Cucurbit[8]uril Induced Molecular Folding Cascade Assembly for NIR Targeted Cell Imaging

Abstract

AbstractA macrocyclic confinement‐activated green phosphorescence and two‐photon near‐infrared (NIR) fluorescence supramolecular cascade assembly is constructed by multivalent interaction based on the alkyl‐bridged triphenylamine‐vinyl pyridine salts (BTPA), cucurbit[8]uril (CB[8]), β‐cyclodextrin‐grafted hyaluronic acid (HACD), and 4‐bromophenyl pyridine salt and CB[8] complex (PY/CB[8]). Taking advantage of CB[8]‐induced macrocyclic confinement and molecular folding, the fluorescence of BTPA is effectively redshifted by 30 nm from 720 to 750 nm. Subsequently, HACD, a cancer cell targeting agent, is co‐assembled with a BTPA/CB[8] supramolecular folder to form a nanoparticle, further enhancing NIR fluorescence from 750 nm up to 810 nm through cascade confinement. Upon introduction of the 2:1 complex PY/CB[8], multicomponent nanoparticles are fabricated, not only showing efficient NIR fluorescence with an increase in quantum yield from 7.21% to 22.92% but also endowing green phosphorescence emission, which is successfully applied for two‐photon cancer cell‐targeted imaging to shield background interference from fluorescent and phosphorescent resources.