Interpretable Causal System Optimization Framework for the Advancement of Biological Effect Prediction and Redesign of Nanoparticles

Nanomedicine has promising applications in disease treatment, given the remarkable safety concerns (e.g., nanotoxicity and inflammation) of nanomaterials, and realizing the trade-off between the immune response and organ burden of NPs and deeply understanding the interactions of the organism-nano systems are crucial to facilitate the biological applications of NPs. Here, we propose an interpretable causal system optimization (ICSO) framework and construct the upstream and downstream tasks of accurate prediction and intelligent NP optimization. ICSO framework screens the key drivers (recovery duration, specific surface area, and nanomaterial size) and potential causal information for immune responses and organ burden, revealing the hidden priming/constraint effects in bionano interactions. ICSO can be used to quantify the thresholds of biological responses to multiple properties (e.g., the specific surface area, diameter, and zeta potential). ICSO provides quantitative information and constraint conditions for the design of highly biocompatible and targeted organ delivery nanomaterials. For example, negative inflammation is reduced by 36.19%, and positive lung accumulation is promoted by 40.14% by optimizing the specific surface areas and shape and increasing the diameter-to-length ratio. ICSO overcomes the limitations of experience-dependent approaches and provides powerful and automated solutions for decision-makers during nanomaterial design.

Hepatotoxic of polystyrene microplastics in aged mice: Focus on the role of gastrointestinal transformation and AMPK/FoxO pathway

Microplastic (MP) toxicity has attracted widespread attention, whereas before triggering hepatotoxicity, ingested MPs first undergo transportation and digestion processes in the gastrointestinal tract, possibly interacting with the gastrointestinal contents (GIC). More alarming is the need for more understanding of how this process may impact the liver health of aged animals. This study selected old mice. Firstly, we incubated polystyrene microplastics (PS-MPs, 1 μm) with GIC extract. The results of SEM/EDS indicated a structural alteration in PS-MPs. Additionally, impurities resembling corona, rich in heteroatoms (O, N, and S), were observed. This resulted in an enhanced aggregating phenomenon of MPs. We conducted a 10-day experiment exposing aged mice to four concentrations of PS-MPs, ranging from 1 × 103 to 1 × 1012 particles/L. Subsequent measurements of tissue pathology and body and organ weights were conducted, revealing alterations in liver structure. In the liver, 12 crucial metabolites were found by LC-MS technology, including purines, lipids, and amino acids. The AMPK/FoxO pathway was enriched, activated, and validated in western blotting results. We also comprehensively examined the innate immune system, inflammatory factors, and oxidative stress indicators. The results indicated decreased C3 levels, stable C4 levels, inflammatory factors (IL-6 and IL-8), and antioxidant enzymes were increased to varying degrees. PS-MPs also caused DNA oxidative damage. These toxic effects exhibited a specific dose dependence. Overall, after the formation of the gastrointestinal corona, PS-MPs subsequently impact various cellular processes, such as cycle arrest (p21), leading to hepatic and health crises in the elderly. The presence of gastrointestinal coronas also underscores the MPs' morphology and characteristics, which should be distinguished after ingestion.

Getting fat and stressed: Effects of dietary intake of titanium dioxide nanoparticles in the liver of turbot Scophthalmus maximus

The extensive use of nanomaterials, including titanium dioxide nanoparticles (TiO2 NPs), raises concerns about their persistence in ecosystems. Protecting aquatic ecosystems and ensuring healthy and safe aquaculture products requires the assessment of the potential impacts of NPs on organisms. Here, we study the effects of a sublethal concentration of citrate-coated TiO2 NPs of two different primary sizes over time in flatfish turbot, Scophthalmus maximus (Linnaeus, 1758). Bioaccumulation, histology and gene expression were assessed in the liver to address morphophysiological responses to citrate-coated TiO2 NPs. Our analyses demonstrated a variable abundance of lipid droplets (LDs) in hepatocytes dependent on TiO2 NPs size, an increase in turbot exposed to smaller TiO2 NPs and a depletion with larger TiO2 NPs. The expression patterns of genes related to oxidative and immune responses and lipid metabolism (nrf2, nfκb1, and cpt1a) were dependent on the presence of TiO2 NPs and time of exposure supporting the variance in hepatic LDs distribution over time with the different NPs. The citrate coating is proposed as the likely catalyst for such effects. Thus, our findings highlight the need to scrutinize the risks associated with exposure to NPs with distinct properties, such as primary size, coatings, and crystalline forms, in aquatic organisms.

Influence of GO-Antisense miRNA-21 on the Expression of Selected Cytokines at Glioblastoma Cell Lines

Introduction

Graphene oxide (GO) is a single layer of carbon atoms with unique properties, which are beneficial due to its surface functionalisation by miRNA. miRNAs are a non-coding small form of RNA that suppress the expression of protein-coding genes by translational repression or degradation of messenger RNA. Antisense miRNA-21 is very promising for future investigation in cancer therapy. This study aimed to detect cytokine expression levels after the administration of GO-antisense miRNA-21 into U87, U118, U251 and T98 glioma cell lines.

Methods

U87, U118, U251 and T98 glioma cell line were investigated in term of viability, human cytokine expression level at protein and genes after treatment with GO, GO-antisense miRNA-21 and antisense miRNA-21. The delivery of antisense miRNA-21 into the glioma cell at in vitro investigation were conducted by GO based transfection and electroporation.

Results

The results of the protein microarray and gene expression profile showed that complexes of GO-antisense miRNA-21 modified the metallopeptidase inhibitor 2 (TIMP-2), interleukin-6 (IL-6), interleukin 8 (IL-8), intercellular adhesion molecule 1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) expression level compared to transfection by electroporation of antisense miRNA-21 at investigated glioblastoma cell lines. The TIMP-2 protein and gene expression level was upregulated after antisense miRNA-21 delivery by GO complex into U87, U251 and T98 glioblastoma cell lines comparing to the non-treated control group. The downregulation at protein expression level of ICAM - 1 was observed at U87, U118, U251 and T98 glioma cell lines. Moreover, the IL-8 expression level at mRNA for genes and protein was decreased significantly after delivery the antisense-miRNA-21 by GO compared to electroporation as a transfection method.

Discussion

This work demonstrated that the graphene oxide complexes with antisense miRNA-21 can effectively modulate the cytokine mRNA and protein expression level at U87, U118, U251 and T98 glioma cell lines.

Impact of physico-chemical properties on the toxicological potential of reduced graphene oxide in human bronchial epithelial cells

The increasing use of graphene-based materials (GBM) requires their safety evaluation, especially in occupational settings. The same physico-chemical (PC) properties that confer GBM extraordinary functionalities may affect the potential toxic response. Most toxicity assessments mainly focus on graphene oxide and rarely investigate GBMs varying only by one property. As a novelty, the present study assessed the in vitro cytotoxicity and genotoxicity of six reduced graphene oxides (rGOs) with different PC properties in the human bronchial epithelial 16HBE14o - cell line. Of the six materials, rGO1-rGO4 only differed in the carbon-to-oxygen (C/O) content, whereas rGO5 and rGO6 were characterized by different lateral size and number of layers, respectively, but similar C/O content compared with rGO1. The materials were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, laser diffraction and dynamic light scattering, and Brunauer-Emmett-Teller analysis. Cytotoxicity (Luminescent Cell Viability and WST-8 assays), the induction of reactive oxygen species (ROS; 2',7'-dichlorofluorescin diacetate-based assay), the production of cytokines (enzyme-linked immunosorbent assays) and genotoxicity (comet and micronucleus assays) were evaluated. Furthermore, the internalization of the materials in the cells was confirmed by laser confocal microscopy. No relationships were found between the C/O ratio or the lateral size and any of the rGO-induced biological effects. However, rGO of higher oxygen content showed higher cytotoxic and early ROS-inducing potential, whereas genotoxic effects were observed with the rGO of the lowest density of oxygen groups. On the other hand, a higher number of layers seems to be associated with a decreased potential for inducing cytotoxicity and ROS production.

Microplastic as an invisible threat to the coral reefs: Sources, toxicity mechanisms, policy intervention, and the way forward

Microplastic (MP) pollution waste is a global macro problem, and research on MP contamination has been done in marine, freshwater, and terrestrial ecosystems. Preventing MP pollution from hurting them is essential to maintaining coral reefs' ecological and economic benefits. However, the public and scientific communities must pay more attention to MP research on the coral reef regions' distribution, effects, mechanisms, and policy evaluations. Therefore, this review summarizes the global MP distribution and source within the coral reefs. Current knowledge extends the impacts of MP on coral reefs, existing policy, and further recommendations to mitigate MPs contamination on corals are critically analyzed. Furthermore, mechanisms of MP on coral and human health are also highlighted to pinpoint research gaps and potential future studies. Given the escalating plastic usage and the prevalence of coral bleaching globally, there is a pressing need to prioritize research efforts on marine MPs that concentrate on critical coral reef areas. Such investigations should encompass an extensive and crucial understanding of the distribution, destiny, and effects of the MPs on human and coral health and the potential hazards of those MPs from an ecological viewpoint.

Emerging Graphitic Carbon Nitride-based Nanobiomaterials for Biological Applications

Graphitic carbon nitride (g-CN) based nanostructures are distinctive materials with unique compositional, structural, optical, and electronic properties with exceptional band structure, moderate surface area, and exceptional thermal and chemical stability. Because of these properties, g-CN based nanomaterials have shown promising applications and higher performance in the biological avenue. This review covers the state-of-the-art synthetic strategies used for the preparation of the materials, the basic structure, and a panorama of different optimization strategies leading to improved physicochemical properties responsible for the biological application. The following sections include the recent progress in the use of g-CN based nanobiomaterials for biosensors, bioimaging, photodynamic therapy, drug delivery, chemotherapy, and the antimicrobial segment. Furthermore, we have summarized the role and evaluation of biosafety and biocompatibility of the material. Finally, the unresolved issues, plausible challenges, current status, and future perspectives for the development and design of g-CN have been summarized and are expected to promote a clinical path for the medical sector and human well-being.

Cytotoxic, Antidiabetic, and Antioxidant Study of Biogenically Improvised Elsholtzia blanda and Chitosan-Assisted Zinc Oxide Nanoparticles

In the present study, we have improvised a biogenic method to fabricate zinc oxide nanoparticles (ZnO NPs) using chitosan and an aqueous extract of the leaves of Elsholtzia blanda. Characterization of the fabricated products was carried out with the help of ultraviolet-visible, Fourier transform infrared, X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray analyses. The size of the improvised ZnO NP measured between 20 and 70 nm and had a spherical and hexagonal shape. The ZnO NPs proved to be highly effective in the antidiabetic test as the sample showed the highest percentage of enzyme inhibition at 74% ± 3.7, while in the antioxidant test, 78% was the maximum percentage of 2,2-diphenyl-1-picrylhydrazyl hydrate scavenging activity. The cytotoxic effect was investigated against the human osteosarcoma (MG-63) cell line, and the IC₅₀ value was 62.61 μg/mL. Photocatalytic efficiency was studied by the degradation of Congo red where 91% of dye degradation was observed. From the various analyses, it can be concluded that the as-synthesized NPs may be suitable for various biomedical applications as well as for environmental remediation.

Nanoengineering of biohybrid micro/nanobots for programmed biomedical applications

Biohybrid micro/nanobots have emerged as an innovative resource to be employed in the biomedical field due to their biocompatible and biodegradable properties. These are tiny nanomaterial-based integrated structures engineered in a way that they can move autonomously and perform the programmed tasks efficiently even at hard-to-reach organ/tissues/cellular sites. The biohybrid micro/nanobots can either be cell/bacterial/enzyme-based or may mimic the properties of an active molecule. It holds the potential to change the landscape in various areas of biomedical including early diagnosis of disease, therapeutics, imaging, or precision surgery. The propulsion mechanism of the biohybrid micro/nanobots can be both fuel-based and fuel-free, but the most effective and easiest way to propel these micro/nanobots is via enzymes. Micro/nanobots possess the feature to adsorb/functionalize chemicals or drugs at their surfaces thus offering the scope of delivering drugs at the targeted locations. They also have shown immense potential in intracellular sensing of biomolecules and molecular events. Moreover, with recent progress in the material development and processing is required for enhanced activity and robustness the fabrication is done via various advanced techniques to avoid self-degradation and cause cellular toxicity during autonomous movement in biological medium. In this review, various approaches of design, architecture, and performance of such micro/nanobots have been illustrated along with their potential applications in controlled cargo release, therapeutics, intracellular sensing, and bioimaging. Furthermore, it is also foregrounding their advancement offering an insight into their future scopes, opportunities, and challenges involved in advanced biomedical applications.

Electrically conductive carbon-based (bio)-nanomaterials for cardiac tissue engineering

A proper self-regenerating capability is lacking in human cardiac tissue which along with the alarming rate of deaths associated with cardiovascular disorders makes tissue engineering critical. Novel approaches are now being investigated in order to speedily overcome the challenges in this path. Tissue engineering has been revolutionized by the advent of nanomaterials, and later by the application of carbon-based nanomaterials because of their exceptional variable functionality, conductivity, and mechanical properties. Electrically conductive biomaterials used as cell bearers provide the tissue with an appropriate microenvironment for the specific seeded cells as substrates for the sake of protecting cells in biological media against attacking mechanisms. Nevertheless, their advantages and shortcoming in view of cellular behavior, toxicity, and targeted delivery depend on the tissue in which they are implanted or being used as a scaffold. This review seeks to address, summarize, classify, conceptualize, and discuss the use of carbon-based nanoparticles in cardiac tissue engineering emphasizing their conductivity. We considered electrical conductivity as a key affecting the regeneration of cells. Correspondingly, we reviewed conductive polymers used in tissue engineering and specifically in cardiac repair as key biomaterials with high efficiency. We comprehensively classified and discussed the advantages of using conductive biomaterials in cardiac tissue engineering. An overall review of the open literature on electroactive substrates including carbon-based biomaterials over the last decade was provided, tabulated, and thoroughly discussed. The most commonly used conductive substrates comprising graphene, graphene oxide, carbon nanotubes, and carbon nanofibers in cardiac repair were studied.

Phenol/Chloroform-Free TiO2-Based miRNA Extraction from Cell Lysate

While microRNAs are considered as excellent biomarkers of various diseases, there are still several remaining challenges regarding their isolation. In this study, we aimed to design a novel RNA isolation method that would help to overcome those challenges. Therefore, we present a novel phenol/chloroform-free, low-cost method for miRNA extraction. Within this method, RNA is extracted from cell lysate with an isopropanol/water/NaCl system, followed by solid-phase extraction using TiO2 microspheres to effectively separate short RNAs from long RNA molecules. We also demonstrated the pH-dependent selectivity of TiO2 microspheres towards different sizes of RNA. We were able to regulate the size range of extracted RNAs with simple adjustments in binding conditions used during the solid-phase extraction.

Genotoxicity of Graphene-Based Materials

Graphene-based materials (GBMs) are a broad family of novel carbon-based nanomaterials with many nanotechnology applications. The increasing market of GBMs raises concerns on their possible impact on human health. Here, we review the existing literature on the genotoxic potential of GBMs over the last ten years. A total of 50 articles including in vitro, in vivo, in silico, and human biomonitoring studies were selected. Graphene oxides were the most analyzed materials, followed by reduced graphene oxides. Most of the evaluations were performed in vitro using the comet assay (detecting DNA damage). The micronucleus assay (detecting chromosome damage) was the most used validated assay, whereas only two publications reported results on mammalian gene mutations. The same material was rarely assessed with more than one assay. Despite inhalation being the main exposure route in occupational settings, only one in vivo study used intratracheal instillation, and another one reported human biomonitoring data. Based on the studies, some GBMs have the potential to induce genetic damage, although the type of damage depends on the material. The broad variability of GBMs, cellular systems and methods used in the studies precludes the identification of physico-chemical properties that could drive the genotoxicity response to GBMs.

A review on the diverse interactions between microalgae and nanomaterials: Growth variation, photosynthetic performance and toxicity

Vast improvements in nanotechnology have led to the wide usage of nanomaterials (NMs) in daily products. This study reviews the interactions between NMs and microalgae in terms of impacts on growth and photosynthetic efficiency, and their toxicity on microalgae. All types of NMs such as carbon-based NMs (CNMs), metal oxide-based NMs (MONMs) and noble metal-based NMs (NMNMs) improve microalgal growth and photosynthetic efficiency at low concentration, typically ranging between 1 and 15 mg/L depending on the type of NMs, due to hormetic responses by microalgae. Higher concentrations of NMs have been found to reduce photosynthetic efficiency and subsequent growth inhibition of microalgae. MONMs-microalgae and NMNMs-microalgae interactions focus on membrane alteration, whereas carbon-based NMs-microalgae focus more on shading effect. The toxicity of each type of NMs on microalgae is in the order rGO > GO > MG > CNT for carbon-based NMs, ZnO > TiO₂ > CuO > Fe₂O₃ for MONMs and Ag > Au > Pt for NMNMs. Incorporation of NMs in microalgae are seen to have promising future on producing higher microalgae yield with increased economic efficiency.

Synthesis of a graphene oxide/agarose/hydroxyapatite biomaterial with the evaluation of antibacterial activity and initial cell attachment

Various materials are used in bone tissue engineering (BTE). Graphene oxide (GO) is a good candidate for BTE due to its antibacterial activity and biocompatibility. In this study, an innovative biomaterial consists of GO, agarose and hydroxyapatite (HA) was synthesized using electrophoresis system. The characterization of the synthesized biomaterial showed that needle-like crystals with high purity were formed after 10 mA/10 h of electrophoresis treatment. Furthermore, the calcium-phosphate ratio was similar to thermodynamically stable HA. In the synthesized biomaterial with addition of 1.0 wt% of GO, the colony forming units test showed significantly less Staphylococcus aureus. Initial attachment of MC3T3-E1 cells on the synthesized biomaterial was observed which showed the safety of the synthesized biomaterial for cell viability. This study showed that the synthesized biomaterial is a promising material that can be used in BTE.

Switching to nanonutrients for sustaining agroecosystems and environment: the challenges and benefits in moving up from ionic to particle feeding

The worldwide agricultural enterprise is facing immense pressure to intensify to feed the world's increasing population while the resources are dwindling. Fertilizers which are deemed as indispensable inputs for food, fodder, and fuel production now also represent the dark side of the intensive food production system. With most crop production systems focused on increasing the quantity of produce, indiscriminate use of fertilizers has created havoc for the environment and damaged the fiber of the biogeosphere. Deteriorated nutritional quality of food and contribution to impaired ecosystem services are the major limiting factors in the further growth of the fertilizer sector. Nanotechnology in agriculture has come up as a better and seemingly sustainable solution to meet production targets as well as maintaining the environmental quality by use of less quantity of raw materials and active ingredients, increased nutrient use-efficiency by plants, and decreased environmental losses of nutrients. However, the use of nanofertilizers has so far been limited largely to controlled environments of laboratories, greenhouses, and institutional research experiments; production and availability on large scale are still lagging yet catching up fast. Despite perceivable advantages, the use of nanofertilizers is many times debated for adoption at a large scale. The scenario is gradually changing, worldwide, towards the use of nanofertilizers, especially macronutrients like nitrogen (e.g. market release of nano-urea to replace conventional urea in South Asia), to arrest environmental degradation and uphold vital ecosystem services which are in critical condition. This review offers a discussion on the purpose with which the nanofertilizers took shape, the benefits which can be achieved, and the challenges which nanofertilizers face for further development and real-world use, substantiated with the significant pieces of scientific evidence available so far.

Graphene-based Nanomaterials in Fighting the Most Challenging Viruses and Immunogenic Disorders

Viral diseases have long been among the biggest challenges for healthcare systems around the world. The recent Coronavirus Disease 2019 (COVID-19) pandemic is an example of how complicated the situation can get if we are not prepared to combat a viral outbreak in time, which brings up the need for quick and affordable biosensing platforms and vast knowledge of potential antiviral effects and drug/gene delivery opportunities. The same challenges have also existed for nonviral immunogenic disorders. Nanomedicine is considered a novel candidate for effectively overcoming these worldwide challenges. Among the versatile nanomaterials commonly used in biomedical applications, graphene has recently earned much attention thanks to its special and inspiring physicochemical properties, such as its large surface area, efficient thermal/electrical properties, carbon-based chemical purity with controllable biocompatibility, easy functionalization, capability of single-molecule detection, anticancer characteristics, 3D template feature in tissue engineering, and, in particular, antibacterial/antiviral activities. In this Review, the most important and challenging viruses of our era, such as human immunodeficiency virus, Ebola, SARS-CoV-2, norovirus, and hepatitis virus, and immunogenic disorders, such as asthma, Alzheimer's disease, and Parkinson's disease, in which graphene-based nanomaterials can effectively take part in the prevention, detection, treatment, medication, and health effect issues, have been covered and discussed.

The adverse effects of injected functionalized multi-walled carbon nanotube (f-MWCNT) on in vivo neurosecretory brain cells of Jamaican field cricket, Gryllus assimilis

Carbon nanotubes (CNTs) have been increasingly more prevalent due to their use in product technology owing to their exceptional electrical and thermal conductivity and tensile strength because of their nanostructure and strength of the bonds among carbon atoms. The potential increase of CNTs in the environment is a concern, and studies to assess the toxic effects of these nanomaterials (NMs) are needed. However, so far, most of the studies are focused on aquatic species and much less is understood about the effects of NM in terrestrial organisms. This investigation used a functionalized multi-walled carbon nanotube (f-MWCNT) and the Jamaican cricket Gryllus assimilis to assess the effects of this NM. Cricket nymphs were injected with f-MWCNT suspension-at three different concentrations. The insecticide Fipronil was used as a positive control. Survival was monitored, and histological analysis was made in the brains. Pyknotic cells were quantified in two brain regions, a neurosecretory called Pars intercerebralis (PI), and an associative region called mushroom body (MB). No mortality was observed in any f-MWCNT concentration tested. A significant increase in pyknotic cells was observed as sub-lethal effect for the intermediate concentration of f-MWCNT, at PI, while any significant change was observed at the Kenyon cells of the MB. These results are discussed in the context of agglomeration and dispersion of the f-MWCNT at different concentrations, and availability of the f-MWCNT on the circulatory system, as well as the natural decay of pyknotic cells with time and different patterns of adult cricket neurogenesis. Our results showed that f-MWCNT had negative effects in the neurosecretory region of the brain.

Mitochondrial Effects in the Liver of C57BL/6 Mice by Low Dose, High Energy, High Charge Irradiation

Galactic cosmic rays are primarily composed of protons (85%), helium (14%), and high charge/high energy ions (HZEs) such as ⁵⁶Fe, ²⁸Si, and ¹⁶O. HZE exposure is a major risk factor for astronauts during deep-space travel due to the possibility of HZE-induced cancer. A systems biology integrated omics approach encompassing transcriptomics, proteomics, lipidomics, and functional biochemical assays was used to identify microenvironmental changes induced by HZE exposure. C57BL/6 mice were placed into six treatment groups and received the following irradiation treatments: 600 MeV/n ⁵⁶Fe (0.2 Gy), 1 GeV/n ¹⁶O (0.2 Gy), 350 MeV/n ²⁸Si (0.2 Gy), ¹³⁷Cs (1.0 Gy) gamma rays, ¹³⁷Cs (3.0 Gy) gamma rays, and sham irradiation. Left liver lobes were collected at 30, 60, 120, 270, and 360 days post-irradiation. Analysis of transcriptomic and proteomic data utilizing ingenuity pathway analysis identified multiple pathways involved in mitochondrial function that were altered after HZE irradiation. Lipids also exhibited changes that were linked to mitochondrial function. Molecular assays for mitochondrial Complex I activity showed significant decreases in activity after HZE exposure. HZE-induced mitochondrial dysfunction suggests an increased risk for deep space travel. Microenvironmental and pathway analysis as performed in this research identified possible targets for countermeasures to mitigate risk.

Direct and Indirect Genotoxicity of Graphene Family Nanomaterials on DNA-A Review

Graphene family nanomaterials (GFNs), including graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs), have manifold potential applications, leading to the possibility of their release into environments and the exposure to humans and other organisms. However, the genotoxicity of GFNs on DNA remains largely unknown. In this review, we highlight the interactions between DNA and GFNs and summarize the mechanisms of genotoxicity induced by GFNs. Generally, the genotoxicity can be sub-classified into direct genotoxicity and indirect genotoxicity. The direct genotoxicity (e.g., direct physical nucleus and DNA damage) and indirect genotoxicity mechanisms (e.g., physical destruction, oxidative stress, epigenetic toxicity, and DNA replication) of GFNs were summarized in the manuscript, respectively. Moreover, the influences factors, such as physicochemical properties, exposure dose, and time, on the genotoxicity of GFNs are also briefly discussed. Given the important role of genotoxicity in GFNs exposure risk assessment, future research should be conducted on the following: (1) developing reliable testing methods; (2) elucidating the response mechanisms associated with genotoxicity in depth; and (3) enriching the evaluation database regarding the type of GFNs, applied dosages, and exposure times.

Nanomaze Lure: Pheromone Sandwich in Graphene Oxide Interlayers for Sustainable Targeted Pest Control

The indiscriminate use of pesticides leads to irreparable damage to the ecosystem, which motivates for sustainable alternatives like pheromone-assisted pest management. The tomato pinworm Tuta absoluta is a major threat to tomato cultivation. Moreover, its green management technology uses a pheromone trap that has a short field life. To overcome this problem, a pheromone composite with graphene oxide (GO) and amine-modified graphene oxide (AGO) that can extend the diffusion path has been developed. The composite stimulates an effective electrophysiological response in the antenna, which results in trapping of a significantly higher number of insects as compared to the commercial septa, thus qualifying it for field evaluation. Compared to AGO, the GO composite has pheromones assembled into a multilayer, which increases the pheromone diffusion path. This in turn resulted in the extension of the pheromone life that proportionally increased the pest trapped. This technique will be beneficial to farmers as they have longer field efficacy to keep the pest damage low in an environmentally friendly manner.

Effect of graphene / metal nanocomposites on the key genes involved in rosmarinic acid biosynthesis pathway and its accumulation in Melissa officinalis

BACKGROUND

Recently, numerous investigations have been done to study graphene and silver nanoparticle in the fields of agriculture and medicine. In the present study, the green synthesis of nanoparticles with two concentrations (0, 40, 60 mM) and their effect on the molecular and biochemical biosynthesis pathway of rosmarinic acid in a new method, low cost, and safe for the environment has been investigated. The transcript levels of key genes in the rosmarinic acid biosynthesis pathway (Tyrosine aminotransferase, rosmarinic acid synthase, and phenylalanine-ammonia lyase) were studied using real-time quantitative polymerase chain reaction. Then, the rosmarinic acid content was evaluated using HPLC.

RESULTS

The results showed that a concentration-dependent manner was observed in treated plants. At the biochemical level, the use of nanocomposites at concentration of 40 mM showed higher soluble carbohydrate (37%), flavonoids (21%), total phenol (35%) as well as total protein (47%) compared to the control plants. HPLC results showed that rosmarinic acid content in the treated plants with a low concentration of nanocomposite (40 mM) was more affected than plants treated with a high concentration of nanocomposite (60 mM) (26%) and also compared to other treatments. At the molecular level, the result showed that Tyrosine aminotransferase and rosmarinic acid synthase gene expression was positively correlated with both silver nanoparticle concentrations and nanocomposite treatments, but phenylalanine-ammonia lyase gene expression was positively correlated only with nanocomposite at 40 mM concentration.

CONCLUDE

It can conclude that the nanocomposite at low concentration is more likely to induce molecular and biochemical parameters. And also, in the rosmarinic acid biosynthesis pathway, the Tyrosine aminotransferase -derived pathway is more efficient than the phenylalanine-ammonia lyase -derived pathway by causing a nano-elicitor. Therefore, it was concluded that studied elicitor at low concentration, can create plants with higher production capacity.

Can nanomaterials induce reproductive toxicity in male mammals? A historical and critical review

The nanotechnology enabled the development of nanomaterials (NMs) with a variety of industrial, biomedical, and consumer applications. However, the mechanism of action (MoA) and toxicity of NMs remain unclear, especially in the male reproductive system. Thus, this study aimed to perform a bibliometric and systematic review of the literature on the toxic effects of different types of NMs on the male reproductive system and function in mammalian models. A series of 236 articles related to the in vitro and in vivo reproductive toxicity of NMs in mammalian models were analyzed. The data concerning the bioaccumulation, experimental conditions (types of NMs, species, cell lines, exposure period, and routes of exposure), and the MoA and toxicity of NMs were summarized and discussed. Results showed that this field of research began in 2005 and has experienced an exponential increase since 2012. Revised data confirmed that the NMs have the ability to cross the blood-testis barrier and bioaccumulate in several organs of the male reproductive system, such as testis, prostate, epididymis, and seminal vesicle. A similar MoA and toxicity were observed after in vitro and in vivo exposure to NMs. The NM reproductive toxicity was mainly related to ROS production, oxidative stress, DNA damage and apoptosis. In conclusion, the NM exposure induces bioaccumulation and toxic effects on male reproductive system of mammal models, confirming its potential risk to human and environmental health. The knowledge concerning the NM reproductive toxicity contributes to safety and sustainable use of nanotechnology.

Graphene-based hybrid materials as promising scaffolds for peripheral nerve regeneration

Peripheral nerve injury (PNI) is a serious clinical health problem caused by the damage of peripheral nerves which results in neurological deficits and permanent disability. There are several factors that may cause PNI such as localized damage (car accident, trauma, electrical injury) and outbreak of the systemic diseases (autoimmune or diabetes). While various diagnostic procedures including X-ray, magnetic resonance imaging (MRI), as well as other type of examinations such as electromyography or nerve conduction studies have been efficiently developed, a full recovery in patients with PNI is in many cases deficient or incomplete. This is the reason why additional therapeutic strategies should be explored to favor a complete rehabilitation in order to get appropriate nerve injury regeneration. The use of biomaterials acting as scaffolds opens an interesting approach in regenerative medicine and tissue engineering applications due to their ability to guide the growth of new tissues, adhesion and proliferation of cells including the expression of bioactive signals. This review discusses the preparation and therapeutic strategies describing in vitro and in vivo experiments using graphene-based materials in the context of PNI and their ability to promote nerve tissue regeneration.

Exposure to Atmospheric Particulate Matter-Bound Polycyclic Aromatic Hydrocarbons and Their Health Effects: A Review

Particulate matter (PM) is a major factor contributing to air quality deterioration that enters the atmosphere as a consequence of various natural and anthropogenic activities. In PM, polycyclic aromatic hydrocarbons (PAHs) represent a class of organic chemicals with at least two aromatic rings that are mainly directly emitted via the incomplete combustion of various organic materials. Numerous toxicological and epidemiological studies have proven adverse links between exposure to particulate matter-bound (PM-bound) PAHs and human health due to their carcinogenicity and mutagenicity. Among human exposure routes, inhalation is the main pathway regarding PM-bound PAHs in the atmosphere. Moreover, the concentrations of PM-bound PAHs differ among people, microenvironments and areas. Hence, understanding the behaviour of PM-bound PAHs in the atmosphere is crucial. However, because current techniques hardly monitor PAHs in real-time, timely feedback on PAHs including the characteristics of their concentration and composition, is not obtained via real-time analysis methods. Therefore, in this review, we summarize personal exposure, and indoor and outdoor PM-bound PAH concentrations for different participants, spaces, and cities worldwide in recent years. The main aims are to clarify the characteristics of PM-bound PAHs under different exposure conditions, in addition to the health effects and assessment methods of PAHs.

Graphene and Reproduction: A Love-Hate Relationship

Since its discovery, graphene and its multiple derivatives have been extensively used in many fields and with different applications, even in biomedicine. Numerous efforts have been made to elucidate the potential toxicity derived from their use, giving rise to an adequate number of publications with varied results. On this basis, the study of the reproductive function constitutes a good tool to evaluate not only the toxic effects derived from the use of these materials directly on the individual, but also the potential toxicity passed on to the offspring. By providing a detailed scientometric analysis, the present review provides an updated overview gathering all the research studies focused on the use of graphene and graphene-based materials in the reproductive field, highlighting the consequences and effects reported to date from experiments performed in vivo and in vitro and in different animal species (from Archea to mammals). Special attention is given to the oxidized form of graphene, graphene oxide, which has been recently investigated for its ability to increase the in vitro fertilization outcomes. Thus, the potential use of graphene oxide against infertility is hypothesized here, probably by engineering the spermatozoa and thus manipulating them in a safer and more efficient way.

Toxicity evaluation of cadmium-containing quantum dots: A review of optimizing physicochemical properties to diminish toxicity

Fluorescent quantum dots (QDs) have received extensive attention because of their excellent optical properties and wide utilization in biological and biomedical areas. Nonetheless, there have been intense concerns on the cytotoxicity assessment of cadmium-containing QDs due to free cadmium ions release and nano-size effects. This paper reviews the representative synthetic strategies for preparation of cadmium-containing QDs and their applications. Then the toxicity assessments of QDs from cell studies to animal models are discussed, which can aid in improving our understanding of the cytotoxicity of QDs, and the toxicity mechanism is proposed. Several critical physicochemical properties of QDs are discussed and suggestions are provided for optimizing QDs design in view of minimal cytotoxicity. Finally, accurate detection techniques and systematic methodologies for the toxicity assessment of QDs are expected to achieve further breakthroughs in the future, especially in-situ, real-time, and rapid quantitative analysis methods.

Gold Nanoparticles and Graphene Oxide Flakes Synergistic Partaking in Cytosolic Bactericidal Augmentation: Role of ROS and NOX2 Activity

Gold nanoparticles (GNPs) and graphene oxide flakes (GOFs) exerted significantly (p < 0.0001) supportive roles on the phagocytosis bioactivity of the immune cells of phagocytic nature against the Gram-positive and Gram-negative human pathogenic bacteria Staphylococcus aureus and Escherichia coli. Under experimental conditions, upon bacterial exposure, the combined GNPs and GOFs induced significant clearance of bacteria through phagosome maturation (p < 0.0001) from time-points of 6 to 30 min and production of reactive oxygen species (ROS, p < 0.0001) through the NADPH oxidase 2 (NOX2, p < 0.0001)-based feedback mechanism. The effects of the combined presence of GNPs and GOFs on phagocytosis (p < 0.0001) suggested a synergistic action underway, also achieved through elevated signal transduction activity in the bone-marrow-derived macrophages (BMDM, p < 0.0001). The current study demonstrated that GNPs’ and GOFs’ bactericidal assisting potentials could be considered an effective and alternative strategy for treating infections from both positive and negative bacterial strains.

Vitellogenin expression, DNA damage, health status of cells and catalase activity in Acheta domesticus selected according to their longevity after graphene oxide treatment

The increased use of graphene oxide (GO) raises worrisome questions regarding its possible threat to various ecosystems. Invertebrates represent valuable organisms for environmental studies. The lifespan can influence the ability to cope with toxins, especially those that act via oxidative stress. Two strains of Acheta domesticus, which are selected for longevity, were tested. The main aim was to investigate how GO, when administrated in food, affects: the condition of cells, DNA stability, ROS generation and the reproduction potential (the Vitellogenin (Vg) protein expression). The "recovery effect" - after removing GO from the diet for 15 days - was also measured. The results revealed different responses to GO in the wild (H) and long-living (D) strains. The D strain had a higher catalase activity compared to the H strain on the 25th day of the imago stage. Removing GO from the food resulted in a decrease in the catalase activity to the level of the control. On the 5th day of the imago stage, the H strain had a higher cell mortality than the D strain in the GO-intoxicated groups. There was more DNA damage in the H strain compared to the long-living strain. A remedial effect was seen after the GO was removed from the diet. The total Vg protein expression was higher in the H strain and lower in the D strain. The results indicated a GO concentration-dependent outcome. In both strains, removing the GO from the food led to a high Vg expression. The Vg expression after GO treatment, particularly translation and post-translational processing, should be studied in detail in the future. The D strain of crickets had more specialized mechanisms for maintaining homeostasis than the H strain. Organisms can fight off negative effects of GO, especially when they have systems that are well developed against oxidative stress.

Graphene Oxide Negatively Regulates Cell Cycle in Embryonic Fibroblast Cells

BACKGROUND

Unique properties of graphene and its derivatives make them attractive in the field of nanomedicine. However, the mass application of graphene might lead to side effects, which has not been properly addressed in previous studies, especially with regard to its effect on the cell cycle.

METHODS

The effect of two concentrations (100 and 200 μg/mL) of nano- and microsized graphene oxide (nGO and mGO) on apoptosis, cell cycle, and ROS generation was studied. The effect of both sizes on viability and genotoxicity of the embryonic fibroblast cell cycle was evaluated. MTT and flow cytometry were applied to evaluate the effects of graphene oxide (GO) nanosheets on viability of cells. Apoptosis and cell cycle were analyzed by flow cytometry.

RESULTS

The results of this study showed that GO disturbed the cell cycle and nGO impaired cell viability by inducing cell apoptosis. Interestingly, both nGO and mGO blocked the cell cycle in the S phase, which is a critical phase of the cell cycle. Upregulation of TP53-gene transcripts was also detected in both nGO- and mGO-treated cells compared to the control, especially at 200 μg/mL. DNA content of the treated cells increased; however, because of DNA degradation, its quality was decreased.

CONCLUSION

In conclusion, graphene oxide at both nano- and micro-scale damages cell physiology and increases cell population in the S phase of the cell cycle.

Toxicity of microwave-synthesized silver-reduced graphene oxide nanocomposites to the microalga Chlorella vulgaris: Comparison with the hydrothermal method synthesized counterparts

The increased applications of nanomaterials in industry and biomedicine have resulted in a rising concern about their possible toxic impacts on living organisms. It has been claimed that the phytosynthesized nanomaterials have lower toxicity in comparison to their chemically synthesized counterparts. Therefore, it is important to evaluate their toxic effects on the environment. In the present study, we investigated the toxic effects of microwave-synthesized silver-reduced graphene oxide nanocomposites (MS-Ag-rGO) on Chlorella vulgaris. Algal cells were treated by 1, 2, 4 and 6 mg L^-1 MS-Ag-rGO for 24 h. The obtained data with three replicates were examined using analysis of variance. Analysis of different growth parameters revealed that MS-Ag-rGO possessed significant dose-dependent toxic effect on C. vulgaris. Scanning electron microscope and fluorescence microscope images of the treated cells established morphological shrinkages and alteration in position of nucleoli. Moreover, reduction in the phenol and flavonoid contents, enhancement of H₂O₂ content, changes in the antioxidant enzymes activity and decreases in the growth parameters as well as photosynthetic pigments quantities confirmed the toxicity of MS-Ag-rGO to the C. vulgaris cells. Our findings revealed that MS-Ag-rGO possessed higher toxicity on C. vulgaris than Ag-rGO synthesized by hydrothermal technique.

Graphene aerogel nanoparticles for in-situ loading/pH sensitive releasing anticancer drugs

Free polymer graphene aerogel nanoparticles (GA NPs) were synthesized by using reduction/aggregation of graphene oxide (GO) sheets in the presence of vitamin C (as a biocompatible reductant agent) at a low temperature (40 °C), followed by an effective sonication. Synthesis of GA NPs in doxorubicin hydrochloride (DOX)-containing solution results in the simultaneous synthesis and drug loading with higher performance (than that of the separately synthesized and loaded samples). To investigate the mechanism of loading and the capability of GA NPs in the loading of other drug structures, two groups of ionized (DOX, Amikacin sulfate and, d-glucosamine hydrochloride) and non-ionized (Paclitaxel (PTX)) drugs were examined. Furthermore, the relationship between the bipolar level of DOX solution (contributing to H-bonding of DOX and GO) and the amount of DOX loading was investigated. The DOX showed higher loading (>3 times) than PTX, as anticancer drugs. Since both DOX and PTX possess aromatic structures, the higher loading of DOX was assigned to its positive partial charge and ionized nature. Accordingly, other drugs (having positive partial charge and ionized nature, but no aromatic structure) such as Amikacin sulfate and d-glucosamine hydrochloride presented higher loading than PTX. These results indicated that although the π-π interactions induced by aromatic structures are important in drug loading, the electrostatic interaction of ionized drugs with GO (especially through H-bonding) is the dominant mechanism. DOX-loaded GANPs showed high pH-sensitive release (equivalent to the carrier weight) after 5 days, which can indicate benefits in tumor cell acidic microenvironments in-vivo.

Widely distributed nanocolloids in water regulate the fate and risk of graphene oxide

The environmental behaviors and risks associated with graphene oxide (GO, a popular 2D nanomaterial) have attracted considerable attention. GO released to aquatic systems will most likely interact with ubiquitous nanocolloids (Nc) in surface water. However, the effects of Nc on the fate and risk of GO remain largely unknown in water. Herein, the binding of Nc onto GO was investigated via electron microscopy, electron paramagnetic resonance, 2D correlation spectroscopy and biolayer interferometry. The results revealed that electron charge transfers, hydrophilic effects and π-π stacking contributed to a strong affinity (K_D = 5.6 nM) and high adsorption capacity (159.8 mg/g) of Nc onto the GO surface. Moreover, GO nanosheets transformed to a scroll morphology or multiple GO particles bridging by Nc, which remarkably reduced the aggregation and sedimentation rates after binding with Nc. Interestingly, co-exposure with Nc greatly alleviated the toxicity (e.g., tail malformation, yolk sac edema and oxidative stress) of GO to zebrafish embryos. Morphological and structural alterations of GO after binding to Nc contributed to the mechanisms for the antagonistic effects on the zebrafish embryos toxicity. The present work provides insights into the environmental fate and risk of GO by ubiquitous Nc in natural water.

Impact of Graphene-Based Surfaces on the Basic Biological Properties of Human Umbilical Cord Mesenchymal Stem Cells: Implications for Ex Vivo Cell Expansion Aimed at Tissue Repair

The potential therapeutic applications of mesenchymal stem/stromal cells (MSCs) and biomaterials have attracted a great amount of interest in the field of biomedical engineering. MSCs are multipotent adult stem cells characterized as cells with specific features, e.g., high differentiation potential, low immunogenicity, immunomodulatory properties, and efficient in vitro expansion ability. Human umbilical cord Wharton's jelly-derived MSCs (hUC-MSCs) are a new, important cell type that may be used for therapeutic purposes, i.e., for autologous and allogeneic transplantations. To improve the therapeutic efficiency of hUC-MSCs, novel biomaterials have been considered for use as scaffolds dedicated to the propagation and differentiation of these cells. Nowadays, some of the most promising materials for tissue engineering include graphene and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO). Due to their physicochemical properties, they can be easily modified with biomolecules, which enable their interaction with different types of cells, including MSCs. In this study, we demonstrate the impact of graphene-based substrates (GO, rGO) on the biological properties of hUC-MSCs. The size of the GO flakes and the reduction level of GO have been considered as important factors determining the most favorable surface for hUC-MSCs growth. The obtained results revealed that GO and rGO are suitable scaffolds for hUC-MSCs. hUC-MSCs cultured on: (i) a thin layer of GO and (ii) an rGO surface with a low reduction level demonstrated a viability and proliferation rate comparable to those estimated under standard culture conditions. Interestingly, cell culture on a highly reduced GO substrate resulted in a decreased hUC-MSCs proliferation rate and induced cell apoptosis. Moreover, our analysis demonstrated that hUC-MSCs cultured on all the tested GO and rGO scaffolds showed no alterations of their typical mesenchymal phenotype, regardless of the reduction level and size of the GO flakes. Thus, GO scaffolds and rGO scaffolds with a low reduction level exhibit potential applicability as novel, safe, and biocompatible materials for utilization in regenerative medicine.

Graphene oxide induces cardiovascular defects in developing zebrafish (Danio rerio) embryo model: In-vivo toxicity assessment

Graphene oxide (GO) has wide engineering applications in various areas, including electronics, energy storage, pharmaceuticals, nanomedicine, environmental remediation and biotechnology, because of its unique physico-chemical properties. In the present study, the risk-related information of GO was evaluated to examine the potential ecological and health risks of developmental toxicity. Although the overall developmental toxicity of GO has been well characterized in zebrafish, however, its release effect at a certain concentration of living organisms with specific cardiovascular defects remains largely elusive. Therefore, this study was conducted to further evaluate the toxicity of GO on embryonic development and cardiovascular defects in zebrafish embryos used as an in-vivo animal model. As a result, the presence of GO at a small concentration (0.1-0.3 mg/mL) does not affect the embryonic development. However, GO at higher concentrations (0.4-1 mg/mL) induces significant embryonic mortality, increase heartbeat, delayed hatching, cardiotoxicity, cardiovascular defects, retardation of cardiac looping, increased apoptosis and decreased hemoglobinization. These results provide valuable information that can be used to study the eco-toxicological effects of GO for assessing its bio-safety according to environmental concentration. In addition, the present results would also be usefully utilized for understanding the environmental risks associated with GO on human health in general.

Graphene Oxide increases mammalian spermatozoa fertilizing ability by extracting cholesterol from their membranes and promoting capacitation

Graphene Oxide (GO) is a widely used biomaterial with an amazing variety of applications in biology and medicine. Recently, we reported the ability of GO to improve the in vitro fertilization (IVF) outcomes in swine, a validated animal model with a high predictive value for human fertility. For that reason, here we characterized the mechanisms involved in this positive interaction by adopting an experimental approach combining biological methods (confocal microscopy analysis on single cell, flow cytometry on cell populations and co-incubation with epithelial oviductal cells), physical-chemical techniques (Differential Scanning Calorimetry and Thermogravimetric Analysis), and chemical methods (mass spectrometry and lipid measurement). As a result, we propose a model in which GO is able to extract cholesterol from the spermatozoa membrane without causing any detrimental effect. In this way, the cholesterol extraction promotes a change in membrane chemical-physical properties that could positively affect male gamete function, modulating sperm signalling function and increasing in this way the fertilizing potential, without losing the ability to physiologically interact with the female environment. In conclusion, these data seem to suggest new intriguing possibilities in engineering sperm membrane for improving assisted reproduction technologies outcomes, even in human medicine.

Study of the Persistence of the Phytotoxicity Induced by Graphene Oxide Quantum Dots and of the Specific Molecular Mechanisms by Integrating Omics and Regular Analyses

Although increasing attention has been paid to the nanotoxicity of graphene oxide quantum dots (GOQDs) due to their broad range of applications, the persistence and recoverability associated with GOQDs had been widely ignored. Interestingly, stress-response hormesis for algal growth was observed for Chlorella vulgaris as a single-celled model organism. Few physiological parameters, such as algal density, plasmolysis, and levels of reactive oxygen species, exhibited facile recovery. In contrast, the effects on chlorophyll a levels, permeability, and starch grain accumulation exhibited persistent toxicity. In the exposure stage, the downregulation of genes related to unsaturated fatty acid biosynthesis, carotenoid biosynthesis, phenylpropanoid biosynthesis, and binding contributed to toxic effects on photosynthesis. In the recovery stage, downregulation of genes related to the cis-Golgi network, photosystem I, photosynthetic membrane, and thylakoid was linked to the persistence of toxic effects on photosynthesis. The upregulated galactose metabolism and downregulated aminoacyl-tRNA biosynthesis also indicated toxicity persistence in the recovery stage. The downregulation and upregulation of phenylalanine metabolism in the exposure and recovery stages, respectively, reflected the tolerance of the algae to GOQDs. The present study highlights the importance of studying nanotoxicity by elucidation of stress and recovery patterns with metabolomics and transcriptomics.

Degradation of Mitochondria and Oxidative Stress as the Main Mechanism of Toxicity of Pristine Graphene on U87 Glioblastoma Cells and Tumors and HS-5 Cells

Due to the development of nanotechnologies, graphene and graphene-based nanomaterials have attracted immense scientific interest owing to their extraordinary properties. Graphene can be used in many fields, including biomedicine. To date, little is known about the impact graphene may have on human health in the case of intentional exposure. The present study was carried out on U87 glioma cells and non-cancer HS-5 cell lines as in vitro model and U87 tumors cultured on chicken embryo chorioallantoic membrane as in vivo model, on which the effects of pristine graphene platelets (GPs) were evaluated. The investigation consisted of structural analysis of GPs using transmission electron microscopy, Fourier transmission infrared measurements, zeta potential measurements, evaluation of cell morphology, assessment of cell viability, investigation of reactive oxygen species production, and investigation of mitochondrial membrane potential. The toxicity of U87 glioma tumors was evaluated by calculating the weight and volume of tumors and performing analyses of the ultrastructure, histology, and protein expression. The in vitro results indicate that GPs have dose-dependent cytotoxicity via ROS overproduction and depletion of the mitochondrial membrane potential. The mass and volume of tumors were reduced in vivo after injection of GPs. Additionally, the level of apoptotic and necrotic markers increased in GPs-treated tumors.

Three-Dimensional Graphene Foams: Synthesis, Properties, Biocompatibility, Biodegradability, and Applications in Tissue Engineering

Presently, clinical nanomedicine and nanobiotechnology have impressively demanded the generation of new organic/inorganic analogues of graphene (as one of the intriguing biomedical research targets) for stem-cell-based tissue engineering. Among different shapes of graphene, three-dimensional (3D) graphene foams (GFs) are highly promising candidates to provide conditions for mimicking in vivo environments, affording effective cell attachment, proliferation,and differentiation due to their unique properties. These include the highest biocompatibility among nanostructures, high surface-to-volume ratio, 3D porous structure (to provide a homogeneous/isotropic growth of tissues), highly favorable mechanical characteristics, and rapid mass and electron transport kinetics (which are required for chemical/physical stimulation of differentiated cells). This review aims to describe recent and rapid advances in the fabrication of 3D GFs, together with their use in tissue engineering and regenerative nanomedicine applications. Moreover, we have summarized a broad range of recent studies about the behaviors, biocompatibility/toxicity,and biodegradability of these materials, both in vitro and in vivo. Finally, the highlights and challenges of these 3D porous structures, compared to the current polymeric scaffold competitors, are discussed.

Screening Priority Factors Determining and Predicting the Reproductive Toxicity of Various Nanoparticles

Due to the numerous factors (e.g., nanoparticle [NP] properties and experimental conditions) influencing nanotoxicity, it is difficult to identify the priority factors dominating nanotoxicity. Herein, by integrating data from the literature and a random forest model, the priority factors determining reproductive toxicity were successfully screened from highly heterogeneous data. Among 10 factors from more than 18 different NPs, the NP type and the exposure pathway were found to dominantly determine NP accumulation. The reproductive toxicity of various NPs primarily depended on the NP type and the toxicity indicators. Nanoparticles containing major elements (e.g., Zn and Fe) tended to accumulate in rats but induced lower toxicity than NPs containing noble elements. Compared with other exposure pathways, i.p. injection posed significantly higher risks for NP accumulation. By combining similarity network analysis and hierarchical clustering, the sources of highly heterogeneous data were identified, the factor-toxicity dependencies were extracted and visualized, and the prediction of nanotoxicity was then achieved based on the screened priority factors. The present work provides insights for the design of animal experiments and the illustration and prediction of nanotoxicity.

Characterization and toxicity of nanoscale fragments in wastewater treatment plant effluent

Much attention has been paid to extracting and isolating specific and well-known nanoparticles (especially for engineered nanomaterials) from complex environmental matrices. However, such research may not provide global information on actual contamination because nanoscale fragments exist as mixtures of various elements and matrices in the real environment. The present work first isolated and characterized nanoscale fragments in effluents from municipal wastewater treatment plants (WWTPs). The nanoscale fragments were found to be composed of 70-85% carbon and low amounts of oxygen, heavy metals and other elements and exhibited nanosheet topographies (approximately 0.87-1.31 nm thickness and 68-187 nm lateral length). Because the isolated nanoscale fragments were mixtures rather than one specific type of nanoparticle, they were present at high concentrations ranging from 0.07 to 0.55 mg/L. It was also found that the accumulation of nanoscale fragments in rice reached 0.59 mg/g under exposure to environmentally relevant concentrations, leading to marked phytotoxicity (e.g., ultrastructural damage to chloroplasts and mitochondria). Metabolic analysis revealed the toxicological mechanisms to be related to disorders of carbohydrate, amino acid and fatty acid metabolism. This study is the first to characterize the properties and analyze the toxicity of nanoscale fragments in the effluents of WWTPs. Given that WWTP effluents containing nanoscale fragments are continuously discharged to the soil, surface water and seas, nanoscale fragment materials deserve considerable attention in future work compared with the few widely studied engineered nanoparticles.

Nanocolloids in Natural Water: Isolation, Characterization, and Toxicity

Nanocolloids are widespread in natural water systems, but their characterization and ecological risks are largely unknown. Herein, tangential flow ultrafiltration (TFU) was used to separate and concentrate nanocolloids from surface waters. Unexpectedly, nanocolloids were present in high concentrations ranging from 3.7 to 7.2 mg/L in the surface waters of the Harihe River in Tianjin City, China. Most of the nanocolloids were 10-40 nm in size, contained various trace metals and polycyclic aromatic hydrocarbons, and exhibited fluorescence properties. Envelopment effects and aggregation of Chlorella vulgaris in the presence of nanocolloids were observed. Nanocolloids entered cells and nanocolloid-exposed cells exhibited stronger plasmolysis, chloroplast damage and more starch grains than the control cells. Moreover, nanocolloids inhibited the cell growth, promoted reactive oxygen species (ROS), reduce the chlorophyll a content and increased the cell permeability. The genotoxicity of nanocolloids was also observed. The metabolomics analysis revealed a significant ( p < 0.05) downregulation of amino acids and upregulation of fatty acids contributing to ROS increase, chlorophyll a decrease and plasmolysis. The present work reveals that nanocolloids, which are different from specific, engineered nanoparticles (e.g., Ag nanoparticles), are present at high concentrations, exhibit an obvious toxicity in environments, and deserve more attention in the future.

Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic

Neutrophils were previously shown to digest oxidized carbon nanotubes through a myeloperoxidase (MPO)-dependent mechanism, and graphene oxide (GO) was found to undergo degradation when incubated with purified MPO, but there are no studies to date showing degradation of GO by neutrophils. Here we produced endotoxin-free GO by a modified Hummers' method and asked whether primary human neutrophils stimulated to produce neutrophil extracellular traps or activated to undergo degranulation are capable of digesting GO. Biodegradation was assessed using a range of techniques including Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and mass spectrometry. GO sheets of differing lateral dimensions were effectively degraded by neutrophils. As the degradation products could have toxicological implications, we also evaluated the impact of degraded GO on the bronchial epithelial cell line BEAS-2B. MPO-degraded GO was found to be non-cytotoxic and did not elicit any DNA damage. Taken together, these studies have shown that neutrophils can digest GO and that the biodegraded GO is non-toxic for human lung cells.

Antioxidant nanomaterials in advanced diagnoses and treatments of ischemia reperfusion injuries

Organ ischemia with inadequate oxygen supply followed by reperfusion (which initiates a complex of inflammatory responses and oxidative stress) occurs in different clinical conditions and surgical procedures including stroke, myocardial infarction, limb ischemia, renal failure, organ transplantation, free-tissue-transfer, cardiopulmonary bypass, and vascular surgery. Even though pharmacological treatments protect against experimental ischemia reperfusion (I/R) injury, there has not been enough success in their application for patient benefits. The main hurdles in the treatment of I/R injury are the lack of diagnosis tools for understanding the complicated chains of I/R-induced signaling events, especially in the acute phase after ischemia, determining the affected regions of the tissue over time, and then, targeting and safe delivery of antioxidants, drugs, peptides, genes and cells to the areas requiring treatment. Besides the innate antioxidant and free radical scavenging properties, some nanoparticles also show higher flexibility in drug delivery and imaging. This review highlights three main approaches in nanoparticle-mediated targeting of I/R injury: nanoparticles (1) as antioxidants for reducing tissue oxidative stress, (2) for targeted delivery of therapeutic agents to the ischemic regions or cells, and (3) for imaging I/R injury at the molecular, cellular or tissue level and monitoring its evolution using contrasts induced by nanoparticles. These approaches can also be combined to realize so called theranostics for providing simultaneous diagnosis of ischemic regions and treatments by targeted delivery.

Single-cell mass cytometry and transcriptome profiling reveal the impact of graphene on human immune cells

Understanding the biomolecular interactions between graphene and human immune cells is a prerequisite for its utilization as a diagnostic or therapeutic tool. To characterize the complex interactions between graphene and immune cells, we propose an integrative analytical pipeline encompassing the evaluation of molecular and cellular parameters. Herein, we use single-cell mass cytometry to dissect the effects of graphene oxide (GO) and GO functionalized with amino groups (GONH₂) on 15 immune cell populations, interrogating 30 markers at the single-cell level. Next, the integration of single-cell mass cytometry with genome-wide transcriptome analysis shows that the amine groups reduce the perturbations caused by GO on cell metabolism and increase biocompatibility. Moreover, GONH₂ polarizes T-cell and monocyte activation toward a T helper-1/M1 immune response. This study describes an innovative approach for the analysis of the effects of nanomaterials on distinct immune cells, laying the foundation for the incorporation of single-cell mass cytometry on the experimental pipeline.

Understanding the interaction of nanomaterials and immune cells at the biomolecular level is of great significance in therapeutic applications. Here, the authors investigated the interaction of graphene oxide nanomaterials and several immune cell subpopulations using single-cell mass cytometry and genome-wide transcriptome analysis.

Aqueously Released Graphene Oxide Embedded in Epoxy Resin Exhibits Different Characteristics and Phytotoxicity of Chlorella vulgaris from the Pristine Form

The environmental release of nanoparticles is attracting increasing attention. Graphene oxide (GO) embedded in epoxy resin (ER) is a popular composite that has been used in various fields, but the environmental release of GO-ER composites and the effects on organisms in the environment remain unknown. The present work found that GO-ER composites in water for 2-7 days resulted in the release of 0.3-2.1% GO-ER at nanoscale (2-3 nm thickness and approximately 70-130 nm lateral length). Interestingly, pristine GO quenched 30-45% hydroxyl and 12% nitroxide free radicals, whereas this capacity was not observed for the released particles from GO-ER. At environmentally relevant concentrations (μg/L), released GO-ER particles, but not GO or ER matrix, promoted algal reproduction by 34% and chlorophyll biosynthesis by 65-127% at 96 h. Released GO-ER entered algal cells and induced a slight increase in reactive oxygen species but did not elicit notable cell structure damage. The upregulated amino acids and phenylalanine metabolism, and the downregulated fatty acid biosynthesis contributed to algal growth promoted by released GO-ER. Previous studies of pristine nanoparticles were unable to reflect the environmental effects of released nanoparticles into the environment, and our research on the exposure-toxicological continuum adds important contributions to this field.

Antibiotic-loaded MoS2 nanosheets to combat bacterial resistance via biofilm inhibition

The emergence of antibiotic resistance has resulted in increasing difficulty in treating clinical infections associated with biofilm formation, one of the key processes in turn contributing to enhanced antibiotic resistance. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance has opened up. Based on the many and diverse properties of MoS2 nanosheets that have attracted wide attention, in particular their antibacterial potential, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of the CM-TH nanocomposites showed the synergetic effect that the combination of nanomaterials and antibiotics was more efficient than either working alone. In particularly, the minimum inhibitory concentration values generally decreased by a factor of dozens, suggesting that CM-TH may become a possible alternative to traditional antibiotics in disrupting biofilms and overcoming antibiotic resistance in treating medical diseases.

Mechanistic understanding toward the toxicity of graphene-family materials to freshwater algae

We systematically investigated the toxicity mechanism of three graphene-family materials (GFMs), graphene oxide (GO), reduced graphene oxide (rGO) and multi-layer graphene (MG), to algae (Chlorella pyrenoidosa). GFMs exhibited much higher toxicity than other carbon materials (carbon nanotube and graphite), with the 96 h median effective concentration (EC₅₀) values of 37.3 (GO), 34.0 (rGO), and 62.2 (MG) mg/L. Shading effect contributed approximately 16.4% of growth inhibition by GO due to its higher dispersibility and transformation while the other GFMs did not show any shading effect. Hydrophobic rGO and MG more readily heteroagglomerated with algae than GO, thus likely leading to more direct contacts with algae. Flow cytometry results showed significant decrease of membrane integrity after GFM exposure, and rGO caused the highest membrane damage, which was confirmed by the increased DNA and K⁺ efflux. The observed membrane damage was caused by a combination of oxidative stress and physical penetration/extraction. Moreover, all the three GFMs could adsorb macronutrients (N, P, Mg, and Ca) from the algal medium, thus leading to nutrient depletion-induced indirect toxicity. GO showed the highest nutrient depletion (53% of total toxicity) due to its abundant functional groups. The information provided in this work will be useful for understanding toxicity mechanism and environmental risk of different GFMs in aquatic environments.