UV/VIS Absorbance Allows Rapid, Accurate, and Reproducible Mass Determination of Corneocytes Removed by Tape Stripping

Abstract

The accurate determination of the mass of the horny layer removed by tape stripping is a decisive prerequisite for the application of this technique in penetration studies. A novel method using optical spectroscopy to determine the amount of stratum corneum (SC) is presented. We could show that the absorbance measured in the visible spectral range accurately reflects the mass of the SC fixed on individual tapes. Furthermore, absorbance measurement allows determination of the absolute mass of corneocyte aggregates on the removed tape strips. Topically applied substances do not disturb the spectroscopic measurements in contrast to the conventionally employed weight determination. Identical results were obtained when performing spectroscopic horny layer quantification independently in two separate institutions. Taken together, this new method is rapid, sensitive, reproducible, and accurate. We anticipate a wide application in penetration studies as well as in dermatopharmacokinetics.

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.…”

“…The tape was handled with forceps during the weighing and removal procedure. The tape strips were weighed with a semi-micro balance (BP 211 D-OCE, Sartorius, Göttingen, Germany) before and after the removal of SC, as described previously [23, 24]. The difference between the two measurements was taken as the mass of the removed SC.…”

“…The corneocytes attached to the tape strip decrease the transmission of light by reflection, diffraction and scattering, providing a pseudo-absorption [23, 24]. Spectra were recorded between 230 and 500 nm using a clean tape (taken from the direct neighbourhood of the tape strip measured) in the reference beam.…”

“…Spectra were recorded between 230 and 500 nm using a clean tape (taken from the direct neighbourhood of the tape strip measured) in the reference beam. The pseudo-absorption was determined at 430 nm as described previously [23, 24]. …”