Molecular code systems

#This application is a national phase of International Application No. PCT/CH2013/000052 filed Mar. 26, 2013 and published in the English language, which claims priority to Application No. EP 12002096.1 filed Mar. 26, 2012.

#The present invention relates to a method for protecting and recovering nucleic acids. This method may be applied in a verification method of products using molecular code systems or it may be applied in a storage method for nucleic acids. The invention further relates to specific particles, in particular silica encapsulated DNA particles, and to their use in secure marking. It further relates to an invisible secure marking or information which is a part of such product. The invention further relates to products suitable for such verification method, to processes for manufacturing such products and methods for reading the information.

#Forgery, grey market and illegal re-imports are considered an increasing issue in industry. Therefore, many attempts are made for secure marking of products.

#The figures attached to this specification are intended to further illustrate the invention.

#FIG. 1 provides and schematic overview of the verification method as described herein. Free nucleic acids may be analyzed using RT-PCR (1). Free nucleic acids do not withstand environmental conditions, such elevated temperatures or as OH radicals (2), and are thus unsuited as a product barcode in commodity products. DNA encapsulated in silica (3) withstands harsh environmental conditions (4) and may be incorporated in a product. It can be separated from the product extracted from the protecting silica particle by treatment with fluoride ions (5). The thus recovered, and optionally purified, DNA may be analysed using RT-PCR (6).

#FIG. 2 provides a schematic drawing of the particles suitable for the verification method and may be obtained according to example 7. Negatively charged DNA is packed in between a silica core and a silica shell. The negative charges of the phosphate group of DNA are compensated by the amine groups of APTES.

#In a first aspect, the invention relates to a verification method for a product, said product comprising a matrix and particles, wherein said particles comprise a nucleic acid core and a silica coating, wherein said method comprises the step of dissolving said particles in an aqueous fluoride solution. This aspect of the invention shall be explained in further detail below:

#Verification Method:

#The inventive method is based on the concept that a specific and known nucleic acid (e.g. a DNA fragment) is encapsulated in silica particles. These particles are added to the product which is to be verified (e.g. polymer matrix of a product or coating of a tablet). After manufacturing, the product is distributed and used as usual. If the manufacturer, or another authorized person, wishes to verify this product, the above particles are isolated (separated) from the product (e.g. oxidation, dissolution of the matrix). In a further step, the above particles are dissolved to extract the previously encapsulated nucleic acid. The obtained mixture may be purified by purification strategies (e.g. magnetic extraction, dialysis). The thus obtained nucleic acid is analysed using known analytical methods for nucleic acid identification and quantification (e.g. PCR). The data set obtained is than compared with the original data set to verify the product.