Cytotoxicity of TiO₂ nanoparticles to mussel hemocytes and gill cells in vitro: Influence of synthesis method, crystalline structure, size and additive

Abstract

Increasing the production and applications of TiO₂ nanoparticles (NPs) has led to grow concerns about the consequences for the environment. In this study, we investigated the effects of a set of TiO₂ NPs on the viability of mussel hemocytes and gill cells using neutral red and thiazolyl tetrazolium bromide assays. For this, we compared the cytotoxicity of TiO₂ NPs (0.1–100 mg Ti/L) produced by different techniques: rutile NPs (60 nm) produced by milling and containing disodium laureth sulfosuccinate (DSLS), rutile NPs (10, 40 and 60 nm) produced by wet chemistry and anatase/rutile NPs (∼100 nm) produced by plasma synthesis. The commercially available P25 anatase/rutile NPs (10–20 nm) were also tested. Exposures were performed in parallel with their respective bulk forms and the cytotoxicity of the additive DSLS was also tested. Z potential values in distilled water indicated different stabilities depending on the NP type and all NPs tested formed agglomerates/aggregates in cell culture media. In general, TiO₂ NPs showed a relatively low and dose-dependent toxicity for both cell models with the two assays tested. NPs produced by milling showed the highest effects, probably due to the toxicity of DSLS. Size-dependent toxicity was found for NPs produced by wet chemistry (10 nm > 40 nm and 60 nm). All TiO₂ NPs tested were more toxic than bulk forms excepting for plasma produced ones, which were the least toxic TiO₂ tested. The mixture bulk anatase/rutile TiO₂ was more toxic than bulk rutile TiO₂. In conclusion, the toxicity of TiO₂ NPs varied with the mode of synthesis, crystalline structure and size of NPs and can also be influenced by the presence of additives in the suspensions.

• Mussel cells viability
• physicochemical properties
• titanium dioxide nanoparticles

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. This work was funded by EU 7th FP (NanoReTox project, CP-FP 214478-2), Spanish Ministry (NanoCancer project CTM2009-13477), Basque Government (consolidated research groups IT810-13 and IT620-13) and University of the Basque Country (UFI 11/37).