Functionalized Acrylonitriles with Aggregation-Induced Emission: Structure Tuning by Simple Reaction-Condition Variation, Efficient Red Emission, and Two-Photon Bioimaging

Acrylonitriles with
aggregation-induced emission (AIE) characteristics
have been found to show promising applications in two-photon biomedical
imaging. Generally, elaborate synthetic efforts are required to achieve
different acrylonitriles with distinct functionalities. In this work,
we first reported the synthesis of two different group-functionalized
AIE-active acrylonitriles (TPAT-AN-XF and 2TPAT-AN) obtained simply
by mixing the same reactants at different temperatures using a facile
and transition metal-free synthetic method. These two AIE luminogens
(AIEgens) exhibit unique properties such as bright red emission in
the solid state, large Stokes shift, and large two-photon absorption
cross section. Water-soluble nanoparticles (NPs) of 2TPAT-AN were
prepared by a nanoprecipitation method. In vitro imaging data show
that 2TPAT-AN NPs can selectively stain lysosome in live cells. Besides
one-photon imaging, remarkable two-photon imaging of live tumor tissues
can be achieved with high resolution and deep tissue penetration.
2TPAT-AN NPs show high biocompatibility and are successfully utilized
in in vivo long-term imaging of mouse tumors with a high signal-to-noise
ratio. Thus, the present work is anticipated to shed light on the
preparation of a library of AIE-active functionalized acrylonitriles
with intriguing properties for biomedical applications.