title: Rapid Macrocycle Threading by a Fluorescent Dye-Polymer Conjugate in Water with Nanomolar Affinity.
abstract: A macrocyclic tetralactam host is threaded by a highly fluorescent squaraine dye that is flanked by two polyethylene glycol (PEG) chains with nanomolar dissociation constants in water. Furthermore, the rates of bimolecular association are very fast with k(on) ≈ 10(6)-10(7) M(-1) s(-1). The association is effective under cell culture conditions and produces large changes in dye optical properties including turn-on near-infrared fluorescence that can be imaged using cell microscopy. Association constants in water are ∼1000 times higher than those in organic solvents and strongly enthalpically favored at 27 °C. The threading rate is hardly affected by the length of the PEG chains that flank the squaraine dye. For example, macrocycle threading by a dye conjugate with two appended PEG2000 chains is only three times slower than threading by a conjugate with triethylene glycol chains that are 20 times shorter. The results are a promising advance toward synthetic mimics of streptavidin/biotin.
authors.affiliation: †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
authors.forename: Evan M
authors.initials: EM
authors.lastname: Peck
authors.affiliation: †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Liu
authors.affiliation: †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
authors.forename: Graeme T
authors.initials: GT
authors.lastname: Spence
authors.affiliation: †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
authors.forename: Scott K
authors.initials: SK
authors.lastname: Shaw
authors.affiliation: ‡School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Davis
authors.affiliation: ‡School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K.
authors.forename: Harry
authors.initials: H
authors.lastname: Destecroix
authors.affiliation: †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Smith
mesh_terms: D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D003503:Cyclobutanes / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007700:Kinetics; D047029:Lactams, Macrocyclic / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D061848:Optical Imaging; D010636:Phenols / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D003503:Cyclobutanes; D005456:Fluorescent Dyes; D047029:Lactams, Macrocyclic; D010636:Phenols; C480596:squaraine; D014867:Water; D011092:Polyethylene Glycols