Zwitterionic red fluorescent polymeric nanoparticles for cell imaging.

Phospholipid monomer and aggregation-induced emission (AIE) dye-based dimers are incorporated via reversible addition-fragmentation transfer polymerization to afford cross-linked zwitterionic fluorescent copolymers. Such copolymers are prone to self-assembly into fluorescent polymeric nanoparticles (FPNs) in physiological solution due to their amphiphilic nature. Characterization of these red FPNs by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy indicates the successful preparation of these zwitterionic copolymers. UV-visible absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and dynamic light scattering are performed to demonstrate the bright red fluorescence of the FPNs and their stable dispersibilities, even below the critical micelle concentration in physiological solution. Finally, studies of the biocompatibility and cell uptake behavior of the FPNs are conducted and show excellent biocompatibility for cell imaging application.