WO2004053161A1

WO2004053161A1 - Method for identification and/or authentication of articles

Info

Publication number: WO2004053161A1
Application number: PCT/GB2003/005423
Authority: WO
Inventors: Pedro Kringen; Haavard Holstad
Original assignee: Hapemo Da; Webber, Philip, Michael
Priority date: 2002-12-12
Filing date: 2003-12-12
Publication date: 2004-06-24
Also published as: AU2003290258A1

Abstract

The present invention relates to a method for identification and/or authentication of articles and objects by utilizing nucleic acid molecules, specifically aptamers. Thus, the invention provide a method of overcoming problems with counterfeits, imitations and forgeries. Furthermore, the invention provides aptamers for use in identification and/or authentication and related kits, apparatus and articles.

Description

METHOD FOR IDENTIFICATION AND/OR AUTHENTICATION OF

ARTICLES

The present invention relates to a method for identification and authentication of articles and objects using nucleic acid molecules, specifically aptamers. Thus, the invention provides a method of overcoming problems with counterfeits, forgeries and imitations, and a method to derive other information from an object, such as its date of production, its batch number, etc.

At the global level, it has been estimated that 5-7% of world trade is counterfeit with an estimated cost for those concerned of EUR 200-300 billion , er annum. The scale of counterfeiting and imitations is huge and is still growing fast (Final Report on Responses to the European Commission Green Paper on Counterfeiting and Piracy, 7 June 1999).

Prices of legitimate goods generally reflect the value put on their design (as in the case of luxury goods); the cost of research and development (e.g. pharmaceuticals); and the value of a trade mark and market position built up through years of advertising and successful trading, and of course of consumers' demand. Once a product is diverted out of the authorized channels of distribution, where merchandise is acquired, stored and transported under unknown conditions, and by unauthorized individuals, its authenticity, quality, and efficiency may be questionable.

The impact on companies through substantial profit losses is also clear. Products of questionable authenticity, efficacy and safety may be offered for sale at traditional retail outlets, leaving the consumer virtually unprotected. Thus, the risk to consumer health and safety may be significant for e.g. pharmaceuticals, toys, spare parts and in food products.

Thus, there is still a considerable need for methods to secure the identity and authenticity of various products, and to protect these products against product copying and diversion. In addition, high potential counterfeiting gains motivate counterfeiters to invest large sums of money and resources to defeat anti- cόunterfeit measures.

Hitherto, various techniques have been used to identify products in an effort to reduce and trace counterfeits and imitations, including the use of nucleic acids as marker molecules. The primary steps in these methods have been to apply nucleic acids onto the object or in the solution or composition to be marked, and then to identify the marked objects by using nucleic acid probes whose sequences are complementary to that of the target nucleic acid applied onto or into the object, and wherein the probe is capable of hybridizing to the targeted nucleic acid sequence. Different methods are available and used for detecting the formed double stranded oligonucleotide.

For example, US 5,139,812 discloses a crypto -marking method for protection of valuable objects in which a target chemical compound suitable for subsequent detection by appropriate detection means is applied to the objects to be marked, wherein the method comprises preparing a solution of a target nucleic acid having a sequence selected to form a marking pattern and possessing a selected degree of fluidity; incorporating a chosen quantity of the solution in each object to be marked and thereby making it possible to identify and authenticate the object by using means for detecting the nucleic acid in order to reveal the marking.

Also, US 6,030,657 relates to the labelling of objects for verifying authenticity and to the use of selectively-perceptible marks for the labelling of objects. In one embodiment, the mark comprises encoded DNA bases.

Free nucleic acids on these objects will however be exposed to nucleases and different kinds of chemicals in the surroundings. Thus, the main problem by applying unprotected nucleic acids onto an object of interest is degradation of the unprotected nucleic acids. When an object which has been marked with a nucleic acid sequence is exposed to the complementary strand for identification, a false negative result is likely to be obtained because the nucleic acid may have been degraded and/or destroyed. One attempt to overcome this problem is to protect the nucleic acid by encapsulation of the nucleic acid as described in US 3,030,657.

Furthermore, November AG provides an anti -counterfeit method where nucleic acids are used to mark articles of manufacture, cf. http://www.november.de/pages/pdf/November brandprotection VI 102dc.pdf. This method is also based on identifying marked objects by providing hybridization of the nucleic acid sequence fixed or added to the object with the complementary nucleic acid structure. In the product information available on the web, it appears that the nucleic acids used as markers are incorporated into porous cellulose covered by a protective foil which then constitutes a tag which may be fixed to the object of interest.

Also, NO 1999 5917 discloses a method wherein it is determined whether an object or fluid has been marked with a specific marker. The marker may inter alia be a nucleic acid sequence, and in one preferred embodiment the marker is a alphanumeric code, i.e. the specific nucleotide sequence constitutes a specific code. Further, a microscopically-detectable amount of cellular particles are present on or in the object to be marked, and wherein the cellular particles include bacterial or fungal spores. The specific marker may also be present inside the cellular particles.

The present inventors have surprisingly discovered that a specific class of oligonucleotides called aptamers may be utilized in the identification and/or authentication of objects. More precisely, when the authentication of an object of interest is to be proven, the present invention utilizes aptamers which recognize and bind to the object with a high specificity and affinity. In the moment of identification, the selected aptamers are applied onto or into the object, and the aptamers then bind directly to the object per se (via an inherent ligand) or to a specific molecular ligand fixed onto, added to or present in the object of interest. Thus, aptamer-target complexes are formed which then can be detected by a variety of suitable methods. A key advantage of the method of the invention is its sensitivity. In particular, the use of aptamers allows high degrees of sensitivity to be achieved at low costs.

Suitable markers may be attached to the selected aptamers and may make the aptamer-target complexes visible or detectable by appropriate means, depending on the specific marker to be used. In preferred embodiments, th e ligands are made visible to the user, thus allowing simple authentication of an article without the need for complex or bulky detection apparatus.

As a consequence of the fact that the nucleic acid molecules, i.e. the aptamers, are not applied prior to the moment of identification, the present invention overcomes the common problem with degradation of the naked, unprotected nucleic acids. Accordingly, as distinct from the prior art, the present invention provides a novel system wherein the specially-adapted aptamers according to the present invention are utilized and wherein said aptamers are applied to the object of interest in the moment of identification and do not have to be constantly present on or in the object of interest.

Furthermore, the present use of aptamers according to the invention is less expensive than other previously-known PCR-based decoding methods and is very simple to perform. The detection may be performed in situ and it is not dependent on complex and expensive laboratory equipment. The identification system and method according to the present invention are also very user- friendly, i.e. no knowledge of the identification technology is necessary to be able to carry out the method of identification according to the present application.

So far, the relevant prior art has mainly been focused on utilizing aptamers in biological systems, such as in therapeutics, drug discovery and in vitro and in vivo diagnostics and methods for analysing various chemical compounds in specimens and samples, cf. US 5,475,096, US 6,261,774, US 6,225,058, US 6,207,388. Accordingly, the invention provides a method for identification and/or authentication of an article by detecting the presence of one or more ligands which are present on or in the article, characterised in that the method comprises the steps of:

(i) bringing one or more aptamers that specifically bind to one or more of the said ligands into contact with the article in order to form one or more aptamer-ligand complexes; and

(ii) detecting the presence or absence of bound aptamers or aptamer-ligand complexes on or in the article.

The invention also provides a method for detecting one or more ligands which are present on or in an article, characterized in that the method comprises the steps of:

The methods of the invention preferably include the further step prior to step (i) of:

(a) selecting one or more suitable ligand(s) which are inherent structures on or in said article or which have been fixed, added or applied directly or indirectly to said article.

The term "aptamer" as used herein means a single and/or double stranded nucleic acid molecule (RNA, DNA, RNA/DNA, PNA, etc.) which through its specific three-dimensional structure is capable of binding to a ligand on or in an article of interest and thus forms an aptamer-ligand complex.

In other terms, an aptamer may be described as a nucleic acid ligand. Preferably, the aptamer is a single-stranded nucleic acid molecule. Preferably, the aptamer is a DNA molecule. Most preferably, the aptamer is a single-stranded DNA molecule.

The aptamers of the invention have a specific binding affinity for a ligand or target which is present on or in the article to be detected or for a ligand or target which may be fixed, added or applied to the article to be detected.

The present invention utilizes specific aptamers to identify articles of interest. Aptamers have a unique nucleic acid sequence that may or may not be modified (for example, modification of the nucleotides, e.g. 2'OH methylation, modification of the 3 ' or 5' termini or the phosphodiester group etc.). Aptamers form non-covalent bonds with a target ligand, thus forming an aptamer-ligand complex. Any modification of the aptamer which retains the ability of the aptamer to bind to its target with a specific binding affinity is included within the scope of the invention.

Detection of aptamer-target /aptamer-ligand complexes is, unlike PCR-detection and enzymatic amplification, not dependent of molecular amplification,

Fluorescence Resonance Energy Transfer (FRET) or on Watson -Crick base pairing. Like peptides and proteins, aptamers have a secondary and tertiary structure. Each aptamer folds in a unique conformation. Due to its specific conformation, an aptamer recognises and binds its target molecule with high affinity and specificity. Thus, the specific conformation of an aptamer depends on the unique nucleic acid sequence of the aptamer. Thus, a variety of different aptamer sequences yield a variety of molecules with different secondary and tertiary structures and conformations, wherein each aptamer may bind to a specific target molecule. Also, any molecule of any size could, essentially, serve as a target molecule for an aptamer.

As mentioned previously, aptamers may bind to their target molecules with a very high affinity and specificity. Aptamers may in fact be far more specific than for example antibodies, and may have 3 to 4 orders of magnitude higher specificity as regards discrimination of stereoisomers. Accordingly, since an aptamer binds its target molecule with such extremely high specificity and affinity, very low levels of target molecules can be present to detect an article of interest.

The aptamers of the invention are of a length that allows them to bind to t he target with high specificity and affinity. Preferably, the aptamers are 30 -200 nucleotides in length, most preferably 50-100 nucleotides and particularly preferably 70-80 nucleotides in length. It is also possible to identify and delete parts of the aptamer sequence that are not essential for the binding characteristics of the aptamer.

For a review on aptamer technology in general, see Jayasena, 1999, "Aptamers: An Emerging Class of Molecules That Rival Antibodies in Diagnostics ", Clin. Chem. 45:9, 1628-1650 and Hermann and Patel, 2000, "Adaptive Recognition by nucleic Acid Aptamers" , Science, vol. 287, pp. 820-825, Wilson and Szostak, 1999, "In Vitro Selection of Functional Nucleic Acids", Annu. Rev. Biochem., 68: 611-647, Eaton et al., 1997, "Post-SELEX Combinatorial Optimization of Aptamers", Bioorganic and Medicinal Chemistry, vol. 5, no.6, pp 1087-1096, Charlton and Smith, 1999, "Estimation ofSELEXpool size by measurement of DNA renaturation rates", RNA, 5: 1326-1332.

The terms "objects" and "articles" are used interchangeably herein and are intended to cover any product that may be identified and/or authenticated using the system and methods of the present invention. The invention particularly relates to consumer products where tampering or counterfeiting is a problem. The terms "objects" and "articles" are intended only to cover macroscopic products, for example consumer goods, household products, merchandise and the like, i.e. products that are visible to the unaided eye. The terms "objects " and "articles" are not intended to cover microscopic products such as isolated cells and cells grown in culture. Furthermore, the term "article" does not refer to the active component of therapeutic and/or diagnostic methods. The term "article" may, however, refer to the pharmaceutical product itself, i.e. to a tablet, blister - pack, container, etc. The terms "objects" and "articles" cover, but are not limited to, electronic products for example computers, printers, monitors, televisions, hard -drives, servers, audio and video equipment, DND -players, cameras, mobile phones and personal organizers; recording media, for example, records, audio and video tape cassettes, floppy disks, CD-ROMs, DVDs, diskettes, flash cards, whether blank or containing recorded information; jewelry, for example, watches; sunglasses; clothing, such as designer or branded clothing; perfumes and after -shaves; tobacco products, for example, cigarettes and cigars; automobile and airplane parts; documents such as securities-like stock certificates, wills, identification cards, passports, drivers' licenses, bank ID cards, social-security cards, credit cards and money; pharmaceuticals and medicines in any form, and their packaging; and food and food packaging, etc. The article may also be a liquid, fluid or solid composition, e.g. oil, solution, perfume, paint, chemical compositions and powders etc., or a mixture or composition of one or more compounds or ingredients. Such a mixture might be a liquid or a powder, for example.

In one preferred embodiment of the invention, the ligand is added directly or indirectly to a pharmaceutical or veterinary product or to the product packaging. Thus the ligand may be present directly on the medicine, for example on a tablet or capsule. Alternatively, the ligand may be present on the blister -pack, container, label or other packaging.

In one embodiment of the invention, the article is a liquid, such a drink, for example an alcoholic drink such a wine, beer or lager.

In another embodiment, the article is an antique, work of art or collectable, for example a painting, sculpture, ceramic, pottery, vase, furniture, carpet, tapestry, book, engraving, etc.

In some embodiments of the invention, the article is a food product, for example poultry, beef, pork, lamb, fish, etc. or a plant product. In such cases, the method of the invention may be used to trace the origin of the food product. In most embodiments of the invention, the aptamers will not be bound to a solid support.

The term "selecting one or more suitable ligand(s)" is intended to encompass either a mental choice of suitable ligand(s) or a physical selection of suitable ligands, for example, using a SELEX procedure.

The term "ligand" or "target" as used herein means a chemical entity or compound, molecule or structure that an aptamer may recognise and form an aptamer-ligand or aptamer-target complex with when the aptamer is applied onto or added into the article. In other words, the "ligand" or "target" is any chemical entity which is capable of being specifically recognized by an aptamer. The person skilled in the art will readily appreciate that the invention is capable of being worked with any such ligand. Processes for synthesizing aptamers against specific chemical entities are well known in the art; they are also referred to below.

The ligand may be an organic compound, inorganic compound, hydrocarbon, protein, peptide, carbohydrate, polysaccharide, glycoprotein, hormone, receptor, antibody, antigen, drug, metabolite, cofactor, dye or any other entity which is capable of being specifically recognized by an aptamer. The ligand may also be an optical isomer, for example an enantiomer, diasteriomer or epimer. In some embodiments of the invention, the ligand may be a branched molecule with chemically diverse substituents or a linear polymer. In other embodiments, the ligand may be a compound which can covalently be bound to other molecules.

In one embodiment of the invention, the ligand is sulfadiazine or a derivative thereof.

The invention is not intended to encompass embodiments wherein the ligand is a nucleic acid molecule or a derivative thereof. In particular, the ligand is not a nucleic acid molecule having a sequence which is complementary to that of the aptamer in question. The ligand may be an inherent structure in or on the article of interest, i.e. the ligand may be one which is originally or naturally present in or on the article. Thus the ligand may be present on a surface of the article, for example an exterior surface of the article or an interior surface of the article. In other embodiments of the invention, the ligand may be present in the article, thus requiring the exposure of the ligand before detection. In some embodiments of this aspect of the invention (i.e. wherein the ligand is an inherent structure in or on the article), the article is a non -biological article or the article does not consist only of biological material, for example, the article is not a cell or a protein.

In embodiments of the invention wherein the ligand is an inherent structure on or in the article, the ligand may serve as an indication of the quality of the article or an indication of its origin, i.e. whether it is an original article or a forgery or counterfeit article. In some recycling schemes, it is important to ensure that only original components are reused; the method of the invention may be used in such schemes.

In yet further embodiments of the invention, the ligand may be one which is not originally or naturally present on the article but which has been fixed, embedded, added or applied directly or indirectly to the article. For example, the ligand may be applied directly to the article by printing, spraying, painting or injection, for example, using an ink -jet, bubble-jet or beam laser printer, with an aerosol spray or using a paint.

In other embodiments, the ligand might have been added to the product during the manufacturing process.

The invention particularly relates to an article to which has been attached a label or tag which comprises a ligand which is capable of being specifically recognized by an aptamer. In most cases, the ligand will be presented on the label or tag in a position which is capable of being bound by the aptamer, for example on its surface. In other cases, the ligand may be embedded in the label or tag. The label or tag may be made of any suitable material, including paper and cloth; and fixed, applied, embedded or added to the article in any suitable manner. Examples include paper labels which may be fixed to an articl e using adhesive means and a label which may be sewn or glued to an item of clothing. Such a label or tag device may be made of various polymers etc. The ligand may be fixed, embedded, added or applied directly or indirectly to the label or tag, for example using one or more of the methods described above.

Furthermore, the ligand may be a specific contaminant, pollutant or impurity in an article of interest, either one that is present naturally present in the article or one that has been added to it.

Ligands are preferably chosen or designed to satisfy special demands such as non-toxicity, stability (e.g. acid-base stable), size, reactive groups, pH stability, novelty, uniqueness (e.g. (R) vs. (S) configuration), cost etc.

In some embodiments of the invention, it is preferred that the ligands are present on or in the articles of interest in such a way that a specific pattern, logo, bar code, combination of numbers, letters or colours are revealed upon detection of the aptamer or aptamer-ligand complex.

Preferably, the true identity and structure of the ligand is only known by the company that manufactures and markets the articles of interest, i.e. the ligand may be an industrial secret.

In some embodiments of the invention, more than one selected ligand is used, i.e. the invention also relates to methods, articles, apparatus and kits, etc. wherein more than one ligand is present on or in the article. The selected ligands may be the same or different. If the selected ligands are different, this would require the use of more than one aptamer to verify the authenticity of the article. This adds an enhanced level of security to the methods, articles, apparatus, kits, etc. of the invention.

The present invention also relates to articles which have one or more lig ands present thereon or therein, wherein one or more aptamers are bound to the ligand or ligands. The comments given above with regard to the aptamers, ligands and markers, etc. apply to such articles, mutatis mutandis. In embodiments of the invention where the ligand is not an inherent ligand, i.e. the ligand is added to the article, label or tag, the ligand may be associated with the article, label or tag by any suitable means, for example, the ligand may be covalently bound to the article, label or tag, or absorbed or adsorbed thereto.

The aptamer-ligand complex may be identified or detected using a specific marker or markers which is/are attached to the aptamer(s) directly or indirectly, or which recognize the aptamer or the aptamer-ligand complex.

The term "marker" as used herein may be any compound or entity that is suitable for the purpose of detecting or identifying the aptamer or aptamer -ligand complex.

The marker may be detected using any suitable means. For example, the marker might be visible to the human eye. Alternatively, it may become visible or recordable/detectable by the use of e.g. means for detecting IR, UN, vision, smell, sound, temperature, radioactivity, any kind of radiation, electricity, etc. Νon-restrictive examples of suitable markers include fluorochromes, daylight fluorescent pigments, radioactive isotopes, pigments, dyes, electrical signals, metals, etc.

Furthermore, as mentioned above, the marker may be bound to the aptamer or it may be capable of binding to an aptamer or aptamer-ligand complex. A marker which forms a complex with an aptamer-ligand complex may be, but is not limited to, e.g. fluorescent compounds, antibodies, compounds that may be detected by enzymes etc. The detection means might optionally include an amplification process, such as biotin-streptavidin.

In one embodiment of the invention, the marker is a gold or silver particle. Preferably, the marker is detected by means of immunogold silver staining, for example using the LI Silver Enhancement Kit made by Mol ecular Probes, Inc. (Kit no. L-24919).

Aptamers are preferably screened according to the SELEX method (Systematic Evolution of Ligands by Exponential enrichment), cf. US 5,475,096 and US 6,261,774, Jayasena, supra. Briefly, SELEX is a method where very large combinatorial libraries of oligonucleotides are screened by an iterative process for in vitro selection and amplification. Firstly, a chemically synthesized random sequence DNA library containing approximately 10¹⁴-10¹⁵ individual molecules having a contiguous randomized sequence flanked by fixed sequence regions is synthesized. Since aptamers are also identified from RNA libraries, the DNA library is subsequently converted to a RNA library by an in vitro RNA synthesis well known to the person skilled in the art. When such a DNA or RNA library is provided, random sequences of oligonucleotides (RNA or DNA) from the library is exposed to the target of interest under defined buffer conditions. Sequences that bind to the target (aptamer candidates with both high and low affinity) are separated and amplified by PCR, and additional rounds of selections are performed until affinity saturation is obtained in an enriched library. Then, the corresponding PCR products are used for cloning and sequencing.

Methods of binding aptamers to markers are well known in the art.

When the article of interest is a solid product (as opposed to a liquid product), the aptamers may be applied to the article in the moment of identification by using any device for delivering oligonucleotides to solid objects known to the person skilled in the art and inter alia described in US 6,235,473. More exactly, US 6,235,473 discloses a device for delivery of oligonucleotides, i.e. a gene pen. Further, November AG (Identif Technologies) markets an anti-counterfeit system wherein oligonucleotides are applied onto a label comprising a complementary oligonucleotide using a pen-like device, cf. http://www.november.de/pages/pdf/november brandprotection Nl 102dc.pdf.

The present invention also relates to an apparatus for dispensing aptamers, comprising at least one reservoir containing a composition comprising aptamers of the invention, fluidly -connected to means for dispensing the composition. Preferably, the apparatus is a pen, spray, sponge or printer. Most preferably, the pen comprises a reservoir containing a composition comprising aptamers of the invention (optionally attached to a marker) and a head for dispens ing the aptamers, the reservoir being fluidly connected to the head. The composition may optionally also comprise one or more of a buffer, preferably a stabilizing buffer, and a preservative.

In some embodiments of the invention, the aptamers which have bound to the ligand may be removed or their binding to the ligands may be disrupted. This can be done by the addition of an excess of the ligand to which the aptamer binds; the addition of an excess of nucleic acid (preferably DNA) which has a sequence which is complementary to that of the aptamer; or by the addition of a destabilising salt/pH solution, which disrupts the interaction between the ligand and the aptamer. The invention therefore relates to apparatus, for example a pen, which is capable of delivering one or more of the above.

Thus the invention also relates to an apparatus, preferably in the form of a pen, spray, sponge or printer, which comprises at least two reservoirs, wherein a first reservoir contains a composition comprising aptamers of the invention and a second reservoir contains a composition for disrupting the binding of an aptamer of the invention to a ligand to which it is capable of binding, such as those mentioned above. In other embodiments of the invention, the apparatus additionally comprises a third reservoir which contains a composition for enhancing the detection of any aptamer-ligand complexes. Each of the reservoirs is fluidly connected to one or more heads capable of independently or combinatorially delivering the compositions in the reservoirs to the article.

The method of the invention may also be used in an automated system.

The method may also be used to verify whether or not articles have been tampered with during the manufacturing or packaging of the article. For example, the authenticity of the article may be checked at a number of stages during the manufacturing and/or packaging process. This is particularly important if these processes occur on more than one site.

When the article of interest is a solution or preparation, the aptamer-complex may be isolated by first connecting the aptamers to magnetic beads by methods well known to the person skilled in the art. After the magnetic beads coated with the aptamers to be used have been added to the solution, the formed magnetic beads-aptamer-ligand complexes are easily separated from the solution by utilizing a suitable magnet, and the aptamer-ligand complex may be detected in a manner according to the marker which is used.

Another possibility, when checking the authenticity of a solution is to use more that one aptamer selected to bind to specifically selected ligands intrinsic and/or added to the solution may be used. One aptamer may bind more than one ligand by combining two independent aptamers. For example, aptamer A is selected against ligand A; aptamer B is selected against ligand B. A and B are combined and by simultaneous binding to ligand A and ligand B, the complex can be detected by precipitation, spectrophotometry, optical measurements, or other suitable means.

Also, aptamers may be used in quality control, i.e. negative identification. Then one uses aptamers that binds specifically to ligands that should not be present or found in the item of interest. The presence of unwanted ligands reveals that the item is not pure. Since the chosen aptamers are very selective and bind to the ligand with high affinity, very small amounts of the unwanted ligands can be detected.

Also, aptamers may be used in quality control of specific objects of interest, i.e. positive identification. Aptamers which bind to the ligand(s) that are intrinsic to the object of interest are preferably selected through the SELEX method and used in the identification process. Said object may be solid, liquid or gas. In this system, aptamers can be used to positively identify products made from quality material from fake products made of different materials.

Thus the invention also provides a method of quality control, wherein the presence or absence of one or more ligands on or in an article is detected, characterized in that the method comprises the steps of:

(i) bringing one or more aptamers that specifically bind to one or more of the said ligands into contact with the article in order to form one or more aptamer- ligand complexes; and (ii) detecting the presence or absence of bound aptamers or aptamer-ligand complexes on or in the article.

Also, according to the present invention, one item may be authenticated more than once by removing the aptamer from the ligand. The aptamers could be removed by addition of a base, acids, salts, enzymes, heat, mechanical force, complementary DNA strand of the aptamer, etc. without destroying the ligand. After the aptamer has been reintroduced to the object of interest, the item can be authenticated once again. In this way, the system and method according to the present invention makes it possible to check the authenticity of the object of interest by the various steps of the product distribution and within the sub - supplier network. The comments given above with regard to the aptamers, ligands and markers, etc., apply to such methods, mutatis mutandis.

The invention also provides a process for modifying an article wherein one or more ligands are present on or in the article, characterised in that the process comprises the step of:

bringing one or more aptamers that specifically bind to one or more of the said ligands into contact with the article in order to form one or more aptamer-ligand complexes.

The comments given above with regard to the aptamers, ligands and markers, etc., apply to such processes, mutatis mutandis.

The invention also provides a kit for identification and/or authentication of an article comprising: (i) an apparatus of the invention; and (ii) a container comprising one or more ligands which are specifically recognized by the said aptamers.

Furthermore, the invention provides a kit for identification and/or authentication of an article, comprising: (i) an apparatus of the invention; and (ii) one or more labels or tags which comprise one or more ligands which are specifically recognized by the said aptamers, wherein the labels and/or tags are capable of being attached to the article. Also provided is a kit for identification and/or authentication of an article, characterised in that the kit comprises one or more aptamers which selectively bind to one or more ligands which are inherently present on or in the article. The invention also provides a kit for identification and/or authentication of an article, characterized in that the kit comprises: (i) a container comprising one or more aptamers; and (ii) one or more labels or tags which comprise one or more ligands which are specifically recognized by the said aptamers, wherein the labels and/or tags are capable of being attached to the article. Preferably, the kit additionally comprises a marker which is capable of binding to the aptamer or to the aptamer-ligand complex. In other embodiments, the markers are covalently or non-covalently attached to the aptamers. The kits might also comprise an apparatus which is adapted for dispensing the aptamers, preferably, a pen, spray, sponge or printer. The features of such apparatus have been described above. In the kits of the invention, the apparatus might contain the aptamers of the invention, or the apparatus might not contain the aptamers of the invention, i.e. the apparatus might be empty. The kits might additionally comprise apparatus for detecting the presence of an aptamer which is bound to a ligand or of an aptamer-ligand complex which is present directly or indirectly on or in the article.

In other embodiments, the invention provides a process for making a kit for the identification and/or authentication of an article, wherein the kit comprises: (i) a container comprising one or more aptamers, and (ii) one or more labels or tags, the process comprising the step of fixing, embedding, adding or applying or associating in any manner one or more ligands which are specifically recognized by the aptamers directly or indirectly to the labels or tags. Preferably, the kit additionally comprises an apparatus for dispensing the aptamers, such as those described herein.

The invention also provides a process for making a kit for the identification and/or authentication of an article, wherein the kit comprises: (i) an apparatus of the invention, and (ii) one or more labels or tags, the process comprising the step of fixing, embedding, adding or applying or associating in any manner one or more ligands which are specifically recognized by the aptamers directly or indirectly to the labels or tags.

The invention further provides a system for identification and authentication of articles of manufacture and/or objects of interest by detecting a ligand, which comprise one or more aptamers that recognize and bind to a lig and present on or in the articles of manufacture, and wherein the aptamer(s) form an aptamer - ligand complex, and wherein said aptamer-ligand complex is visualized or detected due to a marker which optionally is combined with the aptamer or binds to the aptamer-ligand complex.

In one embodiment, the present invention regards a system comprising aptamers that recognize ligands being an inherent structure or compound in or on the articles of manufacture.

In another embodiment, the present invention provides a system comprising aptamers that recognize ligands which originally are not present on or in the article of manufacture but are fixed to the surface of or added into said article and/or object of interest. Preferably, the ligand is non -toxic and acid/base stabile. It is also preferred that ligand are fixed to the articles of manufacture and/or object of interest in such a way that a specific pattern, logo, bar code, combination of numbers, letters or colours are revealed upon detection of the aptamer-ligand complex.

In another embodiment according to the present invention, the aptamers are combined with a marker. Preferably, the said marker is selected from the group consisting of fluorochromes, Daylight fluorescent pigments, radioactivity (isotopes), pigments or dyes. Furthermore, it is preferred that marker is detectable by IR, UN, vision, smell, sound, temperature, radioactivity, any kind of radiation or electric signals.

The article or object according to the present invention may be a solid object or a mixture or composition of one or more compounds or ingredient, e.g. a liquid/solution or a powder. The present invention also provides a method for identification and/or authentication of articles of manufacture and/or object of interest by detecting a ligand, comprising the steps of:

(a) selecting one or more suitable ligand(s) which may be an inherent structure of said articles/objects or may be specifically adapted for said articles/objects;

(b) optionally fixing or adding said ligand(s) onto or into the articles and/or objects;

(c) bringing one or more appurtenant aptamers in contact with said article and/or object to form an aptamer-ligand complex(es); and

(d) detecting said aptamer-ligand complex(es).

Preferably the method comprise the steps of

(a) bringing one or more appurtenant aptamers in contact with said article or object to form an aptamer-ligand complex(es), wherein said aptamer specifically recognize a ligand present in or on said article or object; and

(b) detecting said aptamer-ligand complex(es).

The term "appurtenant aptamer" means an aptamer which through selection has proved to recognize and bind to an object of interest with sufficient affinity and specificity. Thus, the aptamer is appurtenant to the specific ligand wherewith it forms an aptamer-ligand complex.

EXAMPLES

The invention will now be described by way of examples. Although the examples represent preferred embodiments of the present invention, they are not to be interpreted as being restrictive or limiting on the scope of the present invention and the enclosed claims. The preferred solutions used in the following examples are:

Coupling buffer: 0.2M NaHCO₃, 0.5M NaCl, pH 8.3

Binding/washing buffer: 250mM NaCl, 50mM Tris, pH 8.0, 5mM MgCl₂

Column regeneration buffer: 250mM NaCl, 50mM Tris, pH 8.0, lOmM EDTA

Elution buffer: Binding buffer + 100 mg/ml ligand

Example 1:

A. Construction of aptamer library

The library used consisted of ssDNA oligos with fixed 5'- and 3' -ends and a 50 bp randomized central region. The 5'-end region was a T7 promoter and the 3' -end was the complementary strand of a T3 promoter.

dsDNA and/or RNA libraries may also be used in this protocol. In addition 5'-, 3'- and 2'- ends may be modified to enhance or decrease the stability of the aptamers, i.e. by chemical modifications.

1) The complementary strand of the ssDNA strand was extended by mixing T3 primer, Superscript II polymerase, library and dsH₂O followed by incubation at 70°C for 10 min before putting the mixture on ice. The mixture was then heated to 37°C and first-strand-buffer, DDT, dNTP and α-³²P dCTP was added and slightly mixed and incubated at 37°C for 1 hour.

2) Then a second strand synthesis was performed in order to generate a dsDNA library with one biotinylated strand by heating biotinylated T7 primer, dsH₂O and dsDNA aptamer library (from 1)) to 70°C for 5 min before adding first strand buffer, DTT, dNTP, α-³²P dCTP and Superscript II polymerase. This was heated to 42°C for 50 min. 3) The library was amplified by PCR using the T7 and T3 primers, dsDNA aptamer library, dNTP, Thermozyme Polymerase, Thermozyme Buffer and dsH₂O. The mix was denatured at 94°C for 2 min. This was followed by 11 to 17 cycles of 94°C denaturation (30 sec), 53 °C annealing (30sec) and 72°C extension for one minute. A final extension at 72°C for 10 minutes was used followed by 4°C ∞.

PCR purification was carried out according to Qiagen protocol.

DNA Precipitation To a 50 μl PCR-reaction 170 μl (2.5 x volume), 96% EtOH, 2.0 μl glycogen and 21.4 μl 7.5 M NH Ac was added. This was incubated at -80°C for 30 min before centrifugation in a Sorvall SS 34 rotor at 8000 rpm for lh. The DNA was washed with 70% EtOH and dissolved in 300 μl in LoTE (1/3 TE buffer).

Generation of single stranded aptamers

Single Strand Generation was carried out using DynaBeads/GenoVision Beads according to manufacturers' protocol. One additional heating step at 75°C for 5 min was used to elute the aptamers from the beads. The elution solution consisted of 95% (volume) formamide and 5% (volume) 0.5M EDTA in a ratio of 1 :5.33 of "single- stranded-biotinylated-aptamer-on-beads" solution. One ml of the aptamer solution was then precipitated by adding 200 μl 7.5M NFL Ac, 5 μl glycogen (20 mg/ml) and 3x volume 96% EtOH. This was incubated over night at -20°C before centrifugation in a Sorvall SS34 rotor for 30 min at 13 000 rpm. The pellet was washed by 500 μl ice cold 70% EtOH and the centrifugation was repeated. The supernatant was removed before the pellet was dried and dissolved in 100 μl Binding Buffer (described in Amersham Pharmacia Biotech's HiTrap NHS activated column kit).

B. Ligand coupling

By way of example, the ligand of choice was sulfadiazine (4-amino-N-[2- pyrimidinyl] benzene-sulfamide) from Sigma (cat. no. S -3549). Sulfadiazine is a very suitable ligand since it is a non-toxic, generally available, inexpensive, water-soluble compound with several active groups which may be used to couple the ligand to e.g. an object or a solid surface of interest.

Sulfadiazine may also serve as an excellent model for ligands which are fixed onto or added into the object of interest or in cases where the ligands are inherent structures in the said object.

To eliminate aptamers that bound to the column material, the column was pre- absorbed with the aptamers. The aptamers that did not bind to the column were eluted and used in the screening process as described below.

Sulfadiazine was then coupled to a 1 ml HiTrap NHS activated column (Cat. no. 17 - 0716-01) from Amersham Pharmacia Biotech according to the manufacturers' protocol. Standard coupling buffer (0.2M NaHCO₃, 0.5M NaCl, pH 8.3) was used. 10 mg/ml sulfadiazine was dissolved in the coupling buffer. The column was stored in Storage/Regeneration Solution (manufacturer's protocol).

The column may then be blocked with irrelevant DNA (sonicated total DNA) before being used to prevent unspecific binding of DNA.

According to manufacturer's protocol, the Column Coupling Efficiency of Ligand (Sulfadiazine) was 3mM (ca 10% of 10 mg).

C. Screening of aptamer candidates that bind sulfadiazine The screening of aptamer candidates that bind sulfadiazine was performed according to the general principle of the common SELEX method.

The column was prepared by washing with 5 ml Binding Buffer, 8 ml Regeneration Buffer and 10 ml Binding Buffer. The biotinylated ssDNA oligo (aptamer) was then dissolved in 1 ml Binding Buffer. The aptamer/binding solution was incubated for 5 min on the column before washing the column with 10 ml Washing Buffer. One ml Elution Buffer was added to the column and incubated for 5 min before another 5 ml Elution Buffer was applied. The eluate was collected in aliquots of 1 ml and the cpm in each aliquot was measured in a scintillator.

The last 5 five aliquots were pooled and the aptamers precipitated by adding 1 ml 7.5M NH AC, 5 μl glycogen (20 mg/ml) and 3x volume 96% EtOH. This was incubated over night at -20°C before centrifugation in a Sorvall SS34 rotor for 30 min at 13,000 rpm. The pellet was washed by 500 μl ice cold 70% EtOH and the centrifugation was repeated. The supernatant was removed before the pellet was dried and dissolved in 100 μl LoTE.

Towards the end of the selection process, more and more of the aptamers that recognize and bind to sulfadiazine "occupy" the ligand coupled column. At this stage, it is therefore important not to apply to much of the aptamers since one then might lose useful aptamers that are being washed out.

PCR

The library was amplified by using 2 μl from the latest SELEX, 4 μl DMSO, 2 μl of primers (10 pmol/μl), 5 μl BN-Buffer (166 mM (ΝF t)₂SO₄, 670 mM Tris pH 8.8, 67 mM MgCl₂, 100 mM β-mercaptoethanol), 3 μl 10 mM dNTP, 0.5 μl Platinum Taq (5 u/μl) and 31.5 μl dsH₂O. The mix was denatured at 94°C for 5 minutes. This was followed 15 cycles of 94°C denaturation (30 sec), 53°C annealing (30sec) and 72°C extension for 30 sec. A final extension at 72°C for 10 minutes was used followed by 4°C ∞.

The SELEX and PCR procedures were repeated until the aptamers satisfied the quality standards wanted, regarding affinity, on/off rate, specificity, binding time, etc. (9-15 rounds).

Cloning The library was amplified by using 2 μl from the SELEX pool satisfying the desired quality standards, 4 μl DMSO, 2 μl of non-biotinylated primers (10 pmol/μl), 5 μl 10 x BN-Buffer, 3 μl 10 mM dΝTP, 0.5 μl Platinum Taq (5 u/μl) and 31.5 μ 1 dsH₂O. The mix was denatured at 94°C for 5 minutes. This was followed 15-30 cycles of 94°C denaturation (30 sec), 53°C annealing (30sec) and 72°C extension for 30 sec. A final extension at 72°C for 10 minutes was used followed by 4°C oo.

PCR purification was carried out according to Qiagen protocol.

The aptamers were cloned bluntly into a pCR4^®-TOPO^®. Vector and competent cells were from Invitrogen. The individual bacterial colonies harboring unique aptamers were picked and grown in LB medium. DΝA was extracted and sequenced according to standard protocols. The aptamer candidate sequences were aligned and a consensus sequence was found. Individual aptamer candidates can then be applied to a HiTrap column in order to select for the candidate(s) of choice.

The aptamers can further be improved by the use of error-prone polymerases, generation of scrambled consensus sequences and deletion of aptamer 5'- and 3'- ends (affinity maturation).

Example 2: Selection of aptamer candidates

Different candidate aptamers may be tested against various ligands immobilized to different surfaces such as plastics, glass, paper, metals, polymers etc., or dissolved in solutions such as water, oil, oil products, paint, foods, beverages, or organic and inorganic solutions. The aptamers that satisfy the quality standards of choice may then be selected.

Example 3: Assay for the use of aptamers in solid-surface product authentication

Aptamers may be selected to bind to specifically selected ligands attached to the surface of a credit card. The ligands may be applied in such a way that specific pattern, a logo, bar code, combination of numbers, letters or colours appears upon authentication. The ligands may also be concealed by scrambling with almost identical ligands, in respect of chemical and structural properties. These almost identical ligands may be selected so that there are no interactions with the aptamer.

Claims

1. A method for identification and/or authentication of an article by detecting the presence of one or more ligands which are present on or in the article, characterised in that the method comprises the steps of:

(i) bringing one or more aptamers that specifically bind to one or more of the said ligands into contact with the article in order to form one or more aptamer- ligand complexes; and

2. A method for detecting one or more ligands which are present on or in an article, characterized in that the method comprises the steps of:

(ii) detecting the presence of bound aptamers or aptamer-ligand complexes on or in the article.

3. A method as claimed in claim 1 or claim 2, which includes the further step prior to step (i) of:

(a) selecting or identifying one or more suitable ligands which are inherent structures on or in said article or which have been fixed, added or applied directly or indirectly to the article.

4. A method as claimed in any one of the previous claims, wherein the aptamer is a single-stranded nucleic acid.

5. A method as claimed in any one of the previous claims, wherein the aptamer is a DNA molecule.

6. A method as claimed in any one of the previous claims, wherein the aptamer is 30-200 nucleotides in length.

7. A method as claimed in any one of the previous claims, wherein the article is an electronic product, a recording media, jewelry, sunglasses, an item of clothing, a perfume or aftershave, a tobacco product, an automobile or airplane part, a document or money, a pharmaceutical or medicinal product, a food product, a drink, or an antique, work of art or collectable.

8. A method as claimed in any one of claims 1 to 6, wherein the article is a mixture or composition of one or more compounds or ingredients.

9. A method as claimed in any one of the previous claims, wherein the ligand is an inherent structure or compound in or on the article.

10. A method as claimed in any one of the previous claims, wherein the ligand has been fixed, embedded, added or applied directly or indirectly to the article.

11. A method as claimed in any one of the previous claims, wherein the ligand comprises an organic compound, inorganic compound, hydrocarbon, protein, peptide, carbohydrate, polysaccharide, glycoprotein, hormone, receptor, antibody, antigen, drug, metabolite, cofactor, dye or another entity which is capable of being specifically recognised by an aptamer.

12. A method as claimed in any one of claims 1 to 11, wherein the ligand is not a nucleic acid molecule.

13. A method as claimed in any one of the previous claims, wherein the ligand is present on a label or tag which has been attached, fixed or applied directly or indirectly to the article.

14. A method as claimed in any one of the previous claims, wherein the ligand is non-toxic and/or acid/base stable.

15. A method as claimed in any one of the previous claims, wherein the ligand is a contaminant, pollutant or impurity which is either present naturally in or on the article or which has been added to the article.

16. A method as claimed in any one of the previous claims, wherein ligands are present on the article in such a way that a specific pattern, logo, bar code, combination of letters and/or numbers and/or colours are revealed upon detection of the aptamers or aptamer-ligand complexes.

17. A method as claimed in any one of the previous claims, wherein a marker is bound to the aptamer.

18. A method as claimed in any one of the previous claims, wherein the presence of bound aptamers or aptamer-ligand complexes is detected using a marker which is capable of binding to the aptamer and/or the aptamer-ligand complex.

19. A method as claimed in any one of the previous claims, wherein the marker is selected from fluorochromes, daylight fluorescent pigments, radioactivity (isotopes), pigments, dyes and metals.

20. A method as claimed in claim 19 wherein the marker is gold or silver.

21. A method as claimed in any one of the previous claims, wherein the marker is capable of being detected by IR, UN, vision, smell, sound, temperature, radioactivity, any kind of radiation or electric signals.

22. A method as claimed in any one of the previous claims, wherein the presence of bound aptamers or aptamer-ligand complexes is detected using one or more of IR or UV spectroscopy, vision, smell, sound, temperature, radioactivity, any kind of radiation or electric signals.

23. An aptamer for use in a method as claimed in any one of claims 1 to 22.

24. A process for modifying an article wherein one or more ligan ds are present on or in the article, characterised in that the process comprises the step of:

bringing one or more aptamers that specifically bind to one or more of the said ligands into contact with the article in order to form one or more aptamer-ligand complexes on or in the article.

25. An article which has one or more ligands present thereon or therein, wherein one or more aptamers are bound to the ligand or ligands.

26. An article as claimed in claim 25, wherein the aptamer is a single-stranded nucleic acid.

27. An article as claimed in any claims 25 or claim 26, wherein the aptamer is a DNA molecule.

28. An article as claimed in any one of claims 25 to 27, wherein the aptamer is 30- 200 nucleotides in length.

29. An article as claimed in any one of claims 25 to 28, wherein the article is an electronic product, a recording media, jewelry, sunglasses, an item of clothing, a perfume or aftershave, a tobacco product, an automobile or airplane part, a document or money, a pharmaceutical or medicinal product, a food product, a drink, or an antique, work of art or collectable.

30. An article as claimed in any one of claims 25 to 28, wherein the article is a mixture or composition of one or more compounds or ingredients.

31. An article as claimed in any one of claims 25 to 30, wherein the ligand is an inherent structure or compound in or on the article.

32. An article as claimed in any one of claims 25 to 31, wherein the ligand has been fixed, embedded, added or applied directly or indirectly to the article.

33. An article as claimed in any one of claims 25 to 32, wherein the ligand comprises an organic compound, inorganic compound, hydrocarbon, protein, peptide, carbohydrate, polysaccharide, glycoprotein, hormone, receptor, antibody, antigen, drug, metabolite, cofactor, dye or another entity which is capable of being specifically recognised by an aptamer.

34. An article as claimed in any one of claims 25 to 33, wherein the ligand is not a nucleic acid molecule.

35. An article as claimed in any one of claims 25 to 34, wherein the ligand is present on a label or tag which has been attached, fixed or applied to the article.

36. An article as claimed in any one of claims 25 to 35, wherein the ligand is non- toxic and/or acid/base stable.

37. An article as claimed in any one of claims 25 to 36, wherein the ligand is a contaminant, pollutant or impurity which is either present naturally in or on the article or which has been added to the article.

38. An article as claimed in any one of claims 25 to 37, wherein ligands are present on the article in such a way that a specific pattern, logo, bar code, combination of letters and/or numbers and/or colours are revealed upon detection of the aptamers or aptamer-ligand complex.

39. An article as claimed in any one of claims 25 to 38, wherein a marker is bound to the aptamer.

40. An article as claimed in any one of claims 25 to 39, wherein a marker is bound to the aptamer-ligand complex.

41. An article as claimed in any one of claims 25 to 40, wherein the marker is selected from fluorochromes, daylight fluorescent pigments, radioactivity (isotopes), pigments, dyes and metals.

42. An article as claimed in claim 41, wherein the marker is gold or silver.

43. An article as claimed in any one of claims 25 to 42, wherein the marker is capable of being detected by IR, UN, vision, smell, sound, temperature, radioactivity, any kind of radiation or electric signals.

44. Apparatus for dispensing aptamers, comprising a reservoir containing a composition comprising aptamers fluidly connected to composition-dispensing means.

45. Apparatus as claimed in claim 44, wherein the apparatus is a pen, spray, sponge or printer.

46. Apparatus as claimed in claim 45, wherein the apparatus is a pen.

47. Apparatus as claimed in claim 46, wherein the pen comprises at least one reservoir containing a composition comprising aptamers and a head for dispensing the composition, the reservoir being fluidly-connected to the head.

48. Apparatus as claimed in any one of claims 44 to 47, wherein the composition additionally comprises a buffer and/or a preservative.

49. Apparatus as claimed in any one of claims 44 to 48, which additionally comprises a second reservoir, wherein the second reservoir contains a composition for disrupting the binding of the aptamer to the ligand.

50. Apparatus as claimed in any one of claims 44 to 49 which additionally comprises a further reservoir, wherein the further reservoir contains a composition which enhances the detection of any aptamer-ligand complex.

51. A kit for identification and/or authentication of an article comprising: (i) an apparatus as claimed in any one of claims 44 to 50; and

(ii) a container comprising one or more ligands which are specifically recognized by the said aptamers.

52. A kit for identification and/or authentication of an article, comprising: (i) an apparatus as claimed in any one of claims 44 to 50; and

(ii) one or more labels or tags which comprise one or more ligands which are specifically recognized by the said aptamers, wherein the labels and/or tags are capable of being attached to the article.

53. A kit for identification and/or authentication of an article, characterised in that the kit comprises one or more aptamers which selectively bind to one or more ligands which are inherently present on or in the article.

54. A kit for identification and/or authentication of an article, characterised in that the kit comprises:

(i) a container comprising one or more aptamers; and (ii) one or more labels or tags which comprise one or more ligands which are specifically recognized by the said aptamers, wherein the labels and/or tags are capable of being attached to the article.

55. A kit as claimed in claim 53 or claim 54 wherein the kit additionally comprises a marker which is capable of binding to the aptamer or to the aptamer- ligand complex.

56. A kit as claimed in claim 53 or claim 54 wherein markers are covalently or non-covalently attached to the aptamers.

57. A kit as claimed in any one of claims 53 to 56 which additionally comprises an apparatus which is adapted for dispensing the aptamers.

58. A kit as claimed in claim 57, wherein the apparatus is a pen, spray, sponge or printer.

59. A kit as claimed in any one of claims 53 to 58, which additionally comprises apparatus for detecting the presence of an aptamer which is bound to a ligand or of an aptamer-ligand complex which is present directly or indirectly on or in the article.

60. A process for making a kit for the identification and/or authentication of an article, wherein the kit comprises: (i) a container comprising one or more aptamers, and

(ii) one or more labels or tags; the process comprising the step of fixing, embedding, adding or applying one or more ligands which are specifically recognized by the aptamers directly or indirectly to the labels or tags.

61. A process as claimed in claim 60, wherein the kit additionally comprises an apparatus for dispensing the aptamers.

62. A process for making a kit for the identification and/or authentication of an article, wherein the kit comprises:

(i) an apparatus as defined in any one of claims 44 to 50, and (ii) one or more labels or tags; the process comprising the step of fixing, embedding, adding or applying one or more ligands which are specifically recognized by the aptamers directly or indirectly to the labels or tags.