Zinc oxide nanoparticle removal from wounded human skin

Area of Science:

• Dermatology
• Nanotechnology
• Toxicology

Background:

• Topical nanoparticle toxicity is a growing concern, particularly for widely used sunscreen ingredients like zinc oxide nanoparticles (ZnO-NPs).
• Understanding the removal of ZnO-NPs from skin is crucial for assessing potential risks associated with their application.

Purpose of the Study:

• To investigate the penetration and subsequent removal of ZnO-NPs from both intact and injured human skin models.
• To evaluate the efficacy of standard washing procedures in removing ZnO-NPs from different skin conditions.

Main Methods:

• Ex vivo and in vivo human skin models were subjected to tape stripping or microneedling to simulate skin injury.
• ZnO-NPs were applied to the prepared skin, followed by a standard three-time soapy water wash after 2 hours.
• Multiphoton tomography was utilized to quantify the ZnO-NP signal before and after the washing procedure.

Main Results:

• Washing removed over 85% of ZnO-NPs from intact and tape-stripped ex vivo skin.
• In vivo studies showed similar high removal rates of 85-93% for intact and tape-stripped skin.
• Significantly less ZnO-NP removal (28% ex vivo, similar trend in vivo) was observed from puncture wound sites.

Conclusions:

• Standard washing is effective in removing ZnO-NPs from superficial layers of intact and tape-stripped skin.
• Washing is not effective for removing ZnO-NPs that have penetrated puncture wounds.
• These findings highlight the importance of skin barrier integrity in the context of topical nanoparticle safety.