title: Bright fluorescent chemosensor platforms for imaging endogenous pools of neuronal zinc.
abstract: A series of new fluorescent Zinpyr (ZP) chemosensors based on the fluorescein platform have been prepared and evaluated for imaging neuronal Zn(2+). A systematic synthetic survey of electronegative substitution patterns on a homologous ZP scaffold provides a basis for tuning the fluorescence responses of "off-on" photoinduced electron transfer (PET) probes by controlling fluorophore pK(a) values and attendant proton-induced interfering fluorescence of the metal-free (apo) probes at physiological pH. We further establish the value of these improved optical tools for interrogating the metalloneurochemistry of Zn(2+); the novel ZP3 fluorophore images endogenous stores of Zn(2+) in live hippocampal neurons and slices, including the first fluorescence detection of Zn(2+) in isolated dentate gyrus cultures. Our findings reveal that careful control of fluorophore pK(a) can minimize proton-induced fluorescence of the apo probes and that electronegative substitution offers a general strategy for tuning PET chemosensors for cellular studies. In addition to providing improved optical tools for Zn(2+) in the neurosciences, these results afford a rational starting point for creating superior fluorescent probes for biological applications.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Chang
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Nolan
authors.forename: Jacek
authors.initials: J
authors.lastname: Jaworski
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Burdette
authors.forename: Morgan
authors.initials: M
authors.lastname: Sheng
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006624:Hippocampus / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009474:Neurons / Q000737:chemistry* / Q000502:physiology; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013816:Thermodynamics; D015032:Zinc / Q000032:analysis* / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D015032:Zinc