Bound Water in Stratum Corneum Measured by Differential Scanning Calorimetry

Abstract

Differential scanning calorimetry has been used to study water binding in stratum corneum. Samples of various total water contents are frozen and melted and the latent heat of melting measured with a Perkin Elmer differential scanning calorimeter. From this the relative amounts of freezing (unbound) water and non-freezing (bound) water are calculated. The results show that the amount of bound water in human limb corneum is about 0.34 grams per gram of dry corneum. This supports the findings of Hansen and Yellin, based on NMR measurements, of 0.3–0.35 grams of bound water per gram of dry corneum. It indicates also that the 5.0 grams of bound water per gram of dry corneum which Scheuplein and Morgan estimated from rate of weight loss measurements refers to liquid water held in the tissue by diffusion barriers and not to water molecularly bound to other components of the stratum corneum. The effect of extracting lipids and water soluble substances from guinea pig footpad corneum is to increase the amount of bound water it can contain from 0.29 to 0.41 grams per gram of dry corneum