2018 Volume 67 Issue 7 Pages 746-753
Collagen sheets with melanin added or Maillard cross-linking were prepared as models to simulate various human skin types and age groups. The treated collagen sheets were used to study effects of ultraviolet light on the human skin. Extracts were obtained from collagen sheets after ultraviolet light irradiation and analyzed. The results revealed that ultraviolet light irradiation of up to 25 hours mainly formed cross-linkages in collagen sheets with melanin added at 9% or lower, irradiation for 200 hours mainly cleaved collagen molecule chains. In contrast, ultraviolet light was found to promote cross-linkage formation in collagen molecule chains in the collagen sheet with melanin added at 50%, but hardly cleaved the molecule chains even for long durations of ultraviolet light irradiation. Moreover, ultraviolet light irradiation did not cleave the molecule chains but maintained cross-linkage in collagen sheets that were cross-linked by Maillard processes with glyoxal solutions of 0.1 mM or higher. However, exposure to ultraviolet light irradiation for as long as 200 hours cleaved collagen molecule chains. These results demonstrate that collagen sheets that simulate various human skin types could be useful for studying human skin damage caused by ultraviolet light.
