Bright fluorescent chemosensor platforms for imaging endogenous pools of neuronal zinc.
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.
Chang
Christopher J
CJ
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Nolan
Elizabeth M
EM
Jaworski
Jacek
J
Burdette
Shawn C
SC
Sheng
Morgan
M
Lippard
Stephen J
SJ
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
D005456:Fluorescent Dyes; D015032:Zinc