Innovative Techniques and Strategies for a Reliable High-Throughput Genotoxicity Assessment

Enhanced recognition of G-quadruplex DNA oxidative damage based on DNA-mediated charge transfer

G-quadruplex (G4) DNA is present in human telomere oligonucleotide sequences. Oxidative damage to telomeric DNA accelerates telomere shortening, which is strongly associated with aging and cancer. Most of the current analyses on oxidative DNA damage are based on ds-DNA. Here, we developed a electrochemiluminescence (ECL) probe for enhanced recognition of oxidative damage in G4-DNA based on DNA-mediated charge transfer (CT), which could specifically recognize damaged sites depending on the position of 8-oxoguanine (8-oxoG). First, a uniform G4-DNA monolayer interface was fabricated; the G4-DNA mediated CT properties were examined using an iridium(III) complex [Ir(ppy)2(pip)]PF6 stacked with G4-DNA as an indicator. The results showed that G4-DNA with 8-oxoG attenuated DNA CT. The topological effects of oxidative damage at different sites of G4-DNA and their effects on DNA CT were revealed. The sensing platform was also used for the sensitive and quantitative detection of 8-oxoG in G4-DNA, with a detection limit of 28.9 fmol. Overall, these findings present a sensitive platform to study G4-DNA structural and stability changes caused by oxidative damage as well as the specific and quantitative detection of oxidation sites. The different damage sites in the G-quadruplex could provide detailed clues for understanding the function of G4-associated telomere functional enzymes.

DNA damage resulting from human endocrine disrupting chemical exposure: Genotoxicity, detection and dietary phytochemical intervention

In recent years, exposure to endocrine disrupting chemicals (EDCs) has posed an increasing threat to human health. EDCs are major risk factors in the occurrence and development of many diseases. Continuous DNA damage triggers severe pathogenic consequences, such as cancer. Beyond their effects on the endocrine system, EDCs genotoxicity is also worthy of attention, owing to the high accessibility and bioavailability of EDCs. This review investigates and summarizes nearly a decade of DNA damage studies on EDC exposure, including DNA damage mechanisms, detection methods, population marker analysis, and the application of dietary phytochemicals. The aims of this review are (1) to systematically summarize the genotoxic effects of environmental EDCs (2) to comprehensively summarize cutting-edge measurement methods, thus providing analytical solutions for studies on EDC exposure; and (3) to highlight critical data on the detoxification and repair effects of dietary phytochemicals. Dietary phytochemicals decrease genotoxicity by playing a major role in the detoxification system, and show potential therapeutic effects on human diseases caused by EDC exposure. This review may support research on environmental toxicology and alternative chemo-prevention for human EDC exposure.

Assessing Genotoxicity of Ten Different Engineered Nanomaterials by the Novel Semi-Automated FADU Assay and the Alkaline Comet Assay

Increased engineered nanomaterial (ENM) production and incorporation in consumer and biomedical products has raised concerns about the potential adverse effects. The DNA damaging capacity is of particular importance since damaged genetic material can lead to carcinogenesis. Consequently, reliable and robust in vitro studies assessing ENM genotoxicity are of great value. We utilized two complementary assays based on different measurement principles: (1) comet assay and (2) FADU (fluorimetric detection of alkaline DNA unwinding) assay. Assessing cell viability ruled out false-positive results due to DNA fragmentation during cell death. Potential structure–activity relationships of 10 ENMs were investigated: three silica nanoparticles (SiO₂-NP) with varying degrees of porosity, titanium dioxide (TiO₂-NP), polystyrene (PS-NP), zinc oxide (ZnO-NP), gold (Au-NP), graphene oxide (GO) and two multi-walled carbon nanotubes (MWNT). SiO₂-NPs, TiO₂-NP and GO were neither cytotoxic nor genotoxic to Jurkat E6-I cells. Quantitative interference corrections derived from GO results can make the FADU assay a promising screening tool for a variety of ENMs. MWNT merely induced cytotoxicity, while dose- and time-dependent cytotoxicity of PS-NP was accompanied by DNA fragmentation. Hence, PS-NP served to benchmark threshold levels of cytotoxicity at which DNA fragmentation was expected. Considering all controls revealed the true genotoxicity for Au-NP and ZnO-NP at early time points.