Common Nanomaterials Show Mutagenic Potential in Mouse Lung Cell Assay

Two nanomaterials that are quietly spreading through modern industry and medicine—mesoporous silica and graphene oxide—can damage DNA and drive mutations in laboratory-grown lung cells, according to a new study published in the journal Genes and Environment. The work, led by Rikako Ishigamori and colleagues including Yukari Totsuka, examined the cytotoxicity and genotoxicity of these particles in GDL1 cells, aiming to obtain fundamental data for assessing their potential health risks.

The answer to both questions was yes, with distinct mutational fingerprints emerging for each material. Mesoporous silica killed cells in a clean, dose-dependent fashion, while graphene oxide produced a messier toxicity profile—but both left measurable scars in a reporter gene the researchers could sequence.

The cytotoxicity results set the stage. Mesoporous silica, a porous form of silicon dioxide with pore diameters of roughly 2.1 to 2.7 nanometers and a surface area of about 1,000 square meters per gram, reduced GDL1 cell viability in a concentration-dependent manner, with significant growth inhibition at 0.09, 0.13, and 0.25 milligrams per milliliter. Graphene oxide behaved differently: at 0.1 milligrams per milliliter it was essentially harmless, but viability dropped to 57 percent at 0.2 milligrams per milliliter and 70 percent at 0.4 milligrams per milliliter—a pattern the authors attribute in part to uneven dispersion, since the graphene oxide suspensions were prepared by pipetting rather than the ultrasonication used for the silica.

The mutation counts told a striking story. Control cells showed a spontaneous mutation frequency of 19.1 × 10⁻⁶. Mesoporous silica drove that number upward in a dose-dependent manner at both tested concentrations. Graphene oxide produced mutation frequencies of 16.9 × 10⁻⁶ at 0.2 milligrams per milliliter—statistically indistinguishable from control—but a dramatic 101 × 10⁻⁶ at 0.4 milligrams per milliliter, a more than fivefold jump that reached statistical significance. In other words, the higher dose of graphene oxide made cells mutate at rates far beyond what chance alone would produce.

Sequencing the mutated genes revealed material-specific signatures. In mesoporous silica-exposed cells, the proportion of G:C to A:T transitions rose significantly from 14.3 percent in controls to 24.6 percent, and G:C to T:A transversions appeared at 11.5 percent after being essentially absent in untreated cells. Graphene oxide, meanwhile, significantly elevated both G:C to A:T transitions (from 11.1 to 26.5 percent) and G:C to C:G transversions (from 5.6 to 20.6 percent) at its high dose. The G:C to C:G transversion is considered a rare event in both spontaneous and chemically induced mutation, making its prominence here particularly noteworthy.

The positional data were equally revealing. Among 53 mutations induced by mesoporous silica, hotspots appeared at positions 64, 164, and 416 of the gpt gene—sites never mutated in the control group, strongly suggesting these changes were directly caused by the particles. Graphene oxide produced its own exclusive hotspot at position 401. Such position-specific patterns hint that each material interacts with DNA, or the cellular processes surrounding it, in its own characteristic way.

What mechanism could explain these patterns? The authors point to oxidative stress as the leading suspect, while cautioning that they did not directly test mechanisms in this study. Nanosized particles are known to generate reactive oxygen species, and prior work has shown that mesoporous silica induces ROS in human bronchial BEAS-2B cells, while silica nanoparticles trigger ROS production in human lung fibroblasts through interactions with NADPH oxidases in the endoplasmic reticulum and mitochondria. Graphene oxide has similarly been shown to raise intracellular ROS in human lung fibroblasts and in A549 lung cells, an effect that can be blunted by the antioxidant N-acetylcysteine.

The chemistry fits the observed mutations. Guanine is the DNA base most vulnerable to oxidation, forming 8-oxoguanine, which mispairs with adenine during replication and yields exactly the G:C to T:A transversions seen with mesoporous silica. The rarer G:C to C:G transversions linked to graphene oxide cannot arise from 8-oxoguanine itself; instead, the authors suggest other oxidized guanine derivatives—imidazolone, oxazolone, spiroiminodihydantoin, and guanidinohydantoin—as plausible culprits, consistent with earlier reports linking oxidative stress from UV light, hydrogen peroxide, and peroxyl radicals to this mutation class. Notably, a similar surge in G:C to C:G transversions was previously reported in mice exposed to multi-walled carbon nanotubes, a nanocarbon relative of graphene oxide.

The shared increase in G:C to A:T transitions may involve a second pathway: inflammation. Nitric oxide can damage DNA through dinitrogen trioxide formation, generating diazonium ions that drive deamination and 8-nitro-dG production, ultimately favoring G:C to A:T transitions. Rats exposed to mesoporous silica nanoparticles show elevated lung nitric oxide levels, and graphene oxide has been reported to cause acute lung injury, inflammation, apoptosis, and DNA damage through ROS overproduction. The authors suggest both materials may therefore push cells toward this mutation class via nitric oxide generation linked to oxidative stress and inflammation.

Important caveats frame these findings. The authors explicitly note that the detailed mechanisms underlying the genotoxicity were not investigated in the present study. What the work does establish is fundamental: both materials can induce cytotoxicity and mutations in this sensitive assay system, with mutation spectra pointing toward oxidative DNA damage.

That foundation matters because exposure pathways are real and growing. Mesoporous silica is prized for drug delivery systems, diagnostic imaging, and catalysis, thanks to its uniform pores, enormous surface area, and favorable biocompatibility and biodegradability profiles. Graphene oxide, decorated with oxygen-containing functional groups that allow attachment of proteins, DNA, and other biomolecules, is being developed for biosensors, drug delivery platforms, photothermal therapy, and tissue engineering. As these applications multiply, so do opportunities for human contact and environmental release.

The study’s contribution lies in its molecular granularity. Rather than simply declaring nanomaterials ‘toxic,’ it maps which base changes each particle induces and where in a target gene those changes cluster—data that can be compared across materials, exposure conditions, and future in vivo studies. For a field where safety knowledge has lagged behind commercial deployment, mutation spectrum analysis of this kind offers a way to trace mechanisms before health consequences emerge at scale.

The researchers conclude that oxidative DNA damage and associated inflammation likely both contribute to the mutagenicity they observed, and that their results provide fundamental data for assessing potential human health risks of these increasingly ubiquitous nanomaterials. Whether the same mutational signatures appear in animal models and at environmentally relevant doses remains an open question—but the warning flags raised in these mouse lung cells are now clearly visible.

Subject of Research: Genotoxicity and mutational spectra of mesoporous silica and graphene oxide in a mouse lung cell mutation assay

Article Title: Genotoxicity assessment of mesoporous silica and graphene oxide in GDL1 cells

Article References: Ishigamori, R., Ohno, A., Fukuhara, K., Hasegawa, S., & Totsuka, Y. (2025). Genotoxicity assessment of mesoporous silica and graphene oxide in GDL1 cells. Genes and Environment, 48(1), Article 2. https://doi.org/10.1186/s41021-025-00350-y

Image Credits: AI Generated

DOI: 10.1186/s41021-025-00350-y

Keywords: mesoporous silica, graphene oxide, genotoxicity, nanomaterials, GDL1 cells, gpt mutation assay, mutation spectrum, oxidative stress, reactive oxygen species, cytotoxicity, DNA damage, in vitro