Application of attenuated total reflection Fourier transform infrared imaging and tape-stripping to investigate the three-dimensional distribution of exogenous chemicals and the molecular organization in Stratum corneum

Abstract

Attenuated total reflection Fourier transform infrared spectroscopic imaging combined with tape-stripping is an advantageous approach to map the depth penetration and lateral distribution of topically applied chemicals in Stratum corneum (SC) and the conformational order of SC lipids. Tape-stripping progressively removes layers of SC, and chemical imaging provides spatially resolved information on the chemical composition of both the newly exposed SC surface and of the tapes used for stripping. The procedure is rapid, minimally invasive, and does not necessitate cross-sectioning of the skin. This approach offers a simple and direct way to determine the distribution of exogenous volatile and non-volatile chemicals in SC as a function of the chemical composition of the formulation and time, and the conformational order of SC lipids in native and topically treated skin. The procedure described here is well suited to address questions of relevance for the areas of drug delivery, dermatology, and skin care.

Synchrotron X-ray absorption spectroscopy analysis of arsenic chemical speciation in human nail clippings

“…whether it was exogenous, because of surface contamination, or endogenous, where arsenic is embedded in the protein matrix during the nail growth. The extensive information on biomedical applications of these methods for structural and chemical tissue diagnostics can be found in the review by Krafft and Sergo [90] and in several recent papers related to modifications of these methods for high-resolution chemical imaging of biological cells and tissues, see for example the paper by Boncheva et al [91] Conclusions In this study we tested a combination of synchrotron microprobe XRF and XAS methods and the bulk XAS method to study arsenic speciation in nail clippings of volunteers exposed to slightly elevated levels of As in drinking water. It is encouraging that the XAS techniques showed a relatively high sensitivity for the chemical speciation analysis in nail clippings collected from a low level arsenic exposure cohort.…”

Applications of FTIR Spectroscopic Imaging in Pharmaceutical Science

“…It has also been shown that ATR-FTIR imaging provides information on the swelling of the stratum corneum as a function of humidity. This approach was also used to image the penetration of liquid ethanol into the skin [77] and showed good potential for studying the transdermal delivery of drugs [78,79].…”

In situ permeation study of drug through the stratum corneum using attenuated total reflection Fourier transform infrared spectroscopic imaging

“…11,31 This study demonstrated the possibility of measuring SC heterogeneity by observing lipidrich and lipid-poor regions, and the permeation and distribution of a model drug and solvents into the SC. Although this spectroscopic approach measures permeation through the skin, it is not a straightforward method for the accurate calculation of diffusion coefficients because the ATR crystal is present on one side of the skin instead of in an infinite sink.…”

“…To obtain a diffusion coefficient, it is possible to apply a Franz-type cell, as was used by Hartmann et al, 9 in conventional ATR spectroscopic studies or in combination with a tape strip in ATR-FTIR imaging. 31 The ATR-FTIR imaging approach presented here studies permeation of a solvent and model drug through the skin.…”