title: Installing an additional emission quenching pathway in the design of iridium(III)-based phosphorogenic biomaterials for bioorthogonal labelling and imaging.
abstract: We report the synthesis, characterization, photophysical and electrochemical behaviour and biological labelling applications of new phosphorogenic bioorthogonal probes derived from iridium(III) polypyridine complexes containing a 1,2,4,5-tetrazine moiety. In contrast to common luminescent cyclometallated iridium(III) polypyridine complexes, these tetrazine complexes are almost non-emissive due to effective Förster resonance energy transfer (FRET) and/or photoinduced electron transfer (PET) from the excited iridium(III) polypyridine unit to the appended tetrazine moiety. However, they exhibited significant emission enhancement upon reacting with (1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH) (ca. 19.5-121.9 fold) and BCN-modified bovine serum albumin (BCN-BSA) (ca. 140.8-1133.7 fold) as a result of the conversion of the tetrazine unit to a non-quenching pyridazine derivative. The complexes were applied to image azide-modified glycans in live cells using a homobifunctional crosslinker, 1,13-bis((1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethyloxycarbonylamino)-4,7,10-trioxatridecane (bis-BCN).
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Steve Po-Yam
authors.initials: SP
authors.lastname: Li
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Alex Man-Hei
authors.initials: AM
authors.lastname: Yip
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Hua-Wei
authors.initials: HW
authors.lastname: Liu
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; State Key Laboratory of Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China. Electronic address: bhkenlo@cityu.edu.hk.
authors.forename: Kenneth Kam-Wing
authors.initials: KK
authors.lastname: Lo
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis*; D003287:Contrast Media / Q000138:chemical synthesis*; D015195:Drug Design; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D007495:Iridium / Q000737:chemistry*; D008422:Materials Testing; D008856:Microscopy, Fluorescence / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; D007495:Iridium
keywords: Bioorthogonal labelling; FRET; Iridium; Molecular imaging; PET; Tetrazine