Imaging Striatal Dopamine Release Using a Non-Genetically Encoded Near-Infrared Fluorescent Catecholamine Nanosensor

Abraham G. Beyene; Kristen Delevich; Jackson Travis Del Bonis-O’Donnell; David J. Piekarski; Wan Chen Lin; A. Wren Thomas; Sarah J. Yang; Polina Kosillo; Darwin Yang; Linda Wilbrecht; Markita P. Landry

To characterize nIRCats post-synthesis, the full visible and near-infrared absorption spectrum was taken for each nanosensor batch (UV-VIS-NIR spectrophotometer, Shimadzu UV-3600 Plus) or UV-VIS (ThermoFisher Scientific Genesys 20) . SWNT concentrations of as-made nanosensor batches were determined using absorbance at 632 nm (UV-VIS) with an extinction coefficient of  = 0.036 (mg/L) -1 cm -1 . Full spectrum absorbance measurements were made with UV-VIS-NIR after dilution to 5 mg/L SWNT concentration in 100 mM NaCl. For fluorescence spectroscopy, each sensor batch was diluted to a working concentration of 5 mg/L in 100 mM NaCl, and aliquots of 198 µL were placed in each well of a 96-well plate (Corning). Fluorescence measurements were obtained with a 20 X objective on an inverted Zeiss microscope (Axio Observer.D1) coupled to a Princeton Instruments spectrograph (SCT 320) and liquid nitrogen cooled Princeton Instruments InGaAs linear array detector (PyLoN-IR). A 721nm laser (OptoEngine LLC) was used as the excitation light source for all characterization experiments.