Toxic effects of ZnSe/ZnS quantum dots on the reproduction and genotoxiticy of rare minnow (Gobiocypris rarus)

Oxidative stress-induced neurotoxicity of quantum dots and influencing factors

Quantum dots (QDs) have significant potential for treating and diagnosing CNS diseases. Meanwhile, the neurotoxicity of QDs has garnered attention. In this review, we focus on elucidating the mechanisms and consequences of CNS oxidative stress induced by QDs. First, we discussed the pathway of QDs transit into the brain. We then elucidate the relationship between QDs and oxidative stress from in vivo and in vitro studies. Furthermore, the main reasons and adverse outcomes of QDs leading to oxidative stress are discussed. In addition, the primary factors that may affect the neurotoxicity of QDs are analyzed. Finally, we propose potential strategies for mitigating QDs neurotoxicity and outline future perspectives for their development.

A Review of in vivo Toxicity of Quantum Dots in Animal Models

Tremendous research efforts have been devoted to nanoparticles for applications in optoelectronics and biomedicine. Over the past decade, quantum dots (QDs) have become one of the fastest growing areas of research in nanotechnology because of outstanding photophysical properties, including narrow and symmetrical emission spectrum, broad fluorescence excitation spectrum, the tenability of the emission wavelength with the particle size and composition, anti-photobleaching ability and stable fluorescence. These characteristics are suitable for optical imaging, drug delivery and other biomedical applications. Research on QDs toxicology has demonstrated QDs affect or damage the biological system to some extent, and this situation is generally caused by the metal ions and some special properties in QDs, which hinders the further application of QDs in the biomedical field. The toxicological mechanism mainly stems from the release of heavy metal ions and generation of reactive oxygen species (ROS). At the same time, the contact reaction with QDs also cause disorders in organelles and changes in gene expression profiles. In this review, we try to present an overview of the toxicity and related toxicity mechanisms of QDs in different target organs. It is believed that the evaluation of toxicity and the synthesis of environmentally friendly QDs are the primary issues to be addressed for future widespread applications. However, considering the many different types and potential modifications, this review on the potential toxicity of QDs is still not clearly elucidated, and further research is needed on this meaningful topic.

An update on the biological effects of quantum dots: From environmental fate to risk assessment based on multiple biological models

Quantum dots (QDs) are zero-dimension nanomaterials with excellent physical and chemical properties, which have been widely used in environmental science and biomedicine. Therefore, QDs are potential to cause toxicity to the environment and enter organisms through migration and bioenrichment effects. This review aims to provide a comprehensive and systematic analysis on the adverse effects of QDs in different organisms based on recently available data. Following PRISMA guidelines, this study searched PubMed database according to the pre-set keywords, and included 206 studies according to the inclusion and elimination criteria. CiteSpace software was firstly used to analyze the keywords of included literatures, search for breaking points of former studies, and summarize the classification, characterization and dosage of QDs. The environment fate of QDs in the ecosystems were then analyzed, followed with comprehensively summarized toxicity outcomes at individual, system, cell, subcellular and molecular levels. After migration and degradation in the environment, aquatic plants, bacteria, fungi as well as invertebrates and vertebrates have been found to be suffered from toxic effects caused by QDs. Aside from systemic effects, toxicity of intrinsic QDs targeting to specific organs, including respiratory system, cardiovascular system, hepatorenal system, nervous system and immune system were confirmed in multiple animal models. Moreover, QDs could be taken up by cells and disturb the organelles, which resulted in cellular inflammation and cell death, including autophagy, apoptosis, necrosis, pyroptosis and ferroptosis. Recently, several innovative technologies, like organoids have been applied in the risk assessment of QDs to promote the surgical interventions of preventing QDs' toxicity. This review not only aimed at updating the research progress on the biological effects of QDs from environmental fate to risk assessment, but also overcame the limitations of available reviews on basic toxicity of nanomaterials by interdisciplinarity and provided new insights for better applications of QDs.

The DNA damage potential of quantum dots: Toxicity, mechanism and challenge

Quantum dots (QDs) are semiconductor nanoparticles (1-10 nm) with excellent optical and electrical properties. As QDs show great promise for applications in fields such as biomedicine, their biosafety is widely emphasized. Therefore, studies on the potential 'nanotoxicity' of QDs in genetic material are warranted. This review summarizes and discusses recent reports derived from different cell lines or animal models concerning the effects of QDs on genetic material. QDs could induce many types of genetic material damage, which subsequently triggers a series of cellular adverse outcomes, including apoptosis, cell cycle arrest and senescence. However, the individual biological and ecological significance of the genotoxicity of QDs is not yet clear. In terms of mechanisms of genotoxicity, QDs can damage DNA either through their own nanomorphology or through the released metal ions. It also includes the reactive oxygen species generation, inflammation and failure of DNA damage repair. Notably, apoptosis may lead to false positive results in genotoxicity tests. Finally, given the different uses of QDs and the interference of the physicochemical properties of QDs on the test method, genotoxicity testing of QDs should be different from traditional toxic compounds, which requires further research.

A ferritin gene in the marine copepod Acartia tonsa as a highly sensitive biomonitor for nano-contamination

Toxicology is not only for eco-risk assessments, but also for the real-time environmental monitoring based on the quick response of specific biomarkers. Ferritin gene (ftn) is a potential biomarker involving in crucial protective responses in biota. However, little information is available concerning the ftn in marine copepod Acartia tonsa (A. tonsa), a model organism widely applied in toxicology assessments. Our study for the first time identified and characterized the ftn in A. tonsa, along with its time-dependent transcriptional response to the reproductive toxicity of two newly emerged nanomaterials. The full-length cDNA of ftn contains a 114-bp 5'-untranslated region (UTR), a 236-bp 3'-untranslated region, and a 510-bp open reading frame which encodes an 18.51 kDa polypeptide composed of 169 amino acids. The ftn sequence has an iron binding signature and a potential phosphorylation site, which is closely-related to the ftn of Calanus sinicus and Pseudodiaptomus annandalei genes at the phylogenetical level. The ftn showed a quick and highly sensitive response to nanomaterial exposures, even at no observed effect concentrations. In detail, after exposure to nickel nanomaterials (up to 17.0 mg/L), the ftn was significantly upregulated immediately at 0.5 h and peaked at 9.5-fold in adults within 48 h, along with a significant reduction of egg hatching rate. When exposed to CdSe/ZnS quantum dots (up to 135 mg/L), no significant change in egg productions or hatching rates was observed, while the expression of ftn still significantly increased to over 3.0-fold in the initial 48 h. After that, the upregulation of ftn induced by CdSe/ZnS quantum dots or nickel nanoparticles both gradually returned back within 96 h. These findings demonstrate the highly sensitive response of this new cloned ftn to nanomaterial exposures, and highlight the suitability of ftn in A. tonsa as a promising biomonitor for nano-contamination in marine environments.

Adverse reproductive and developmental consequences of quantum dots

Quantum dots (QDs), with a size of 1-10 nm, are luminescent semiconductor nanocrystals characterized by a shell-core structure. Notably, QDs have potential application in bioimaging owing to their higher fluorescence performance than conventional fluorescent dyes. To date, QDs has been widely used in photovoltaic devices, supercapacitors, electrocatalysis, photocatalysis. In recent years, scientists have focused on whether the use of QDs can interfere with the reproductive and developmental processes of organisms, resulting in serious population and community problems. In this study, we first analyze the possible reproductive and development toxicity of QDs. Next, we summarize the possible mechanisms underlying QDs' interference with reproduction and development, including oxidative stress, altered gametogenesis and fetal development gene expression, autophagy and apoptosis, and release of metal ions. Thereafter, we highlight some potential aspects that can be used to eliminate or reduce QDs toxicity. Based on QDs' unique physical and chemical properties, a comprehensive range of toxicity test data is urgently needed to build structure-activity relationship to quickly evaluate the ecological safety of each kind of QDs.

Reproductive toxicity of InP/ZnS QDs in male rare minnow (Gobiocypris rarus)

InP/ZnS quantum dots (QDs) stand out among cadmium-free alternatives for higher exciton Bohr radius and strong quantum confined effect. In this study, the reproductive toxicity and mechanism of InP/ZnS QDs at different concentrations in male Chinese rare minnows (Gobiocypris rarus) were investigated. The results showed that QDs in 800 nmol/L concentration group could enter the testes after 1 d of exposure and caused changes in the structure of the testes, including the scattered distribution of seminal vesicles, reduction in germ cells and vacuolation in some areas of interstitial cells. The expression levels of androgen receptor (Ar) and doublesex and mab-3 related transcription factor 1 (Dmrt1) and the tight junction protein-related genes β-catenin and occludin were upregulated in rare minnows. The sperm quality and ATP content of parents in the 800 nmol/L treatment group were significantly decreased. Continuous detection of the development of F1 generation embryos showed that parental exposure to InP/ZnS QDs reduced the heart rate and spontaneous movement frequency of F1 generation embryos, and the fertilization rate of the F1 generation in the 800 nmol/L treatment group was significantly reduced. In general, the sperm quality and testicular structure of adult rare minnows were not significantly affected by concentrations below 400 nmol/L. High-concentration InP/ZnS QDs exposure can damage the integrity of the blood-testis barrier (BTB) and cause reproductive damage to the parents of rare minnows, which will continue to the next generation and affect their development.