Titanium Dioxide Nanoparticle Penetration into the Skin and Effects on HaCaT Cells.
Titanium dioxide nanoparticles (TiO2NPs) suspensions (concentration 1.0 g/L) in synthetic sweat solution were applied on Franz cells for 24 h using intact and needle-abraded human skin. Titanium content into skin and receiving phases was determined. Cytotoxicity (MTT, AlamarBlue(®) and propidium iodide, PI, uptake assays) was evaluated on HaCat keratinocytes after 24 h, 48 h, and seven days of exposure. After 24 h of exposure, no titanium was detectable in receiving solutions for both intact and damaged skin. Titanium was found in the epidermal layer after 24 h of exposure (0.47 ± 0.33 μg/cm(2)) while in the dermal layer, the concentration was below the limit of detection. Damaged skin, in its whole, has shown a similar concentration (0.53 ± 0.26 μg/cm(2)). Cytotoxicity studies on HaCaT cells demonstrated that TiO2NPs induced cytotoxic effects only at very high concentrations, reducing cell viability after seven days of exposure with EC50s of 8.8 × 10(-4) M (MTT assay), 3.8 × 10(-5) M (AlamarBlue(®) assay), and 7.6 × 10(-4) M (PI uptake, index of a necrotic cell death). Our study demonstrated that TiO2NPs cannot permeate intact and damaged skin and can be found only in the stratum corneum and epidermis. Moreover, the low cytotoxic effect observed on human HaCaT keratinocytes suggests that these nano-compounds have a potential toxic effect at the skin level only after long-term exposure.
Clinical Unit of Occupational Medicine, Department of Medical Sciences, University of Trieste, Via della Pietà 19, Trieste 34129, Italy. gadami@units.it.|Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Giorgeri 1, Trieste 34127, Italy. gadami@units.it.
Matteo
M
Crosera
Clinical Unit of Occupational Medicine, Department of Medical Sciences, University of Trieste, Via della Pietà 19, Trieste 34129, Italy. andrea.prodi@gmail.com.
Andrea
A
Prodi
Clinical Unit of Occupational Medicine, Department of Medical Sciences, University of Trieste, Via della Pietà 19, Trieste 34129, Italy. marcella.mauro82@gmail.com.
Marcella
M
Mauro
Department of Life Sciences, University of Trieste, Via L. Giorgeri 7/9, Trieste 34127, Italy. mpelin@units.it.
Marco
M
Pelin
Department of Life Sciences, University of Trieste, Via L. Giorgeri 7/9, Trieste 34127, Italy. florioc@units.it.
Chiara
C
Florio
Clinical Unit of Occupational Medicine, Department of Medical Sciences, University of Trieste, Via della Pietà 19, Trieste 34129, Italy. bellomo.francesca@gmail.com.
Francesca
F
Bellomo
Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Giorgeri 1, Trieste 34127, Italy. gadami@units.it.
Gianpiero
G
Adami
Dipartimento di Specialità Medico Chirurgiche, Scienze Radiologiche, Sanità Pubblica, University of Brescia, Piazza del Mercato 15, Brescia 25121, Italy. pietro.apostoli@unibs.it.
Pietro
P
Apostoli
Dipartimento di Specialità Medico Chirurgiche, Scienze Radiologiche, Sanità Pubblica, University of Brescia, Piazza del Mercato 15, Brescia 25121, Italy.
Giuseppe
G
De Palma
Clinical Unit of Occupational Medicine, Department of Medical Sciences, University of Trieste, Via della Pietà 19, Trieste 34129, Italy. bovenzi@units.it.
Massimo
M
Bovenzi
IMEM-CNR Institute, Parco Area delle Scienze 37/A, Parma 43124, Italy. marco.campanini@imem.cnr.it.
Marco
M
Campanini
Clinical Unit of Occupational Medicine, Department of Medical Sciences, University of Trieste, Via della Pietà 19, Trieste 34129, Italy. larese@units.it.
Francesca Larese
FL
Filon
D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism; D053758:Nanoparticles / Q000378:metabolism / Q000633:toxicity*; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D012869:Skin Absorption; D014025:Titanium / Q000493:pharmacokinetics / Q000633:toxicity*
C009495:titanium dioxide; D014025:Titanium
cytotoxicity; human skin absorption; in vitro; nanoparticles (NPs); titanium dioxide