Zinc-oxide nanoparticles are being used in a wide range of commercial applications and are therefore expected to find their way into the soil ecosystem. Problems concerning Zinc-oxide nanoparticle toxicity, in-vitro and in-vivo testing methods for living organisms, the development of environmental health criteria and the acceptance of toxicity limits of metal nanoparticles, are topical. This review will contribute to understanding the fate and behaviour of Zinc-oxide nanoparticles in soil, their uptake and distribution within plants, animals, and microbes as well as their interactions with other pollutants. It is an essential prerequisite to environmentally realistic studies of the ecotoxicology of nanoparticles. Increased application of nanoparticles threatens communities as well as plants, terrestrial and aquatic animals. Thus, it is important to explore whether nanoparticles could compromise soil biodiversity and the important functions maintained by soil communities.

Effects of zinc-oxide nanoparticles on soil, plants, animals and soil organisms: A review

In the past decade, the number of epidemiological publications addressing environmental chemical exposures and autism has grown tremendously. These studies are important because it is now understood that environmental factors play a larger role in causing autism than previously thought and because they address modifiable risk factors that may open up avenues for the primary prevention of the disability associated with autism.

Environmental chemical exposures and autism spectrum disorders: a review of the epidemiological evidence (Journal article)

Research advances in the detection of miRNA.

The unique or enhanced properties of manufactured nanomaterials (MNs) suggest that their use in nanoenabled products will continue to increase. This will result in increased potential for human and environmental exposure to MNs during manufacturing, use, and disposal of nanoenabled products. Scientifically based risk assessment for MNs necessitates the development of reproducible, standardized hazard testing methods such as those provided by the Organisation of Economic Cooperation and Development (OECD). Currently, there is no comprehensive guidance on how best to address testing issues specific to MN particulate, fibrous, or colloidal properties. This paper summarizes the findings from an expert workshop convened to develop a guidance document that addresses the difficulties encountered when testing MNs using OECD aquatic and sediment test guidelines. Critical components were identified by workshop participants that require specific guidance for MN testing: preparation of dispersions, dose metrics, the ...

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Adapting oecd aquatic toxicity tests for use with manufactured nanomaterials: key issues and consensus recommendations

Zinc oxide (ZnO) is the most commonly used nanoparticles among different nanoparticles. Its applications ranged from personal care products, sensors, antibacterial creams, and biomedical applicatio...

Zinc oxide nanoparticles impacts: cytotoxicity, genotoxicity, developmental toxicity, and neurotoxicity.

Zinc oxide nanoparticles (ZnO NPs) are being utilized in an increasing number of fields and commercial applications. While their general toxicity and associated oxidative stress have been extensively studied, the toxicological pathways that they induce in developmental stages are still largely unknown. In this study, the developmental toxicity of ZnO NPs to embryonic/larval zebrafish was investigated. The transcriptional expression profiles induced by ZnO NPs were also investigated to ascertain novel genomic responses related to their specific toxicity pathway. Zebrafish embryos were exposed to 0.01, 0.1, 1, and 10 mg/L ZnO NPs for 96 h post-fertilization. The toxicity of ZnO NPs, based on their Zn concentration, was quite similar to that in embryonic/larval zebrafish exposed to corresponding ZnSO4 concentrations. Pericardial edema and yolk-sac edema were the principal malformations induced by ZnO NPs. Gene-expression profiling using microarrays demonstrated 689 genes that were differentially regulated (fold change >1.5) following exposure to ZnO NPs (498 upregulated, 191 downregulated). Several genes that were differentially regulated following ZnO NP exposure shared similar biological pathways with those observed with ZnSO4 exposure, but six genes (aicda, cyb5d1, edar, intl2, ogfrl2 and tnfsf13b) associated with inflammation and the immune system responded specifically to ZnO NPs (either in the opposite direction or were unchanged in ZnSO4 exposure). Real-time reverse-transcription quantitative polymerase chain reaction confirmed that the responses of these genes to ZnO NPs were significantly different from their response to ZnSO4 exposure. ZnO NPs may affect genes related to inflammation and the immune system, resulting in yolk-sac edema and pericardia edema in embryonic/larval developmental stages. These results will assist in elucidating the mechanisms of toxicity of ZnO NPs during development of zebrafish.

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Developmental Toxicity of Zinc Oxide Nanoparticles to Zebrafish (Danio rerio): A Transcriptomic Analysis.

MicroRNAs (miRNAs), short non-coding RNAs, have emerged as promising next-generation biomarkers of diverse diseases. In general, conventional quantitative real-time PCR and miRNA microarray methods have been utilized for the quantitative detection of miRNA. However, owing to their complicated procedures and expensive reagents/instruments, these methods cannot be widely applied by medical experts such as doctors and nurses, and are thus limited for practical clinical application. Here, we established a new graphene oxide (GO)-based NET strategy for facile miRNA detection with enhanced sensitivity, which is applicable for point-of-care testing (POCT). The proposed miRNA sensing strategy is fundamentally based on the peroxidase-mimicking DNAzyme (Dz) mediated colorimetric assay in response to target miRNA using rationally designed duplex molecular beacon (dMB). The application of GO as a net in this basic system (designated GONET) allows for gathering of the target-dependently activated Dz, which enhances the sensitivity and extends the applicability for POCT. The GONET system provides clear visualization of the target at the 10−9 M scale with the naked eye without any complicated amplification steps.

Graphene oxide-based NET strategy for enhanced colorimetric sensing of miRNA

MicroRNAs (miRNAs) are short, non-coding RNAs, which have emerged as promising next-generation biomarkers for clinical diagnostics. Here, we developed a graphene oxide (GO)-based fluorescent nano-sensor for miRNA sensing with high specificity and sensitivity. GO is a water-soluble derivative of graphene, which has emerged as one of the most popular nanomaterials in the bio-medical field over the last few decades. Common strategies in the design of GO-based sensors rely on the fluorescence quenching capability of GO and the strong adsorption of ssDNA probes on GO surface through pi-pi interactions or hydrogen bonding. Unfortunately, the interaction between DNA and GO is easily interrupted by other molecules present in biological samples, such as proteins, lipids, and nucleic acids, which results in the nonspecific desorption of probes. Therefore, we designed a fluorescence-labeled dsDNA probe, with an embedded locked nucleic acid (LNA). The probe was then attached onto GO by covalent coupling, instead of nonspecific adsorption. The probes on GO recognized the target miRNA sequence specifically and released the fluorescent strand via toehold-mediated strand displacement (TMSD), which furnished the recovery of quenched fluorescence. This platform displayed improved signal to noise ratio with detection limits at the pico-molar levels. We believe that this new GO-based sensor can be a suitable tool for miRNA-based practical diagnostics of diseases, and provides a valuable resource for basic and applied research.

Duplex DNA-functionalized graphene oxide: A versatile platform for miRNA sensing

Many studies of the toxic effects of zinc oxide nanoparticles (ZnO NPs) in aquatic organisms have been performed because of increasing ZnO NP use. However, the toxicological pathways are not understood. In this study, ZnO NPs were found to be more toxic than ZnSO4 to zebrafish larvae, but ZnO NP toxicity did not involve transcript alterations. Biological processes affected by ZnO NPs and ZnSO4 were investigated by performing ingenuity pathway analysis on differently expressed genes in larvae exposed to sub-lethal ZnO NP and ZnSO4 concentrations. We identified upregulated and downregulated differently expressed genes in fish exposed to ZnO NPs and ZnSO4, and found that ZnO NPs slightly induced cell differentiation and pathways associated with the immune system and activated several key genes involved in cancer cell signaling. The results may be key to predicting and elucidating the mechanisms involved in ZnO NP and ZnSO4 toxicity in zebrafish larvae.

Comparative Analysis of Transcriptional Profile Changes in Larval Zebrafish Exposed to Zinc Oxide Nanoparticles and Zinc Sulfate.

Autism spectrum disorder (ASD) is a serious neurodevelopmental disorder characterized by impaired or abnormal social interaction and communication and by restricted and repetitive behaviour. ASD is highly prevalent in Asia, Europe, and the United States, and the frequency of ASD is growing each year. Recent epidemiological studies have indicated that ASD may be caused or triggered by exposure to chemicals in the environment, such as those in the air or water. Thus, toxicological studies are needed to examine chemicals that might be implicated. However, the experimental efficiency of existing experimental models is limited, and many models represent challenges in terms of animal welfare. Thus, alternative ASD animal models are necessary. To address this, we examined the efficacy of the zebrafish embryo/larva as an alternative model of ASD. Specifically, we exposed zebrafish to valproic acid (0, 12.5, 25, 50, or 100 μM), which is a chemical known to induce autism-like effects. We then analysed subsequent developmental, behavioural, and transcriptomic changes. We found that 100 μM and 50 μM valproic acid decreased the hatching rate and locomotor activity of zebrafish embryos/larvae. Transcriptomic analysis revealed significant alterations in a number of genes associated with autism, such as adsl, mbd5, shank3, and tsc1b. Additionally, we found changes in gene ontology that were also reported in previous studies. Our findings indicate that zebrafish embryos/larvae and humans with ASD might have common physiological pathways, indicating that this animal model may represent an alternative tool for examining the causes of and potential treatments for this illness.

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Woo-Keun Kim

Papers

Developmental Toxicity of Zinc Oxide Nanoparticles to Zebrafish (Danio rerio): A Transcriptomic Analysis.

Graphene oxide-based NET strategy for enhanced colorimetric sensing of miRNA

Duplex DNA-functionalized graphene oxide: A versatile platform for miRNA sensing

Comparative Analysis of Transcriptional Profile Changes in Larval Zebrafish Exposed to Zinc Oxide Nanoparticles and Zinc Sulfate.

Plausibility of the zebrafish embryos/larvae as an alternative animal model for autism: A comparison study of transcriptome changes.