The subject of the invention is a process, including a marking phase and an identifying phase, for marking and identifying entities individually with the use of distinguishable nucleic acid sequences as marker substances, wherein the process ensures individual marking and identification of entities being several orders of magnitude greater in number than the used nucleic acid sequences. During the mentioned marking phase, the mentioned nucleic acid sequences are sorted in groups, mixtures are formed within the groups by combining nucleic acid sequences, then a mixture is selected from each group, and the selected mixtures are formed into a marker mixture. In preferable cases, the mentioned marker mixture contains polymer, preferably resin, more preferably vegetable resin.

THE STATE OF THE ART

Nowadays, it is very important to identify most industrial products, materials or devices that are in use or human contact, or that we be able to precisely analyze their origins or their composition throughout their life cycle.

WO2003/064688 International patent publication document discloses a procedure for modeling and synthesizing nucleic acid chains (e.g. DNA) for storing a unique identifier. The essence of the process is a mechanism, by which a unique numeric code is clearly assigned to a base sequence within a nucleic acid chain. In a preferred embodiment, for example, the values 1, 2, 3 and 4 are assigned to adenine, cytosine, guanine and thymine nucleotides, respectively, said values being expressed by a three-digit binary code. The three-digit binary codes are sequenced according to the nucleic acid sequence, and the resulting binary number is converted to a decimal number. The resulting decimal number is a numeric code that is clearly assigned to the base sequence. According to the specification, this principle is used to track and identify products. In the referred document, the unique identifier is assigned to the base sequence of the nucleic acid chain used, the disadvantage of said method is that a separate nucleic acid chain must be used and synthesized for each individual identifier.

US2009/0112347 US Patent document discloses a process and apparatus for marking products. The marking is performed with a material suspended in a liquid, where the liquid can be in the form of an adhesive, paint, polymer, foam or coating. According to the description, the marker liquid may comprise a number of marking elements, in one example up to 7000 marking elements. In one embodiment, the products are vehicles, where a marking element, such as a DNA, is assigned to a Vehicle Identification Number (VIN) for each vehicle however, the attribution principle is not described in the description. In the process described, each marking and identification of each product requires a new marker liquid, which requires a large number of markers to clearly identify a large number of products. Conversely, in the case of a process of the present invention, in the case of a number of millions or more items, the product marking can be solved by few different nucleic acid chains. US2011/0006110 US patent document describes a method and apparatus for marking and tracking objects. According to the description, the most important advantage of the method is that it provides a very large number of codes for identifying objects. The identification is based on various spectroscopic measurements carried out on the same sample. The principle of the production of a unique code is that in a test performed by a given spectroscopy, a component in a mixture is present or not, more precisely, it can be detected, or not. Thus, the number of unique codes that can be produced can be expressed as the power of 2, where the exponent is the product of the number of components that can be distinguished by the given measurement and the number of different spectroscopic measurements performed successively. The disadvantage of the disclosed method is that, in order to provide a large number of codes, there is a need for as many spectroscopic measurements and equipment for such measurements as possible, the implementation of which is rather complicated.

WO2016/114808 International patent publication document discloses a solution that allows for traceability of foodstuffs using synthetic or natural DNA as a marker to identify specific characteristics of the marked food (e.g., the producer, the packer, dates of process steps). In order to mark foodstuffs, a so called DNA bar code is used, which essence is that binary numbers are represented by DNA. The presence of a specific DNA fragment is indicated by " 1" and its absence is "0", so that the number of possible combinations can be set to 2. The number of possible combinations is increased in one embodiment by taking into account the length of the DNA chains (e.g., short, medium-long and long chains). According to the cited document, the DNA used is incorporated into food and should therefore remain suitable for human consumption.

WO2013/079952 International patent publication document discloses an adhesive which, in one embodiment, is preferably used to render certain objects (e.g. money) unusable or stained. In another embodiment, the adhesive also contains unique identifiers for tracking products, where the identifiers may be, for example, non-naturally occurring combinations of rare earth metal elements or, for example, individual, natural or synthetic DNA sequences. The marking and identification is not detailed further in the description, but apparently the disadvantage of this solution is that a large number of products require a large number of distinguishable markers.

US5665538 US patent document describes a process for tracing traces of substances such as oil or petroleum products, where DNA is used as a marker additive in a very small amount of 0.01 to 1000 pg DNA/μΙ. The detection of such a small amount of DNA is achieved by amplification by polymerase chain reaction. In the process, the DNA, the sequence of which has been previously determined, is administered alone, in an organism or in formulated form (e.g. gelatin or polymer embedded in pearls) to the substance to be marked. Obviously, this process also has the disadvantage that each marking and identification requires a newer DNA sequence that, in case of identification of a large number of products, can only be provided with a large number of different sequences.

WO2004/083819 international patent publication document describes molecular identifiers for marking and identifying biological samples as judicial evidence. Preferably, said molecular identifier is a double-stranded DNA that is of ca. 300-500 base pairs length, having a unique sequence. In one embodiment, the sequence of the double-stranded DNA is modified by mutagenic PCR. The method described in the document also has the disadvantage of requiring another unique DNA sequence for each sample, which can only be obtained in case of a large number of samples with a large number of different sequences.

US2008/0299559 US patent document describes a process for authenticating products. In the disclosed process, the products are marked with an optical reporter coupled to a nucleic acid taggant. The optical marker is detected by a suitable method and the product-coupled nucleic acid marker is identified, for example, by sequencing technique. The nucleic acid marker may be, for example, DNA, a single- or double-stranded nucleic acid fragment containing nucleic acids or nucleic acid derivatives. As described, the nucleic acid marker may comprise one or more specific nucleic acid sequences. By the use of the nucleic acid tag unique information for the marked product is encoded.

Known is a solution where individual marking of electronic components (e.g., microchips) is accomplished by the use of a DNA of plant origin, by inserting a structured DNA mark (engineered mark) on the surface of the designated device. Such a structured mark is damaged by a mechanical attack, a removal attempt, the ordered structure of the signal is disrupted, the DNA code becomes unreadable. For example, see Hayward and J Meraglia,„DNA Marking and Authentication: A unique, secure anti- counterfeiting program for the electronics industry", Applied DNA Sciences. According to the cited reference, the marking involves the production of complicated DNA marking molecules (taggants), which duplication is statistically impossible.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 : An element of the nucleic acid code according to the present invention. The specific nucleic acid chain is located at the center of the chain, at the two ends of it the two unique PI a, P2a primer binding sites are located, through which the primers PI, P2 are attached to the chain.

Figure 2: The results of the analysis of the melting curve after the QPCR reaction of four mixtures of nucleic acid chains belonging to one group, which nucleic acid chains are different from each other in physical properties, for the mixtures containing only A, only B, only C and D nucleic acid chains.

Figure 3 : The results of the analysis of the melting curve after the QPCR reaction of four mixtures of nucleic acid chains belonging to one group, which nucleic acid chains are different from each other in physical properties, for the mixtures containing A and B, A and C, A and D, and B and C nucleic acid chains.

Figure 4: The results of the analysis of the melting curve after the QPCR reaction of four mixtures of nucleic acid chains belonging to one group, which nucleic acid chains are different from each other in physical properties, for the mixtures containing B and D; C and D; A, B and C; and A, C and D nucleic acid chains.

Figure 5: The results of the analysis of the melting curve after the QPCR reaction of four mixtures of nucleic acid chains belonging to one group, which nucleic acid chains are different from each other in physical properties, for the mixtures containing A, B and D; B, C and D; and A, B, C and D nucleic acid chains.

THE PROBLEM TO BE SOLVED BY THE PRESENT INVENTION

The technical problem to be solved by the present invention is to provide for a process for the unique identification of entities, such as persons, objects or materials, said process being suitable to ensure the marking and identification of entities in multiple orders of magnitude greater number than the number of the distinguishable markers used. THE DISCOVERY ACCORDING TO THE INVENTION

This object is accomplished by the invention based on the discovery that by combining a predetermined number of distinct nucleic acid chains, a greater number of mixtures can be created by orders of magnitude than the number of said nucleic acid chains to uniquely mark and identify entities.

Further, it is surprisingly recognized by the inventors of the present invention that a special organic polymer, a resin, is suitable for formulating a marking mixture containing nucleic acid chains because the resin suspension does not inhibit the polymerase enzyme activity in the reaction mixture of the polymerase chain reaction (PCR), the PCR amplification.

BRIEF DESCRIPTION OF THE INVENTION

1. A process for the unique marking and identification of entities, characterized in that the following steps are implemented:

A) in the marking phase

a) selecting among n numbers (where n is a positive integer) of the specific nucleic acid chains at least one, and by adding excipient forming mixtures of different compositions, by selecting one specific nucleic acid chain for one mixture only once, and not taking the sequence of selection into consideration, and marking each mixture, preferably with one or more alpha-numeric characters (Group I);

b) together with Group I created in the previous step, forming a total of m (where m is a positive integer) groups by repeating step a) m-1 times in each case with additional n specific nucleic acid chains, thus forming groups in a total number of m (group number I, II, III, ... m);

c) selecting one mixture from each of the groups formed in the preceding steps, which are mixed to give a marking mixture;

d) optionally composing a unique identifier consisting of a m-members from the marks of the mixtures selected from step c), such that member "i" of the unique identifier is a mark of the mixture selected from group "i", thus obtaining a unique identifier consisting of m members assigned mutually unambiguously to the marking mixture obtained in step c);

e) marking the entity by means of a marking mixture obtained in step c) by applying the marking mixture onto its surface or mixing it with its material; B) in the optional identification phase

f) taking a sample from the entity marked during the marking phase;

g) identifying the specific nucleic acid chains in the sample by a distinctive feature of the specific nucleic acid chains, or by a combination of their two distinctive features;

h) determining, which mixture is included in the sample based on identified nucleic acid chains;

i) optionally, from the mark of the identified mixtures, forming an identifier consisting of m members (where m is a positive integer), so that member "i" of the identifier is a mark of the mixture selected from the group "i", thus recovering the unique identifier consisting of m members assigned mutually unambiguously to the marking mixture, optionally used for the marking.

2. The process according to item 1, wherein the specific nucleic acid chains used in the mixing of step a) of the marking phase are selected such that their distinctive feature is their different base sequence.

3. The process according to item 2, wherein the specific nucleic acid chains used in the mixing of step a) of the marking phase are selected such that their different base sequence is accompanied by different melting points.

4. The process according to item 1, wherein the specific nucleic acid chains used in the mixing of step a) of the marking phase are selected such that their distinctive feature is their different concentration.

5. The process according to item 4, wherein specific nucleic acid chains having a 4-fold, 16-fold or 64-fold concentration difference are used.

6. The process according to item 1, wherein the specific nucleic acid chains used in the mixing of step a) of the marking phase are selected such that their distinctive feature is their different base sequence and different concentration.

7. The process according to items 1-6, wherein during the identification according to step g) of the identification phase, the identification of the nucleic acid chains is carried out by a direct method, by the determination of the complete sequence of the individual nucleic acid chains.

8. The process according to items 1-6, wherein during the identification according to step g) of the identification phase, the identification of the nucleic acid chains is carried out by an indirect method, preferably by PCR or QPCR method, CD spectroscopy, IR spectroscopy, absorption or fluorescent spectroscopy.

9. The process according to items 1-8, wherein during the mixing of step a) of the marking phase according to step a) of item 1, the specific nucleic acid chains are dissolved in a polar solvent as excipient, preferably in water or in an aqueous buffer, more preferably in a Tris: HC1 solution, in a NaCl solution or in an EDTA solution, and the marking mixture according to step c) of item 1, obtained by mixing of the resulting mixtures is applied to the surface of the entity to be marked in step e) of item 1, preferably sprayed or incorporated in its material.

10. The process according to item 9, wherein the marking mixture according to step c) of item 1, is admixed with a solution containing an organic polymer, preferably PEG, lacquer, polystyrene or resin, preferably pine resin as a further auxiliary material, then in step e) of item 1 the resulting mixture is applied onto the surface of the entity to be marked or incorporated into its material. 11. The process according to item 9, wherein the solution containing an organic polymer, preferably PEG, lacquer, polystyrene or resin, preferably pine resin is applied onto the surface of the entity to be marked, thus, a coating is formed, and the marking mixture is applied onto the surface of this solution- coating.

12. The process according to items 10 to 11, wherein the organic polymer is dissolved in an organic solvent, preferably in alcohol, acetone, ethyl acetate, more preferably in ethyl alcohol or acetone.

13. The process according to item 9, wherein the marking mixture is admixed into a solution containing an organic polymer, preferably PEG, lacquer, polystyrene or resin, preferably pine resin, the solution is dried, optionally formulated, and the resulting product is applied onto the surface of the entity to be marked in dry or re-suspended form, or incorporated into its material.

14. The process according to item 13, wherein as dried and formulated product, particles in micro or nanoscale, preferably 20-5000 nm in terms of their diameter, more preferably 100-1000 nm in terms of their diameter are used.

15. The process according to items 10 to 13, wherein as said solution of the resin dissolved in an organic solvent, a solution containing the resin in a concentration of 2-20%, preferably 5-10% based on the total amount of the solution of the resin.

16. The process according to item 1, wherein the entity to be marked is a person, an object or material, preferably human skin, paper, plastic, wood, metal, glass, rubber or stone, or any combination thereof.

17. A marking mixture comprising a plant resin, preferably a pine resin and a nucleic acid or nucleic acid chain, preferably a specific nucleic acid chain according to the invention or a mixture thereof.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, the term "specific nucleic acid chains" refers to nucleic acid chains that can be distinguished from one another by virtue of their characteristics or a combination of their two characteristics. Said characteristics may be the base sequence or concentration. These two characteristics are optionally available on the basis of a physical property, i.e. without the sequence being defined, such as e.g. the melting point. The combination of said two characteristics may be, for example, a combination of sequence and concentration or a combination of physical property, which can be derived from a sequence and concentration. In chemical terms, the structure, chemical composition, natural or synthetic origin of the specific nucleic acid chains, etc. is not limited; the nucleic acid chain may also be, for example, a ribonucleic acid chain, a deoxy -ribonucleic acid chain, or any derivative thereof, but is not limited to these. Accordingly, the ability to understand the expression specific nucleic acid chain, and the ability to select a chemical entity belonging to a specific nucleic acid chain according to the scope of the present invention is the basic knowledge of the person skilled in the art. (For the sake of clarity, here it is indicated that in the examples of the present invention the specific nucleic acid chains include base sequences A, B, C and D. This indication is to be understood that nucleic acid chains A, B, C and D represent specific nucleic acid chains used in the nucleic acid chain combinations forming the so-called Group I according to the wording of the Examples; nucleic acid chains A', B', C'and D' represent specific nucleic acid chains used in the nucleic acid chain combinations of Group II, distinguishable from those hereinabove; nucleic acid chains A", B", C", and D" represent specific nucleic acid chains used in the nucleic acid chain combinations forming a group III, which can be distinguished from those hereinabove, etc. In another example, said distinguishable nucleic acid chains are marked with Al, A2, A3, B l, B2, and B3, said marking meaning that the nucleic acid chains A and B represent specific nucleic acid chains present in a nucleic acid chain combinations forming Group I in a # 1, 2, or 3 concentration; nucleic acid chains A' and B' represent specific nucleic acid chains distinguishable from those hereinabove, present in a nucleic acid chain combinations forming Group II in a # Γ, 2', or 3 ' concentration; A" and B" represent specific nucleic acid chains distinguishable from those hereinabove, present in a nucleic acid chain combinations forming Group III in a # 1 ", 2", or 3 " concentration, etc.)

In the present invention, the terms "mixture of nucleic acid chains" and "combination of nucleic acid chains" are to be used interchangeably and their meaning should be understood to include one or more specific nucleic acid chains together with one or more excipients. The excipients used in the present invention will be described in detail later in this specification. For purposes of clarity, the combination of nucleic acid chains indicated by the nomenclature used in the examples of the present description may be for example, but not limited to, nucleic acid base sequence A with one or more excipients, or the combination AB produced from A and B as a specific nucleic acid chain with one or more excipients.

According to the present invention, the terms "code" and "unique identifier" are to be used interchangeably, and their meaning is a series of symbols, where the first member of the series of the symbols is the symbol of a nucleic acid chain combination selected from Group I according to the wording of the Examples, the second member of the series of the symbols is the symbol of a nucleic acid chain combination selected from Group II, etc.

The present invention relates to a process for marking and identifying entities by combinations of specific nucleic acid chains. The said entity is, for example, a person, object, or material.

The method of the invention comprises a marking phase and/or an identification phase.

Said marking phase comprises the following steps:

a) forming mixtures of different compositions by selecting at least one of n specific nucleic acid chains under such conditions that one specific nucleic acid chain is selected only once for one mixture, and the order of selection is not taken into account (carrying out of uncompensated combinations). Each mixture is marked, preferably with one or more alpha-numeric characters. All of the mixtures thus obtained together are considered as Group I. (For the sake of clarity, we indicate that in some examples case n = 4 was performed, where the distinguishable specific nucleic acid chains are labeled with A, B, C and D.)

b) Together with Group I generated in the previous step, a total of m groups are generated by repeating step a) m-l times, in each case with additional n specific nucleic acid chains. Thus, a total number of groups of m (I, II, III, ... m -groups) are generated. Preferably, for each group, an equal number of mixtures are prepared, and for each group the same set of symbols is used for marking the mixtures. (For the sake of clarity we indicate that in the examples we have generated m = 6 group.)

c) One mixture is selected from each of the groups formed in the previous steps, which are mixed with each other to form a marking mixture.

d) Optionally, a unique identifier consisting of m elements is formed by the symbol of mixtures selected in step c), such that the /-member of the unique identifier is a sign of the mixture selected from the /-group. Thus, a unique identifier consisting of m members mutually unambiguously assigned to the marking mixture obtained in step c) is obtained.

e) The marking mixture obtained in step c) is used to indicate the entity.

When selecting k specific nucleic acid chains from n specific nucleic acid chains in step a) of the identifying phase, mixtures of different compositions are formed by selecting one nucleic acid chain only once for one mixture, and the order of selection being ignored, then combinations of n elements of Λ-class (C _n:k ) are generated, the number of which is:

If all possible cases are taken into account, using the binomial equation we get the following

That is, we can compile up to 2 ⁿ mixtures (uncompensated combinations) per group. Case k = 0 is the case when no specific nucleic acid chain has been selected.

When in step d) of the said marking phase, the unique identifier consisting of m members is formed, preferably by generating the same number of mixtures for each group, and using the same set of symbols for each group to denote mixtures, then the possible orders of m number of elements selected from 2 ⁿ of different elements, that is, its repetitive variations are accomplished by being allowed to select an element any time but at most m times. The number of repeating variants is (2 ⁿ ) ^m .

The identification phase of the method according to the invention comprises the following steps: a) A sample is taken from the entity marked during the marking phase.

b) The specific nucleic acid chains in the sample are identified by a distinctive feature of specific nucleic acid chains, or by a combination of at least two distinctive features.

c) Based on the identified nucleic acid chains, it is established, which blend is included in the sample, and optionally, an identifier consisting of m members is composed from the sign of the identified mixtures, such that the /-member of the identifier is a sign of the mixture selected from the /-group, so as to obtain a unique identifier consisting of m members that is mutually unambiguously assigned to the marking mixture used in the particular case.

The specific nucleic acid chains in the groups formed in the above-mentioned marking phase may be single-stranded or double-stranded DNA molecules or RNA molecules. The identification of nucleic acid sequences (nucleic acid chains) can be carried out by techniques and methods known in the art. Such is, for example, the polymerase chain reaction (PCR) method, but it is not limited thereto.

The essence of the PCR process is that a nucleic acid chain can be multiplied (amplified) in vitro and enzymatically. The importance of this process is that it can be implemented from a very small sample. The PCR reaction is carried out in three steps, and these three steps are repeated cyclically. The first step is the denaturing step, when the DNA sample is heated to a temperature such that the two DNA strands are separated. The second, so-called anellating step, two known sequence primers are hybridized to two chains of denatured DNA at a lower temperature. At the third stage of polymerization, a new DNA complementary DNA is synthesized on the two strands by use of a DNA polymerase.

The present invention uses said PCR method to identify nucleic acid chains of specific base sequences and their corresponding combinations, that are useful in identifying individual entities in the systems described herein. The present invention provides a number of such nucleic acid chain combining methods, which are suitable for the generation of security nucleic acid code systems. These nucleic acid code systems are suitable for marking and identifying individual objects or persons.

According to the foregoing, in one embodiment of the invention, said specific nucleic acid chains may be synthetic nucleic acid chains.

The efficiency of the process according to the invention is increased by the possibility of designing and producing custom synthetic nucleic acid sequences, using methods, which are known in the art, said sequences being suitable for being used in the process according to the present invention. The sequence of artificially produced synthetic DNA molecules is designed to minimize the sequence homology with DNA sequences occurring in previously known biological systems. Planning is done on the basis of the known sequences available in databases. The significance of this is that the code of the DNA molecule will be unique.

In one embodiment of the invention, the specific nucleic acid chains used in said marking phase are selected such that they are nucleic acid chains having different base sequences or nucleic acid chains of different concentrations.

If the specific nucleic acid chains used in the marking phase are selected such that they are nucleic acid chains having different base sequences, the identification of nucleic acid chains may be done by a direct method by determining the complete sequence of single nucleic acid chains. The determination of the sequence can be carried out by techniques and methods known in the art, the knowledge of which is known to those skilled in the art. For example, different conventional or new generation sequencing methods may be mentioned.

The partial determination of the sequence of nucleic acid chains, which are different from each other in their base sequence may also be done by indirect methods. One of these methods is the so-called Taqman-based PCR assays, when synthetic oligonucleotides containing the so called quencher molecules are used, which are identical or complementary with the sequence to be detected, labeled by (5')- fluorescence at one end of the molecule, and is suitable to kill a fluorescence signal at the other end of the molecule (3'-) or when matched to one of the central bases of the molecule. In the present state of the art, this process can be performed by real-time quantitative PCR (QPCR) method, the knowledge of which belongs to the knowledge of those skilled in the art.

In one embodiment of the invention, different base sequences or different concentrations are determined by a method capable of determining the physical properties based on these properties. These physical characteristics can be detected, for example, but not limited to, from CD spectra, IR spectra, absorption or fluorescence spectra (herein they are also referred to as physical properties). In these cases, considering the given physical property, a specific detection method and instrument connected to the given physical property must be used. The other physical properties listed above can be measured by known methods and processes, and the nucleic acid chains with different properties can be isolated by analytical methods.

In a preferred embodiment of the invention, using the nucleic acid coding systems based on physical property a nucleic acid amplification method is applied that multiplies the number of molecules in the sample encoded by nucleic acids to 1000 (one thousand), 10000 (ten thousand), 100000 (one hundred thousand) or even more than one million times.

The multiplication of the encoding nucleic acid sequences can be done by known techniques and methods known in the art, for example, but not exclusively, by the PCR process, which techniques and methods belong to the knowledge those skilled in the art.

In the application of said PCR method, such different nucleic acid chains having individual physical properties are selected, which have a unique sequence domain characteristic of a given group at each end. These unique sequences are bound by the synthetic oligonucleotide primers used in the PCR. Figure 1 schematically illustrates the structure of a nucleic acid chain used in the PCR process as one element of the nucleic acid code according to the present invention. The specific nucleic acid chain is located at the center of the chain, at the two ends thereof the two unique Pla, P2a primer binding and recognizing sites, through which the primers PI, P2 are attached to the chain. Unique, specific PCR primers belong to various groups to be produced in the process of the present invention, which result in unique, specific QPCR multiplication. Sequences of PI, P2 primers should be designed considering the rules applied in the PCR technique, which are currently well-known.

In a preferred embodiment of the present invention, the sequence of said nucleic acid chains different in their individual physical property, between the two primer binding and recognizing sites Pla, P2a, is chosen so that a double stranded DNA having a different melting point ("melting temperature" or "T _m point" in Anglo-Saxon literature) is obtained. Said melting point is the temperature at which exactly half of the nucleotide pairs forming the double-stranded nucleic acid chain are dissociated. For example, but not limited to, the degree of melting temperature can be varied by varying the content of G and C (guanosine and cytosine) of the nucleic acid sequences between the two primer binding and recognizing sites Pla, P2a. If the G/C content in the sequence increases, the melting point of the double-stranded DNA also rises. The magnitude of the melting point also depends on the length of the nucleic acid, the G/C content of the boundary sections. In a preferred embodiment of the invention, the specific nucleic acid chains used in said marking phase are selected such that they are double-stranded DNA molecules or RNA molecules of different melting points (T _m ) from each other.

Detection of the melting point can be carried out by known techniques and methods known in the art, for example, but not exclusively, by QPCR (Quantitative PCR), which belongs to the knowledge of those skilled in the art.

In one embodiment of the present invention, the sequences of nucleic acid chains that are different from one another in a physical property, said sequences being in the same group, are formed in such a way that the boundary sequences are the same, and only the nucleic acid base portions defining the different physical properties (preferably the melting point) are different. Thus, in one reaction, QPCR multiplies the nucleic acid sections characteristic to a group or combinations thereof. The decoding of nucleic acids encoding is then determined by the melting point analysis of the reaction products after QPCR reaction. The melting point is a well-defined value, and depending on how many reaction products with different melting point are generated in the reaction, so many melting points are obtained.

In an embodiment of the present invention, during the QPCR, nucleic acid chains different in a physical property or, in combination, chains, in the same group, are multiplied by a predetermined pair of primers. After the multiplication, the QPCR device is suitable for determining the melting point of the reaction product or, in combination, the reaction products. For example, when only such mixtures are present in the reaction, which have been formed with a single melting point nucleic acid chain in one mixture, the multiplication and melting point analysis will only give one different melting point value per mixture. When only such mixtures are present in the reaction, which have been formed by only two nucleic acid chains with a unique melting point per mixture, then accordingly, only two different melting points per QPCR mixture will be resulted, said two melting points, will differ by the mixtures, so that melting points clearly define the reacting nucleic acid chain mixtures. The same is true for triple and four nucleic acid chain combinations (Example 2).

Based on the foregoing, nucleic acid chains (having a different physical property, preferably a melting point determining the member of given position of the nucleic acid code, i.e., the individual identifier) belonging to the same group, have the same PCR Pla, P2a primer binding sites. In contrast, the PCR Pla, P2a primer binding sites are different between the groups, they do not interact with the PCR PI, P2 primers belonging to other group, so that the multiplication of the nucleic acid chains of the mixtures in given group can only be performed with the corresponding PCR PI, P2 primers. Consequently, it is sufficient to analyze the same sample when identifying mixtures belonging to each group. The results of each QPCR test, therefore, depend on which group of specific pre-defined QPCR PI, P2 primers we have used.

Based on the foregoing, in one embodiment of the invention, unique, specific PCR PI, P2 primers are assigned to the different groups, resulting in a unique, specific QPCR multiplication.

According to an embodiment of the present invention, the specific nucleic acid chains defining nucleic acid codes are synthetic, single-stranded or double-stranded oligonucleotides having 10-30 nucleotide length sequences generating PCR PI a, P2a primer binding and recognition sites at the two ends, said oligonucleotides further having specific sequences of 10-1000, preferably of 15-300, more preferably, of 20 to 40 nucleotides in length at the midpoint, wherein the specific sequence determines the distinct characteristic of the specific nucleic acid chains.

According to an embodiment of the invention, the specific nucleic acid chains that define nucleic acid codes are PCR products that have 10-30 nucleotide length sequences generating PCR Pla, P2a primer binding and recognition sites at the two ends, said oligonucleotides further having specific sequences of 10-1000, preferably of 15-300, more preferably, of 20 to 40 nucleotides in length at the midpoint, wherein the specific sequence determines the distinct feature of the specific nucleic acid chains.

In a further embodiment of the invention, the specific nucleic acid chains used in said marker phase are selected such that they can be distinguished by their base sequence and concentration. There may be for example, but without limitation, 4 times, 16 times or 64 times differences between the individual concentrations.

In the foregoing embodiment, the sequence property of nucleic acid chain sequences different in their sequence in the same group can be determined by the direct sequencing method described hereinabove or by indirect QPCR (e.g., using a Taqman-based PCR assay). Determination of the amount (concentration) of nucleic acid chains of the same a sequence in the same group can be determined using state of the art QPCR method. Quantitative determination of the nucleic acid chains can be done, for example, but without limitation using intercalating dyes (e.g. SybrGreen) or Taqman or other fluorescence probe (e.g. hybridization test, scorpion test, etc.). During QPCR, when determining the amount of each nucleic acid in the initial sample, the Ct value is taken into account. The Ct value represents the cycle number, where the amplification curve starts to rise. The exact value of this is automatically calculated and given by the currently used QPCR devices. The smaller the value, the higher the concentration of the starting nucleic acid is. Thus, the different concentration of the nucleic acid chain with the same sequence in each group will result in different Ct values at QPCR, thereby determining the initial concentration and determining the DNA pattern.

In a preferred embodiment, the determination of more accurate starting nucleic acid is possible by using so-called digital PCR. In this case, a special PCR reagent kit and a device suitable for performing digital PCR are required. Since the digital PCR method can be used to determine even smaller quantitative differences, in this case, even 8 or more concentrations may be used in case of some nucleic acid chains with a given sequence. For example, but without limitation, theoretically using 8 concentrations and only 2 different sequences, 81 kinds of mixtures can be made within a group, including the case containing no specific nucleic acid chain. For 6 groups, the number of possible variations is 81 ⁶ , representing 282,429,536,481 variations. It will be appreciated that the number of possible variants of the nucleic acid code increases significantly by increasing the concentrations or the possible sequences or the number of sequences with possible physical properties.

According to one embodiment of the invention, the foregoing labeling mixture is in the form of a suspension or powder. According to an embodiment of the invention, a mixture of the specific nucleic acid chains during the marking phase is prepared by dissolving the specific nucleic acid chains to a polar solvent, preferably water or an aqueous buffer, more preferably 50 mM Tris: HQ (pH 7.2) 50 mM NaCl solution or 2 mM EDTA. The marking mixture obtained by mixing the mixtures thus obtained is applied to the surface of the desired product, preferably sprayed.

In a further embodiment of the invention, the marking mixture obtained during the marking phase is mixed with a solution of organic polymer (e.g., but not limited to, PEG, lacquer, polystyrene) and the resulting mixture is applied to the surface or into the component of the object to be labeled.

During our work, the unexpected, favorable properties of a special organic polymer, namely the resin, was found when it was contacted with a nucleic acid solution. The resin was previously dissolved in an organic solvent. When a solution containing the nucleic acid code is added to the solution of the resin in a proportion of 0.1 to 5% by volume, the resin does not precipitate from the water-containing solution. The solution thus prepared was sprayed onto human skin, paper, plastics, wood, metal, rubber, and stone to form a thin coating while the nucleic acid code was uniformly applied to the surface. When the treated surface was washed several times with water and scraped from the surface, the nucleic acid code could be shown. Moreover, adding the resin scraping to the PCR reaction mixture, the nucleic acid chains of the nucleic acid code could be multiplied. This was due to the fact that the resin was able to bind the nucleic acids not covalently by virtue of the fact that even aqueous washing did not dissolve the nucleic acids. In addition, in the PCR reaction mixture the resin suspension did not inhibit the polymerase enzyme activity, the PCR amplification.

Based on the foregoing, according to a further embodiment of the present invention, the marking mixture obtained during the marking phase is mixed with a solution of a resin, preferably a vegetable resin, more preferably a pine resin with an organic solvent, preferably alcohol, acetone, ethyl acetate, more preferably ethyl alcohol or acetone, the resulting mixture is applied to the surface of the object to be marked. Said organic solvent solution of the resin contains the resin at a concentration of 0.1 to 5% relative to the total amount of resin solution.

The resin containing the nucleic acid code could also be prepared in powder form by injecting a solution of the resin with alcohol or acetone at a high speed for an aqueous solution containing nucleic acid sequences determining the nucleic acid code under continuous agitation. The resin, as it was precipitated from the aqueous solution, formed a microparticulate suspension which could be centrifuged and then dried. The resulting resin powder in wet or dried form is suitable for mixing with other polymers. It has been shown that the resin thus produced was in wet or dried form suitable in small quantities to reverse the nucleic acid code using PCR technique.

Based on the foregoing, in a further embodiment of the invention, a solution of the resin with an organic solvent, preferably alcohol or acetone, is injected to an aqueous solution of the marking mixture obtained in the marking phase at high speed with continuous stirring to obtain a suspension. The resulting suspension is separated, preferably by centrifugation, and then dried to yield a resin powder containing specific nucleic acid chains that define the nucleic acid code, which is optionally mixed with another polymer. The organic solvent solution of the resin contains the resin at a concentration of 2-20%, preferably 5-10%, relative to the total amount of resin solution.

According to an embodiment of the invention, the above-mentioned marking mixture comprises polymer particles containing DNA molecules. The polymer particles are micro or nanoscale particles, preferably 20 to 5000 nm in diameter, more preferably 100 to 1000 nm in diameter. These particles may, depending on their DNA content, carry a quantity of information that may include, inter alia, the manufacture, primary use, owner, origin, purpose of production or use, type of material and conditions of manufacture of a product (for example, but without limitation, time or warranty features). The DNA molecule enclosed in polymer particles has the advantage that environmental and biological impurities do not affect the code when it is read.

According to an embodiment of the invention, labeling with the marking mixture is effected by mixing into a solution or melt of raw materials providing for the bulk of industrial scale products (such as, but not limited to, polymers, glass, rubber, or solidifying source material) the DNA containing micro or nanoscale polymer particles, which are mixed in the form of a compatible powder or suspension in the raw material used in the manufacture.

In a further embodiment of the invention, marking with the marking mixture is effected by mixing the micro or nanoscale polymeric particles containing the above-mentioned DNA into dye, lacquer or other coating material used for surface treatment, which are applied to the surface of industrial products (e.g. but not exclusively, metal, plastic, wood, glass). This allows to mark products that have already been prepared with DNA-code .

According to a further embodiment of the invention, marking with a marking mixture is performed by processing micro or nanoscale polymer particles comprising the aforementioned DNA, e.g., but not limited to, by dissolving, mixing, mixing them in powder form or homogenizing the feedstock with the material of the manufactured products. Semi-finished or finished products prepared in this way already contain the marked and information-rich DNA sequences encapsulated.

According to a further embodiment of the invention, marking with the marking mixture is performed by applying the DNA nanoparticles embedded in the polymer by surface application (for example, but not limited to, scattering or spraying). The DNA particles deposited on the surface can be dissolvable or stably deposited on the surface according to the technique of application. In the first case, at the place of use, the marked object leaves a trace, so that its location, path, or the identity of the person in contact with the marked object can be tracked. In the second case, the product can be identified prolonged by reading the readable DNA sequences on the surface.

The nucleic acid coding procedure of the present invention uses a unique approach. The code represents a set of unique symbols defined groups, preferably a set of alphanumeric characters. In the examples below, the code consists of six members. It is important to understand from the aspect of the invention that the code can be assembled from more than six members, thus increasing the security and uniqueness of the code. The code is compiled randomly, and since the encoding set is available to any user, and with these kits, the user can - independently of one service provider - create their own codes, code systems and use them according to their needs.

In the following, the invention is illustrated by means of working examples which are not intended to be construed as limiting the invention.

EXAMPLES

Example 1 : Forming of combinations of nucleic acid chains different in the base sequence

6 kinds of groups (I-VI) were formed from mixtures of nucleic acid chains different in base sequence, by mixing in each group 4 nucleic acid chains (A, B, C and D) per group. Thus, a total of 16 different mixtures were made per group. The composition of a mixture of a given group is shown in Table 1.

Table 1: Mixtures belonging to given group Since in each case of the groups the four nucleic acid chains different in the base sequence are different from each other, they represent an independent combination, so in the case of the exemplified six groups (Group I-VI) 16 ⁶ =16,777,216, individual variants could be defined, which is six orders of magnitude higher, than the number of nucleic acid chains (6 ^ 4 = 24).

Example 2

A total of 15 mixtures (combinations) of 4 nucleic acid chains (A, B, C and D) were formed, which are different in their melting point (Ύ^). When forming the mixtures, the 16th combination was ignored, when there was no single nucleic acid chain in the mixture, since no melting point could be assigned thereto.

Using QPCR method, the melting points that are clearly characteristic of each combination were determined for each combination. The resulting melting points are shown in Table 2.

Table 2: The melting points values obtained after the QPCR reaction of 15 kinds of combinations of four different nucleic acid chains with different melting points, constituting one single group. Any code may be assigned to each combination (in this case, alphanumeric characters).

Representation of melting points was also indicated by melting curves. The melting curves of the 15 combinations shown in the example are shown in Figure 2. It can be seen that in samples with nucleic acid with only one melting point present in the system, there was only one peak curve. It is also apparent that in the case of at least two nucleic acid chains with different melting points, the resulting peaks are in a different position. Therefore, it was possible to identify mixtures of nucleic acid chains with two (AB, AC, AD, BC, BD, CD), three (ABC, ABD, BCD) and four (ABCD) melting points. The mixtures resulted in peaks which are characteristic of the nucleic acids with various melting points forming them.

Example 3 Similar to Example 2, 6 groups (I-VI) are formed from mixtures of nucleic acid chains different from each other in melting point (T _m ), by forming mixtures of 4 nucleic acid chains (A, B, C and D) with different melting points in each group. Thus, a total of 15 mixtures of mixtures per group were formed, ignoring the case when the mixture did not contain any specific nucleic acid chain. Each mixture was identified by an alphanumeric character by using the same set of symbols, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, E, F, G, H, I for each group.

A mixture was selected from each group from which a marking mixture was prepared from which a sample was taken.

In the sample, each mixture selected from each group was identified by 6 independent QPCR assays. Upon multiplication of the Group I sequence, 3 melting points were obtained which corresponded to the mixture of Έ', ABC, selected from group I. When multiplying the sequence belonging to group II, 2 melting points were obtained, which corresponded to mark 5 mixture with composition AC. When multiplying the sequence belonging to group III, 2 melting points were obtained, which corresponded to mark 9 mixture with composition CD. When multiplying the sequence belonging to group IV, 1 melting point was obtained, which corresponded to mark 1 mixture with composition A. When multiplying the sequence belonging to group V, 1 melting point was obtained, which corresponded to mark 2 mixture with composition B. Finally, when multiplying the sequence belonging to group VI, 3 melting points were obtained, which corresponded to mark E mixture with composition ABC. A 6-digit unique identifier from each mixture selected from 6 groups: E5912E.

The definition of the unique identifier was based on 3 + 2 + 2 + l + l + 3 = 12 nucleic acid chains with different melting points.

Example 4

Six groups of mixtures of nucleic acid chains different from each other in their base sequence (I-VI) were obtained such that in each group from two nucleic acid chains different by groups (A and B) mixtures were formed with three different predetermined concentrations (Al, A2, A3, B 1, B2 and B3).

Thus, a total of 16 different mixtures were made per group. The composition of a mixture of a given group is shown in Table 3.

Number Composition of the mixture

1 It does not contain a nucleic acid chain with a specific base sequence

2 Nucleic acid chain A in concentration 1

3 Nucleic acid chain A in concentration 2

4 Nucleic acid chain A in concentration 3

5 Nucleic acid chain B in concentration 1

6 Nucleic acid chain B in concentration 2

7 Nucleic acid chain B in concentration 3

Nucleic acid chain A in concentration 1 and

8

Nucleic acid chain B in concentration 1

Nucleic acid chain A in concentration 1 and

9

Nucleic acid chain B in concentration 2

Nucleic acid chain A in concentration 1 and

10

Nucleic acid chain B in concentration 3

Nucleic acid chain A in concentration 2 and

11

Nucleic acid chain B in concentration 1

Nucleic acid chain A in concentration 2 and

12

Nucleic acid chain B in concentration 2

Nucleic acid chain A in concentration 2 and

13

Nucleic acid chain B in concentration 3

Nucleic acid chain A in concentration 3 and

14

Nucleic acid chain B in concentration 1

Nucleic acid chain A in concentration 3 and

15

Nucleic acid chain B in concentration 2

Nucleic acid chain A in concentration 3 and

16

Nucleic acid chain B in concentration 3

Table 3 : Mixtures belonging to one given group

Since each of the groups has different two types of nucleic acid chains of different sequences and the three different nucleic acid chain concentrations are different, therefore they represent an independent combination, so we can define 16 ⁶ individual variants in the six groups (I-VI) we have exemplified. INDUSTRIAL APPLICABILITY

The method of the invention allows entities, such as objects, materials or persons, to be individually marked and identified. In the method, nucleic acid chains are used as identifiers which can be distinguished, by the combination of which entities with several orders of magnitude greater in number than the number of nucleic acid chains used can be marked and identified. The marking mixture produced in the process may be formulated, for example, with a polymer, preferably a resin, more preferably a plant resin, which does not inhibit marking and identification.