ON EFFECT OF DIMETHYL SULFOXIDE ON HAIR KERATIN

[摘要] Stress relaxation measurements were made using a single human hair through a series of progressively more concentracted DMSO [dimethylsulfoxide] solutions and water. The force decay in water and in DMSO solutions up to 70% was essentially the same. In 80 to 100% DMSO solutions stress relaxation was rapid and more complete. Disulfide interchange accounts for most of the increased stress relaxation in the concentrated DMSO solutions. A 2nd experiment measured changes in force in a hair suddenly immersed in 100% DMSO after prior conditioning in water. Immediately after addition of the DMSO the force increased, reached a maximum, remained there for a time, and then decreased to a final low level. The initial force rise is due to the dehydrating action of DMSO which produces an effective increase in applied strain. The decrease of force over longer times has 3 probable causes As DMSO enters the fiber the length increases to cause an apparent relaxation by a reverse of the initial desiccant action; The static extension modulus of hair in 100% DMSO is less than that in water so that at constant strain the initial force is reduced by about half; As high concentrations of DMSO are reached within the hair, disulfide interchange occurs. Dimethyl sulfoxide interacts with hair keratin in at least 4 ways: an initial dehydration effect, a swelling effect, lowering of the modulus, and promotion of disulfide interchange. Dimethyl sulfoxide concentrations above 80% produce a marked increase in stress relaxation of a hair; weaker concentrations behave essentially the same as water. The changes within the fiber are almost reversible. There is the suggestion that the same mechanisms responsible for the increased rate of relaxation of hair keratin may also account for the increased diffusion rate through another keratin system, namely stratum corneum.