Localization of fluorescent probes in rat brain tissue stained with hematoxylin: a methodology development study

Abstract

<p>Biocompatible probes can be promising diagnostic and drug targeting molecules; however the ability to localize them in their target organs maybe difficult. In this study, hematoxylin stained and unstained paraformaldehyde-fixed brain tissue sections harvested from adult rats injected with fluorescent probes (FP)-[Excitation 450-580 nm, emission 630-670 nm] and uninjected vehicle control rats were examined using epifluorescence microscopy [Excitation 545-580 nm, emission cutoff 610 nm]. Unstained brain sections from control and FP-injected rats showed significant tissue auto-fluorescence which could interfere with visualization of fluorescent probes in brain sections. We observed that tissue stained with hematoxylin had significantly reduced auto-fluorescence both in control and FP-injected rats while the fluorescence of FPs in injected animals was not noticeably different in stained versus unstained sections. The visible absorbance spectrum for hematoxylin in solution has a broad peak centered at 557 nm and thus would not interfere with the FP fluorescence emission. We conclude that brain tissue stained with hematoxylin specifically quenches tissue autofluorescence while sparing the fluorescence signals from the fluorescent probes.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 16, 2010</p>