End Functionalized Nonionic Water‐Dispersible Conjugated Polymers. Issue 18 (16th May 2017) - Zhan, Ruoyu
Abstract : Two nonionic, water‐dispersible conjugated polymers with high oligo(ethylene glycol) densities have been synthesized to show excellent water solubility, high quantum yields, good ionic strength resistance, and minimal nonspecific interactions with bovine serum albumin. They are further biotinylated to bind with streptavidin on solid surface to yield bright green fluorescence. Abstract : 2, 7‐Dibromofluorene monomers carrying two or four oligo(ethylene glycol) (OEG) side chains are synthesized. Heck coupling between the monomers and 1, 4‐divinylbenzene followed by end capping with [4‐(4‐bromophenoxy)butyl]carbamic acid tert ‐butyl ester leads to two nonionic water‐dispersible poly(fluorene‐ alt ‐1, 4‐divinylenephenylene)s end‐functionalized with amine groups after hydrolysis. In water, the polymer with a lower OEG density (P1 ) has poor water dispersibility with a quantum yield of 0.24, while the polymer with a higher OEG density (P2 ) possesses excellent water‐dispersibility with a high quantum yield of 0.45. Both polymers show fluorescence enhancement and blue‐shifted absorption and emission maxima in the presence of surfactant sodium dodecyl sulfate and dodecyltrimethylammonium bromide. The polymers are also resistant to ionic strength with minimal nonspecific interactions to bovine serum albumin. When biotin is incorporated into the end of the polymer backbones through N ‐hydroxysuccinimide/amine coupling reaction, the biotinylated polymers interact specifically with streptavidin on solid surface.