Abnormal neural differentiation in response to graphene quantum dots through histone modification interference

Retinal Degeneration Response to Graphene Quantum Dots: Disruption of the Blood-Retina Barrier Modulated by Surface Modification-Dependent DNA Methylation

Graphene quantum dots (GQDs) are used in diverse fields from chemistry-related materials to biomedicines, thus causing their substantial release into the environment. Appropriate visual function is crucial for facilitating the decision-making process within the nervous system. Given the direct interaction of eyes with the environment and even nanoparticles, herein, GQDs, sulfonic acid-doped GQDs (S-GQDs), and amino-functionalized GQDs (A-GQDs) were employed to understand the potential optic neurotoxicity disruption mechanism by GQDs. The negatively charged GQDs and S-GQDs disturbed the response to light stimulation and impaired the structure of the retinal nuclear layer of zebrafish larvae, causing vision disorder and retinal degeneration. Albeit with sublethal concentrations, a considerably reduced expression of the retinal vascular sprouting factor sirt1 through increased DNA methylation damaged the blood-retina barrier. Importantly, the regulatory effect on vision function was influenced by negatively charged GQDs and S-GQDs but not positively charged A-GQDs. Moreover, cluster analysis and computational simulation studies indicated that binding affinities between GQDs and the DNMT1-ligand binding might be the dominant determinant of the vision function response. The previously unknown pathway of blood-retinal barrier interference offers opportunities to investigate the biological consequences of GQD-based nanomaterials, guiding innovation in the industry toward environmental sustainability.

Application of quantum dots in brain diseases and their neurotoxic mechanism

The early-stage diagnosis and therapy of brain diseases pose a persistent challenge in the field of biomedicine. Quantum dots (QDs), nano-luminescent materials known for their small size and fluorescence imaging capabilities, present promising capabilities for diagnosing, monitoring, and treating brain diseases. Although some investigations about QDs have been conducted in clinical trials, the concerns about the toxicity of QDs have continued. In addition, the lack of effective toxicity evaluation methods and systems and the difference between in vivo and in vitro toxicity evaluation hinder QDs application. The primary objective of this paper is to introduce the neurotoxic effects and mechanisms attributable to QDs. First, we elucidate the utilization of QDs in brain disorders. Second, we sketch out three pathways through which QDs traverse into brain tissue. Ultimately, expound upon the adverse consequences of QDs on the brain and the mechanism of neurotoxicity in depth. Finally, we provide a comprehensive summary and outlook on the potential development of quantum dots in neurotoxicity and the difficulties to be overcome.

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.

Cortical Organoid-on-a-Chip with Physiological Hypoxia for Investigating Tanshinone IIA-Induced Neural Differentiation

Cortical organoids represent cutting-edge models for mimic human brain development during the early and even middle stage of pregnancy, while they often fail to recreate the complex microenvironmental factors, such as physiological hypoxia. Herein, to recapitulate fetal brain development, we propose a novel cortical organoid-on-a-chip with physiological hypoxia and further explore the effects of tanshinone IIA (Tan IIA) in neural differentiation. The microfluidic chip was designed with a micropillar array for the controlled and efficient generation of cortical organoids. With low oxygen, the generated cortical organoids could recapitulate key aspects of early-gestational human brain development. Compared to organoids in normoxic culturing condition, the promoted neurogenesis, synaptogenesis and neuronal maturation were observed in the present microsystem, suggesting the significance of physiological hypoxia in cortical development. Based on this model, we have found that Chinese herbal drug Tan IIA could promote neural differentiation and maturation, indicating its potential therapeutic effects on neurodevelopmental disorders as well as congenital neuropsychiatric diseases. These results indicate that the proposed biomimetic cortical organoid-on-a-chip model with physiological hypoxia can offer a promising platform to simulate prenatal environment, explore brain development, and screen natural neuroactive components.

Triazole fungicides exert neural differentiation alteration through H3K27me3 modifications: In vitro and in silico study

Considering that humans are unavoidably exposed to triazole fungicides through the esophagus, respiratory tract, and skin contact, revealing the developmental toxicity of triazole fungicides is vital for health risk assessment. This study aimed to screen and discriminate neural developmental disorder chemicals in commonly used triazole fungicides, and explore the underlying harmful impacts on neurogenesis associated with histone modification abnormality in mouse embryonic stem cells (mESCs). The triploblastic and neural differentiation models were constructed based on mESCs to expose six typical triazole fungicides (myclobutanil, tebuconazole, hexaconazole, propiconazole, difenoconazole, and flusilazole). The result demonstrated that although no cytotoxicity was observed, different triazole fungicides exhibited varying degrees of alterations in neural differentiation, including increased ectodermal differentiation, promoted neurogenesis, increased intracellular calcium ion levels, and disturbance of neurotransmitters. Molecular docking, cluster analysis, and multiple linear regressions demonstrated that the binding affinities between triazole fungicides and the Kdm6b-ligand binding domain were the dominant determinants of the neurodevelopmental response. This partially resulted in the reduced enrichment of H3K27me3 at the promoter region of the serotonin receptor 2 C gene, finally leading to disturbed neural differentiation. The data suggested potential adverse outcomes of triazole fungicides on embryonic neurogenesis even under sublethal doses through interfering histone modification, providing substantial evidence on the safety control of fungicides.

Maternal exposure to sunlight-irradiated graphene oxide induces neurodegeneration-like symptoms in zebrafish offspring through intergenerational translocation and genomic DNA methylation alterations

The physiochemical properties of graphene oxide may be affected by sunlight irradiation. However, the underlying mechanisms that alter the properties and subsequent intergenerational effects are not sufficiently investigate. Epigenetics is an early sensitive marker for the intergenerational effects of nanomaterial exposure due to the epigenetic memory. In this study, we investigate changes in the physicochemical properties and the intergenerational effects of maternal exposure to simulated sunlight-irradiated polyethyleneimine-functionalized graphene oxide (SL-PEI-GO). Results show that the physicochemical properties of polyethyleneimine-functionalized graphene oxide (PEI-GO) can be altered significantly by the oxidation of carbon atoms with unpaired electrons present in the defects and on the edges of PEI-GO by sunlight. First, the positive charges, sharp edges, defects and disordered structures of SL-PEI-GO make it translocate from maternal zebrafish to offspring, thus catalyzing the production of reactive oxygen species and damaging mitochondria directly. In addition, changes in DNA methylation reduce the expression of protocadherin1a, protocadherin19 and cadherin4, thus destroying cell membrane integrity, cell adhesion and Ca2+ binding. The alteration of DNA methylation induced by maternal exposure activates the Ca2+-CaMKK-brsk2a pathway, which catalyzes the phosphorylation of Tau and eventually results in the appearance of neurodegeneration-like symptoms, including the loss of neurons and neurobehavioral disorders. This study demonstrates that maternal exposure to SL-PEI-GO induces clear neurodegeneration-like symptoms in offspring through both the intergenerational translocation of nanomaterials and differential DNA methylation. These findings may provide new insights into the health risks of nanomaterials altered by nature conditions.