Dye-condensed biopolymeric hybrids: Chromophoric aggregation and self-assembly toward fluorescent bionanoparticles for near infrared bioimaging

Novel fluorescent bionanoparticles (GC3CNx) 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 GC3CNx 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 GC3CNx 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. &copy 2009 American Chemical Society.