Researchers demonstrate a low-cost, nondestructive, unclonable anti-counterfeiting strategy that takes advantage of multifunctional fluorescein-embedded silver@silica core-shell NPs as information carriers for graphical and spectral coding. A shadow-mask-lithography-assisted self-assembly method is developed for the fabrication of the plasmonic security labels, in which the multifunctional core-shell nanoparticles (NPs) are electrostatically adsorbed onto an amino-terminated micropattern generated by shadow mask lithography. The random arrangement of discrete NPs on the micropatterns, originating from Brownian motion during the self-assembly, makes the security labels unclonable.
- core-shell nanoparticles
- dark-field and fluorescence microscopy
- security labels
- surface-enhanced Raman scattering