Copper and Cobalt Ions Released from Metal Oxide Nanoparticles Trigger Skin Sensitization

Area of Science:

• Toxicology
• Materials Science
• Dermatology

Background:

• Human skin encounters diverse nanomaterials daily through cosmetics, pollution, and industry.
• Metal-containing nanomaterials raise concerns regarding potential skin sensitization.
• Understanding nanomaterial-induced skin reactions is crucial for safety assessments.

Purpose of the Study:

• To compare the skin sensitization potential of metal oxide nanoparticles (NPs) with their constituent metal chlorides.
• To investigate the role of metal ion release in NP-induced skin sensitization.
• To evaluate both in vitro and in vivo responses to selected metal oxide NPs.

Main Methods:

• Five metal oxide NPs (CuO, CoO, Co3O4, NiO, TiO2) and two metal chlorides (CoCl2, CuCl2) were tested.
• In vitro assessment using KeratinoSens™ cells to evaluate luciferase induction and cytotoxicity.
• In vivo assessment in BALB/C mice lymph nodes to confirm NP responses.

Main Results:

• Copper oxide (CuO) and cobalt monoxide (CoO) NPs showed positive luciferase induction and cytotoxicity, similar to their respective metal chlorides.
• Cobalt oxide (Co3O4), nickel oxide (NiO), and titanium dioxide (TiO2) NPs did not induce significant sensitization responses.
• Ion chelation data confirmed that metal ion release is the primary factor in skin sensitization.

Conclusions:

• Fast-dissolving metal oxide NPs, specifically CuO and CoO, induce skin sensitization through the release of metal ions.
• The study highlights the importance of metal ion release as a mechanism for NP skin sensitization.
• Further research is needed to fully elucidate the complex mechanisms of NP-induced skin sensitization.