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Dioxygen diffusion in the stratum corneum: an EPR spin label study
1Department of Chemistry and Biochemistry, San Francisco State University, CA 94132.
Biochimica Et Biophysica Acta
|June 18, 1993
Summary
This study quantifies molecular oxygen diffusion across the skin's stratum corneum using EPR spectroscopy. Oxygen diffusion coefficient (D(O2)) was determined, revealing enhancement by permeation-enhancing chemicals.
Area of Science:
- Skin barrier function
- Molecular diffusion
- Biophysics
Background:
- The stratum corneum, the skin's outermost layer, acts as a critical barrier against environmental factors.
- Understanding molecular transport, particularly oxygen diffusion, is vital for skin physiology and drug delivery.
Purpose of the Study:
- To investigate the permeability barrier function of the stratum corneum concerning molecular oxygen diffusion.
- To determine the oxygen diffusion coefficient (D(O2)) in human stratum corneum.
Main Methods:
- Electron Paramagnetic Resonance (EPR) spectroscopy was employed to study the stratum corneum.
- A stearic acid spin probe was used to monitor oxygen diffusion.
- Line broadening of EPR spectra correlated with oxygen concentration and diffusion rates.
Main Results:
- The oxygen diffusion coefficient (D(O2)) in human stratum corneum was determined to be 3 x 10(-7) cm2/s at 37°C.
- The activation energy for oxygen diffusion was approximately 44 kJ/mol.
- Permeation enhancers DeMSO and DMSO increased D(O2) by two- to three-fold.
Conclusions:
- This study successfully quantified oxygen diffusion across the stratum corneum.
- The findings provide crucial data on skin's barrier properties and oxygen transport.
- Permeation enhancers significantly impact oxygen diffusion, suggesting potential applications in transdermal delivery.