title: Synthesis and characterization of citrate-based fluorescent small molecules and biodegradable polymers.
abstract: Novel citric acid based photoluminescent dyes and biodegradable polymers are synthesized via a facile "one-pot" reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior. Applications in molecular labeling and cell imaging were demonstrated. The above discoveries contribute to the field of fluorescence chemistry and have laid a solid foundation for further development of new fluorophores and materials that show promise in a diversity of fluorescence-based applications.
  
  
  
  Photoluminescent materials are pivotal for fluorescence based imaging, labeling and sensing applications. Understanding their fluorescence mechanism is challenging and imperative. We develop a new class of citric acid-derived fluorescent materials in forms of polymers and small molecular dyes by a one-step solvent free reaction. We discovered two different classes of citric acid-derived fluorophores. A two-ring thiozolopyridine structure demonstrates strong fluorescence and exceptional resistance to photo-bleaching. A one-ring dioxopyridine exhibits relative weak fluorescence but with intriguing excitation and solvent-dependent emission wavelength shifting. Our methodology of synthesizing citric acid-derived fluorophores and the understanding on their luminescence are instrumental to the design and production of a large number of new photoluminescent materials for biological and biomedical applications.
authors.affiliation: Department of Biomedical Engineering, Materials Research Institutes, The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16801, United States.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Department of Biomedical Engineering, Materials Research Institutes, The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16801, United States.
authors.forename: Jimin P
authors.initials: JP
authors.lastname: Kim
authors.affiliation: Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Cai
authors.affiliation: Institute of Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, Materials Research Institutes, The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16801, United States.
authors.forename: Jinshan
authors.initials: J
authors.lastname: Guo
authors.affiliation: Department of Biomedical Engineering, Materials Research Institutes, The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16801, United States.
authors.forename: Ranjodh S
authors.initials: RS
authors.lastname: Dhami
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX 76010, United States.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Kong
authors.affiliation: Department of Biomedical Engineering, Materials Research Institutes, The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16801, United States.
authors.forename: Yixue
authors.initials: Y
authors.lastname: Su
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX 76010, United States.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Schug
authors.affiliation: Department of Biomedical Engineering, Materials Research Institutes, The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16801, United States. Electronic address: jxy30@psu.edu.
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013844:Thiazoles / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002264:Carboxylic Acids; D005456:Fluorescent Dyes; D011108:Polymers; D011725:Pyridines; D012996:Solutions; D013844:Thiazoles; D012710:Serum Albumin, Bovine; D019343:Citric Acid; C023666:pyridine
keywords: Degradable; Dyes; Fluorescence; Fluorescence spectroscopy; Polymers