Photoswitchable ultrahigh-brightness red fluorescent polymeric nanoparticles for information encryption, anti-counterfeiting and bioimaging

Abstract

Photoswitchable fluorescent nanomaterials have received much attention due to their versatile applications but they normally do not show high-contrast red fluorescence. Herein, we report novel photoswitchable red fluorescent polymer nanoparticles (PRFPNs) based on fluorescence resonance energy transfer (FRET) from nile red (fluorescent donor) to spirothiopyran (photochromic acceptor). Both the donor and the acceptor are covalently incorporated into nanoparticles through a facile miniemulsion polymerization. The obtained PRFPNs exhibit not only reversible photoswitching of fluorescence characteristics under alternate UV and visible light irradiation, but also tunable FRET efficiency, favorable photoreversibility, excellent fluorescence stability, ultrahigh brightness and high contrast on/off fluorescence. We demonstrate that these PRFPNs can be used in rewritable information encryption, anti-counterfeiting and reversible fluorescence bioimaging in living cells.