Silver percutaneous absorption after exposure to silver nanoparticles: A comparison study of three human skin graft samples used for clinical applications C. Bianco a, *, G. Adami a , M. Crosera a , F. Larese b , S. Casarin c , C. Castagnoli c , M. Stella c , G. Maina d a Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Giorgeri 1, 34127 Trieste, Italy b Institute of Occupational Medicine, University of Trieste, Department of Medical Sciences, University of Trieste, Via della Pieta ` 19, 34129 Trieste, Italy c Department of Plastic Surgery and Burn Unit ‘‘Skin Bank,’’ CTO Hospital, Via Zuretti 29, 10126 Turin, Italy d Department of Clinical and Biological Sciences, University of Turin, Regione Gonzole 10, 10043 Orbassano, Turin, Italy 1. Introduction Skin is a dynamic interface between the inner body and the environment in which complex chemical–physical equilibria take place. The outer layer of the skin, the stratum corneum (SC), is made of corneocytes embedded in a lipid matrix and is the main barrier for penetration of chemicals and particles, and helps in the expulsion of water from the body. The composition of SC is strongly related to its structural and mechanical properties and is subjected to physiological variations. Many factors affect the barrier function of SC, both external (surfactants, environmental conditions, me- chanical stress, etc.) and individual factors (age, gender, b u r n s x x x ( 2 0 1 4 ) x x x – x x x a r t i c l e i n f o Article history: Accepted 9 February 2014 Keywords: Silver nanoparticles Skin Percutaneous absorption Wound healing a b s t r a c t Silver nanoparticles (AgNPs) are increasingly applied to a wide range of materials for biomedical use. These enable a close contact with human skin, thanks to the large release of silver ions that is responsible for a broad spectrum of antimicrobial activity. Silver can permeate the skin; however, there are no data available on silver permeation through skin grafts commonly used in burns recovery. The aim of our study was to evaluate silver penetration using fresh, cryopreserved, and glycerolized human skin grafts after exposure to a suspension of AgNPs in synthetic sweat using a Franz diffusion cell apparatus for 24 h. Silver permeation profiles revealed a significantly higher permeation through glycer- olized skin compared with both fresh and cryopreserved skin: 24-h silver flux penetration was 0.2 ng cm 2 h 1 (lag time: 8.2 h) for fresh skin, 0.3 ng cm 2 h 1 (lag time: 10.9 h) for cryopreserved skin, and 3.8 ng cm 2 h 1 (lag time: 6.3 h) for glycerolized skin. Permeation through glycerolized skin is significantly higher compared to both fresh and cryopreserved skin. This result can generate relevant clinical implications for burns treat- ment with products containing AgNPs. # 2014 Elsevier Ltd and ISBI. All rights reserved. * Corresponding author at: Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Giorgeri 1, 34127 Trieste, Italy. Tel.: +39 040 558 3944. E-mail address: carlotta.bianco@unito.it (C. Bianco). JBUR-4296; No. of Pages 7 Please cite this article in press as: Bianco C, et al. Silver percutaneous absorption after exposure to silver nanoparticles: A comparison study of three human skin graft samples used for clinical applications. Burns (2014), http://dx.doi.org/10.1016/j.burns.2014.02.003 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/burns http://dx.doi.org/10.1016/j.burns.2014.02.003 0305-4179/# 2014 Elsevier Ltd and ISBI. All rights reserved.