Nanoparticles (NPs) appear to be promising in the medical domain due to their unique physicochemical properties. In particular, zinc oxide (ZnO) NPs are extensively incorporated into sunscreens to protect the skin from exposure to ultraviolet radiation. However, there are many health concerns about skin penetration and the resultant toxicity. The methodologies for assessing NP toxicity are under development, therefore, it is difficult to thoroughly assess the toxicity of ZnO NPs toward humans.

A study published in the Analytical and Bioanalytical Chemistry journal showed that researchers have developed a platform to simultaneously detect skin permeability to and pro-inflammatory activity mediated by zinc ion released from NPs. Firstly, they generated a stable reporter cell line expressing green fluorescent protein (GFP) under the control of interleukin-8 (IL-8) promoter activity. The expression levels of this protein induced by zinc reflected the endogenous IL-8 expression levels and the pro-inflammatory responses. Subsequently, they found that fibrin hydrogel can reproduce permeability to zinc ion of a human skin equivalent model and is thus a promising material to evaluate skin permeability to zinc ion. Then, they constructed a fibrin hydrogel-based in vitro bioassay system for simultaneously detecting skin permeability to and pro-inflammatory activity mediated by zinc ion released from NPs by using a stable reporter cell line and a fibrin hydrogel layer. The researchers stated that technical simplicity and good predictability of this bioassay system make it a promising in vitro permeation test. This system is likely to be used widely in the cosmetics and pharmaceutical industries.

Source: Anal Bioanal Chem. 2020 Oct 6.doi: 10.1007/s00216-020-02970-5. Online ahead of print.