nIRCat characterization and acute brain slice imaging

Dopamine neuromodulation of neural synapses is a process implicated in a number of critical brain functions and diseases. Development of protocols to visualize this dynamic process is essential to understanding how dopamine modulates neurochemical brain function. We have developed a non-genetically encoded, near infrared (nIR) catecholamine nanosensor (nIRCat) capable of identifying ~2 µm dopamine release hotspots in the dorsal striatal brain slices. This platform is readily introduced into both genetically tractable and intractable organisms and is compatible with a number of dopamine receptor agonist and antagonists. In the following work, we describe the synthesis, characterization, and implementation of nIRCat in brain slices. We show how to image electrically and optogenetically stimulated dopamine release using nIRCat, and how these imaging protocols can be adapted to study the effects of dopamine receptor pharmacology. We also detail the development of video-analysis software to identify and track the location and kinetics of dopamine release hot spots over the course of nIRCat imaging experiments. Altogether, synthesis and characterization of nIRCat takes 5 hours and imaging live brain slices takes 6 hours. 

Methods
These data were collected using absorbance spectroscopy, fluorescence spectroscopy, and wide-field near-infrared fluorescence microscopy