Toxicity screenings of nanomaterials: challenges due to interference with assay processes and components of classic in vitro tests

Abstract

Given the multiplicity of nanoparticles (NPs), there is a requirement to develop screening strategies to evaluate their toxicity. Within the EU-funded FP7 NanoTEST project, a panel of medically relevant NPs has been used to develop alternative testing strategies of NPs used in medical diagnostics. As conventional toxicity tests cannot necessarily be directly applied to NPs in the same manner as for soluble chemicals and drugs, we determined the extent of interference of NPs with each assay process and components. In this study, we fully characterized the panel of NP suspensions used in this project (poly(lactic-co-glycolic acid)–polyethylene oxide [PLGA–PEO], TiO₂, SiO₂, and uncoated and oleic-acid coated Fe₃O₄) and showed that many NP characteristics (composition, size, coatings, and agglomeration) interfere with a range of in vitro cytotoxicity assays (WST-1, MTT, lactate dehydrogenase, neutral red, propidium iodide, ³H-thymidine incorporation, and cell counting), pro-inflammatory response evaluation (ELISA for GM-CSF, IL-6, and IL-8), and oxidative stress detection (monoBromoBimane, dichlorofluorescein, and NO assays). Interferences were assay specific as well as NP specific. We propose how to integrate and avoid interference with testing systems as a first step of a screening strategy for biomedical NPs.

• nanoparticles
• nanomedicine
• cytotoxicity
• oxidative stress
• pro-inflammatory response
• NanoTEST
• testing strategy

Acknowledgements

This work was supported by NanoTEST project (Contract EC FP7 number 201335), EC FP7 QualityNano [INFRA-2010-1.131], Contract no: 214547-2, EC FP7 NANoREG, [NMP.2012.1.3-3], Contract no: 310584, and EC FP7 NanoTOES [PITN-GA-2010-264506]. The authors thankfully acknowledge Riccardo Cossi (Qi srl, Pomezia, Italy) for his valuable technical support, as well as Flavia Visin (University “Ca' Foscari” Venice) for ICP-OES analysis, respectively and to Imago Seine, imaging platform of Institut Jaques Monod (Nicole Boggetto) for flow cytometric analysis. The work undertaken by UH Bristol was carried out with the support of the Bristol Centre for Nanoscience and Quantum Information. Kevin Moreau provided technical help for work done at University Paris Diderot and work was supported by national funding from afsset (Contract N°EST-2008/1/49).Eric Rytting performed DLS analysis of SiO₂ NP samples.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.