Carboxylated nanodiamonds are neither cytotoxic nor genotoxic on liver, kidney, intestine and lung human cell lines

Abstract

Although nanodiamonds (NDs) appear as one of the most promising nanocarbon materials available so far for biomedical applications, their risk for human health remains unknown. Our work was aimed at defining the cytotoxicity and genotoxicity of two sets of commercial carboxylated NDs with diameters below 20 and 100 nm, on six human cell lines chosen as representative of potential target organs: HepG2 and Hep3B (liver), Caki-1 and Hek-293 (kidney), HT29 (intestine) and A549 (lung). Cytotoxicity of NDs was assessed by measuring cell impedance (xCELLigence® system) and cell survival/death by flow cytometry while genotoxicity was assessed by γ-H2Ax foci detection, which is considered the most sensitive technique for studying DNA double-strand breaks. To validate and check the sensitivity of the techniques, aminated polystyrene nanobeads were used as positive control in all assays. Cell incorporation of NDs was also studied by flow cytometry and luminescent N-V center photoluminescence (confirmed by Raman microscopy), to ensure that nanoparticles entered the cells. Overall, we show that NDs effectively entered the cells but NDs do not induce any significant cytotoxic or genotoxic effects on the six cell lines up to an exposure dose of 250 µg/mL. Taken together these results strongly support the huge potential of NDs for human nanomedicine but also their potential as negative control in nanotoxicology studies.

Surface Modifications of Nanodiamonds and Current Issues for Their Biomedical Applications

“…4.9). As a comparison, 25 nm SiO 2 NPs are 9 times more genotoxic at a 10 times lower concentration [25].…”

“…Cumulative effects were even obtained as lysozyme adsorption is combined with cytochrome c [215]. Depending on the [25] functionality of the biologic unit, covalent grafting via organic chemistry could be suitable to get a specific binding site on the ND or to avoid modifications of the biomolecule conformation. Grafting routes which may involve a linker molecule could be performed from different surface terminations of NDs [28].…”

“…A recent study [25] focuses on in vitro cytotoxicity and genotoxicity of HPHT NDs perfectly characterized in terms of size (20 nm and 100 nm) and surface chemistry. The cellular induced effects of two sets of NDs were investigated in six human cell lines: HepG2 and Hep3B (liver), Caki-1 and Hek-293 (kidney), HT29 (intestine) and A549 (lung).…”

“…Nanodiamonds are also available in large quantities at reasonable prices (< $1/g). Several studies reported their very low toxicity related to the high chemical inertia of diamond [22][23][24][25]. Recent research demonstrates they are even biocompatible with advantages for drug delivery or fluorescence labels [26,27].…”

High throughput toxicity screening and intracellular detection of nanomaterials

“…Real‐time measuring of cellular impedance is a useful and sensitive method for screening effects of NMs, at different concentrations, on a range of cell lines simultaneously,97 without variation due to artifacts affecting the measured signal 82, 98, 99, 100. It can also be used to assess changes in cellular motility and adhesion in physiological conditions 101…”