In a paper published in Nano Letters, scientists at the University of Rochester found that quantum dot nanoparticles penetrated UV damaged skin more than non-compromised skin.
The conclusion was reached from in-vivo tests carried out on mice exposed to UV light levels similar to those that would induce medium level sunburn in humans.
Gauging the impact of sun damage
To gauge the impact of sun damage on the penetrative capabilities of nano-based sunscreens the scientists used quantum dot nanoparticles.
These are not generally used in sunscreens despite their UV absorption properties but they are a similar size to the titanium dioxide nanoparticles used commonly in sunscreens.
The authors of the study said the higher penetration levels observed in sunburned skin led them to the conclusion that the condition of the skin strongly influences penetration.
“This is an important discovery for nanoparticle safety concerns as consumers often apply sunscreens containing metal oxide nanoparticles of similar size and raw material properties to UV-exposed skin,” said the authors.
They said direct comparisons were impossible to make at this stage as a wide variety of surface coatings are used in commercial sunscreens that may alter skin penetration characteristics.
The authors called for further research. “Future in-vivo studies using custom imaging modalities and commercial sunscreen formulations are planned to generate the necessary insight to assess human health risks from applying nanoparticle sunscreens to UV-damaged skin.”
In Vivo Skin Penetration of Quantum Dot Nanoparticles in the Murine Model: The Effect of UVRLuke J. Mortensen, Gunter Oberdörster, Alice P. Pentland, and Lisa A. DeLouiseNano Lett.; 2008; ASAP Web Release Date: 08-Aug-2008; (Letter) DOI: 10.1021/nl801323y