Dynamic multicolor luminescent anti-counterfeiting based on spiropyran-engineered gold nanoclusters

Multicolor luminescent materials with time-dependent optical responses are attractive for developing advanced anti-counterfeiting techniques, but it still remains challenging to rationally design and fabricate these emerging materials. Herein, we report the design of novel dynamic luminescent materials based on spiropyran-engineered gold nanoclusters (AuNCs) for anti-counterfeiting applications. Encapsulating fluorescent AuNCs with spiropyran-labeled bovine serum albumin enables the construction of dynamic multicolor luminescent nanoparticles (DML NPs) based on fluorescence resonance energy transfer. These AuNCs-based DML NPs exhibit photochromism and dynamic fluorescence color change from green to yellow to orange-red with the extension of UV irradiation time. Moreover, the photochromism and dynamic fluorescent behavior is highly reversible when exposed to the irradiation of visible light. By taking advantage of photochromic and time-dependent dynamic fluorescence, potential application in optical information storage, dynamic anti-counterfeiting authentication and multi-mode anti-counterfeiting are successfully demonstrated based on DML NPs-deposited polyvinyl alcohol film. This study provides a new strategy of designing novel dynamic multicolor luminescent materials with promising optical properties, which can further advance the practical application of AuNCs-based luminescent materials in the field of information encryption and anti-counterfeiting.