Information encryption gels based respectively on acid-induced response and fluorescence resonance energy transfer white-light materials

Abstract

In this study we developed white light-emitting gel materials based on two mechanisms, namely, acid-induced protonation and Förster resonance energy transfer (FRET), and applied them to information protection and encryption. The newly synthesized compound, Q, forms different protonation states after protonation, and the multicolor emissions from these states ultimately achieve white-light emission through spectral superposition. When Q is paired with dyes such as Nile red, rhodamine 6G, and acridine red, it can act as an energy donor in the FRET system, enabling white-light emission at a specific, optimized ratio. Two functional gels based on polyvinyl alcohol (PVA) were developed, namely a PVA–Q–Nile red composite material and a PVA–Q–H⁺ (150 eq. H⁺ to Q) responsive gel. These gels exhibit stable white light emission properties and can be used for writing and encrypting high-resolution information. Additionally, the PVA–Q–H⁺ responsive gel possesses time-dependent encryption functionality: triggered by OH⁻, the written traces can realize controllable self-erasure. The gel material developed in this study based on a white-light emission system with dual-responsive mechanisms provides a novel strategy for the design and synthesis of intelligent anti-counterfeiting materials.