Tape stripping is one of the few techniques that allows the stratum corneum to be physically explored layer by layer, in a non-invasive manner and without biopsy. Used both as a barrier challenge model and as a stratum corneum analysis tool, it holds a central place in cosmetic claim substantiation studies focused on repair, lipid reconstruction, and epidermal differentiation. This guide details the principles, protocols, associated analyses, and CRO selection criteria for this type of study.
Tape stripping principle: a non-invasive biopsy of the stratum corneum
Tape stripping involves successively applying standardized adhesive strips to the skin surface and then removing them. Each strip mechanically removes one or more layers of corneocytes, allowing sequential in-depth exploration of the stratum corneum. The technique relies on the adhesion between the strip and the superficial corneocytes, which is greater than the intercorneocyte cohesion force.
What distinguishes tape stripping from other barrier evaluation methods is its dual utility: it can be used as a challenge model (to impair the barrier before applying a test product) or as an analysis tool (to collect corneocytes and extract biomarkers from them). These two uses serve different objectives and involve distinct protocols.
Reference adhesive strips: D-Squame, CuDerm, and alternatives
The choice of adhesive strip is critical for reproducibility and comparability of results. Several products are available on the market, with varying adhesion and surface characteristics.
| Strip | Manufacturer | Surface (cm²) | Characteristics |
|---|---|---|---|
| D-Squame® | CuDerm (USA) | 3.8 | International reference, transparent, suitable for imaging |
| Corneofix® | Courage+Khazaka | 2.5 | Compatible with infrared spectroscopy analysis |
| Sebutape® | CuDerm | Variable | Primarily used for sebum, secondary use |
| Generic adhesive strips | Various | Variable | Not recommended for substantiation studies |
D-Squame® is the most widely used strip in the international literature and in specialized CROs. Its transparency allows direct analysis by colorimetry (toluidine blue staining) to quantify the amount of material collected and estimate the depth of exploration. For infrared spectroscopy analysis (FTIR-ATR), Corneofix® is preferred due to its chemically compatible composition.
Tape stripping as a barrier challenge model
Standardized challenge protocol
To create reproducible barrier impairment, the repeated tape stripping protocol follows strictly defined steps. The target area (generally the flexor forearm) is cleaned with water and dried for 10 minutes in a controlled room. A D-Squame® strip is applied with standardized pressure (weighted disc at 22 g/cm² for 10 seconds, or standardized pressure roller) then removed in a quick, dry motion, perpendicular to the skin surface.
This gesture is repeated 15 to 30 times on the same anatomical site depending on the desired level of impairment. After the final strips, TEWL is measured immediately to confirm effective impairment. An increase in TEWL of 100 to 300% compared to the healthy baseline indicates significant stratum corneum disruption.
Recovery kinetics under treatment
Once impairment is confirmed, the test product is applied daily on the impaired area. TEWL is measured at D0 (impairment), D1, D3, D7, D14, and D28. The comparison of recovery kinetics between the treated site and the untreated site (spontaneous recovery) constitutes proof of the repairing effect.
The advantage of tape stripping over the SLS model is the absence of chemical irritant residue after impairment: the disruption is purely mechanical, which eliminates interferences linked to the presence of residual surfactant in the skin during subsequent measurements.
| Criterion | Repeated tape stripping | SLS model |
|---|---|---|
| Nature of impairment | Mechanical | Chemical |
| Residue in skin | None | Possible (surfactant) |
| Reproducibility | High | Very high |
| Depth of impairment | Controlled (number of strips) | Dose and time-dependent |
| Complementary analyses | Proteins, lipids on strips | Limited |
| External validity | Good | Excellent |
Tape stripping as a stratum corneum analysis tool
Depth profiling: the logic of sequential series
When tape stripping is used as an analysis tool, the strips are collected sequentially and numbered. The first strips (n°1 to 3) collect the most superficial layers of the stratum corneum, while subsequent strips (n°4 to 15 or more) explore deeper layers. This depth profiling allows the study of biochemical composition gradients across the thickness of the stratum corneum.
Analyses performed on collected strips
Tape stripping strips constitute a rich biological material, exploitable for numerous analyses:
Quantification of collected material: toluidine blue staining or measurement of the optical absorbance of strips allows estimation of the quantity of corneocytes collected and therefore the depth of exploration. This normalization step is essential for comparing results between subjects or between sessions.
Protein extraction and quantification: corneocytes collected are extracted in an appropriate buffer. Proteins of interest (filaggrin, loricrin, involucrin, caspase-14, kallikreins) are measured by ELISA, Western blot, or quantitative proteomics. These markers provide information on the state of epidermal differentiation and barrier functionality.
Lipid analysis: intercellular stratum corneum lipids (ceramides, free fatty acids, cholesterol) can be extracted from the strips and analyzed by liquid chromatography coupled to high-resolution mass spectrometry (LC-MS/MS). This approach allows characterization of ceramide subclasses, their molar ratios, and their organization, directly correlated to barrier efficacy.
FTIR-ATR spectroscopy: applied directly to Corneofix® strips, Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR) provides information on the organization and conformation of intercellular lipids (gauche/trans conformer ratio of acyl chains), as well as on the water content of the analyzed layers.
Raman spectroscopy: combined with tape stripping, Raman spectroscopy allows measurement of molecular water content and lipid organization at different depths of the stratum corneum, offering biochemical depth profiling not accessible by other non-invasive methods.
| Analysis | Required material | Parameter measured | Information obtained |
|---|---|---|---|
| Toluidine blue staining | D-Squame strips | Quantity of corneocytes | Depth of exploration, normalization |
| ELISA / Western blot | Protein extract | Filaggrin, loricrin, caspase-14… | State of epidermal differentiation |
| LC-MS/MS | Lipid extract | Ceramide subclasses | Lipid composition and organization |
| FTIR-ATR | Corneofix strips | Lipid conformation, water | Molecular organization |
| Raman spectroscopy | Strips or in situ | Water, lipids | Biochemical depth profiling |
| Quantitative proteomics | Protein extract | Broad protein panel | Global mechanism of action |
Parameters to define before launching a tape stripping study
Anatomical area: the flexor forearm is the reference area. The face (cheek, forehead) is possible for facial product studies but presents greater inter-individual variability and reduced tolerance to repeated stripping.
Number of strips: depends on the objective. For moderate barrier impairment (repair studies): 15 to 20 strips. For deep impairment: 25 to 30. For biochemical profile analysis without major impairment: 5 to 10 sequential strips.
Application pressure: standardized by a weighted disc (22 g/cm², 10 seconds) or calibrated pressure roller. Pressure variability is the main source of error in tape stripping studies; its control is non-negotiable.
Population: dry or atopic skin for lipid reconstruction studies, normal skin for mechanism of action studies on healthy barrier, sensitive skin for tolerance studies.
Sample size: 20 to 30 subjects minimum in an intra-individual design. For biochemical analyses on strips, the quantities of material collected per subject may limit the number of analyses feasible; this point must be anticipated with the CRO.
Selecting a CRO for a tape stripping study
Tape stripping is an apparently simple technique that nevertheless requires real operational expertise and appropriate analytical equipment. The selection criteria for a CRO for this type of study are as follows:
Mastery of the technique: the reproducibility of tape stripping depends directly on the operator’s experience. A CRO trained in this technique must be able to present intra-operator and inter-operator variability data.
Analytical capacity: depending on the desired analyses (proteomics, lipidomics, FTIR, Raman), the CRO must have the equipment in-house or a network of qualified analytical partners. The strip preservation chain (temperature, delay between collection and analysis) must be documented.
Standardization equipment: calibrated weighted disc, standardized pressure roller, temperature- and humidity-controlled room for associated TEWL measurements.
Documented experience: publications or studies conducted on similar protocols, references available on request.
On the Skinobs platform, brands can identify laboratories with expertise in tape stripping and associated biochemical analyses, among the 138 referenced laboratories in 38 countries for skin barrier substantiation.
Conclusion
Tape stripping is a versatile and powerful tool in the skin barrier evaluation arsenal. A clean and controlled challenge model, it is also a unique window into the biochemical composition of the stratum corneum, layer by layer. Combined with protein, lipid, and spectroscopic analyses, it allows documentation not only of a formula’s effect on the barrier, but also its molecular mechanism of action — a level of evidence now expected for the most ambitious claims.
Looking for a laboratory with tape stripping expertise for your barrier studies? Skinobs allows you to identify CROs adapted to your protocol and desired analyses. [Access the platform]
