Adhesion Failure of External Hair Cuticles Caused by Prussian Blue: Possible Electrochemical Roles of Sulfur and Cystine

Abraham A. Embi

13442 SW 102 Lane Miami, Florida 33186, USA

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Background: The effect of Prussian Blue on the hair fiber is unknown. In this report a new optical microscopy technique tailored to evaluate the effect of chemicals in solution on the hair shaft is introduced. The hair is a natural fiber consisting of keratin, a protein containing high concentration of disulfide derivative cystine. Prussian Blue (PB) is the main ingredient used to stain iron particles in tissue and advertised as ingredient in some hair coloring products. The effects on ex vivo human hairs are herein reported.

Methods: A working solution of 2,5% Potassium Ferrocyanide was prepared by mixing the crystals with deionized water. Working solution, 2.5% Aqueous Solution of Potassium Ferrocyanide: Potassium ferrocyanide, Trihydrate (K4Fe(CN)6.3H2O (2.5 g); Deionized water (100 ml).  Mix to dissolve. Freshly plucked human hairs were placed in the center of a 25x75x1mm glass slide. Three small drops of the PB solution were delivered via a micropipette surrounding the hair. Then a second slide was placed covering the first and secured by thin masking tape strips placed at the slides edge. At this point the solution spreads interstitially between the slides. Care should be taken to avoid air pockets. This preparation will be referred as a sandwich (SDW) throughout the manuscript. The solution was then allowed to evaporate (average time 4 hours) and images were documented by optical microscopy and recorded n=10. After drying, the same hair was sequentially remounted in similar fashion x4 times. Ancillary testing: Hairs stored for 20 months in dry cardboard slide boxes were also evaluated.  Equipment used: All specimens were viewed and digitally recorded at different magnifications via a video microscope interfaced with a computer system.

Results: In both, freshly harvested and old hairs when in contact with Prussian Blue, exo-cuticles separation was observed. 

Conclusions: Exposure of human hair to Prussian Blue causes large sections of imbricate pattern cuticles segments to separate from the shaft. These segmental adhesion failures were observed intermittently around the length of the shaft. The observed cuticle segments detachment failure caused by PB is hypothesized to be caused by a reaction between PB and the intrinsic sulfur and cystine  present in the hair fiber. This reaction is hypothesized to be of an electromagnetic nature. Journal of Nature and Science (JNSCI), 2(6):e194, 2016

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