Use of single particle ICP-MS to estimate silver nanoparticle penetration through baby porcine mucosa

Children are potentially exposed to products that contain nanoparticles (NPs). In particular, silver NPs are commonly present both in products used by and around children, primarily due to their antibacterial properties. However, very few data are available regarding the ability of silver NPs to penetrate through the oral mucosa in children. In the present work, we used baby porcine buccal mucosa mounted on vertical Franz diffusion cells, as an in vitro model to investigate penetration of silver NPs (19 ± 5 nm). Permeability experiments were performed using pristine physiologically-relevant saline solution in the receiver chamber and known concentrations of NPs or ions in the donor chamber; conditions mimicked the in vivo physiological pH conditions. After physicochemical characterization of silver nanoparticles dispersed in physiological solution, we evaluated the passage of ions and NPs through the mucosa, using single particle inductively coupled plasma mass spectrometry. A flux of 4.1 ± 1.7 ng cm^-2min^-1 and a lag time of 159 ± 17 min were observed through mucosa exposed to silver nanoparticles. The latter suggests nanoparticle penetration through the baby porcine mucosa and release Ag⁺ ions in the receptor fluid, as confirmed by computational model. Due to physiological similarity between human and pig membranes it is reasonable to assume that a trans-oral mucosa penetration could occur in children upon contact with silver nanoparticles.