10.1021/acsami.7b01587.s001 Shanshan Wang Shanshan Wang Charles J. Zeman Charles J. Zeman Junlin Jiang Junlin Jiang Zhenxing Pan Zhenxing Pan Kirk S. Schanze Kirk S. Schanze Intercalation of Alkynylplatinum(II) Terpyridine Complexes into a Helical Poly(phenylene ethynylene) Sulfonate: Application to Protein Sensing American Chemical Society 2017 PPESO sulfonate-conjugated polyelectrolytes Pt polymer helix 3 MMLCT 3 MMLCT state emission state emission protein complex ensemble fluorescence 2017-04-11 12:48:29 Journal contribution https://acs.figshare.com/articles/journal_contribution/Intercalation_of_Alkynylplatinum_II_Terpyridine_Complexes_into_a_Helical_Poly_phenylene_ethynylene_Sulfonate_Application_to_Protein_Sensing/4854662 The interactions of two anionic poly­(phenylene ethynylene) sulfonate-conjugated polyelectrolytes (<i>m</i>PPESO<sub>3</sub><sup>–</sup> and <i>p</i>PPESO<sub>3</sub><sup>–</sup>) with two alkynylplatinum­(II) terpyridine complexes (Pt<sup>2+</sup> and Pt<sup>3+</sup>) were studied. The Pt­(II) complexes interact with helical <i>m</i>PPESO<sub>3</sub><sup>–</sup> by intercalation within the polymer helix to form a “guest–host” ensemble. Titration of Pt­(II) complexes into an aqueous solution of <i>m</i>PPESO<sub>3</sub><sup>–</sup> gives rise to efficient quenching of the polymer’s fluorescence; meanwhile, triplet metal–metal-to-ligand charge transfer (<sup>3</sup>MMLCT) state emission from the intercalated Pt­(II) complexes appears when the ensembles are excited into the polymer’s absorption band. The <sup>3</sup>MMLCT state emission implies that the Pt­(II) complexes aggregate or dimerize on the <i>m</i>PPESO<sub>3</sub><sup>–</sup> scaffold. The responses of the <i>m</i>PPESO<sub>3</sub><sup>–</sup> and Pt­(II) complex ensembles to various proteins were examined by monitoring the <i>m</i>PPESO<sub>3</sub><sup>–</sup> fluorescence change. Negatively charged proteins recover the <i>m</i>PPESO<sub>3</sub><sup>–</sup> fluorescence more than the positively charged proteins under physiological pH, indicating that electrostatics play an important role in the protein–ensemble interaction.