Photoacoustic detection of genetically encoded fluorophores for neuronal subtype identification.

Abstract

<i>Objective.</i>Elucidating neurological processes in the mammalian brain requires improved methods for imaging and detecting neuronal subtypes. Transgenic mouse models utilizing Cre/lox recombination have been developed to selectively label neuronal subtypes with fluorophores, however, light-scattering attenuation of both excitation light and emission light limits their effective range of detection.<i>Approach</i>. To overcome these limitations, this study investigates the use of a near-infrared fluorophore, iRFP713, for subtype labeling of neurons found within brain regions that are typically inaccessible by optical methods. Towards this goal, a custom photoacoustic (PA) system is developed for detection of iRFP in neurons in brain slices, expressed via Cre/lox, and within<i>in vitro</i>cell culture.<i>Main results</i>. In this study, a custom system is developed to detect iRFP in neuronal cells both in brain slices and<i>in vitro</i>. Furthermore, this work validates iRFP expression in the brains of transgenic mice and neuronal cell culture.<i>Significance</i>. Combining iRFP with advanced imaging and detection strategies, such as PA microscopy, is critical for expanding the type and variety of neurons that scientists can observe within the mammalian brain.