In Caenorhabditis elegans nanoparticle-bio-interactions become transparent: silica-nanoparticles induce reproductive senescence

Size, polyglycerol grafting, and net surface charge of iron oxide nanoparticles determine their interaction and toxicity in Caenorhabditis elegans

The widespread application of engineered nanoparticles (NPs) in environmental remediation has raised public concerns about their toxicity to aquatic organisms. Although appropriate surface modification can mitigate the ecotoxicity of NPs, the lack of polymer coating to inhibit toxicity completely and the insufficient knowledge about charge effect hinder the development of safe nanomaterials. Herein, we explored the potential of polyglycerol (PG) functionalization in alleviating the environmental risks of NPs. Iron oxide NPs (ION) of 20, 100, and 200 nm sizes (IONS, IONM and IONL, respectively) were grafted with PG to afford ION-PG. We examined the interaction of ION and ION-PG with Caenorhabditis elegans (C. elegans) and found that PG suppressed non-specific interaction of ION with C. elegans to reduce their accumulation and to inhibit their translocation. Particularly, IONS-PG was completely excluded from worms of all developmental stages. By covalently introducing sulfate, carboxyl and amino groups onto IONS-PG, we further demonstrated that positively charged IONS-PG-NH3+ induced high intestinal accumulation, cuticle adhesion and distal translocation, whereas the negatively charged IONS-PG-OSO3- and IONS-PG-COO- were excreted out. Consequently, no apparent deleterious effects on brood size and life span were observed in worms treated by IONS-PG and IONS-PG bearing negatively charged groups. This study presents new surface functionalization approaches for developing ecofriendly nanomaterials.

Evaluating the adverse effects and mechanisms of nanomaterial exposure on longevity of C. elegans: A literature meta-analysis and bioinformatics analysis of multi-transcriptome data

Exposure to large-size particulate air pollution (PM2.5 or PM10) has been reported to increase risks of aging-related diseases and human death, indicating the potential pro-aging effects of airborne nanomaterials with ultra-fine particle size (which have been widely applied in various fields). However, this hypothesis remains inconclusive. Here, a meta-analysis of 99 published literatures collected from electronic databases (PubMed, EMBASE and Cochrane Library; from inception to June 2023) was performed to confirm the effects of nanomaterial exposure on aging-related indicators and molecular mechanisms in model animal C. elegans. The pooled analysis by Stata software showed that compared with the control, nanomaterial exposure significantly shortened the mean lifespan [standardized mean difference (SMD) = -2.30], reduced the survival rate (SMD = -4.57) and increased the death risk (hazard ratio = 1.36) accompanied by upregulation of ced-3, ced-4 and cep-1, while downregulation of ctl-2, ape-1, aak-2 and pmk-1. Furthermore, multi-transcriptome data associated with nanomaterial exposure were retrieved from Gene Expression Omnibus (GSE32521, GSE41486, GSE24847, GSE59470, GSE70509, GSE14932, GSE93187, GSE114881, and GSE122728) and bioinformatics analyses showed that pseudogene prg-2, mRNAs of abu, car-1, gipc-1, gsp-3, kat-1, pod-2, acdh-8, hsp-60 and egrh-2 were downregulated, while R04A9.7 was upregulated after exposure to at least two types of nanomaterials. Resveratrol (abu, hsp-60, pod-2, egrh-2, acdh-8, gsp-3, car-1, kat-1, gipc-1), naringenin (kat-1, egrh-2), coumestrol (egrh-2) or swainsonine/niacin/ferulic acid (R04A9.7) exerted therapeutic effects by reversing the expression levels of target genes. In conclusion, our study demonstrates the necessity to use phytomedicines that target hub genes to delay aging for populations with nanomaterial exposure.

Amorphous silica nanoparticles and the human gut microbiota: a relationship with multiple implications

Amorphous silica nanoparticles (ASNP) are among the nanomaterials that are produced in large quantities. ASNP have been present for a long time in several fast-moving consumer products, several of which imply exposure of the gastrointestinal tract, such as toothpastes, food additives, drug excipients, and carriers. Consolidated use and experimental evidence have consistently pointed to the very low acute toxicity and limited absorption of ASNP. However, slow absorption implies prolonged exposure of the intestinal epithelium to ASNP, with documented effects on intestinal permeability and immune gut homeostasis. These effects could explain the hepatic toxicity observed after oral administration of ASNP in animals. More recently, the role of microbiota in these and other ASNP effects has attracted increasing interest in parallel with the recognition of the role of microbiota in a variety of conditions. Although evidence for nanomaterial effects on microbiota is particularly abundant for materials endowed with bactericidal activities, a growing body of recent experimental data indicates that ASNPs also modify microbiota. The implications of these effects are recounted in this contribution, along with a discussion of the more important open issues and recommendations for future research.

Comprehensive Neurotoxicity of Lead Halide Perovskite Nanocrystals in Nematode Caenorhabditis elegans

To date, all-inorganic lead halide perovskite quantum dots have emerged as promising materials for photonic, optoelectronic devices, and biological applications, especially in solar cells, raising numerous concerns about their biosafety. Most of the studies related to the toxicity of perovskite quantum dots (PeQDs) have focused on the potential risks of hybrid perovskites by using zebrafish or human cells. So far, the neurotoxic effects and fundamental mechanisms of PeQDs remain unknown. Herein, a comprehensive methodology is designed to investigate the neurotoxicity of PeQDs by using Caenorhabditis elegans as a model organism. The results show that the accumulation of PeQDs mainly focuses on the alimentary system and head region. Acute exposure to PeQDs results in a decrease in locomotor behaviors and pharyngeal pumping, whereas chronic exposure to PeQDs causes brood decline and shortens lifespan. In addition, some abnormal issues occur in the uterus during reproduction assays, such as vulva protrusion, impaired eggs left in the vulva, and egg hatching inside the mother. Excessive reactive oxygen species formation is also observed. The neurotoxicity of PeQDs is explained by gene expression. This study provides a complete insight into the neurotoxicity of PeQD and encourages the development of novel nontoxic PeQDs.

Prospects and hazards of silica nanoparticles: Biological impacts and implicated mechanisms

With the thrive of nanotechnology, silica nanoparticles (SiNPs) have been extensively adopted in the agriculture, food, cosmetic, and even biomedical industries. Due to the mass production and use, SiNPs inevitably entered the environment, resulting in ecological toxicity and even posing a threat to human health. Although considerable investigations have been conducted to assess the toxicity of SiNPs, the correlation between SiNPs exposure and consequent health risks remains ambiguous. Since the biological impacts of SiNPs can differ from their design and application, the toxicity assessment for SiNPs may be extremely difficult. This review discussed the application of SiNPs in different fields, especially their biomedical use, and documented their potential release pathways into the environment. Meanwhile, the current process of assessing SiNPs-related toxicity on various model organisms and cell lines was also detailed, thus estimating the health threats posed by SiNPs exposure. Finally, the potential toxic mechanisms of SiNPs were also elaborated based on results obtained from both in vivo and in vitro trials. This review generally summarizes the biological effects of SiNPs, which will build up a comprehensive perspective of the application and toxicity of SiNPs.

Nanobiotechnology in crop stress management: an overview of novel applications

Agricultural crops are subject to a variety of biotic and abiotic stresses that adversely affect growth and reduce the yield of crop plantss. Traditional crop stress management approaches are not capable of fulfilling the food demand of the human population which is projected to reach 10 billion by 2050. Nanobiotechnology is the application of nanotechnology in biological fields and has emerged as a sustainable approach to enhancing agricultural productivity by alleviating various plant stresses. This article reviews innovations in nanobiotechnology and its role in promoting plant growth and enhancing plant resistance/tolerance against biotic and abiotic stresses and the underlying mechanisms. Nanoparticles, synthesized through various approaches (physical, chemical and biological), induce plant resistance against these stresses by strengthening the physical barriers, improving plant photosynthesis and activating plant defense mechanisms. The nanoparticles can also upregulate the expression of stress-related genes by increasing anti-stress compounds and activating the expression of defense-related genes. The unique physico-chemical characteristics of nanoparticles enhance biochemical activity and effectiveness to cause diverse impacts on plants. Molecular mechanisms of nanobiotechnology-induced tolerance to abiotic and biotic stresses have also been highlighted. Further research is needed on efficient synthesis methods, optimization of nanoparticle dosages, application techniques and integration with other technologies, and a better understanding of their fate in agricultural systems.

Preparation of enzyme-responsive composite nanocapsules with sodium carboxymethyl cellulose to improve the control effect of root-knot nematode disease

Developing an efficient drug delivery system to mitigate the harm caused by root-knot nematodes is crucial. In this study, enzyme-responsive release abamectin nanocapsules (AVB1a NCs) were prepared using 4, 4-diphenylmethane diisocyanate (MDI) and sodium carboxymethyl cellulose as response release factors. The results showed that the average size (D₅₀₎ of the AVB1a NCs was 352 nm, and the encapsulation efficiency was 92 %. The median lethal concentration (LC₅₀) of AVB1a NCs for Meloidogyne incognita activity was 0.82 mg L^-1. Moreover, AVB1a NCs improved the permeability of AVB1a to root-knot nematodes and plant roots and the horizontal and vertical soil mobility. Furthermore, AVB1a NCs greatly reduced the adsorption of AVB1a by the soil compared to AVB1a emulsifiable concentrate (EC), and the effect of the AVB1a NCs on controlling root-knot nematode disease was increased by 36 %. Compared to the AVB1a EC, the pesticide delivery system significantly reduced the acute toxicity to the soil biological earthworms by approximately 16 times that of the AVB1a and had a lower overall impact on the soil microbial communities. This enzyme-responsive pesticide delivery system had a simple preparation method, excellent performance, and high level of safety, and thus has great application potential for plant diseases and insect pests control.

Dietary Transfer of Zinc Oxide Nanoparticles Induces Locomotive Defects Associated with GABAergic Motor Neuron Damage in Caenorhabditis elegans

The widespread use of zinc oxide nanoparticles (ZnO-NPs) and their release into the environment have raised concerns about the potential toxicity caused by dietary transfer. However, the toxic effects and the mechanisms of dietary transfer of ZnO-NPs have rarely been investigated. We employed the bacteria-feeding nematode Caenorhabditis elegans as the model organism to investigate the neurotoxicity induced by exposure to ZnO-NPs via trophic transfer. Our results showed that ZnO-NPs accumulated in the intestine of C. elegans and also in Escherichia coli OP50 that they ingested. Additionally, impairment of locomotive behaviors, including decreased body bending and head thrashing frequencies, were observed in C. elegans that were fed E. coli pre-treated with ZnO-NPs, which might have occurred because of damage to the D-type GABAergic motor neurons. However, these toxic effects were not apparent in C. elegans that were fed E. coli pre-treated with zinc chloride (ZnCl₂). Therefore, ZnO-NPs particulates, rather than released Zn ions, damage the D-type GABAergic motor neurons and adversely affect the locomotive behaviors of C. elegans via dietary transfer.

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.

Multiomics analyses uncover nanoceria triggered oxidative injury and nutrient imbalance in earthworm Eisenia fetida

The toxic stress caused by nanoceria remains vague owing to the limited efforts scrutinizing its molecular mechanisms. Herein, we investigated the impacts of nanoceria on earthworm Eisenia fetida, at the molecular level using the multiomics-based profiling approaches (transcriptomics, metabolomics, and 16 S rRNA sequencing). Nanoceria (50 and 500 mg/kg) significantly increased the contents of malondialdehyde (MDA), Fe, and K in worms, suggesting oxidative injury and nutrient imbalance. This was corroborated by the transcriptomic and metabolomic analyses. Nanoceria decreased the levels of certain genes and metabolites associated with glycerolipid and glycerophospholipid metabolisms, suggesting the production of reactive oxygen species and subsequent oxidative stress. Additionally, the ABCD3 gene belonging to ABC transporter family was upregulated, facilitating Fe uptake by worms. Moreover, the higher contents of MDA, Fe, and K after exposure were tightly associated with the imbalanced intestinal flora. Specifically, a higher relative abundance of Actinobacteriota and a lower relative abundance of Proteobacteria and Patescibacteria were induced. This study, for the first time, revealed that nanoceria at nonlethal levels caused oxidative stress and nutrient imbalance of earthworms from the perspective of genes, metabolites, and gut microbiome perturbations, and also established links between the gut microbiome and the overall physiological responses of the host.

Exposome, Molecular Pathways and One Health: The Invertebrate Caenorhabditis elegans

Due to its preferred habitats in the environment, the free-living nematode Caenorhabditis elegans has become a realistic target organism for pollutants, including manufactured nanoparticles. In the laboratory, the invertebrate animal model represents a cost-effective tool to investigate the molecular mechanisms of the biological response to nanomaterials. With an estimated number of 22,000 coding genes and short life span of 2–3 weeks, the small worm is a giant when it comes to characterization of molecular pathways, long-term low dose pollutant effects and vulnerable age-groups. Here, we review (i) flows of manufactured nanomaterials and exposition of C. elegans in the environment, (ii) the track record of C. elegans in biomedical research, and (iii) its potential to contribute to the investigation of the exposome and bridge nanotoxicology between higher organisms, including humans. The role of C. elegans in the one health concept is taken one step further by proposing methods to sample wild nematodes and their molecular characterization by single worm proteomics.

A critical review of advances in reproductive toxicity of common nanomaterials to Caenorhabditis elegans and influencing factors

In recent decades, nanotechnology has rapidly developed. Therefore, there is growing concern about the potential environmental risks of nanoparticles (NPs). Caenorhabditis elegans (C. elegans) has been used as a powerful tool for studying the potential ecotoxicological impacts of nanomaterials from the whole animal level to single cell level, especially in the area of reproduction. In this review, we discuss the reproductive toxicity of common nanomaterials in C. elegans, such as metal-based nanomaterial (silver nanoparticles (NPs), gold NPs, zinc oxide NPs, copper oxide NPs), carbon-based nanomaterial (graphene oxide, multi-walled carbon nanotubes, fullerene nanoparticles), polymeric NPs, silica NPs, quantum dots, and the potential mechanisms involved. This insights into the toxic effects of existing nanomaterials on the human reproductive system. In addition, we summarize how the physicochemical properties (e.g., size, charge, surface modification, shape) of nanomaterials influence their reproductive toxicity. Overall, using C. elegans as a platform to develop rapid detection techniques and prediction methods for nanomaterial reproductive toxicity is expected to reduce the gap between biosafety evaluation of nanomaterials and their application.

In vivo toxicity assessment of eugenol and vanillin-functionalised silica particles using Caenorhabditis elegans

The toxicological properties of different silica particles functionalised with essential oil components (EOCs) were herein assessed using the in vivo model C. elegans. In particular, the effects of the acute and long-term exposure to three silica particle types (SAS, MCM-41 micro, MCM-41 nano), either bare or functionalised with eugenol or vanillin, were evaluated on different biological parameters of nematodes. Acute exposure to the different particles did not reduce nematodes survival, brood growth or locomotion, but reproduction was impaired by all the materials, except for vanillin-functionalised MCM-41 nano. Moreover, long-term exposure to particles led to strongly inhibited nematodes growth and reproduction. The eugenol-functionalised particles exhibited higher functionalisation yields and had the strongest effects during acute and long-term exposures. Overall, the vanillin-functionalised particles displayed milder acute toxic effects on reproduction than pristine materials, but severer toxicological responses for the 96-hour exposure assays. Our findings suggest that the EOC type anchored to silica surfaces and functionalisation yield are crucial for determining the toxicological effects of particles on C. elegans. The results obtained with this alternative in vivo model can help to anticipate potential toxic responses to these new materials for human health and the environment.

Mulberry-Leaves-Derived Red-Emissive Carbon Dots for Feeding Silkworms to Produce Brightly Fluorescent Silk

Fluorescent silk has promising applications in dazzling textiles, biological engineering, and medical products, but the natural Bombyx mori silk has almost no fluorescence. Here carbon dots (CDs) made from mulberry leaves are reported, which have a strong near-infrared fluorescence with absolute quantum yield of 73% and a full width at half maximum of 20 nm. After feeding with such CDs, silkworms exhibit bright red fluorescence, grow healthily, cocoon normally, and turn to moths finally. The cocoons are pink in daylight and show bright red fluorescence under ultraviolet light. After breaking out of such cocoons, the red-emissive moths can mate and lay fluorescent eggs which would hatch normally. The growth cycle of the second generation of the test silkworm is the same as that of the control group, which means such CDs have excellent biocompatiblility. Dissection and analyses on both the test silkworms and cocoons disclose the metabolic route of the CDs, that is, the fluorescent CDs are absorbed by silkworms from alimentary canals, then transferred to silk glands, and finally to cocoons, while those unabsorbed CDs are excreted with the feces. All experimental results confirm the excellent biocompatibility and fluorescence stability of such CDs.

Novel dual labelled nanoprobes for nanosafety studies: Quantification and imaging experiment of CuO nanoparticles in C. elegans

Metal oxide nanoparticles have been extensively studied for their toxicological impacts. However, accurate tracing/quantification of the nanomaterials and their biological responses are difficult to measure at low concentrations. To overcome the challenge, we developed a dual-labelling technique of CuO nanoparticles with a stable isotope of ⁶⁵Cu, and with rhodamine dye. In vivo experiments on C. elegans were performed using natural feeding of Rhodamine B isothiocyanate-(3 aminopropyl) triethoxysilane functionalized ⁶⁵CuO nanoprobes (RBITC-APTES@⁶⁵CuO) (size = 7.41 ± 1 nm) within the range of Predicted Environmental Concentration (PEC) of CuO nanoparticles in soil and sediments. Fluorescence emission (570 nm) was detected in the lumen of the intestine and the pharynx of C. elegans with no impact of nanoparticle exposure on the brood size and life span of worms. The ingested fluorescent labelled RBITC-APTES@⁶⁵CuO nanoprobes did not enter the reproductive system and were distributed in the alimentary canal of C. elegans. Strong fluorescent signals from the ingested RBITC-APTES@⁶⁵CuO nanoprobes were achieved even after 24 h of exposure demonstrating the high stability of these nanoprobes in vivo. The net accumulation measured of ⁶⁵Cu in C. elegans after background subtraction was 0.001 μg mg^-1 (3.52 %), 0.005 μg mg^-1 (1.76 %) and 0.024 μg mg^-1 (1.69 %) for an exposure concentration of 0.0284 μg mg^-1, 0.284 μg mg^-1, and 1.42 μg mg^-1 of ⁶⁵Cu, respectively. Using C. elegans as a model organism, we demonstrated that RBITC-APTES tagged ⁶⁵CuO nanoparticles acted as novel nanoprobes for measuring the uptake, accumulation, and biodistribution through quantification and imaging the nanoprobes at a very low exposure concentration (⁶⁵CuO concentration: 0.033 μg mg^-1).

Effects of silicon dioxide, zinc oxide and titanium dioxide nanoparticles on Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani disease complex of carrot

Foliar spray of silicon dioxide (SiO₂ NPs), zinc oxide (ZnO NPs) and titanium dioxide (TiO₂ NPs) nanoparticles were used for the management of Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani disease complex of carrot. Foliar spray of SiO₂ NPs/ZnO NPs or TiO₂ NPs increased plant growth attributes, chlorophyll and carotenoid of carrot. Foliar spray of 0.10 mg ml^-1 SiO₂ NPs caused the highest increase in plant growth, chlorophyll and carotenoid content of leaves followed by spray of 0.10 mg ml^-1 ZnO NPs_, 0_.05 mg ml^-1 SiO₂ NPs, 0.05 mg ml^-1 ZnO NPs, 0.10 mg ml^-1 TiO₂ NPs and 0.05 mg ml^-1 TiO2 NPs. Use of SiO₂ NPs caused a higher reduction in root galling, nematode multiplication and disease indices followed by ZnO NPs and TiO₂ NPs. Two principal components analysis showed a total of 97.84% overall data variance in plants inoculated with single pathogen and 97.20% in plants inoculated with two or more pathogens. Therefore, foliar spray of SiO₂ NPs appears interesting for the management of disease complex of carrot.

Evaluation of the influence of food intake on the incorporation and excretion kinetics of mesoporous silica particles in C.elegans

The effect of the presence of food on the incorporation and excretion of silica particles was studied in this work using the biological model Caenorhabditis elegans and image analysis techniques. The experiment was based on two 24-hour phases: exposure and depuration. During exposure, nematodes were maintained for 24 h in liquid medium with silica particles, but some with and others without food. During depuration, nematodes were transferred to medium without particles. Nematodes were analysed by an image analysis in both phases to quantify the properties of particle distributions in nematodes' bodies with time. No differences were found in the proportion of nematodes carrying particles in the exposure phase when food was present. However in the depuration phase, lack of food generated a high proportion of particle carriers. Particle distribution properties were also similar in the exposure phase. Nevertheless, lack of food produced particle accumulation due to decelerated excretion because digestive tube relaxed under these conditions. Thus after the depuration phase, lack of food led particles to persist in digestive tubes. According to these results, intake of silica particles had no retention effects when a food flux was provided, but particles were not easily excreted when the food flux was interrupted.

Lignin-Modified Electronegative Epoxy Resin Nanocarriers Effectively Deliver Pesticides against Plant Root-Knot Nematodes (Meloidogyne incognita)

It is highly desirable to fabricate a pesticide delivery system with excellent permeability to reduce the damage caused by root-knot nematodes in the soil. In this work, a novel electronegative pesticide nanocarrier was established by bonding anionic lignosulfonate with epoxy resin nanocarriers, which were loaded with abamectin (Aba). The results demonstrated that nanoparticles were negatively charged (-38.4 mV) spheres with an average size of 150 nm, and the encapsulation efficiency of nanocarriers for Aba was 93.4%. Polymer nanocarriers could prevent premature release of Aba and protect active ingredients from microbiological degradation. The adsorption strength of the soil to Aba loaded in nanocarriers was reduced by 6 to 10 times, so nanonematicides have remarkable soil mobility. Meanwhile, nanoparticles could easily penetrate the roots and nematodes. The application test confirmed that the control effect of this nanopesticide was 26-40% higher than that of the other agrochemicals. In consideration of its superior bioactivity and utilization rate, this pesticide delivery system has promising potential to control root-knot nematodes and improve the pesticide's utilization efficiency.

Silica nanoparticles enhance germ cell apoptosis by inducing reactive oxygen species (ROS) formation in Caenorhabditis elegans

Silica nanoparticles (SiO₂ NPs) are widely used in daily life and can enter organisms through several pathways, often causing unpredictable toxicity. Although SiO₂ NPs are known to cause damage to the respiratory system, little is known about their oral toxicity, and their potential harm to the reproductive system is unclear. In this study, we used a Caenorhabditis elegans model to clarify SiO₂ NPs oral toxicity in vivo and explore their effect on the reproductive system. We exposed C. elegans to 0.25, 0.5 and 1 mg /mL SiO₂ NPs for 24 hr. Our results showed that SiO₂ NPs exposure for 24 hr did not affect nematode survival rates, but did affect, to varying degrees, the reproduction, development, and movement of nematodes, with nematode fecundity being the most sensitive to SiO₂ NPs toxicity. The NPs exposed group showed enhanced germ cell apoptosis and increased oxidative stress as seen through an increase in ROS and malondialdehyde (MDA), and decrease in reduced glutathione (GSH). N-acetyl-L-cysteine (NAC), an antioxidant, negated SiO₂ NPs effect on germ cells and restored nematodes reproductive ability. We also found that SiO₂ NPs could affect the expression of genes related to metal detoxification, oxidative stress, and apoptosis. The expression of metallothionein coding genes mtl-1 and mtl-2 changed most significantly among the tested genes. We demonstrated that SiO₂ NPs could enhance germ cell apoptosis by inducing oxidative stress, providing a new area for studies of the mechanism of SiO₂ NP toxicity.

Celecoxib substituted biotinylated poly(amidoamine) G3 dendrimer as potential treatment for temozolomide resistant glioma therapy and anti-nematode agent

Glioblastoma multiforme (GBM) is a one of the most widely diagnosed and difficult to treat type of central nervous system tumors. Resection combined with radiotherapy and temozolomide (TMZ) chemotherapy prolongs patients' survival only for 12 - 15 months after diagnosis. Moreover, many patients develop TMZ resistance, thus important is search for a new therapy regimes including targeted drug delivery. Most types of GBM reveal increased expression of cyclooxygenase-2 (COX-2) and production of prostaglandin E2 (PGE₂), that are considered as valuable therapeutic target. In these studies, the anti-tumor properties of the selective COX-2 inhibitor celecoxib (CXB) and biotinylated third generation of the poly(amidoamine) dendrimer substituted with 31 CXB residues (G3BC31) on TMZ -resistant U-118 MG glioma cell line were examined and compared with the effect of TMZ alone including viability, proliferation, migration and apoptosis, as well as the cellular expression of COX-2, ATP level, and PGE₂ production. Confocal microscopy analysis with the fluorescently labeled G3BC31 analogue has shown that the compound was effectively accumulated in U-118 MG cells in time-dependent manner and its localization was confirmed in lysosomes but not nuclei. G3BC31 reveal much higher cytotoxicity for U-118 MG cells at relatively low concentrations in the range of 2-4 µM with compared to CBX alone, active at 50-100 µM. This was due to induction of apoptosis and inhibition of proliferation and migration. Observed effects were concomitant with reduction of PGE₂ production but independent of COX-2 expression. We suggest that investigated conjugate may be a promising candidate for therapy of TMZ-resistant glioblastoma multiforme, although applicable in local treatment, since our previous study of G3BC31 did not demonstrate selectivity against glioma cells compared to normal human fibroblasts. However, it has to be pointed that in our in vivo studies conducted with model organism, Caenorhabditis elegans indicated high anti-nematode activity of G3BC31 in comparison with CXB alone that confirms of usefulness of that organism for estimation of anti-cancer drug toxicity.

Nanomaterials and Aging

As the proportion of the elderly population increases, more and more people suffer from aging-related diseases. Even if aging is inevitable, prolonging the time of healthy aging, delaying the progression of aging-related diseases, and the incidence of morbidity can greatly alleviate the pressure on individuals and society. Current research and exploration in the field of materials related to aging are expanding tremendously. Here, we present a summary of recent research in the field of nanomaterials relevant to aging. Some nanomaterials, such as silica nanomaterials (NMs) and carbon nanotubes, cause damage to the cells similar to aging processes. Other nanomaterials such as fullerenes and metalbased nanomaterials can protect the body from endogenous and exogenous harmful substances such as ROS by virtue of their excellent reducing properties. Another new type of nucleic acid nanomaterial, tetrahedral framework nucleic acids, works effectively against cell damage. This material selectively clears existing senescent cells in the tissue and thus prevents the development of the chronic inflammatory environment caused by senescent cells secreting senescence-associated secretory phenotype to the surroundings. We believe that nanomaterials have tremendous potential to advance the understanding and treatment of aging-related disorders, and today's research only represents the beginning stages.

Comprehensive phenotyping and transcriptome profiling to study nanotoxicity in C. elegans

Engineered nanoparticles are used at an increasing rate in both industry and medicine without fully understanding their impact on health and environment. The nematode Caenorhabditis elegans is a suitable model to study the toxic effects of nanoparticles as it is amenable to comprehensive phenotyping, such as locomotion, growth, neurotoxicity and reproduction. In this study, we systematically evaluated the effects of silver (Ag) and five metal oxide nanoparticles: SiO₂, CeO₂, CuO, Al₂O₃ and TiO₂. The results showed that Ag and SiO₂ exposures had the most toxic effects on locomotion velocity, growth and reproduction, whereas CeO₂, Al₂O₃ and CuO exposures were mostly neurotoxic. We further performed RNAseq to compare the gene expression profiles underlying Ag and SiO₂toxicities. Gene set enrichment analyses revealed that exposures to Ag and SiO₂consistently downregulated several biological processes (regulations in locomotion, reproductive process and cell growth) and pathways (neuroactive ligand-receptor interaction, wnt and MAPK signaling, etc.), with opposite effects on genes involved in innate immunity. Our results contribute to mechanistic insights into toxicity of Ag and SiO₂ nanoparticles and demonstrated that C. elegans as a valuable model for nanotoxicity assessment.

Effects of Amorphous Silica Nanopowders on the Avoidance Behavior of Five Soil Species-A Screening Study

Silica nanoparticles (SiO2NPs) are one of the most used in commercial products and biomedical tools, however, their environmental effects have not been fully described. Although negative effects of SiO2NPs on the behavior of freshwater invertebrates have been reported, the knowledge is limited, especially the effect of nanopowders in terrestrial organisms. Accordingly, the aim of the present study is to understand the effects of SiO2NPs on the avoidance behavior of five soil species, whose niche may differ thus contributing to differential harmful SiO2NPs effects. Hence, avoidance assays testing SiO2NPs concentrations of 0, 10, 100, 250, 500 and 1000 mg/kg were performed with Enchytraeus crypticus, Folsomia candida, Tenebrio molitor, Porcellionides pruinosus and Eisenia fetida. SiO2NPs induced different behavioral effects, depending on the invertebrate ecology/habitat, exposure route and physiology. T. molitor, P. pruinosus and F. candida did not avoid contaminated soil; however, E. crypticus and E. fetida significantly avoided SiO2NPs spiked soil. Since these terrestrial worms (oligochaetes) live mostly burrowed in the soil, this can provide greater opportunity for SiO2NPs' uptake. On the other hand, the other tested organisms mainly living on the upper part of the soil did not avoid the SiO2NPs spiked soil. The avoidance data obtained here also highlight the need for further studies to understand whether (or not) the detected behavioral responses are linked to either neurotransmission processes or sensorial aspects of the biological models.

Surface-Related Toxicity of Polystyrene Beads to Nematodes and the Role of Food Availability

Microplastics released into freshwaters from anthropogenic sources settle in the sediments, where they may pose an environmental threat to benthic organisms. However, few studies have considered the ecotoxicological hazard of microplastic particles for nematodes, one of the most abundant taxa of the benthic meiofauna. This study investigated the toxic effects of polystyrene (PS) beads (0.1-10.0 μm) and the underlying mechanisms thereof on the reproduction of the nematode Caenorhabditis elegans. The observed effect of the PS beads on the nematodes correlated well with the total surface area of the beads per volume, with a 50% inhibition of reproduction at 55.4 ± 12.9 cm²/mL, independent of the bead size. The adverse effects were not explained by styrene monomers leaching from the beads because chemical activities of styrene in PS suspensions were well below the toxic levels. However, the observed effects could be related to the bead material because the same-sized silica (SiO₂) beads had considerably less impact, probably due to their higher specific density. PS and SiO₂ beads affected the food availability of C. elegans, with greater effects by the PS beads. Our results demonstrate the importance of including indirect food web effects in studies of the ecological risks posed by microplastics.

Mechanisms of engineered nanoparticle induced neurotoxicity in Caenorhabditis elegans

The wide-spread implementation of nanoparticles poses a major health concern. Unique biokinetics allow them to transfer to neurons throughout the body and inflict neurotoxicity, which is challenging to evaluate solely in mammalian experimental models due to logistics, financial and ethical limitations. In recent years, the nematode Caenorhabditis elegans has emerged as a promising nanotoxicology experimental surrogate due to characteristics such as ease of culture, short life cycle and high number of progeny. Most importantly, this model organism has a well conserved and fully described nervous system rendering it ideal for use in neurotoxicity assessment of nanoparticles. In that context, this mini review aims to summarize the main mechanistic findings on nanoparticle related neurotoxicity in the setting of Caenorhabditis elegans screening. The injury pathway primarily involves changes in intestinal permeability and defecation frequency both of which facilitate translocation at the site of neurons, where toxicity formation is linked partly to oxidative stress and perturbed neurotransmission.

Comparative toxicity of a food additive TiO2, a bulk TiO2, and a nano-sized P25 to a model organism the nematode C. elegans

To help fill the knowledge gap regarding the potential human health impacts of food pigment TiO₂, a comparative toxicity study was performed on a food-grade TiO₂ (f-TiO₂), a bulk TiO₂ (b-TiO₂), and a nano-sized TiO₂ (Degussa P25), and in the nematode Caenorhabditis elegans. Acute phototoxicity and chronic toxicity effects including reproduction, lifespan, and vulval integrity were evaluated. The f-TiO₂, b-TiO₂, and P25 had a primary particle size (size range) of 149 (53-308) nm, 129 (64-259) nm, and 26 (11-52) nm, respectively. P25 showed the greatest phototoxicity with a 24-h LC50 of 6.0 mg/L (95% CI 5.95, 6.3), followed by the f-TiO₂ (LC50 = 6.55 mg/L (95% CI 6.35, 6.75)), and b-TiO₂ was the least toxic. All three TiO₂ (1-10 mg/L) induced concentration-dependent effects on the worm's reproduction, with a reduction in brood size by 8.5 to 34%. They all caused a reduction of worm lifespan, accompanied by an increased frequency of age-associated vulval integrity defects (Avid). The impact on lifespan and Avid phenotype was more notable for P25 than the f-TiO₂ or b-TiO₂. Ingestion and accumulation of TiO₂ particles in the worm intestine was observed for all three materials by light microscopy. These findings demonstrate that the food pigment TiO₂ induces toxicity effects in the worm and further studies are needed to elucidate the human health implication of such toxicities.

Anabaenopeptins and cyanopeptolins induce systemic toxicity effects in a model organism the nematode Caenorhabditis elegans

Cyanobacterial blooms represent a significant risk to environmental and human health due to their production of toxic secondary metabolites, cyanopeptides. Anabaenopeptins and cyanopeptolins are cyanopeptides increasingly detected in surface waters at concentrations exceeding regulatory toxicity levels for other cyanotoxins such as microcystins. Yet their toxicity to aquatic organisms are not well understood. Here we assessed the toxicological effects of three anabaenopeptins (AP-A, AP-B, and AP-F) and three cyanopeptolins (CYP-1007, CYP-1020, and CYP-1041) to a model organism the nematode Caenorhabditis elegans. Examined toxicity endpoints included reproduction, hatching time, growth rate, lifespan, and age-related vulval integrity. Microcystin RR (MC-RR) and microginin 690 were also included in the study for comparisons. At an identical mass concentration (10 μg/L, corresponding to a molar concentration ranging 0.01-0.014 μM depending on the specific peptide), anabaenopeptins (APs) showed the greatest toxicity among all cyanopeptides tested. APs decreased worm reproduction by 23%-34% and shortened worm lifespan by 5 days (a 30% reduction) compared to the controls. APs also induced a remarkable age-related vulval integrity defect (Avid phenotype) in the worm, where over 95% of exposed worms developed the phenotype, compared to a less than 15% in control worms. CYPs showed similar toxicity as MC-RR, and Microginin 690 was the least toxic. These findings suggest that APs and CYPs may pose significant health risks to aquatic organisms. More toxicological studies of these cyanopeptides using different species across different trophic levels are needed to gain a thorough understanding of their potential impact on ecological systems and human health.

Matricidal hatching can induce multi-generational effects in nematode Caenorhabditis elegans after dietary exposure to nanoparticles

In this study, we investigated multi-generational effects and generation particle transfer in Caenorhabditis elegans following maternal food exposure to core-shell quantum dots. We found that that the Bag of Worms (BOW) phenotype in aged worms induces changes in quantum dot distribution in the parental body, which is related to the inter-generation transfer of these nanoparticles and to their effects in the offspring. To confirm these results we examined a variety of endpoints, namely, survival, reproduction, aging phenotype, oxidative stress, and intestinal fat metabolism. We show that worms born to parents at different times after exposure show different phenotypic effects as a consequence of quantum dot transfer. This evidence of trans-generational transfer and the effects of nanoparticles highlights the complex multi-generational effects and potential safety hazards that can occur under real environmental conditions.

Sublethal Effects of Ionic and Nanogold on the Nematode Caenorhabditis elegans

The nematode Caenorhabditis elegans is used as an ecotoxicological model species in both aqueous medium and solid substrates. It is easy and of low cost to maintain in the laboratory and it produces hundreds of offspring within a short period of time. It also has a small body size (1 mm), making it possible for in vivo assays to be conducted in 12-well plates. Engineered nanomaterials (ENMs) are a class of emerging pollutants. Nanogold (nAu) is used in many consumer products and in vivo drug delivery. These materials can be released into the aquatic environment during production or discarding of consumer products. As nAu is insoluble in water, the sediment would become the final depository for the materials. It has become increasingly important to use sediment dwelling organisms to screen for possible toxicity of these ENMs. In this study C. elegans was exposed to a range of concentrations of nAu and ionic gold in M9-media, acting as a substitute for pore water. After 96-hour growth, fertility and reproduction were determined. Internal structure damage and internalisation of particles in C. elegans were determined by using SEM and CytoViva® Darkfield Imaging. From these images the nanomaterials are distributed around the oocytes in the reproductive organs, as well as the pharynx. Results obtained indicate that nAu affects reproduction more than growth due to internal gonad damage, albeit at very high exposure concentrations, indicating no toxicity at environmentally relevant concentrations. Ionic Au is more toxic than nAu and effects fertility and reproduction due to ion release. These results give more information regarding the toxicity and in vivo uptake of nAu and form part of an environmental risk assessment of ENMs.

Toxicological assessment of mesoporous silica particles in the nematode Caenorhabditis elegans

Here we report the toxicological evaluation of mesoporous silica particles (MSPs) in the nematode C. elegans. Specifically, we have investigated the effect of bare micro- (M0) and nano-sized (N0) MSPs, and their corresponding functionalized particles with a starch derivative (Glu-N) (M1 and N1, respectively) on C. elegans ageing parameters. The toxicity of MSPs, their impact on C. elegans lifespan, movement capacity, progeny and ability to survive upon exposure to acute oxidative stress were assessed. This study demonstrated that both size particles assayed (M0 and N0), labeled with rhodamine and monitored through fluorescence microscopy, are ingested by the nematode. Moreover, toxicity assays indicated that bare nano-sized particles (N0) have a negative impact on the C. elegans lifespan, reducing mobility and progeny production. By contrast, micro-sized particles (M0) proved innocuous for the nematodes. Furthermore, functionalization of nanoparticles with starch derivative reduced their toxicity in C. elegans. Thus, oral intake of N1 comparatively increased the mean lifespan and activity rates as well as resistance to oxidative stress. The overall findings presented here demonstrate the influence of MSP size and surface on their potential toxicity in vivo and indicate the silica-based mesoporous particles to be a potential support for encapsulation in oral delivery applications. Furthermore, the good correlation obtained between healthy aging variables and viability (mean lifespan) validates the use of C. elegans as a multicellular organism for nanotoxicology studies of MSPs.

Laser-induced remote release in vivo in C. elegans from novel silver nanoparticles-alginate hydrogel shells

Non-destructive, controllable, remote light-induced release inside cells enables studying time- and space-specific processes in biology. In this work we demonstrate the remote release of tagged proteins in Caenorhabditis elegans (C. elegans) worms using a near-infrared laser light as a trigger from novel hydrogel shells functionalized with silver nanoparticles responsive to laser light. A new type of hydrogel shells was developed capable of withstanding prolonged storage in the lyophilized state to enable the uptake of the shell by worms, which takes place on an agar plate under standard culture conditions. Uptake of the shells by C. elegans was confirmed using confocal laser scanning microscopy, while release from alginate shells in C. elegans and the laser effect on the shells on a substrate in air was followed using fluorescence microscopy. In addition, Raman microscopy was used to track the localization of particles to avoid the influence of autofluorescence. Hierarchical cluster spectral analysis is used to extract information about the biochemical composition of an area of a nematode containing the hydrogel shells, whose Raman signal is enhanced by the SERS (Surface Enhanced Raman Scattering) effect due to hot spots formed by silver nanoparticles present in the shells. The in vivo release demonstrated here can be used to study intestinal microbiota and probiotic compounds as well as a possible future strategy for gene delivery in the worms, other insects and other organisms.

Toxicity interactions between manganese (Mn) and lead (Pb) or cadmium (Cd) in a model organism the nematode C. elegans

Manganese (Mn) is considered as an emerging metal contaminant in the environment. However, its potential interactions with companying toxic metals and the associated mixture effects are largely unknown. Here, we investigated the toxicity interactions between Mn and two commonly seen co-occurring toxic metals, Pb and Cd, in a model organism the nematode Caenorhabditis elegans. The acute lethal toxicity of mixtures of Mn+Pb and Mn+Cd were first assessed using a toxic unit model. Multiple toxicity endpoints including reproduction, lifespan, stress response, and neurotoxicity were then examined to evaluate the mixture effects at sublethal concentrations. Stress response was assessed using a daf-16::GFP transgenic strain that expresses GFP under the control of DAF-16 promotor. Neurotoxicity was assessed using a dat-1::GFP transgenic strain that expresses GFP in dopaminergic neurons. The mixture of Mn+Pb induced a more-than-additive (synergistic) lethal toxicity in the worm whereas the mixture of Mn+Cd induced a less-than-additive (antagonistic) toxicity. Mixture effects on sublethal toxicity showed more complex patterns and were dependent on the toxicity endpoints as well as the modes of toxic action of the metals. The mixture of Mn+Pb induced additive effects on both reproduction and lifespan, whereas the mixture of Mn+Cd induced additive effects on lifespan but not reproduction. Both mixtures seemed to induce additive effects on stress response and neurotoxicity, although a quantitative assessment was not possible due to the single concentrations used in mixture tests. Our findings demonstrate the complexity of metal interactions and the associated mixture effects. Assessment of metal mixture toxicity should take into consideration the unique property of individual metals, their potential toxicity mechanisms, and the toxicity endpoints examined.

High-throughput tool to discriminate effects of NMs (Cu-NPs, Cu-nanowires, CuNO3, and Cu salt aged): transcriptomics in Enchytraeus crypticus

The current testing of nanomaterials (NMs) via standard toxicity tests does not cover many of the NMs specificities. One of the recommendations lays on understanding the mechanisms of action, as these can help predicting long-term effects and safe-by-design production. In the present study, we used the high-throughput gene expression tool, developed for Enchytraeus crypticus (4 × 44k Agilent microarray), to study the effects of exposure to several copper (Cu) forms. The Cu treatments included two NMs (spherical and wires) and two copper-salt treatments (CuNO₃ spiked and Cu salt field historical contamination). To relate gene expression with higher effect level, testing was done with reproduction effect concentrations (EC₂₀, EC₅₀), using 3 and 7 days as exposure periods. Results showed that time plays a major role in the transcriptomic response, most of it occurring after 3 days. Analysis of gene expression profiles showed that Cu-salt-aged and Cu-nanowires (Nwires) differed from CuNO₃ and Cu-nanoparticles (NPs). Functional analysis revealed specific mechanisms: Cu-NPs uniquely affected senescence and cuticle pattern formation, which can result from the contact of the NPs with the worms' tegument. Cu-Nwires affected reproduction via male gamete generation and hermaphrodite genitalia development. CuNO₃ affected neurotransmission and locomotory behavior, both of which can be related with avoidance response. Cu salt-aged uniquely affected phagocytosis and reproductive system development (via different mechanisms than Cu-Nwires). For the first time for Cu (nano)materials, the adverse outcome pathways (AOPs) drafted here provide an overview for common and unique effects per material and linkage with apical effects.

Triclosan (TCS) and triclocarban (TCC) induce systemic toxic effects in a model organism the nematode Caenorhabditis elegans

The broad application of triclosan (TCS) and triclocarban (TCC) as antimicrobials in household and personal care products has led to the concerns regarding their human health risk and environmental impact. Although many studies have examined the toxicological effects of these compounds to a wide range of aquatic organisms from algae to fish, their potential toxicity to an important model organism the nematode Caenorhabditis elegans has never been systematically investigated. Here we assessed the toxicological effects of TCS and TCC in C. elegans using endpoints from organismal to molecular levels, including lethality, reproduction, lifespan, hatching, germline toxicity, and oxidative stress. L4 stage or young adult worms were exposed to TCS or TCC and examined using above-mentioned endpoints. Both TCS and TCC showed acute toxicity to C. elegans, with 24-h LC50s of 3.65 (95% CI: 3.15, 4.3) mg/L and 0.91 (95% CI: 0.47, 1.53) mg/L, respectively. TCS at 0.1-2 mg/L and TCC at 0.01-0.5 mg/L, respectively, induced concentration dependent reduction in the worm's reproduction, lifespan, and delay in hatching. Using a DAF-16:GFP transgenic strain, we found both compounds induced oxidative stress in the worm, indicated by the relocalization of DAF-16:GFP from cytoplasm to the nucleus upon exposure. Germline toxicity of the two compounds was also demonstrated using a xol-1:GFP transgenic strain. These findings suggest that TCS and TCC induce systemic toxic effects in C. elegans. Further studies are needed to elucidate the potential mechanisms of toxicity of these antimicrobials in the model organism, especially their potential endocrine disruption effects.

Materials and toxicological approaches to study metal and metal-oxide nanoparticles in the model organism Caenorhabditis elegans

Understanding the in vivo fate and transport of nanoparticles (NPs) is challenging, but critical. We review recent studies of metal and metal oxide NPs using the model organism Caenorhabditis elegans, summarizing major findings to date. In a joint transdisciplinary effort, we highlight underutilized opportunities offered by powerful techniques lying at the intersection of mechanistic toxicology and materials science,. To this end, we firstly summarize the influence of exposure conditions (media, duration, C. elegans lifestage) and NP physicochemical properties (size, coating, composition) on the response of C. elegans to NP treatment. Next, we focus on the techniques employed to study NP entrance route, uptake, biodistribution and fate, emphasizing the potential of extending the toolkit available with novel and powerful techniques. Next, we review findings on several NP-induced biological responses, namely transport routes and altered molecular pathways, and illustrate the molecular biology and genetic strategies applied, critically reviewing their strengths and weaknesses. Finally, we advocate the incorporation of a set of minimal materials and toxicological science experiments that will permit meta-analysis and synthesis of multiple studies in the future. We believe this review will facilitate coordinated integration of both well-established and underutilized approaches in mechanistic toxicology and materials science by the nanomaterials research community.

Toxicity evaluation of boron nitride nanospheres and water-soluble boron nitride in Caenorhabditis elegans

Boron nitride (BN) nanomaterials have been increasingly explored for potential biological applications. However, their toxicity remains poorly understood. Using Caenorhabditis elegans as a whole-animal model for toxicity analysis of two representative types of BN nanomaterials – BN nanospheres (BNNSs) and highly water-soluble BN nanomaterial (named BN-800-2) – we found that BNNSs overall toxicity was less than soluble BN-800-2 with irregular shapes. The concentration thresholds for BNNSs and BN-800-2 were 100 µg·mL⁻¹ and 10 µg·mL⁻¹, respectively. Above this concentration, both delayed growth, decreased life span, reduced progeny, retarded locomotion behavior, and changed the expression of phenotype-related genes to various extents. BNNSs and BN-800-2 increased oxidative stress levels in C. elegans by promoting reactive oxygen species production. Our results further showed that oxidative stress response and MAPK signaling-related genes, such as GAS1, SOD2, SOD3, MEK1, and PMK1, might be key factors for reactive oxygen species production and toxic responses to BNNSs and BN-800-2 exposure. Together, our results suggest that when concentrations are lower than 10 µg·mL⁻¹, BNNSs are more biocompatible than BN-800-2 and are potentially biocompatible material.

The role of high-throughput screening in ecotoxicology and engineered nanomaterials

The field of environmental toxicology developed as a result of growing concerns about anthropogenic influences on the environment and how to ameliorate ecological impact. Many governmental bodies are beginning to emphasize prevention rather than mitigation when addressing novel products, leading to more of a focus on identifying potential toxicity prior to release. With the exponential advances in their development and sale, novel metamaterials and biotechnology are set to dramatically outpace the capabilities of current testing strategies. To address the need for a fast, cost-effective means of testing chemicals, high-throughput screening (HTS) is currently being used in toxicology and being adapted to ecotoxicology in projects such as ToxCast and Tox21. Despite the growth of research using HTS platforms, its role in ecotoxicology is still uncertain, particularly in how it should be applied in regulation. The aim of the present review is to discuss common test strategies used in designing HTS platforms, the current potential applications for ecotoxicological research, its role in regulatory policies, and its ability to address growing concerns such as engineered nanomaterials. Environ Toxicol Chem 2017;36:1704-1714. © 2017 SETAC.

Shorter lifetime of a soil invertebrate species when exposed to copper oxide nanoparticles in a full lifespan exposure test

Toxicity tests that last the all life duration of the organisms are not common, instead, long-term tests usually include one reproductive cycle. In the present study we optimized and propose a lifespan (all life) term test using Enchytraeus crypticus (Oligochaeta). The effect of copper oxide nanoparticles (CuO-NPs) was assessed in this lifespan test and compared to copper salt (CuCl₂), using the same effect concentrations on reproduction (EC₅₀). Monitored endpoints included survival and reproduction over-time (202 days). Results from survival showed that CuO-NPs caused shorter life of the adults compared to CuCl₂ (control LT₅₀: 218 days > CuCl₂ LT₅₀: 175 days > CuO-NPs LT₅₀: 145 days). The effect was even more amplified in terms of reproduction (control ET₅₀: 158 days > CuCl₂ ET₅₀: 138 days > CuO-NPs ET₅₀: 92 days). Results suggest that CuO-NPs may cause a higher Cu effect via a trojan horse mechanism. The use of lifespan tests brings a novel concept in soil ecotoxicity, the longevity. This is a particularly important aspect when the subject is nanomaterials toxicity, where longer term exposure time is expected to reveal unpredicted effects via the current short/long-term tests. The present study confirms this higher effect for CuO-NPs.

Safety assessment of nanopesticides using the roundworm Caenorhabditis elegans

The extensive use of pesticides is causing environmental pollution, affecting animal organisms in different habitats and also leading human health at risk. In this study, we present as an alternative the use of nanoparticles loaded with pesticides and report their toxicological assessment to a soil organism, Caenorhabditis elegans. Three nanoparticle formulations were analyzed: solid lipid nanoparticles loaded or not with atrazine and simazine, SLN; polymeric nanoparticles, NC_PCL loaded with atrazine; and chitosan/tripolyphosphate, CS/TPP, loaded or not with paraquat. All formulations, loaded or not with pesticides, increased lethality in a dose- dependent manner with similar LC50. Both loaded and unloaded NC_PCL were the most toxic formulations to developmental rate, significantly reducing worms length, even at low concentrations. In contrast, both CS/TPP nanoparticles were the least toxic, not affecting reproduction and body length at higher concentrations, probably due to the biocompatibility of chitosan. The physico-chemical characterization of nanoparticles after incubation in saline solution (used in exposure of organisms) has shown that these colloidal systems are stable and remain with the same initial characteristics, even in the presence of saline environment. Notably, our results indicate that the observed effects were caused by the nanoparticles per se. These results suggest that the development of nanoparticles aiming agriculture applications needs more studies in order to optimize the composition and then reduce their toxicity to non-target organisms.

The Annona muricata leaf ethanol extract affects mobility and reproduction in mutant strain NB327 Caenorhabditis elegans

The C. elegans NB327 mutant strain is characterized for the knockdown of the dic-1 gene. The dic-1 gene is homologous to the dice-1 gene in humans, encoding the protein DICE-1 as a tumor suppressor. Absence or under-regulation of the dice-1 gene can be reflected in lung and prostate cancer [17], [18]. This study evaluated the effect of EEAML on the C. elegans NB327 mutant strain. Phenotypic aspects such as morphology, body length, locomotion, and reproductive behaviour were analyzed. It is important to emphasize that the strain presents a phenotype characteristic with respect to egg laying and hatching. Reported studies showed that Annona muricata extract and its active components evidence anti-cancer and anti-tumor effects, through experimentation in vivo and in vitro models. However, neurotoxicity has been reported as a side effect. The results showed that the mutant strain NB327 was exposed to EEAML (5 mg/ml) concentration, it showed a significant decrease in average locomotion, resulting in 13 undulations in 30 s. This contrasts with the control strain's 17.5 undulations in 30 s. Similarly, the number of progenies was reduced from 188 progenies (control strain) to 114 and 92 progenies at the dose of (1 mg/ml and 5 mg/m) EEAML. The results of this study suggest that EEAML has a possible neurotoxic effect in concentrations equal to or greater than 5 mg/ml. Also, it does not have positive effects on the mutant strain of Caenorhabditis elegans NB327 phenotype.

In vivo testing of gold nanoparticles using the Caenorhabditis elegans model organism

Gold nanoparticles (AuNPs) are present in many man-made products and cosmetics and are also used by the food and medical industries. Tight regulations regarding the use of mammalian animals for product testing can hamper the study of the specific interactions between engineered nanoparticles and biological systems. Invertebrate models, such as the nematode Caenorhabditis elegans (C. elegans), can offer alternative approaches during the early phases of nanoparticle discovery. Here, we thoroughly evaluated the biodistribution of 11-nm and 150-nm citrate-capped AuNPs in the model organism C. elegans at multiple scales, moving from micrometric to nanometric resolution and from the organismal to cellular level. We confirmed that the nanoparticles were not able to cross the intestinal and dermal barriers. We investigated the effect of AuNPs on the survival and reproductive performance of C. elegans, and correlated these effects with the uptake of AuNPs in terms of their number, surface area, and metal mass. In general, exposure to 11-nm AuNPs resulted in a higher toxicity than the larger 150-nm AuNPs. NP aggregation inside C. elegans was determined using absorbance microspectroscopy, which allowed the plasmonic properties of AuNPs to be correlated with their confinement inside the intestinal lumen, where anatomical traits, acidic pH and the presence of biomolecules play an essential role on NP aggregation. Finally, quantitative PCR of selected molecular markers indicated that exposure to AuNPs did not significantly affect endocytosis and intestinal barrier integrity.

STATEMENT OF SIGNIFICANCE

This work highlights how the simple, yet information-rich, animal model C. elegans is ideally suited for preliminary screening of nanoparticles or chemicals mitigating most of the difficulties associated with mammalian animal models, namely the ethical issues, the high cost, and time constraints. This is of particular relevance to the cosmetic, food, and pharmaceutical industries, which all have to justify the use of animals, especially during the discovery, development and initial screening phases. This work provides a detailed and thorough analysis of 11-nm and 150-nm AuNPs at multiple levels of organization (the whole organism, organs, tissues, cells and molecules).

Selective growth inhibition of cancer cells with doxorubicin-loaded CB[7]-modified iron-oxide nanoparticles

Cucurbit[7]uril-modified iron-oxide nanoparticles (CB[7]NPs) were loaded with doxorubicin hydrochloride (Dox) and tested as a drug delivery system.

Diamond nanostructures for drug delivery, bioimaging, and biosensing

This review summarizes the superior properties of diamond nanoparticles and vertically aligned diamond nanoneedles and their applications in biosensing, bioimaging and drug delivery.

Functional Genomics Tools for Haemonchus contortus and Lessons From Other Helminths

The availability of genome and transcriptome data for parasitic nematodes, including Haemonchus contortus, has highlighted the need to develop functional genomics tools. Comparative genomic analysis, particularly using data from the free-living nematode Caenorhabditis elegans, can help predict gene function. Reliable approaches to study function directly in parasitic nematodes are currently lacking. However, gene knockdown by RNA interference (RNAi) is being successfully used in schistosome and planarian species to define gene functions. Lessons from these systems may be applied to improve RNAi in H. contortus. Previous studies in H. contortus and related nematodes demonstrated reliable RNAi-mediated silencing of some genes, but not others. Current data suggest that susceptibility to RNAi in these nematodes is limited to genes expressed in sites accessible to the environment, such as the gut, amphids and excretory cell. Therefore, RNAi is functional in H. contortus, but improvements are needed to develop this system as a functional genomics platform. Here, we summarize RNAi studies on H. contortus and discuss the optimization of RNA delivery and improvements to culture methods to enhance larval development, protein turnover and the induction of phenotypic effects in vitro. The transgenic delivery of RNA or dominant-negative gene constructs and the recently developed CRISPR/Cas genome-editing technique are considered as potential alternative approaches for gene knockout. This is a key time to devote greater effort in progressing from genome to function, to improve our understanding of the biology of Haemonchus and identify novel targets for parasite control.

A MicroRNA-Mediated Insulin Signaling Pathway Regulates the Toxicity of Multi-Walled Carbon Nanotubes in Nematode Caenorhabditis elegans

The underlying mechanisms for functions of microRNAs (miRNAs) in regulating toxicity of nanomaterials are largely unclear. Using Illumina HiSeq(TM) 2000 sequencing technique, we obtained the dysregulated mRNA profiling in multi-walled carbon nanotubes (MWCNTs) exposed nematodes. Some dysregulated genes encode insulin signaling pathway. Genetic experiments confirmed the functions of these dysregulated genes in regulating MWCNTs toxicity. In the insulin signaling pathway, DAF-2/insulin receptor regulated MWCNTs toxicity by suppressing function of DAF-16/FOXO transcription factor. Moreover, we raised a miRNAs-mRNAs network involved in the control of MWCNTs toxicity. In this network, mir-355 might regulate MWCNTs toxicity by inhibiting functions of its targeted gene of daf-2, suggesting that mir-355 may regulate functions of the entire insulin signaling pathway by acting as an upregulator of DAF-2, the initiator of insulin signaling pathway, in MWCNTs exposed nematodes. Our results provides highlight on understanding the crucial role of miRNAs in regulating toxicity of nanomaterials in organisms.

Fluorescent approach for visually observing quantum dot uptake in living organisms

This study examines the in vivo uptake and internalization of fluorescent quantum dots (QDs) in Escherichia coli and Caenorhabditis elegans models. E. coli cells were directly exposed to QDs of different concentrations (up to 20 nM), and the uptake or sorption of QDs was monitored by flow cytometry. We observed a concentration-dependent increase in QD fluorescence with no changes in the forward or side scatter for any QD concentration, likely because the QDs are very small. Furthermore, QD uptake/adsorption did not significantly affect E. coli viability assessed by colony formation and size. QD-exposed E. coli were then fed to C. elegans to monitor the localization and effects of QDs. In our study, QDs had no observable effect on the viability or reproduction of C. elegans. We visualized QD incorporation and biodistribution by using confocal laser scanning microscopy (CLSM) with z-stacks, lambda scanning, and linear unmixing techniques, which allowed us to observe QDs in vivo and deconvolute QD fluorescence from autofluorescence. CLSM z-stacks with 10-μm depth revealed that the QDs exclusively localized to the gut and intestine with no transfer to other tissues. The combination of these techniques for in vivo imaging of QDs and other fluorescent nanoparticles will be a powerful tool for future studies examining the uptake and biodistribution of nanoparticles.