Conjugated polyelectrolytes have been developed into a class of materials for use in multiple disciplines such as optoelectronic devices, chemo- and bio-sensors. Among them, poly(fluorene) derivatives are promising materials for two-photon cell imaging and photodynamic therapy (PDT) because of the large two-photon absorption (TPA) cross sections within the biological tissue transparency window (700–1000 nm). However, its application is constrained because there are limited methods to achieve post-polymerization modification with bio-active moieties directly in water with high yield and convention, so the polymer structure needs to be redesigned from the beginning to induce different targeting groups. Herein, we designed a clickable conjugated polyelectrolyte platform with polyfluorene backbone, solubilizing groups, and vinyl-terminated side-chains, which can be modified by different bio-active moieties in water. Without adding a toxic metal catalysis as in CuAAC, thiol–ene reactions can be triggered in water with high yield and conversion. The copolymer precursor is synthesized by three different fluorene derivatives, using microwave-assisted Suzuki-Miyauara cross-coupling with tuned reaction conditions to minimize Heck coupling side products. Then, the charged solubilizing groups are produced from the copolymer precursor, forming the clickable CPE platform. The clickable CPE platform exhibits good solubility in water without aggregation indicated by the narrow fluorescence emission band. Post-polymerization modifications can be performed with multiple thiol-terminated bio-activated moieties directly in water by a radical intermediated thiol–ene reaction for different applications without redesigning the whole structure from the beginning.

Clickable conjugated polyelectrolyte platform for two-photon cell imaging

254th National Meeting (2017)

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