Physical stability of stealth nanobeacon using surface-enhanced Raman scattering for anti-counterfeiting and monitoring medication adherence: Deposition on various coating tablets.

Microtaggant technologies can encode individual numbers on coating tablet to authenticate pharmaceutical products and, therefore, combat the global spread of falsified medicine. In this study, a novel microtaggant, stealth nanobeacon (NB), with surface-enhanced Raman scattering (SERS) activity was applied to various coating tablets and its physical stability was evaluated. The NBs were composed of a reporter molecule (AH, adenine hydrochloride) and prepared with different sizes of gold nanoparticles (AuNPs). The NBs were directly deposited on the surface of various model coatings (e.g., hydroxypropyl cellulose, hydroxypropyl methyl cellulose, Eudragit® RS30D, ethyl cellulose). To investigate physical stability of the NB on the coating tablets, SERS spectra of the NB after friability test and acceleration test (store at 75% RH, 40 °C) were evaluated using a portable Raman spectrometer. After the friability test, there was no significant decrease in the peak intensity of the SERS signal (P) for authentication in all samples. In the acceleration test, the SERS signals of the samples were attenuated, but sufficient SERS signal intensity (P > 70) was maintained in the seven types of coating for authentication. These results demonstrate that the microtaggant NB has the potential to be used for a wide range of coating tablets.