A supramolecular assembly of a novel green fluorescent protein chromophore-based analogue and its application in fluorescence anti-counterfeiting.

Supramolecular fluorescent materials with switchable behavior and induced luminescence enhancement are a new class of special materials for constructing fluorescence anti-counterfeiting materials. Since these materials are constructed by self-assembly through supramolecular host-guest interactions of non-covalent bonds, such fluorescent materials can regulate their optical properties through a reversible assembly-disassembly process. Inspired by the role of the β-barrel scaffold in activating strong fluorescence of a green fluorescent protein (GFP) chromophore, we designed a supramolecular system based on a novel GFP analogue (CA) and cucurbit[7]uril (CB[7]). CA molecules are encapsulated by CB[7] to form a 1 : 2 host-guest assembly, thereby the fluorescence brightness of CA can be tuned. The reversible regulation of fluorescence intensity was additionally realized by controlling the dynamic assembly-disassembly process in the presence of a higher binding competitor, amantadine hydrochloride. The CA-CB[7] system was successfully used for information anti-counterfeiting through the reversible fluorescence readout on A4 paper, which enables the GFP chromophore analogue and cucurbituril system to become a potential candidate for constructing intelligent information encryption and anti-counterfeiting materials.