Researchers from the University of Bath has constructed a "nanoneedle" at the end of an atomic force microscopy (AFM) probe to study the stratum corneum (SC) in detail, which may lead to better skin treatments and a greater understanding of skin aging.
In a Journal of Investigative Dermatology article, the researchers (James Beard, PhD; Sergey Gordeev and Prof. Richard Guy, PhD) demonstrate the nanoneedle’s ability to probe corneocytes, the predominant cell type in the epidermis of the skin.
Although AFM can characterize the mechanical properties of biological samples, its ability has previously been limited to the surface. However, the nanoneedle AFM probes allowed the researachers to characterize the mechanical properties deep into the corneocyte. The method evaluates the forces experienced by a nanoneedle as it is pushed into and then retracted from the cell. Indentation loops yield the stiffness profile and information on the elastic and nonelastic mechanical properties at a specific depth below the surface of the corneocytes.
A clear difference between the softer ~50-nm-thick external layer and the more rigid internal structure of corneocytes is apparent, which is consistent with the current understanding of the structure of these cells.
There are also significant variations in the mechanical properties of corneocytes from different volunteers. The small diameter of the nanoneedle allows this “mechanical tomography” to be performed with high spatial resolution, potentially offering an opportunity to detect biomechanical changes in corneocytes because of, e.g., environmental factors, aging, or dermatological pathologies.
This new third dimension of imaging for corneocytes, according to the researchers, could lead to new applications in biology, nano medicine and material science.