Translocation of silver nanoparticles in the ex vivo human placenta perfusion model characterized by single particle ICP-MS.

Didier Astruc,Katrin Loeschner,Kailen Boodhia,Pius Manser,Janja Vidmar,Manuel Correia,Erik H. Larsen,Zahraa S. Al-Ahmady,Adrian Wichser,Tina Buerki-Thurnherr,Jaimé Ruiz

doi:10.1039/c8nr02096e

Abstract

With the extensive use of silver nanoparticles (AgNPs) in various consumer products their potential toxicity is of great concern especially for highly sensitive population groups such as pregnant women and even the developing fetus. To understand if AgNPs are taken up and cross the human placenta, we studied their translocation and accumulation in the human ex vivo placenta perfusion model by single particle ICP-MS (spICP-MS). The impact of different surface modifications on placental transfer was assessed by AgNPs with two different modifications: polyethylene glycol (AgPEG NPs) and sodium carboxylate (AgCOONa NPs). AgNPs and ionic Ag were detected in the fetal circulation in low but not negligible amounts. Slightly higher Ag translocation across the placental barrier for perfusion with AgPEG NPs and higher AgNP accumulation in placental tissue for perfusion with AgCOONa NPs were observed. Since these AgNPs are soluble in water, we tried to distinguish between the translocation of dissolved and particulate Ag. Perfusion with AgNO3 revealed the formation of Ag containing NPs in both circulations over time, of which the amount and their size in the fetal circulation were comparable to those from perfusion experiments with both AgNP types. Although we were not able to clarify whether intact AgNPs and/or Ag precipitates from dissolved Ag cross the placental barrier, our study highlights that uptake of Ag ions and/or dissolution of AgNPs in the tissue followed by re-precipitation in the fetal circulation needs to be considered as an important pathway in studies of AgNP translocation across biological barriers.

Highlights

Silver nanoparticles (AgNPs) are, due to their antibacterial properties, one of the most widely used engineered NPs, and are found in many commercial and medical products
For AgPEG NPs in perfusion medium (PM), a slightly broader size distribution was observed in comparison to ultrapure water (UPW)
Agglomeration/aggregation of AgCOONa NPs in PM was further confirmed by spICP-MS measurements (Table 2 and Fig. 2)

Summary

Introduction

Silver nanoparticles (AgNPs) are, due to their antibacterial properties, one of the most widely used engineered NPs, and are found in many commercial and medical products (e.g. food packaging, textiles, laundry detergents, prosthetic devices, dietary supplements, cosmetics). Humans may come into contact with AgNPs either accidentally (e.g. through exposure from contaminated drinking water, inhalation or by direct skin contact) or intentionally (e.g. in the case of nanomedical wound dressings or other applications).[1] This raises concerns about AgNP accumulation, long-term retention in an organism and subsequent adverse health effects. There is increasing evidence for potential human toxicity of AgNPs2 and possible mechanisms of AgNP toxicity have been described and include their adverse effects on cell membranes, mitochondria and genetic material, causing induction of reactive oxygen species (ROS), oxidative stress, genotoxicity and apoptosis.[2,3,4]. The growing fetus is vulnerable to harmful compounds even at concentrations that are non-toxic for adults. The placenta provides a protective barrier for the entry of harmful substances, previous studies have demon-

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