Non‐invasive Technique for Obtaining Fluorescence Excitation and Emission Spectra in Vivo

An intensified photodiode array forms the heart of a sensitive spectrophotofluorometry system that permits the rapid and non‐invasive determination of fluorescence emission spectra in the skin of living, non‐anesthetized animals. Using this system, we found it possible to obtain good emission and excitation spectra of the material responsible for the weak red fluorescence that characterizes normal mouse skin, and to follow the biosynthesis and subsequent clearance of protoporphyrin IX in the skin of non‐anesthetized mice that had been given various doses of the porphyrin precursor 5‐aminolevulinic acid.