Dye-Condensed Biopolymeric Hybrids: Chromophoric Aggregation and Self-Assembly toward Fluorescent Bionanoparticles for Near Infrared Bioimaging

Novel fluorescent bionanoparticles (GC3CN x ) were prepared by self-assembly of biopolymeric amphiphiles that are composed of hydrophilic glycol chitosan (GC) as a biopolymeric backbone and a dipolar tricyanostilbene derivative (3CN) as a densely conjugated hydrophobic pendant. In the molecular design of 3CN, a dipolar electronic structure was introduced to spectrally shift the aggregation-induced enhanced fluorescence of the α-cyanostilbene skeleton toward the near-infrared (NIR) useful for bioimaging. It has been found that the fluorescence of GC3CN x nanoparticles is red-shifted and intensified by increasing the 3CN content in the biopolymeric amphiphile. By cellular and in vivo imaging experiments, we demonstrate that GC3CN x nanoparticles have great potential for NIR bioimaging, with attractive properties including enhanced fluorescence signal, efficient cellular uptake, and better spectral coincidence with the in vivo transparent window.