Comparative toxicity of 24 manufactured nanoparticles in human alveolar epithelial and macrophage cell lines

TLDR

Nanomaterials’ potential toxicity is a critical issue requiring clear understanding. The study evaluated the toxic effect of 24 nanoparticles on A549 and THP‑1 cells and aimed to develop a generic rapid screening experimental set‑up. The authors compared MTT and Neutral Red cytotoxicity assays at 3 and 24 h, calculated TC50 values where possible, and found that MTT on THP‑1 cells after 24 h was the most sensitive design. Copper‑ and zinc‑based nanoparticles were the most toxic, titania, alumina, ceria, and zirconia showed moderate toxicity, tungsten carbide was non‑toxic, and no correlation with size or surface area was observed, highlighting cell‑type and assay sensitivity differences.

Abstract

A critical issue with nanomaterials is the clear understanding of their potential toxicity. We evaluated the toxic effect of 24 nanoparticles of similar equivalent spherical diameter and various elemental compositions on 2 human pulmonary cell lines: A549 and THP-1. A secondary aim was to elaborate a generic experimental set-up that would allow the rapid screening of cytotoxic effect of nanoparticles. We therefore compared 2 cytotoxicity assays (MTT and Neutral Red) and analyzed 2 time points (3 and 24 hours) for each cell type and nanoparticle. When possible, TC50 (Toxic Concentration 50 i.e. nanoparticle concentration inducing 50% cell mortality) was calculated.The use of MTT assay on THP-1 cells exposed for 24 hours appears to be the most sensitive experimental design to assess the cytotoxic effect of one nanoparticle. With this experimental set-up, Copper- and Zinc-based nanoparticles appear to be the most toxic. Titania, Alumina, Ceria and Zirconia-based nanoparticles show moderate toxicity, and no toxicity was observed for Tungsten Carbide. No correlation between cytotoxicity and equivalent spherical diameter or specific surface area was found.Our study clearly highlights the difference of sensitivity between cell types and cytotoxicity assays that has to be carefully taken into account when assessing nanoparticles toxicity.