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. 2020 May 15;21(10):3512.
doi: 10.3390/ijms21103512.

Keratin Biomembranes as a Model for Studying Onychomycosis

Anton Valkov  1 , Michael Zinigrad  1 , Alexander Sobolev  1 , Marina Nisnevitch  1
Affiliations

Keratin Biomembranes as a Model for Studying Onychomycosis

Anton Valkov et al. Int J Mol Sci. .

Abstract

Difficulties in obtaining human nails that are large enough for examining the penetration of drug formulations led us to produce keratin films regenerated from human hair. We assume that these films can simulate human nail plates in drug penetration and permeation tests and can serve as a biological model for studying onychomycosis. The films were formed from keratin extracted from human hair using dithiothreitol, urea and thiourea. The obtained keratin extract was dispensed into Teflon rings and dried at 40 °C and then cured at 110 °C. The structure, surface morphology, chemical characterization and thermal stability of the films were characterized and were compared to those of human nail, hair and bovine hoof samples using SDS-electrophoresis, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The structure of the obtained films was found to be closer to human nails than to hair or bovine hooves. The keratin films were infected with Trichophyton rubrum and were proven to be appropriate for serving as a model for studying onychomycosis.

Keywords: Trichophyton rubrum; keratin films; onychomycosis model.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Protein extraction from human hair using β-mercaptoethanol (sol-ME) and 1,4-dithiothreitol (sol-DTT) containing solutions. Protein was extracted at 50 °C from delipidized human hair. Protein concentration was measured by the Bradford assay. Error bars present standard errors.
Figure 2
Figure 2
SDS–PAGE of a molecular weight markers (lane a); human nail extract (lane b); bovine hoof extract (lane c) and human hair extract (lane d).
Figure 3
Figure 3
Keratin films: (a) Intermediate soft keratin films (KF-40) obtained in 20 mm Teflon rings; (b) KF-40 keratin films before punching; (c) 16 mm diameter KF-40 keratin films after punching; and (d) KF-110 keratin films after curing.
Figure 4
Figure 4
X-ray diffraction patterns of human hair, nail, KF-110 and bovine hoof samples.
Figure 5
Figure 5
Fourier transform infrared spectroscopy (FTIR) spectra of human hair, nail, KF-110 and bovine hoof samples.
Figure 6
Figure 6
Thermogravimetric analysis (TGA) (a) and derivative thermogravimetry (DTG) (b) curves for human hair, nail, KF-110 and bovine hoof samples.
Figure 7
Figure 7
Scanning electron microscopy (SEM) micrographs of KF-110 films (a,c) and nail plates (b,d) at magnifications of 1000× (a,b) and 25,000× (c,d). White circles on (c) and (d) point on pores size of which was measured.
Figure 8
Figure 8
Keratin films infected by the dermatophyte T. rubrum: (a) a top view and (b) a side view of the film framed in Figure 8a.
See this image and copyright information in PMC

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Supplementary concepts