Use of Bacillus subtilis spores in printing and additive manufacturing as a robust, DNA‑based anti‑counterfeiting and identification feature: stresses, processing and evaluation

Abstract

 Part labeling is a crucial security feature as it can prevent product counterfeiting. Deoxyribonucleic acid (DNA), the information carrier of life, is started to be explored as an engineered information molecule with immense potential in respect to information density and encryption. Most research in this direction is concerned with how to encode binary data into DNA and read the stored information from this DNA. Little to no effort is made on how to apply DNA and the information stored within as an identification label for counterfeit protection. In this study, we explore DNA in various printing processes for its suitability as an anti‑counterfeiting and identification tag. DNA is sensitive to environmental influences, which is why we compare the suitability of free DNA against using the spores of the bacterium Bacillus subtilis as a naturally evolved DNA protective shell. To integrate these two DNA species into products, we aim to use both conventional printing methods and additive manufacturing processes. Foremost we investigate the stresses on the DNA as well as spores, then derive suitable printing techniques and assess the practical application – processing, extraction and subsequent detection via polymerase chain reaction (PCR). The stresses are differentiated into four groups – solvents, UV irradiation, temperature and shear stress, to which both DNA species are exposed and characterized. In actual printing processes several kinds of stresses are combined and thus we test two exemplary and complementary methods. Namely gravure printing as a conventional 2D– and masked stereolithography as a 3D printing method. We were able to show that both free DNA as well as DNA encapsulated in spores can be readily integrated into printing processes and detected using PCR where there are some significant advantages for DNA protected in spores. Consequently, spores, which can be applied economically, fast and in large quantities using printing, offer great potential for counterfeit protection, for example on drug packaging.