Porcupine, developed in a partnership between the University of Washington and Microsoft (USA), is a complete DNA-tagging system described in the scientific literature3. The specifics of its design and functionality are therefore known. The molecular bits (molbits) used in this portable end-to-end molecular tagging system, which does not require access to specialized laboratories or equipment, incorporate highly separable nanopore signals to facilitate subsequent readout. In the molecular tag mixture, the presence or absence of particular molbits is represented by 1 and 0, respectively. They categorize molecular tags directly from the raw nanopore signal using a portable nanopore device provided, for instance, by ONT third-generation sequencers, thereby omitting the base calling process of converting DNA back to sequence at the readout stage.
Other concepts related to the utilization of DNA tags are expounded in the scientific literature. The development of DNA ink involves the combination of synthetic DNA with printing inks21. Another approach involved the combination of double-stranded DNA with a pigment that is sensitive to infrared light and exhibits fluorescence when exposed to ultraviolet light. In another study, DNA molecular tags were integrated into lactose tablets or pharmaceutical-grade printing ink as a potential anti-counterfeiting monitor in the pharmaceutical industry22,23. The study conducted by Puddu et al.24 involved the encapsulation of DNA within magnetic particles that are both heat-resistant and inert, demonstrating potential for food tracing.
Apart from the scientific investigation of DNA tagging, commercial enterprises offer DNA-oriented technologies for the purpose of labelling tangible objects. Although many of these organizations do not divulge the precise details of their inventions, it is possible to uncover certain aspects to some degree25,26,27.
SigNature DNA is a botanical DNA-tagging technique that has been developed by Applied DNA Sciences. The detection of DNA taggants is accomplished by PCR with specific primers and capillary electrophoresis (CE). SigNature DNA taggants have the capability to be incorporated into a range of marking systems, including but not limited to RFID devices, labels, serial numbers, and holograms22,25,28,29,30,31.
The Haelixa company provides a DNA taggant that is enclosed in silica capsules with a diameter of ~100 nm. This enables the protection of delicate DNA and its attachment to tangible goods32,33. In addition, this company offers a liquid solution that contains DNA. The identification of a DNA tag is accomplished through the utilization of PCR or modifications34,35.
Next, SelectaDNA (the brand of Selectamark Security Systems) developed a two-step system whereby DNA serves as an alternative authentication solution if the primary method is unavailable. In scenarios of property theft recovery, law enforcement officials utilize a UV lamp to identify adhesive markings and a magnifying glass to locate microdots. This enables them to extract the registration code and contact information, which can then be used to retrieve the owner’s details from the service provider’s database. If microdots are not present, a laboratory analyses the unique DNA composition to identify the owner. The genetic material’s structure involves the integration of two discrete synthetic nucleotide oligomers, each of which encompasses a binding sequence for a primer and an identifier sequence. The tag appears to be read by DNA sequencing26,36,37.
CypherMark technology (TraceTag) is designed with a pair of primer sequences, also known as keys, and the detection of tags is executed through the utilization of qPCR (quantitative PCR)15. A suggested utilization entails the dissemination of a composite comprising the nucleic acid marker and marking fluid onto objects, such as currency notes. TraceTag offers a range of DNA inks suitable for different applications27,38.
Holoptica offers DNA SmartMarks, which combines distinctive DNA segments, additional biological markers, and visual indications. Optical indicators utilize a laser scanner that is calibrated to generate spectral and temporal signals to electronically or visually confirm the existence and legitimacy of a mark. The DNA component is a molecule consisting of 100 base pairs that can be incorporated into an inkjet cartridge39,40. The patent filed by Holoptica delineates a technological innovation that involves a base layer of metallized foil with an integrated QR code. This is further augmented by the application of moulded layers of synthetic DNA, nanoparticles and, finally, a protective transparent film41.
DNA Technologies has developed a technology that incorporates DNA-laced ink for tagging and safeguarding valuable products, brands, and intellectual property. The technology, known as “DNA Matrix™” involves adding DNA taggants with unique photoluminescent properties, including activation frequency and fluorescence fading patterns, to printing inks. These characteristics render each mark machine-readable, enabling differentiation between genuine and counterfeit items through specialized scanners. Originating as an art authentication system, DNA Technologies has since expanded its applications across various industries, including pharmaceuticals42,43.
Tagsmart introduced Smart DNA Tags in 2016. The company specializes in the authentication and security of artworks. The utilization of synthetic DNA tags for identification purposes is facilitated by linking them to an online platform. Each individual tag possesses a distinct reference number that is associated with the artwork’s secure certificate of authenticity and its corresponding digital version. The aforementioned technology has also been applied to the manufacturing of premium books44,45.
The DNA Guardian system employs technologies that are subject to limited information availability. It involves the use of a marking agent that contains nucleic acid, along with a UV-detectable stain46,47.
Aanika Biosciences has been developing microbial tags that can be used as biological barcodes for various food items, such as grains, fruit, and vegetables. The aforementioned tags employ bacterial spores. However, many technical details about genetically engineered bacterial spores remain undisclosed. The use of genetically modified organisms (GMOs) in Aanika Biosciences’ technology also raises concerns regarding the potential release of these organisms into the environment, and their presence in food may elicit distress among consumers48,49,50.
Table 1 presents all the companies described in the text, selected features of the technologies they use, and the markets that are described in terms of the application of individual DNA-tagging technologies.
A considerable fraction of the abovementioned companies employ short DNA strands, with a maximum length of a few hundred nucleotides, which are recognized through conventional PCR, qPCR, or occasionally DNA sequencing. The lack of information pertaining to the implementation of sophisticated technologies, such as the storage of larger quantities of data inside longer DNA molecules, is evident. This could be supported by the increased probability of the perseverance of molecules with shorter lengths in diverse conditions51. Nevertheless, a diverse array of mechanisms are employed to protect DNA, spanning from silica microbeads to bacterial cells. In particular cases, DNA is employed as an additional means of verification, rather than serving as the principal method of recognizing an object. SelectaDNA, for instance, is a company that utilizes microdots as its principal taggant technology while simultaneously incorporating DNA as an extra layer of security26,36,37. The main justification for this is that the validation of a DNA marker’s presence within a laboratory increases the expense of the procedure and prolongs the timeframe for the delivery of results.
Notwithstanding the potential advantages of DNA-tagging technologies, it is crucial to consider their drawbacks and limitations. The current use of laboratory analysis of samples to identify DNA tags may limit the ability of these technologies to scale up. On the other hand, PCR’s great sensitivity allows the use of minimal quantities of DNA tags, since the tag could theoretically be detected from as little as one DNA molecule52. However, high sensitivity may also lead to false positives or increase susceptibility to contamination. Finally, the claim that DNA tags cannot be copied, which is supported by numerous companies, may be contested by the prospective use of next-generation sequencing methods that do not require DNA fragment amplification before sequencing53.