Nanotechnologies represent new promising approach for conservation and preservation of cultural heritage. Nanomaterials (NMs) have been shown to improve efficacy, durability and quality of the restoration due to their unique properties that can be achieved and tuned by controlling particle physico-chemical characteristics. The same characteristics, however, affect the way how NMs interact with biological systems and may potentially underlie their enhanced or unexpected toxicity. In this pilot study, we compared the toxic potential of representatives of three of the most common oxide materials applicable in restoration: TiO2 (standard and purified P25, a mixture of prevailing anatase with rutile crystalline modifications), SiO2 (bare A200, and R805, R9200 as coated forms of A200), and ZnO. Using two in vitro cytotoxicity assays, WST-1 and LDH, evaluating metabolic activity and cell membrane integrity, respectively, we preliminary ranked the tested substances according to their cytotoxic potential, which may be used for their prioritization for further testing and applications. After 24h exposure, a dose-dependent decrease in cell viability was only detected in ZnO NPs and uncoated silica (A200). Hydrophobic coated silicas (R805 and R9200) and TiO2 NPs (purified and unpurified P25) did not exhibit cytotoxic effects up to the highest tested concentration of 250 μg/mL. Toxicological data related to the physico-chemical characteristics will be applicable in developing both more efficient and safer nano-based products for restoration and conservation.Keywords: Nanotechnology, cytotoxicity, restoration, work of art, safe-by-design
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