Evaluation of the Pseudo-Absorption Method to Quantify Human Stratum corneum Removed by Tape Stripping Using Protein Absorption

Abstract

Tape stripping is a well-known method to study the barrier function of the stratum corneum (SC) and penetration processes of topically applied substances into the horny layer. The quantification of the removed corneocytes for each tape strip is the prerequisite for these studies. The pseudo-absorption of the corneocytes was proposed as a measure for the quantification of the removed corneocyte aggregates. In this study, the pseudo-absorption of the corneocytes in the visible range (430 nm) is compared with the protein absorption in the UV range (278 nm) and an absorption at 652 nm obtained after staining of the SC proteins with Trypan blue. Both the protein absorption and the absorption measured after staining correlate well with the pseudo-absorption measured at 430 nm (R² = 0.92 ± 0.04 and R² = 0.95 ± 0.04, respectively).

Gender-Related Differences in the Physiology of the Stratum Corneum

“…However, no significant differences between females and males in the amount of the SC were obtained by different methods of investigation [23, 24, 32, 35, 36]. This finding is in agreement with the observation that SC thickness appears to be independent of gender [42.]…”

“…Some tape strips were contaminated and hence their exact amount of SC could not be determined, this was due, for instance, to errors during handling (noted in the protocol) or the presence of endogenous or exogenous substances [23, 24, 35]. Therefore the values obtained for each of the 20 tape strips were compared with all six methods and the pseudo-absorption of the corneocytes was used as reference.…”

“…Therefore the spectra recorded between 230 and 500 nm were corrected by the linearly increasing pseudo-absorption of the corneocytes with decreasing wavelength, using the baseline correction as reported previously [35]. Thus the absorption of proteins contained in the removed corneocytes was determined as the difference of the maximum and the baseline spectrum (reflecting the pseudo-absorption of the corneocytes) at a wavelength of 278 nm.…”

“…Corneocytes proteins were stained using trypan blue (0.4% solution, Sigma-Aldrich, Deisenhofen, Germany) as already described [35]. Spectra were recorded between 400 and 800 nm and the absorption of the stained proteins was determined at 600 nm, using the baseline correction to avoid any influence of the pseudo-absorption of the corneocytes.…”

Mass Spectrometry in Cosmetic Science: Advanced Ionization Techniques for Detecting Trace Molecules in or on Human Skin

“…28) Figure 4(b) shows the absorbance at 430 nm for tape-stripped stratum-corneum samples that were taken repeatedly from the three vicinal sites from the inner forearm of the male volunteer. e results reveal that the absorbance decreases for the deeper strips, which is consistent with the population of the cells, as determined by visual inspection [ (Fig.…”