Anomalous Fluorescence of White Hair Compared to Other Unpigmented Keratin Fibers

The study demonstrated that the tryptophan (Trp) fluorescence of natural white hair was significantly weaker than that of other unpigmented keratin fibers like wool, cashmere, rabbit hair, and mink fur, although its visible fluorescence emission was stronger. The weak Trp fluorescence in white hair was not significantly affected by oxidation, reduction, or decuticulation, suggesting that quenching by cystine or cuticle scales was not responsible. The study proposed that the low Trp fluorescence intensity might be due to greater environmental exposure to UVB wavelengths in sunlight or possibly due to quenching by an unknown substance introduced during keratinization or from personal care products. Further research was needed to determine the exact cause.