The use of the fluorescent probe 8-anilinonaphthalene sulfate (ANS) for collagen and elastin histochemistry

The reactivity of skin elastin and collagen to ANS (8-anilinonaphthalene-1-sulphonate) dissolved in nonpolar (e.g. butanol) and polar (distilled water, phosphate buffer at pH 2.8 and 8.2) solvents was compared in histological sections. The elastin fibers were demonstrated to differ from collagen at the fluorescence microscopy level under certain ANS staining conditions. When treated with butanol-ANS solutions, both fiber types exhibit a blue fluroescence with spectral emission profiles alike. However, the elastin emission values in fluorescence-relative units are larger than those exhibited by collagen. On the other hand, for fibers treated with ANS dissolved in polar solvents, elastin and collagen differ in terms of wavelengths of their emission maxima. The ANS attachment to substrate is ascribed to be predominantly nonpolar for dye butanol solutions. When the dye is dissolved in polar solvents, however, polar bindings between ANS and the stained substrate may be established that contribute to emission maximum shift to longer wavelengths.