Visible security ink blended by Prussian blue analogues encapsulated gold (Au@PBA) nanoparticles for information hiding

Developing visible security ink with simple preparation, high optical stability and interference-free secret signals are critical to hiding security information. Here, two Prussian blue analogue encapsulated gold nanoparticles (Au@PBA NPs) with different triple-bond Raman emissions were synthesized to prepared novel red inkjet inks for security labels. And the ink formulation was well optimized to obtain suitable surface tension and viscosity. The labels contain public information in red as well as secret information that can only be acquired using Raman spectroscopy. With the visible public information on the labels, the secret information is not easy to be noticed. Also, the secret information written by the triple-bond Raman scattering is readily identifiable without interference. This method improves the security of secret information transmission, providing a new strategy for information hiding technology.