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An anionic water-soluble polyfluorene derivative, poly(9,9-bis(6′-phosphatehexyl)fluorene-alt-1,4-pheny lene) sodium salt (PFHPNa), was synthesized by Suzuki coupling reaction in DMF/water. Polymer PFHPNa was well soluble in water with a strong blue fluorescence emission. Effect of the side chain length on fluorescence sensory properties was studied by comparing quenching efficiencies toward different quenchers of PFHPNa with a reported polymer poly(9,9-bis(3′-phosphatepropyl)fluorene-alt-1,4-phenylene) sodium salt (PFPPNa), which have different side chains in length. For small molecular quenchers (methylviologen, MV2+) and meso-5,10,15,20-tetrakis-(N-methyl-4-pyridyl)porphine (TMPyP4), polymer PFHPNa had lower sensitivity due to the much longer side chain length. The positively charged metalloprotein cytochrome c could quench fluorescence of conjugated polymers via energy transfer and electron transfer. Moreover, polymer PFHPNa showed higher fluorescence quenching toward large biomolecules than PFPPNa. The corresponding Stern-Volmer (Ksv) value of polymer PFHPNa was determined to be 2.1×108 M-1 for cytochrome c. It could be used as a sensitive and selective fluorescence sensor for protein cytochrome c.
An anionic water-soluble polyfluorene derivative, poly (9,9-bis (6’-phosphatehexyl) fluorene-alt- 1,4-pheny lene) sodium salt (PFHPNa) was synthesized by Suzuki coupling reaction in DMF / water. PFHPNa was well soluble in water with a strong blue fluorescence emission. Effect of the side chain length on fluorescence sensory properties was studied by comparing quenching efficiencies toward different quenches of PFHPNa with a reported polymer poly (9,9-bis (3’-phosphatepropyl) (PFPPNa), which has different side chains in length. For small molecular quenchers (methylviologen, MV2 +) and meso-5,10,15,20-tetrakis- (N- methyl-4-pyridyl) porphine (TMPyP4), polymer PFHPNa had lower sensitivity due to the much longer side chain length. The positively charged metalloprotein cytochrome c could quench fluorescence of conjugated polymers via energy transfer and electron transfer. fluorescence quenching toward large bio molecules than PFPPNa. The corresponding Stern-Volmer (Ksv) value of polymer PFHPNa was determined to be 2.1 × 108 M-1 for cytochrome c. It could be used as a sensitive and selective fluorescence sensor for protein cytochrome c.