Paintable Physical Unclonable Functions using DNA

Controversy over artwork's authenticity is ongoing despite numerous technologies for copyright protection. Artists should build their own ways to protect the authority, but these are still open to piracy. Here, a platform is proposed for developing anticounterfeiting labels based on physical unclonable functions (PUFs), in an artist‐friendly manner, brushstrokes. Deoxyribonucleic acid (DNA), which is natural, biocompatible, and eco‐friendly, can be applied as a paint that shows entropy‐driven buckling instability of the liquid crystal phase. Brushed and wholly dried DNA exhibits line‐shaped zig‐zag textures with inherent randomness as a source of the PUF, and its primary performance and reliability are systematically examined. This breakthrough enables the utilization of these drawings in a wider range of applications. DNA liquid crystals (LCs), which are extracted from nature, biocompatible, and eco‐friendly, are used as a paint for anti‐counterfeiting labels. The entropy‐driven instability in the evaporation process of DNA LCs induces a stochastic birefringent pattern that provides high‐level security codes based on physical unclonable functions. The platform can allow the fabrication of protective barriers with a simple method, brushstrokes.