Two-photon active polymeric nanoparticles for high contrast in vitro imaging

Two water dispersible and two-photon (TP) active polymer nanoparticles were synthesized from poly[2-(3-thienyl) ethanol n-butoxy carbonyl methyl-urethane] and poly(3,3'''-didodecyl quarter thiophene) polymers using a simple miniemulsion technique. Strong TP fluorescence was observed from each of these nanoparticles using a femtosecond laser operated at 800 nm. Interestingly, these polymeric nanoparticles were found to be non-toxic in dose dependent cell viability studies for 24 h nanoparticle incubation time period. TP microscopic imaging and Z-stacking confirmed cellular internalization of TP active nanoparticles by human macrophage THP-1 cells. These fluorescent polymer nanoparticles could be suitable candidates for in vitro TP bioimaging.