral excluding barrier to provide a safer assay method for use with potentially infected material. The forces used to move solutes and solvents through a membrane with a viral tight pore size are mainly provided by osmotically driven ultrafiltration and dialysis.

This results in a system for the analysis of biological fluids with a significant reduction in the risk of bacterial or viral infection to those carrying out the analysis.

Our earlier patent application covered two separate but related situations: a) Applications where reagents are required to enter the container in which the biological sample is present and interact with material within the container.

b) Applications where a component present in the biological fluid leaves the container and interacts with reagents etc. that are outside of that container.

An object of the present invention is to enable these systems to be carried out in a self-contained manner.

According to the present invention we provide a container for testing a sample containing potentially infectious, toxic or dangerous material, the container comprising: one or more primary chambers for for retaining potentially infectious, toxic or dangerous substances, one or more secondary chambers linked to the primary chamber(s) via at least one common wall, one or more semi-permeable membranes forming at least part of the common walls);; the arrangement being such that using appropriate chemical, physiochemical or physical methods, test reagent(s) in the secondary chamber(s) having a lower molecular weight (or effective molecular diameter) than the cut-off point of the membrane, pass through the membrane(s) and react with the sample(s) within the primary chamber(s) whilst potentially infectious, toxic or dangerous material of higher molecular weight or effective molecular diameter are retained within the primary chamber(s) or a lower molecular weight fraction from the primary chamber(s) pass into the secondary chambers for reaction with reagents therein.

In use, solutes are usually moved across the membrane via "osmotically driven ultrafiltration". Here the presence of osmotically active solutes on one side of a semipermeable membrane drive both solutes and solvents across a semi-permeable membrane without external power or additional hydrostatic pressure. Suitable membranes are already in production with a pore size as low as 200 Daltons. Membranes of this porosity will exclude all viral particles and even toxins and pions ensuring that potentially infected material can be retained in the first compartment while fluids in the second compartment can be handled with complete safety as even the smallest viral particle is many thousand times larger than these pores.The pore size of the membrane could be significantly increased to allow through relatively large organic molecules e.g. diagnostic anti-bodies but still retain a viral tight barrier.

Normally the membrane will have pores significantly smaller that the smallest potentially infecting particle but still allow through a significant movement of solutes and solvents using forces such as those generated by dialysis and those involved in the rehydration of certain compounds.

Howeever the invention utilises any one of a range of physico-chemical forces that are capable of moving solutes and solvents through membranes of extremely fine porosity. Further more these forces can be used in isolation or in any combination. I.e. there is no need for any significant hydrostatic or similar forces to be involved. Where such methods are used, as by way of example only in centrifugation, these methods are used to enhance the movement of the solutes and solvents and not as the primary method for the movement of solutes and solvents across the membrane.

A feature of many of the embodiments of the present invention is that within the container there will be in most cases a combined collecting and assay chamber which are separated by a selective membrane which is completely viral tight but across which there can be selective movement of solutes and or solvents.

The prefered embodiment will be a container having two chambers separated from each other by a semipermeable membrane, one of the chambers being sealable for the containment of potentially infected or toxic material to be assayed, the other chamber being adapted to receive reagents for assay or reaction with the material in the primary chamber.

The final design of any embodiment will depend on manufacturing processes and the equipment in which the sample will be handled. In this example there is a two compartment chamber where once the biological fluid is collected from the patient, the contents of the first chamber are permanently sealed in.

This chamber is separated from the second chamber by the semipermeable membrane to give in effect a double chamber. The second chamber is then used for the addition or removal of test reagents in complete safety. Within this general design the final embodiment shape will depend on the complexity of the diagnostic tests and whether it is intended to carry out quantitative or non-quantitative tests. It will be realised that in some cases it be preferable to make the first compartment entirely out of semi-permeable membrane and insert this in a re-usable second chamber.

As in our previous application the products cover the present application can be divided into two classes'of products: The first class of products are intended for testing biological samples containing potentially infectious, toxic or dangerous material from any plant, animal or microorganism which are retained in one or more primary chambers. In these products the primary chamber is linked to one or more secondary chambers via a common wall which is all or least in part formed of a semipermeable membrane.Test reagents that are present in a secondary chamber of the same embodiment and having a lower molecular weight (or effective molecular diameter) than the cut-off point of the membrane can then pass through the membrane and react with material within the primary chamber whilst potentially infectious, toxic or dangerous materials of higher molecular weight or effective molecular diameter are retained within the primary chamber. This is achieved using appropriate chemical, physiochemical or physical methods. I.e. these products have a common feature that reagents pass from a secondary chamber and enter a primary sealed chamber via a semipermeable membrane and interact with the contents.

The second class of products are intended for testing biological samples containing potentially infectious, toxic or dangerous material from any plant, animal or microorganism which are retained in one or more primary chambers. In these products the primary chamber is linked to one or more secondary chambers via a common wall which is all or least in part formed of a semipermeable membrane. Materials that are initially present in the primary chamber of these products and having a lower molecular weight (or effective molecular diameter) than the cut-off point of the membrane, pass through the membrane and react with material within the secondary chamber of the same products whilst potentially infectious, toxic or dangerous materials of higher molecular weight or effective molecular diameter are retained within the primary chamber.This is achieved using appropriate chemical, physiochemical or physical methods. I.e. these products have a common feature that materials initially present in the primary chamber leave one or more primary sealed chambers via a semi-permeable membrane and interact with materials in one or more secondary chambers.

Within these two main classes of products containers can be designed for specific applications and having additional specific or unique features. By way of example only, additional features that may be present in certain products will now be described together with examples of additional technical features which may or may not be present in specific products.

The "sample" can be any biological material that is placed in the primary chamber. These samples will most commonly be, but not exclusively so, blood and related fluids, urine samples, faecal samples (solid or liquid), cells, tissues or organs or exudates. The material of biological origin may constitute all or part of the specimen. Examples of the latter type could included potentially contaminated clothes,fabrics, hair, skin or soil samples.

Similarly the material in the primary chamber will be most commonly, but not exclusively so, of human origin. However, they could be of veterinarian origin or come from any animal or plant species or microorganism including, but not restricted to, bacteria, viruses, fungal and other botanical material or any of the recently discovered infecting particles of which bovine spongiform encephalopathy (BSE) is an example and for which the collective term "prions" is commonly used.

The potentially infectious material within this primary chamber could originate from any plant or animal species or microorganism including, but not restricted to bacteria, viruses, fungal and other botanical material or any of the recently discovered infecting particles of which BSE is an example and for which the collective term "prions" is commonly used. I.e any living material that poses a risk to man or any other species that he wishes to protect. The only restriction in any design of this embodiment is that this material must be remain in the primary container and cannot pass through the membrane that has been selected for that particular application.

Similarly there are no restrictions on the type of test or assay that can be carried out on material in or released from the sample in the primary chamber. I.e. it will include but not be restricted to, chemical, hormonal and other tests which relate to a fraction of the contents or substances that are present in or can or have leached out of the sample. In addition, it will include the specific identification of parasitic and microscopic organisms that may be present within the primary chamber.

For the avoidance of doubt the primary chamber of this embodiment is any chamber into which the biological material is collected and which is then sealed in such a manner that the material can be handled safely or at least with a reduced risk of infection. Similarly, the secondary chamber is any chamber which is linked to the primary chamber via a semipermeable membrane but where the contents can be handled with complete or at least increased safety. These could be sealed or open depending on the requirements of a particular assay.

In the majority of cases products will be designed in such a way that once the biological material has been added to the primary chamber it is then sealed in such a way that there is no possible leakage of or contact with potentially infected material outside of this sealed chamber. By way of example only this can be achieved using a screw cap design that current laboratory practice has shown to be safe and will completely seal in potentially infected material. However, when used with blood samples (or similar liquids) existing specialised blood collection tubes could be adapted to fit in with the design criteria of the present invention and this will apply to other specialist containers under development.

The membrane is that part of the embodiment through which material below the effective molecular size of the potentially infective material can move between the primary and secondary chambers. It must be stressed that the term "membrane" is used for convenience only as it could have a rigid structure as the required porosity could be generated, by way of example only, using specially formulated and structured, metals, glass or rigid plastic. In fact in terms of embodiment strength and safety such a embodiment would have considerable advantages over one made with a thin floppy membrane.

Similarly the type and porosity of this semipermeable membrane used in any particular embodiment are defined in terms of its properties only and it can be made of any material so long as it allows through specific components of the sample or reagent but at the same time provides a barrier to the potentially infectious material present in the primary chamber. I.e its porosity is not defined in detail as this will depend on specific case requirements. Thus, if the sample is expected to contain viral particles it will require much smaller holes than a embodiment used in cases where the sample is expected to contain only protozoa or even multicellular parasites.

I.e provided the membrane satisfied the criteria of retaining in the primary chamber material that it has to be contained on safety grounds for that particular application there are no other restrictions on the design or exclusion criteria of the semipermeable membrane. By way of example only, to retain safely any toxins from Ricinus communis (form RCA60) would require a membrane with a cut-off of approximately 60,000 Daltons but if only protozoa were to be retained the pore size could be thousands of times larger.

It will be realised that by increasing the effective pore size of the membrane the rate of movement of solutes will be increased and where appropriate the time to reach equilibrium will be reduced. Thus, for those products where it can be assumed there are no viral particles present the effective pores size could be increased to, for example, 10 million Daltons which would significantly reduce the time taken to reach equilibrium or to move a particular substance from one compartment to the other. whilst at the same time retaining any bacteria or similar sized microorganisms in the primary chamber.

A critical factor in determining the rate, speed and mass at which solute and solvent will move across the membrane will be the effective area of contact of the membrane to the any material that enhances the movement of material across that membrane. Thus any method that is compatable with the assays to be carried out that improves this effective area of contact could be used.

Examples include directly coating the membrane with material that will enhance this movement or simply improving the contact of such material with the membrane.

Although it is assumed that in the majority of cases the embodiment will made safe by autoclaving or similar processes, until this takes place there is still a health risk associated with the living material present in the primary chamber. These risks can be reduced even more by designing the embodiment in such a way that a disinfecting substance can permeate through the semipermeable membrane into the primary chamber and so result in immediate complete or at least partial disinfection of the contents of the primary chamber and so reduce the risks even further in the handling of this sample and in its eventual disposal. If the embodiment is to be disposed of by incineration it would be advantageous to make it all of inflammable material and ideally of a type that did not generate toxic fumes.

Membranes vary in their physical and chemical properties including pore size and which chemical substances they may facilitate or restrict the movement of. For this reason it may be advantageous in certain embodiment designs to have multiple layers of membranes where at least one of these will not allow through the passage of potentially infectious material. Depending on the application these multiple membranes could be designed so that they were separated or even fused together. By separating the multiple membranes in such a way that there was a significant space between them the embodiment would effectively produce a sequence of chambers each separated by a semipermeable membrane which may have similar or dissimilar properties and structure.

By way of example only, one particular design of products could be made so that the contents are fractionated into specific sub-fractions. So long as these secondary chambers were distal to the membrane that acted as the barrier to the infected material they could be open or even designed in such a manner that allowed for the rinsing or continuous replacement of their contents. The latter could be used to dilute any permeable solute or solvents that may be present in any particular chamber including the primary chamber.

One particular application of multiple membranes would be to reduce the incidence of defects as it is likely that in the majority of cases a minor defect will overlay an intact part of the other membrane.

So long as there was no significantly detrimental effect on the performance or total amount of membrane available across which solutes and solvents can pass the membrane can be reinforced, strengthened or supported to reduce the chance of it being accidentally damaged or compromised. By way of example only, products can be made that included a strong but fully porous layer or even a nylon net on the exposed surface. Similarly, the membrane could be coated or treated to enhance or inhibit the movement of specific solutes or solvents through it.

In certain cases products can be made that would use a membrane that would restrict the movement of material that is not infectious but still dangerous.

This material could include not only toxins but specific chemicals etc. which may be toxic or dangerous to handle or whose release could be extremely dangerous. These could include carcinogenic or teratogenic chemicals as well as material that is not even in solution such as asbestos particles and material that is suspension or colloidal state. A possible example of such material would be in the determination of venoms or lectins where total containment would be advantageous on safety grounds.

Although in many cases it may be appropriate to have the membrane that separates the primary and secondary chamber in a vertical position it will be appreciated that for the determination of specific substances and with specific substances in any specific chambers it may be advantageous to depart from this simple design. By way of example only, the membrane could be restricted to the upper part of the common wall so that it was less likely to be subjected to physical damage or to the forces generated during centrifugation or other separation procedures.

Alternatively, it could be specifically be placed near the base of any compartment so that any physical or chemical process that was used to move material from one compartment to the other would be enhanced. I.e., within the overall design the semi-permeable membrane can be placed in different positions to satisfy other secondary design characteristics. This could include, by way of example only, placing the membrane horizontal in which case the primary chamber(s) could be above or below the secondary chamber(s).

Complete integrity of the primary chamber is an important feature of the majority of products covered by this patent. For this reason it would, in certain applications, be advantageous to know if the there had been a breach of the integrity of the primary chamber. By way of example only, this could be achieved by including appropriate substances in the primary and secondary chambers which on mixing produces an easily identified third substance. If both of these substances had an effective molecular size greater than the intended pore size of the membrane this reaction would only take place if there had been a breach of the integrity of the primary chambers. The same result could be achieved if one component had a relatively small molecular weight but was bound in some way to the chamber it originated from.As the size of the defect in the membrane could be relatively small the identifying substance present in a particular embodiment could effectively amplify any chemical reaction taking place via this defect. One possible type of reaction that would do this would be an enzyme based reaction.

If the semipermeable membrane were made, by way of example only, of Visking (TM) tubing it would have a stated pore size of approximately 10,000 Daltons which will totally prevent the movement of bacteria and viral particles but will allow the free passage of most common sugars, electrolytes and most hormones into the second chamber. It would then be possible then for appropriate reagents to be added to the second chamber and then using appropriate physical and chemical methods, components present in the sealed primary chamber will enter the second chamber and so allow them to be detected.

Conversely, a larger but still viral excluding pore size could be used and the appropriate test reagents actively transported into the sealed primary chamber. An example of an application suitable for a embodiment made with this type of membrane would be the direct detection of viral infections using reagents that utilised antibody/antigen reactions. In this case the pores in this embodiment would allow through relatively large proteins but would still completely block the movement of viral particles.

For products intended for quantitative assays, once equilibrium has been reached in respect of the component to be assayed, aliquots (or even the total amount) of material in the secondary chamber can be removed in complete safety to carry out routine chemical analysis. These aliquots can then be assayed using manual or semi-manual methods. Alternatively, this secondary chamber can be designed so that aliquots can be removed by standard (or specifically designed) sampling devices intended for semi-automatic or fully automatic systems. In these cases the secondary chamber could be open or the material removed by an appropriate septum sampling system. The technology to achieve this is not limited to generalised equipment but extends to specially designed instrumentation.For example, the embodiment could be designed so that all or part of it could be placed in instrumentation designed for specific assays. Again by way of example, in appropriate cases the external dimensions of the embodiment could be made to conform to the internal dimensions of the chambers or assay compartment of proprietary instrumentation. Although not restricted to products designed for automated equipment it would be advantageous in certain applications to include a bar code or similar or dissimilar identifying system used in laboratories for sample identification.

Where appropriate any of the chambers could contain a device for indicating that a specific volume of liquid was present in any particular chamber to enable quantitative or at least semi-quantitative assays to be carried out.

This could, by way of example only, be provided by volume indicators on the walls of the chambers.

Any chamber chamber could be designed to allow for the rinsing or continuous replacement of its contents to dilute any permeable solute or solvents that may be present in it.

Any chamber could contain chemical or physical binding agents that could bind to specific solutes and so reduce the movement of all or specific components of that solute across the semipermeable membrane and or reduce their participation in subsequent chemical reactions.

A group of similar but distinct products could be made where specific products in the series contained different specific reagents for different test procedures. These could be coded in some way, to identify particular test procedures. By way of example only, these could be colour coded using a system that could be unique to this invention or comply with a system already in standard clinical use. As similar system can be used for sample identification.

In those applications where it is intended to make observations or determinations that involve any wavelength of light (including infra-red and ultra-violet) any appropriate chamber would be constructed of clear material, with respect to that assay wavelength, that allows the contents to be seen and if required directly facilitate the direct assay of their contents. A further refinement of this type of embodiment would be to include in it optically clear surfaces which may be of specific dimensions. For example the solvent path length could be exactly one centimetre in length.

A separate and special class of products are those intended for the direct examination of the contents of the chambers using any design of microscope via an optically clear surface. In this situation the contents could, by way of example only, be examined using an inverted microscope to allow for the examination and possible identification of bacteria present in the primary chamber.

To increase the movement of solutes or solvents from one chamber to the other, inert (in respect of the assay being carried out) material that will enhance the movement of solutes or solvents can be placed in the appropriate chamber. Appropriate material could be osmotically active substances e.g glucose which will eventually reach equilibrium or similar acting substances but of larger effective molecular weight that will not themselves cross the membrane. These, by way of example only, could include high molecular weight dextrans. If ionic dextrans (or similar disassociating material were used) these would more rapidly dissolve and would act faster than their non-ionic equivalent compound. Solutes or solvents could be added to any chamber whose purpose is to intitate the movement of substances across the membrane.For example, wetting any hydroscopic substances would enhance the initial movement of material across the membrane. It will be realised that in some situations the primary driving force for the movement of solutes or solvents will be dialysis and not osmosis.

Alternatively the movement of solutes and solvents could be enhanced by hydroscopic substances, deliquescent substances or material that will rehydrate in any way as well as substances that work by dialysis. An example of this class of material is a high molecular weight polyelectrolyte. Within this general group of substances that would work in this way is Salsorb (TM) made by Allied Colloids Ltd. For these substances to have their greatest effect they would have a molecular weight greater than the effective molecular exclusion size of the membrane separating the primary chamber (s) from the secondary chamber (s).

It will be realised by any expert in the field that an optimum molecular weight for such a substance would be to be just above the pore size of the membrane to maximise the number of molecular particles but still prevent any leakage of the substance through the membrane.

Any of the substances that acted to move the solutes or solvents across the membrane could themselves have additional physical or chemical properties that enhanced their use in these systems. For example, incorporated into their molecular structure or bound to them in any way could be other reagents or components that themselves were pass of the assay system. A specific example of this would be to incorporate into a hydroscopic substance a dye that indicated a specific substance was present or absent from the solute or solvent that was originally present in the primary chamber.

A special case of such substances would be a embodiment in which once an adequate amount of liquid (usually but not exclusively water) enabled the solution to became transparent or at least translucent with respect to a specific wavelength of light. Thus, if the apparatus was made of material that was transparent to that wave-length of light then the sample in the chamber could be directly assayed in an appropriate piece of apparatus. An example of this would be a spectrophotometer. It should be obvious that this type system would work with solute entering or leaving the primary chamber but in some cases additional water may be required to ensure adequate transparency or dilution of the material.

It will also be obvious to any expert in this field that with the use of such water absorbing substances an equilibrium will not always be achieved in all solutes and solvents in all chambers. For example, if a large mass of high molecular weight polyelectrolyte were placed in the secondary chamber it may be possible to remove all (or at least a significant fraction) of any solute or solvent present in the primary chamber while at the same time ensuring that all infectious or toxic material remained in the primary chamber.

It will be obvious to those who are expert in this field that quantitative analysis is still possible even in those cases where there is not an equilibrium state between the contents of the primary and secondary compartments. For example in those situations where virtually all the material to be quantified is carried across the membrane to the other compartment or a known mass or ratio is left behind.

If any powerful agent were used to move the transportable solute or solute fraction out of the primary chamber this would result in concentration of any material in the primary chamber that was of greater molecular weight than the effective molecular exclusion of the selective membrane. Thus in certain situations (and obviously with additional precautions) the concentrated material in the primary chamber could be directly sampled for analysis. The use of water absorbing substances in this way would significantly reduce the need for conventional concentrating methods such as centrifugation etc.

In addition to these chemical methods that are used to enhance the movement of solutes and solvents across the membrane, products can be made where these chemical processes are enhanced by any appropriate physical method. These features could be incorporated into specific products for example, accelerate movement of material between the various chambers or to compact material within specific chambers to aid the assay of their contents. For example, it may be advantageous to separate and/or compact the cellular component of blood to enhance their observations in the primary chamber or to facilitate the removal of a fraction of material from that chamber. The physical methods that can be used could include, by way of example only, centrifugation, ultrasound, vibration, shaking, stirring, heating and agitation.They could also include physico/chemical methods such as electrophoresis and reverse iontophoresis. The actual embodiment could include, by way of example only, vanes on the external surface of one or more chambers to fit into proprietary agitation systems. Similarly, the embodiment could be specifically designed to allow for centrifugation.

Conversely, it may in certain situations be advantageous to have products that contain chemical or physical binding agents that could bind to specific solutes and so reduce the movement of specific components of that solute across the semipermeable membrane and/or reduce their participation in subsequent chemical reactions. This could similarly apply to the solvent phase where, by way of example only, the membrane could be coated with a hydrophylic substance to reduce the movement of water across it.

Conversely once any material that is likely to adversely affect the analysis of material in the primary chamber is removed from the primary chamber via the selective membrane then the ease of certain assays will be enhanced.

The majority of the embodiment designs considered so far assume that any determination made on any particular sample will be qualitative or at the very best semiquantitative. However, by fixing the volume of sample, solvents and the mass of solutes present in the present in the embodiment it is possible to make any appropriate assay semiquantitative or even fully quantitative. The required increase in precision and accuracy can be achieved using any of the standard methods used in the industry. These would include the use of any appropriate device that delivered standard volumes or masses of reagents or primary substances. Where the requirements for precision or accuracy were limited any appropriate chamber could simply incorporate gradations or any other appropriate indicators for the amount of liquid to be added to that specific chamber. In this their use would be enhanced (although it would not be a primary requirement of any such embodiment) by using material for the chambers that was of transparent or at the very least translucent material.

In the majority of embodiment designs already considered it has been assumed that there will be a single primary collecting chamber for the potentially infected material and a single assay chamber. However, in certain cases these are unnecessary design limitations and for particular applications more complex chamber designs will be advantageous which could where appropriate be combined with any other variable that may be incorporated into any specific embodiment. In practice the products made with these more complex chambers can be divided into two groups although obviously both components could be incorporated into a single embodiment. In the first group of products there will be a single primary chamber connected to multiple secondary chambers so that two or more separate assays can be determined on the contents of the same primary chamber.In the second group of products there will be multiple primary chambers connected to a single secondary chamber so that multiple identical or dissimilar assays can be carried out at the same time but using a common pool of reagents. For certain applications these more complex products would include additional features to ensure there was not crosscontamination via the common chamber.

For certain applications embodiments would be constructed such that some or all of the chambers are pre-loaded with dried reagents prior to its use. By way of example only, these could include freeze-dried reagents of even labile components whose activity has been preserved using specialised methods.

Examples of this type are the reagents made by Pafra Ltd. in Cambridge, England. Products in which material is preloaded could be extended to preloading appropriate chambers with living or dead reference microorganisms to increase the ease of the identification of related microorganisms.

By way of example only, these could be freeze-dried or even in a suspended state using specialised methods. Examples of this type are the techniques used by Quadrant Research Ltd. in Cambridge, England.

In a specialised example of pre-loaded reagents it may be advantageous to release into any chamber, reagents etc. from a separate area of that chamber in such a manner that any.risk to the operator is avoided. For example, material could be released from a sub-compartment of the primary chamber at any stage in the analysis. This could be achieved using any of the conventional systems available for such a process. Examples of apparatus in use for such processes are those already in use for mixing two-part adhesives where pressure or mechanical forces are used to break a septum between the two compartments but without affecting the external integrity of the whole container.

In addition to products primarily designed for the determination of the products and components from living organisms products can also be designed for the direct identification of organisms that may be present in the primary chamber. By way of example only, these could include potentially infectious micro-organisms or visible parasites whose identification is enhanced by the addition of reagents that are placed in any appropriate chamber.

To enhance the identification of either the components of living organisms or the living organisms themselves the embodiment could be designed so that the contents of the primary chamber can be cultured under appropriate conditions prior to the identification and or identification of such organisms.

In general it will be advantageous to have the primary and secondary chambers permanently fixed together. However, there may be applications and situations where it is advantageous to separate the primary and secondary chambers so that the secondary chambers or their contents could be removed or separated from the primary chamber to facilitate the assay or analysis of their contents. In these products it is essential that there will be retention of the total integrity of the primary chamber so that there can be no loss or release of any potentially infectious material. Within these design limitations there could be break-lines or any other systems that would enable complete separation of the two chambers.In one particular variation of this design there could be duplicate membranes in very close proximity so that on separation virtually no material would be lost from the secondary chamber. Once separated the primary chamber could be placed in one or more additional secondary chambers or immediately sterilised while the safe compartment can be handled with minimum risk.

By way of example only we will now describe in more detail specific design features which may be present in specific types of apparatus covered by this patent.

EXAMPLE 1 For a particular group of applications blood etc. will be collected, using standard clinical aseptic methods, into a new design of blood collecting tube. Part of the wall of this tube will consist of a semipermeable membrane, common with a second chamber. As already considered, if this membrane were constructed from Visking (TM) tubing it would have a pore size of approximately 10,000 Daltons which will totally retain any bacteria and viral particles within the primary chamber but will allow the free passage of sugars, electrolytes and most hormones into the second chamber. In use, appropriate reagents will be added to the open second chamber. Using appropriate physical and chemical methods, substances to be tested will enter the second chamber and so allow them to be detected and or quantified.In this situation once equilibrium has been reached, aliquots of this diluent can be removed in complete safety to carry out routine chemical analysis. By using defined quantities of blood and reagents the system becomes quantitative.

A specific example of this design of tube, for use as a new design of blood collection and assay tube will now be described in more detail. In this example the external dimensions of the combined primary and secondary chambers are similar to existing standard blood collecting tubes. Into the primary chamber blood is deposited by the use of any standard method (including slight negative pressure via a septum the cap). This is formed as the upper part of the combined tube. The lower part of this primary chamber, consisting part of a semi-permeable membrane, projects into the secondary chamber. The latter is joined externally to the primary chamber by a water tight screw fit and consequently the walls of this tube would give physical protection to the projecting semi-permeable membrane. In the laboratory reagents could be added (quantitatively or qualitatively) to this secondary chamber by temporarily unscrewing the interface between the two tubes. It should be obvious to those who are expert in this field that this secondary chamber could be preloaded with solutes or even solvents. If the latter was in place at the time the blood was added then movement of solutes and solvents would commence as soon as the blood sample was added to the primary chamber. This would minimise the time between collecting the blood and being able to carry out any analysis on the samples.

EXAMPLE 2 For simple non-quantitative tests, e.g the detection of glucose in the blood, apparatus will be designed in which a small quantity of inert but osmotically active substance is combined with the test reagent and is placed in the second chamber so that it is in contact with the semipermeable membrane.

This will draw the solvent (containing for example dissolved glucose) across the membrane where chemical analysis can be completed.

EXAMPLE 3 For the detection of viral infections many tests depend on antibody/antigen reaction. For this application a larger but still viral excluding pore size would be used and the appropriate test reagents would be actively transported into the sealed primary chamber.

EXAMPLE 4 Fecal samples are frequently collected using applicators that are inserted into or around the rectum. These applicators are, using existing technology, transported to the appropriate laboratory in an additional sleeve/cover which is then removed so that the fecal material can be sampled or analysised.

Using our invention part of the wall of this protective sleeve would incorporate a selective membrane through which these test would be carried out with significantly improved safety.

To help understanding of the invention, various specific embodiments thereof will now be described by way of example and with reference to the accompanying drawings.

In these drawings the following abbreviations have been used: PC The primary chamber(s) in which potentially toxic or infections material remains sealed in.

SC The secondary chamber(s) from which solutes or solvents can be removed or added with reduced risk to the operator.

Me The membrane(s) that separate the primary and secondary chambers.

Figure 1 This illustrates one of the possible methods of use of the container. In this example reagents from the secondary chamber, of lower molecular weight than the material that must on safety grounds be retained in the primary chamber, pass into the primary chamber to interact with its contents.

Figure 2 This illustrates one of the possible methods of use of the container. In this example material from within the primary chamber, of lower molecular weight than the material that must on safety grounds be retained in the primary chamber, pass out of the primary chamber to interact with material in the secondary chamber.

Figure 3 This illustrates a possible design of the container in which the membrane is restricted to the upper part of the chambers.

Figure 4 This illustrates a possible design of the container in which the membrane is restricted to the lower part of the chambers.

Figure 5 This illustrates a possible design of the container in which the distance between the faces of the chamber(s) is (are) exactly 1 cm apart and where the material of the chambers at this point are manufactured to a specification applicable for use in a spectrophotometer or similar instrument. This can be seen in "view B" where the container is shown in side view with respect to the chambers.

Figure 6 This illustrates a possible design of the container in which the contents of the primary chamber can be examined using an inverted microscope.

Figure 7 This illustrates a possible design of the container in which graduations are made on the walls on the chamber(s) to improve precision and/or accuracy of any analysis that may be carried out.

Figure 8 This illustrates a possible design of the container in which there is a single common primary chamber and two or more secondary chambers.

Figure 9 This illustrates a possible design of the container in which there are two or more primary chambers and a common single secondary chamber.

Figure 10 This illustrates a possible design of the container in which the primary and secondary chambers can be separated and in which each has its own membrane but in which the membrane that is part of the primary chamber will retain any toxic or dangerous material.

Claims

1A container for testing a sample containing potentially infectious, toxic or dangerous material, the container comprising: one or more primary chambers for for retaining potentially infectious, toxic or dangerous substances, one or more secondary chambers linked to the primary chamber(s) via at least one common wall, one or more semi-permeable membranes forming at least part of the common wall(s);; the arrangement being such that using appropriate chemical, physiochemical or physical methods, test reagent(s) in the secondary chamber(s) having a lower molecular weight (or effective molecular diameter) than the cut-off point of the membrane, pass through the membrane(s) and react with the sample(s) within the primary chamber(s) whilst potentially infectious, toxic or dangerous material of higher molecular weight or effective molecular diameter are retained within the primary chamber(s) or a lower molecular weight fraction from the primary chamber(s) pass into the secondary chambers for reaction with reagents therein.

2 A container as claimed in claim 1, wherein the semipermeable membrane is in the upper part of the common wall so that it was less likely to be subjected to significant forces during centrifugation or other separation procedures.

3 A container as claimed in claim 1, wherein the semipermeable membrane is placed near the base of the tube so that during centrifugation or other separation procedures the movement of solutes and solvents across the membrane was enhanced.

4 A container as claimed in claim 1 or claim 2, wherein the primary chamber(s) with the material retained therein are separable from the secondary chamber(s).

5 A container as claimed in claim 4, wherein the majority of the primary chamber is of semipermeable membrane and this and its contents can be capable of being removed or moved from one secondary chamber to the next.

6 A container as claimed in any preceeding claim, wherein at least one of the chambers is of clear material to allow the contents to be seen and if required directly facilitate the direct assay of their contents in any part of the electromagnetic spectrum.

7 A container as claimed in claim 6 wherein there is an optically clear wall portion of one of the chambers to facilitate the direct examination of their contents using a microscope, preferably in inverted microscope via the optically clear wall portion.

8 A container as claimed in any preceeding claim, including a single primary chamber connected to multiple secondary chambers so that more than one separate assays could be determined on the contents of the same primary chamber.

9 A container as claimed in any preceeding claim, including multiple primary chambers connected to a single secondary chamber so that multiple identical or dissimilar assays could be carried out at the same time but using a common pool of reagents.

10 A container as claimed in any preceeding claim, wherein one or more of the chambers includes means for adding or removing a specific volume or mass of reagent or biological material 11 A container as claimed in any preceeding claim, including means for enhancing the speed and/or mass of movement of contents through the semipermeable membrane.

14 A container as claimed in any preceeding claim, wherein the semipermeable membrane is coated or treated to enhance or inhibit the movement of specific solutes or solvents.

15 A container as claimed in any preceedding claim, wherein the membrane is reinforced, strengthened or supported to reduce the chance of it being accidentally damaged or compromised.

16 A container as claimed in any preceeding claim, wherein some or all of the chambers are pre-loaded with dried reagents prior to its use.

17 A container as claimed in any preceeding claim, wherein some or all of the chambers are pre-loaded with living or dead reference microorganisms to increase the ease of the identification of related microorganisms.

18 A container as claimed in any preceding claim, wherein some or all chambers contain substances which act as an osmotic driver and/or dialysing substance to enhance the movement of solvent across the semipermeable membrane in any appropriate direction.

19 A container as claimed in any preceding claim, wherein some or all chambers contain substances which are capable of rehydration or are hygroscopic and so enhance the movement of solvent across the semipermeable membrane in any appropriate direction.

20 A container as claimed in any preceeding claim, wherein the secondary chamber(s) is/are open to allow for the removal and/or rinsing and/or dilution of all or part of its contents.

21 A container as claimed in any preceeding claim, wherein one or more chamber contains chemical or physical binding agents that bind specific substances to reduce the movement of all or specific components that would normally move across the semipermeable membrane and/or reduce their participation in subsequent chemical reactions.

22 A container as claimed in any preceeding claim, wherein two or more chambers are placed in sequence each separated by a semipermeable membrane which may have similar or dissimilar properties and structure.

23 A container as claimed in any preceeding claim, wherein one or more of the chambers contains a device for indicating that a specific volume of liquid was present in any particular chamber to enable quantitative or at least semi-quantitativeassays to be carried out.

24 A container as claimed in any preceeding claim, wherein one or more of the chambers contain a specific substance that provides visible, chemical or physical evidence that there had been a breach of the integrity of the primary chambers.

25 A container as claimed in any preceeding claim, wherein multiple membranes are present to reduce the chance of leakage.

26 A container as claimed in any preceeding claim, wherein the hygroscopic or similar acting substance is included in the secondary chamber(s) to concentrate the material in the primary chamber(s).

27 A container as claimed in any preceeding claim, wherein dry solutes or complete solutions are retained in a sub-compartment separated from one or more of the chambers by a burstable septum which can be broken at an appropritate time without affecting the total integrity of the whole chamber.

28 A method of testing a sample containing potentially infectious, toxic or dangerous material, the sample being contined in the or one of the primary chambers of a container as claimed in any one of the preceeding claims, the method including the step of allowing material initially present in the primary chamber(s) and having a lower molecular weight (or effective molecular diameter) than the cut-off point of the membrane to pass through the membrane and react with material within the secondary chamber(s) whilst potentially infectious, toxic or dangerous material of higher molecular weight or effective molecular diameter are retained within the primary chamber(s).

29 A method of testing a sample containing potentially infectious, toxic or dangerous material, the sample being contined in the or one of the primary chambers of a container as claimed in any one of the preceeding claims, the method including the step of allowing material initially present in the secondary chamber(s) and having a lower molecular weight (or effective molecular diameter) than the cut-off point of the membrane to pass through the membrane and react with material within the primary chamber(s) whilst potentially infectious, toxic or dangerous material of higher molecular weight or effective molecular diameter are retained within the primary chamber(s).

30 A method as claimed in claim 28 or claim 29, including the preliminary step of culturing living organisms in the primary chamber(s) prior to their identification.

31 A method as claimed in claim 28 or claim 29 or claim 30 in which subsequent to testing a disinfecting substance is added to the secondary chamber(s) and allowed to permeate through the semipermeable membrane to the primary chamber(s).