title: Fluorescent metallacycle-cored polymers via covalent linkage and their use as contrast agents for cell imaging.
abstract: The covalent linkage of supramolecular monomers provides a powerful strategy for constructing dynamic polymeric materials whose properties can be readily tuned either by the selection of monomers or the choice of functional linkers. In this strategy, the stabilities of the supramolecular monomers and the reactions used to link the monomers are crucial because such monomers are normally dynamic and can disassemble during the linking process, leading to mixture of products. Therefore, although noncovalent interactions have been widely introduced into metallacycle structures to prepare metallosupramolecular polymers, metallacycle-cored polymers linked by covalent bonds have been rarely reported. Herein, we used the mild, highly efficient amidation reaction between alkylamine and N-hydroxysuccinimide-activated carboxylic acid to link the pendent amino functional groups of a rhomboidal metallacycle 10 to give metallacycle-cored polymers P1 and P2, which further yielded nanoparticles at low concentration and transformed into network structures as the concentration increased. Moreover, these polymers exhibited enhanced emission and showed better quantum yields than metallacycle 10 in methanol and methanol/water (1/9, vol/vol) due to the aggregation-induced emission properties of a tetraphenylethene-based pyridyl donor, which serves as a precursor for metallacycle 10. The fluorescence properties of these polymers were further used in cell imaging, and they showed a significant enrichment in lung cells after i.v. injection. Considering the anticancer activity of rhomboidal Pt(II) metallacycles, this type of fluorescent metallacycle-cored polymers can have potential applications toward lung cancer treatment.
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112; stang@chem.utah.edu mingming.zhang@utah.edu yucaiwang@ustc.edu.cn.
authors.forename: Mingming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: The Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Diseases, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei 230027, People's Republic of China.
authors.forename: Shuya
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112.
authors.forename: Xuzhou
authors.initials: X
authors.lastname: Yan
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112.
authors.forename: Zhixuan
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112.
authors.forename: Manik Lal
authors.initials: ML
authors.lastname: Saha
authors.affiliation: The Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Diseases, School of Life Sciences and Medical Center, University of Science & Technology of China, Hefei 230027, People's Republic of China stang@chem.utah.edu mingming.zhang@utah.edu yucaiwang@ustc.edu.cn.
authors.forename: Yu-Cai
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112; stang@chem.utah.edu mingming.zhang@utah.edu yucaiwang@ustc.edu.cn.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stang
mesh_terms: D058948:Cell Tracking / Q000379:methods*; D003287:Contrast Media / Q000737:chemistry*; D005453:Fluorescence; D006801:Humans; D057054:Molecular Imaging / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D003287:Contrast Media; D011108:Polymers; D014867:Water
keywords: aggregation-induced emission; cell imaging; covalent linkage; fluorescent polymers; supramolecular coordination complex