• Lowry assay;
  • homogeneity of removal;
  • microassay;
  • drug discovery

Background/aims: Examination of stratum corneum (SC) content with tape stripping and a colorimetric method is increasingly used. We examined the possible use of microplates in tandem with a colorimetric method to examine SC removed with tape stripping. As a corollary to this examination, the homogeneity of tape strips was examined.

Method: The commonly used Lowry assay was adapted for 96-well plates. Tapes were divided into four regions and sample disks of 5 mm diameter were taken from each and analyzed for SC mass using the adapted Lowry assay.

Results: Homogeneity of SC removal over different areas across a tape strip is limited.

Conclusion: Quantification of SC by means of a 96-well microplate-based colorimetric method is feasible and shortens the time of analysis. However, when using D-Squame® tape disks, SC removal on a limited area of the tape is not predictive for SC removal on the entire tape as removal is inhomogenous. Therefore, SC protein extraction should be performed on a large enough area, eventually on the entire tape when quantifying SC mass removed by tape stripping.