Human skin penetration of sunscreen nanoparticles: in-vitro assessment of a novel micronized zinc oxide formulation.
The extent to which topically applied solid nanoparticles can penetrate the stratum corneum and access the underlying viable epidermis and the rest of the body is a great potential safety concern. Therefore, human epidermal penetration of a novel, transparent, nanoparticulate zinc oxide sunscreen formulation was determined using Franz-type diffusion cells, 24-hour exposure and an electron microscopy to verify the location of nanoparticles in exposed membranes. Less than 0.03% of the applied zinc content penetrated the epidermis (not significantly more than the zinc detected in receptor phase following application of a placebo formulation). No particles could be detected in the lower stratum corneum or viable epidermis by electron microscopy, suggesting that minimal nanoparticle penetration occurs through the human epidermis.
Cross
Sheree E
SE
Therapeutics Research Unit, Southern Clinical Division, Department of Medicine, University of Queensland, Princess Alexandra Hospital, Woolloongabba, Australia. shereec@soms.uq.edu.au
Innes
Brian
B
Roberts
Michael S
MS
Tsuzuki
Takuya
T
Robertson
Terry A
TA
McCormick
Paul
P
D000279:Administration, Cutaneous; D002626:Chemistry, Pharmaceutical; D015194:Diffusion Chambers, Culture; D004817:Epidermis / Q000378:metabolism; D005260:Female; D006801:Humans; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D009924:Organ Culture Techniques; D010316:Particle Size; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D013473:Sunscreening Agents / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D013678:Technology, Pharmaceutical / Q000379:methods; D013997:Time Factors; D015034:Zinc Oxide / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*
D013473:Sunscreening Agents; D015034:Zinc Oxide