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

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/356543 doi: bioRxiv preprint A #1.5 glass coverslip was functionalized with (3-Aminopropyl) triethoxysilane (APTES, Sigma Aldrich) by soaking in 10% APTES in ethanol for 5 min. The coverslip was then rinsed with DI water and left to dry. The coverslip was then fixed onto an ibidi sticky-Slide VI 0.4 forming 6 microfluidic channels. First, 100 μL of PBS was pipetted through a channel. Next, the channel was filled 50 μL of a 5 mg/L solution of nIRCats and left to incubate at room temperature for 5 min. The channel was rinsed using three 50 μL PBS washes, keeping the channel filled with solution at all times. The surface immobilized nIRCats in PBS were imaged on an epifluorescence microscope with 721 nm excitation and a Ninox VIS-SWIR 640 camera (Raptor). One end of the flow channel was connected to a syringe pump (Harvard Appartus) using Luer lock fittings. Prior to the start of image acquisition, the opposite flow reservoir was filled with PBS and the pump was set to refill mode at a volumetric flow rate of 40 μL min -1 . Once the liquid in the reservoir was depleted, 40 μL of 10 μM dopamine in PBS was added. The process was repeated using alternating additions of 80 μL of PBS washes and 40 μL of dopamine solution.