Evaluation of Functional SiO₂ Nanoparticles Toxicity by a 3D Culture Model.

Context: as a kind of non-metal oxide SiO2 NPs have been extensively used in biomedicine, pharmaceuticals and other industrial manufacturing fields, such as DNA delivery, cancer therapy… Our group had developed a method based on microemulsion process to prepare SiO2 NPs incorporating photonic or magnetic nanocrystals and luminescent nanosized inorganic metal atom clusters. However, the toxicity of nanoparticles is known to be closely related to their physico-chemical characteristics and chemical composition.

Object: it is therefore of interest to investigate the toxicity of these novel SiO2 NPs to the cells that may come in contact.

Materials And Methods: the potential toxic effect of the functional @SiO2 NPs containing Mo6 clusters with or without gold nanoparticles was investigated, at concentrations 1 μg/mL, 10 μg/mL and 100 μg/mL each, on three different cell lines. Cell viability was measured by the MTT test in monolayer's culture whereas the cytotoxicity in spheroid model was examined by the APH assay. In a second time, oxidative-stress-induced cytotoxicity was investigated through glutathione levels dosages.

Results: the results indicated that both A549 and L929 cell lines did not exhibit susceptibility to functional @SiO2 NPs-induced oxidative stress unlike KB cells.

Discussion: SiO2 NPs containing CMB may become toxic to cultured cells but only at a very high dosage level. Therefore, this toxicity depends on cell lines and more, on the model of cell cultures. The selection of appropriate cell line remains a critical component in nanotoxicology.

Conclusion: these results are relevant to future applications of SiO2 gold-cluster NPs in controlled release applications.