Anomalous Fluorescence of White Hair Compared to Other Unpigmented Keratin Fibers

The study found that tryptophan (Trp) fluorescence in natural white hair was significantly weaker compared to 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 affected by oxidation, reduction, or decuticulation, suggesting that these factors were not responsible. The study proposed that the low Trp fluorescence intensity might be due to greater environmental exposure to UV sunlight or quenching by an unknown substance introduced during keratinization or through personal care products. Further research was needed to determine the exact cause.