Surface-Enhanced Raman Scattering-Encoded Gold Nanostars for Multiplexed Steganographic Anticounterfeiting Labels

Steganography is a technique that encrypts information by hiding it in another medium, such as video, audio, images, and text. The principal purpose of steganography is to conceal the existence of information so that it cannot be easily recognized by a third-party during transmission, which guarantees information security. Surface-enhanced Raman scattering (SERS) probes contain rich spectral information. With the increasing application of SERS in optical anticounterfeiting field, the development of SERS labels with superior encoding capacity has become research hotspot. In this study, we mixed Au nanostar SERS probes with ordinary commercial ink to obtain SERS ink for optical steganography and anticounterfeiting labels. Au nanostars have abundant tip “hotspots” and large specific surface area, and strong SERS signals can be manufactured by modifying Raman molecules on its surface. Fifteen different kinds of Raman molecules were chosen as a demonstration, and the signal molecules were tightly modified on the surface of Au nanostars by dopamine encapsulation and then mixed with ordinary ink to obtain SERS ink with different signals. Then, the information recorded by SERS ink was extracted and interpreted by a micro-Raman imaging system. In addition, SERS ink can also be used in barcodes and quick response (QR) codes, and the possibility of being cracked can be greatly reduced through Raman signal multiplexing. Due to the advantages of SERS ink, such as simple preparation, good photostability, long-term stability, multiplexing steganography, and convenient use, we believe that Au nanostar-based SERS ink has broad prospects in the application of optical steganography and anticounterfeiting.