A new marking system for leather based on encapsulated DNA
The use of synthetic DNA as a marking system is a new traceability concept in the leather industry, especially for supplier and batch tracing. DNA is outstandingly suited for the usage as a marking system because of its code diversity, invisibility and doubtlessness. However, DNA labeling is a great challenge for products exposed to DNA damaging influences during their production, such as acidic pH, elevated temperatures in combination with high humidity or sunlight radiation. Leather is such a product. We attached single-strand DNA (ssDNA) to hydroxyapatite and enhanced the stability of these DNA particles by encapsulation in polystyrene-codivinylbenzene (PS-DVB) microcapsules. Furthermore, the ssDNA containing microcapsules were improved with functional groups on the surface of the capsule to irreversibly attach them to the collagen matrix of leather by chrome tanning. Laboratory scale tests using acidic conditions as well as elevated temperatures in the presence of high humidity showed that the stability of the leather marking system was enhanced. Marking trials were conducted in crust leathers, and the light fastness of these labeled crusts were tested. The results indicate that encapsulated DNA-hydroxyapatite-particles are more stable at sunlight radiation than non-encapsulated DNA. These marking trials showed that the system could be a suitable leather marking system in the leather industry to establish a powerful supplier and batch tracing.