Smart Responsive Luminescent Aptamer-Functionalized Covalent Organic Framework Hydrogel for High -Resolution Visualization and Security Protection of Latent Fingerprints

Covalent organic frameworks (COFs) have been proposed as alternative candidates for smart materials due to their ordered pi-columnar structures. However, it remains a challenge to develop external-stimuli-responsive luminescent COFs for confidential information protection. Here, we have designed and synthesized a water-dispersible and smart responsive luminescent carboxymethyl cellulose-COF hydrogel encapsulated 5-(dimethylamino)-N,N-bis (pyridin-2-ylmethyl) napthalene-l-sulfonamide, named CMC-COF-LZU1JDPYNS, for latent fingerprint imaging and encryption. We show that the fluorescence of CMC-COF-LZU1DDPYNS is reversibly switchable upon addition of Cu2+/H2O. This effect endows potential applications of tunable luminescent COFs based hydrogel as an invisible security probe for imaging, recording, storage, and security of latent fingerprint information. It is shown that the latent fingerprint information incubated by the aptamer-functionalized CMC-COF-LZU1DDPYNS hydrogel is invisible in the presence of Cu2+, but three levels of fingerprint features with high-resolution patterns could be readable upon addition of H2O under UV light. The design strategy provides a promising platform for the responsive luminescent COFs and their detection and protection of valuable latent fingerprint information.