Full assessment of fate and physiological behavior of quantum dots utilizing Caenorhabditis elegans as a model organism

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.

Exploring the environmental factor fulvic acid attenuates the ecotoxicity of graphene oxide under food delivery exposure

There is limited understanding of nanoparticle potential ecotoxicity, particularly regarding the influence of environmental factors that can be transferred through the food chain. Here, we assessed the transfer behavior and the ecotoxicity of commercially manufactured graphene oxide nano-materials (GO, <100 nm) in a food chain perspective spanning from Escherichia coli (E. coli) to Caenorhabditis elegans (C. elegans) under simulated environmental conditions. Our findings revealed that E. coli preyed upon GO, subsequently transferring it to C. elegans, with a discernible distribution of GO observed in the digestive system and reproductive system. Accumulated GO generated serious ecological consequences for the higher level of the food chain (C. elegans). More importantly, GO and the resulting injurious effects of germ cells could be transferred to the next generation, indicating that GO exposure could cause genetic damage across generations. Previous research has demonstrated that GO can induce degradation of both the inner and outer cell membranes of E. coli, which is then transmitted to C. elegans through the food chain. Additionally, fulvic acid (FA) possesses various functional groups that enable interaction with nanomaterials. Our findings indicated that these interactions could mitigate ecotoxicity caused by GO exposure via food delivery, and this approach could be extended to modify GO in a way that significantly reduced its toxic effects without compromising performance. These results highlighted how environmental factors could attenuate ecological risks associated with nanomaterial transmission through the food chain.

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.

In situ label-free X-ray imaging for visualizing the localization of nanomedicines and subcellular architecture in intact single cells

Understanding the intracellular behaviors of nanomedicines and morphology variation of subcellular architecture impacted by nanomaterial-biology (nano-bio) interactions could help guide the safe-by-design, manufacturing and evaluation of nanomedicines for clinical translation. The in situ and label-free analysis of nano-bio interactions in intact single cells at nanoscale remains challenging. We developed an approach based on X-ray microscopy to directly visualize the 2D or 3D intracellular distribution without labeling at nanometer resolution and analyze the chemical transformation of nanomedicines in situ. Here, we describe an optimized workflow for cell sample preparation, beamline selection, data acquisition and analysis. With several model bionanomaterials as examples, we analyze the localization of nanomedicines in various primary blood cells, macrophages, dendritic cells, monocytes and cancer cells, as well as the morphology of some organelles with soft and hard X-rays. Our protocol has been successfully implemented at three beamline facilities: 4W1A of Beijing Synchrotron Radiation Facility, BL08U1A of Shanghai Synchrotron Radiation Facility and BL07W of the National Synchrotron Radiation Laboratory. This protocol can be completed in ~2-5 d, depending on the cell types, their incubation times with nanomaterials and the selected X-ray beamline. The protocol enables the in situ analysis of the varieties of metal-containing nanomaterials, visualization of intracellular endocytosis, distribution and excretion and corresponding subcellular morphological variation influenced by nanomedicines in cell lines or primary cells by using this universal and robust platform. The results facilitate the understanding of the true principle and mechanism underlying the nano-bio interaction.

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

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

Quantum Dots Mediated Imaging and Phototherapy in Cancer Spheroid Models: State of the Art and Perspectives

Quantum Dots (QDs) are fluorescent nanoparticles known for their exceptional optical properties, i.e., high fluorescence emission, photostability, narrow emission spectrum, and broad excitation wavelength. These properties make QDs an exciting choice for bioimaging applications, notably in cancer imaging. Challenges lie in their ability to specifically label targeted cells. Numerous studies have been carried out with QDs coupled to various ligands like peptides, antibodies, aptamers, etc., to achieve efficient targeting. Most studies were conducted in vitro with two-dimensional cell monolayers (n = 8902) before evolving towards more sophisticated models. Three-dimensional multicellular tumor models better recapitulate in vivo conditions by mimicking cell-to-cell and cell-matrix interactions. To date, only few studies (n = 34) were conducted in 3D in vitro models such as spheroids, whereas these models could better represent QDs behavior in tumors compared to monolayers. Thus, the purpose of this review is to present a state of the art on the studies conducted with Quantum Dots on spheroid models for imaging and phototherapy purposes.

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.

Advanced Light Source Analytical Techniques for Exploring the Biological Behavior and Fate of Nanomedicines

Exploration of the biological behavior and fate of nanoparticles, as affected by the nanomaterial-biology (nano-bio) interaction, has become progressively critical for guiding the rational design and optimization of nanomedicines to minimize adverse effects, support clinical translation, and aid in evaluation by regulatory agencies. Because of the complexity of the biological environment and the dynamic variations in the bioactivity of nanomedicines, in-situ, label-free analysis of the transport and transformation of nanomedicines has remained a challenge. Recent improvements in optics, detectors, and light sources have allowed the expansion of advanced light source (ALS) analytical technologies to dig into the underexplored behavior and fate of nanomedicines in vivo. It is increasingly important to further develop ALS-based analytical technologies with higher spatial and temporal resolution, multimodal data fusion, and intelligent prediction abilities to fully unlock the potential of nanomedicines. In this Outlook, we focus on several selected ALS analytical technologies, including imaging and spectroscopy, and provide an overview of the emerging opportunities for their applications in the exploration of the biological behavior and fate of nanomedicines. We also discuss the challenges and limitations faced by current approaches and tools and the expectations for the future development of advanced light sources and technologies. Improved ALS imaging and spectroscopy techniques will accelerate a profound understanding of the biological behavior of new nanomedicines. Such advancements are expected to inspire new insights into nanomedicine research and promote the development of ALS capabilities and methods more suitable for nanomedicine evaluation with the goal of clinical translation.

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.

Toxicity mitigation and biodistribution of albumin corona coated graphene oxide and carbon nanotubes in Caenorhabditis elegans

In this work, the toxicity and biodistribution of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (MWCNT) were investigated in Caenorhabditis elegans. Bovine serum albumin (BSA) was selected as a model protein to evaluate the influence of protein corona formation on materials physicochemical properties, colloidal stability, and toxicity. Biological assays were performed to assess the effects of bare and albumin corona coated materials on survival, oxidative stress, intestinal barrier permeability, growth, reproduction, and fertility. Critical alterations in topography, surface roughness and chemistry of GO and MWCNT were observed due to albumin corona formation. These modifications were associated with changes in colloidal stability of materials and prevention of their aggregation and sedimentation in nematode testing medium. Both GO and MWCNT caused damage to nematode survival, growth, reproduction, and fertility, as well as enhanced oxidative stress and permeability of the intestinal barrier. But GO was more toxic than MWCNT to C. elegans, especially at long-term assays. Albumin corona mitigated 100% of acute and chronic effects of MWCNT. In contrast, the negative effects of GO were not completely mitigated; GO inhibited 16.2% of nematode growth, 86.5% of reproduction, and 32.0% of fertility at the highest concentration evaluated (10 mg L^-1), while corona coated GO mitigated 50% and 100% of fertility and growth, respectively. Confocal Raman spectroscopy imaging was crucial to point out that bare and albumin corona coated GO and MWCNT crossed the C. elegans intestinal barrier reaching its reproductive organs. However, BSA corona protected the nematodes targeted organs from negative effects from MWCNT and blocked its translocation to other tissues, while coated GO was translocated inside the nematode affecting the functionality of crucial organs. In addition, coated MWCNT was excreted after 2 h of food resumption, whereas coated GO still accumulated in the nematode intestine. Our results demonstrate that the materials different translocation and excretion patterns in C. elegans had a relation to the impaired physiological functions of primary and secondary organs. This work is a contribution towards a better understanding of the impacts of protein corona on the toxicity of graphene oxide and carbon nanotubes; essential information for biological applications and nanosafety.

The In Vivo Toxicity Assessments of Water-Dispersed Fluorescent Silicon Nanoparticles in Caenorhabditis elegans

Fluorescent silicon nanoparticles (SiNPs), resembling a typical zero-dimensional silicon nanomaterial, have shown great potential in a wide range of biological and biomedical applications. However, information regarding the toxicity of this material in live organisms is still very scarce. In this study, we utilized Caenorhabditis elegans (C. elegans), a simple but biologically and anatomically well-described model, as a platform to systematically investigate the in vivo toxicity of SiNPs in live organisms at the whole-animal, cellular, subcellular, and molecular levels. We calculated the effect of SiNPs on C. elegans body length (N ≥ 75), lifespan (N ≥ 30), reproductive capacity (N ≥ 10), endocytic sorting (N ≥ 20), endoplasmic reticulum (ER) stress (N ≥ 20), mitochondrial stress (N ≥ 20), oxidative stress (N ≥ 20), immune response (N ≥ 20), apoptosis (N ≥ 200), hypoxia response (N ≥ 200), metal detoxification (N ≥ 200), and aging (N ≥ 200). The studies showed that SiNPs had no significant effect on development, lifespan, or reproductive ability (p > 0.05), even when the worms were treated with a high concentration (e.g., 50 mg/mL) of SiNPs at all growth and development stages. Subcellular analysis of the SiNP-treated worms revealed that the intracellular processes of the C. elegans intestine were not disturbed by the presence of SiNPs (p > 0.05). Toxicity analyses at the molecular level also demonstrated that the SiNPs did not induce harmful or defensive cellular events, such as ER stress, mitochondria stress, or oxidative stress (p > 0.05). Together, these findings confirmed that the SiNPs are low in toxicity and biocompatible, supporting the suggestion that the material is an ideal fluorescent nanoprobe for wide-ranging biological and biomedical applications.

Radiolabeling of Nanomaterials: Advantages and Challenges

Quantifying the distribution of nanomaterials in complex samples is of great significance to the toxicological research of nanomaterials as well as their clinical applications. Radiotracer technology is a powerful tool for biological and environmental tracing of nanomaterials because it has the advantages of high sensitivity and high reliability, and can be matched with some spatially resolved technologies for non-invasive, real-time detection. However, the radiolabeling operation of nanomaterials is relatively complicated, and fundamental studies on how to optimize the experimental procedures for the best radiolabeling of nanomaterials are still needed. This minireview looks back into the methods of radiolabeling of nanomaterials in previous work, and highlights the superiority of the “last-step” labeling strategy. At the same time, the problems existing in the stability test of radiolabeling and the suggestions for further improvement are also addressed.

A novel insight into mechanism of derangement of coagulation balance: interactions of quantum dots with coagulation-related proteins

Background

Quantum dots (QDs) have gained increased attention for their extensive biomedical and electronic products applications. Due to the high priority of QDs in contacting the circulatory system, understanding the hemocompatibility of QDs is one of the most important aspects for their biosafety evaluation. Thus far, the effect of QDs on coagulation balance haven’t been fully understood, and limited studies also have yet elucidated the potential mechanism from the perspective of interaction of QDs with coagulation-related proteins.

Results

QDs induced the derangement of coagulation balance by prolonging the activated partial thromboplastin time and prothrombin time as well as changing the expression levels of coagulation and fibrinolytic factors. The contact of QDs with PTM (prothrombin), PLG (plasminogen) and FIB (fibrinogen) which are primary coagulation-related proteins in the coagulation and fibrinolysis systems formed QDs-protein conjugates through hydrogen-bonding and hydrophobic interaction. The affinity of proteins with QDs followed the order of PTM > PLG > FIB, and was larger with CdTe/ZnS QDs than CdTe QDs. Binding with QDs not only induced static fluorescence quenching of PTM, PLG and FIB, but also altered their conformational structures. The binding of QDs to the active sites of PTM, PLG and FIB may promote the activation of proteins, thus interfering the hemostasis and fibrinolysis processes.

Conclusions

The interactions of QDs with PTM, PLG and FIB may be key contributors for interference of coagulation balance, that is helpful to achieve a reliable and comprehensive evaluation on the potential biological influence of QDs from the molecular level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00458-x.

Biodistribution of Quantum Dots-Labelled Halloysite Nanotubes: A Caenorhabditis elegans In Vivo Study

Halloysite is a promising building block in nanoarchitectonics of functional materials, especially in the development of novel biomaterials and smart coatings. Understanding the behavior of materials produced using halloysite nanotubes within living organisms is essential for their safe applications. In this study, quantum dots of different compositions were synthesized on the surface of modified clay nanotubes, and the biodistribution of this hybrid material was monitored within Caenorhabditis elegans nematodes. The influence of the modification agent as well as the particles’ composition on physicochemical properties of hybrid nanomaterials was investigated. Several microscopy techniques, such as fluorescence and dark-field microscopy, were compared in monitoring the distribution of nanomaterials in nematodes’ organisms. The effects of QDs-halloysite composites on the nematodes’ life cycle were investigated in vivo. Our fluorescent hybrid probes induced no acute toxic effects in model organisms. The stable fluorescence and low toxicity towards the organisms suggest that the proposed synthesis procedure yields safe nanoarchitectonic materials that will be helpful in monitoring the behavior of nanomaterials inside living cells and organisms.

Mitigation of graphene oxide toxicity in C. elegans after chemical degradation with sodium hypochlorite

Graphene oxide (GO) is a promising and strategic carbon-based nanomaterial for innovative and disruptive technologies. It is therefore essential to address its environmental health and safety aspects. In this work, we evaluated the chemical degradation of graphene oxide by sodium hypochlorite (NaClO, bleach water) and its consequences over toxicity, on the nematode Caenorhabditis elegans. The morphological, chemical, and structural properties of GO and its degraded product, termed NaClO-GO, were characterized, exploring an integrated approach. After the chemical degradation of GO at room temperature, its flake size was reduced from 156 to 29 nm, while NaClO-GO showed changes in UV-vis absorption, and an increase in the amount of oxygenated surface groups, which dramatically improved its colloidal stability in moderately hard reconstituted water (EPA medium). Acute and chronic exposure endpoints (survival, growth, fertility, and reproduction) were monitored to evaluate material toxicities. NaClO-GO presented lower toxicity at all endpoints. For example, an increase of over 100% in nematode survival was verified for the degraded material when compared to GO at 10 mg L^-1. Additionally, enhanced dark-field hyperspectral microscopy confirmed the oral uptake of both materials by C. elegans. Finally, this work represents a new contribution toward a better understanding of the links between the transformation of graphene-based materials and nanotoxicity effects (mitigation), which is mandatory for the safety improvements that are required to maximize nanotechnological benefits to society.

Research Advances on the Adverse Effects of Nanomaterials in a Model Organism, Caenorhabditis elegans

Along with the rapid development of nanotechnology, the biosafety assessment of nanotechnology products, including nanomaterials (NMs), has become more and more important. The nematode Caenorhabditis elegans is a valuable model organism that has been widely used in the field of biology because of its excellent advantages, including low cost, small size, short life span, and highly conservative genomes with vertebral animals. In recent years, the number of nanotoxicological researchers using C. elegans has been growing. According to these available studies, the present review classified the adverse effects of NMs in C. elegans into systematic, cellular, and molecular toxicity, and focused on summarizing and analyzing the underlying mechanisms of metal, metal oxide, and nonmetallic NMs causing toxic effects in C. elegans. Our findings provide insights into what further studies are needed to assess the biosafety of NMs in the ecosystem using C. elegans. Environ Toxicol Chem 2021;40:2406-2424. © 2021 SETAC.

Molybdenum derived from nanomaterials incorporates into molybdenum enzymes and affects their activities in vivo

Many nanoscale biomaterials fail to reach the clinical trial stage due to a poor understanding of the fundamental principles of their in vivo behaviour. Here we describe the transport, transformation and bioavailability of MoS2 nanomaterials through a combination of in vivo experiments and molecular dynamics simulations. We show that after intravenous injection molybdenum is significantly enriched in liver sinusoid and splenic red pulp. This biodistribution is mediated by protein coronas that spontaneously form in the blood, principally with apolipoprotein E. The biotransformation of MoS2 leads to incorporation of molybdenum into molybdenum enzymes, which increases their specific activities in the liver, affecting its metabolism. Our findings reveal that nanomaterials undergo a protein corona-bridged transport-transformation-bioavailability chain in vivo, and suggest that nanomaterials consisting of essential trace elements may be converted into active biological molecules that organisms can exploit. Our results also indicate that the long-term biotransformation of nanomaterials may have an impact on liver metabolism.

Multiscale Synchrotron-Based Imaging Analysis for the Transfer of PEGylated Gold Nanoparticles In Vivo

High spatial resolution imaging analysis is urgently needed to explore the biodistribution, transfer and clearance profiles, and biological impact of nanoparticles in the body, which will be helpful to clarify the efficacy of nanomedicine in clinical applications. Herein, by combination with multiscale synchrotron-based imaging techniques, including X-ray fluorescence (XRF) spectrometry, Fourier transform infrared (FTIR) spectroscopy, and micro X-ray phase contrast computed tomography (micro-XPCT), we visually displayed the transfer patterns and site-specific distribution of PEGylated gold nanoparticles (PEG-GNPs) in the suborgans of the liver, spleen, and kidney after an intravenous injection in mice. A combination of XRF and FTIR imaging analysis showed that the PEG bands presented similar distribution patterns with Au in the intraorgans, suggesting the stability of PEGylation on GNPs. We show that the PEG-GNPs presented heterogeneous distribution in the hepatic lobules with a large amount around the portal vein zone and then a gradient decrease in the sinusoidal region and the CV zone; in the spleen, it gradually accumulated in the splenic red pulp over time; and in the kidney, it quickly transported via the bloodstream to the renal pyramids and renal pelvis, and parts of PEG-GNPs finally accumulated in the renal medulla and renal cortex. Multidimensional micro-XPCT images further show that the PEG-GNP transfer in the liver induced hepatic blood vessel dilatation while they transferred in the liver, providing evidence of GNP transport across the blood vessel endothelial barrier.

Redesign of hydrophobic quantum dots mitigates ligand-dependent toxicity in the nematode C. elegans

Surface properties of engineered nanomaterials (ENMs) have been shown to influence their interaction with biological systems. However, studies to date have largely focused on hydrophilic materials, likely due to biocompatibility concerns and aqueous exposure conditions necessary for many model systems. Therefore, a knowledge gap exists in nanotoxicity literature for impacts of hydrophobic ENMs, with studies of hydrophobic materials largely limited to carbon ENMs. Here we demonstrate testing of hydrophobic quantum dots (QDs) using the nematode C. elegans, a model soil organism cultured on solid media and amenable to hydrophobic exposures. To evaluate the influence of hydrophobicity, we compared CdSe/ZnS QDs functionalized with hydrophobic trioctylphosphine oxide (TOPO) to identical QDs functionalized with hydrophilic dihydrolipoic acid-polyethylene glycol (DHLA-PEG) and alternative hydrophobic CdSe/ZnS QDs functionalized with oleic acid (OA). Results show that hydrophobic TOPO QDs are significantly more toxic than hydrophilic DHLA-PEG QDs, and substitution of TOPO with OA yields relatively non-toxic hydrophobic QDs. Fluorescence microscopy shows TOPO QDs loosely associated with the organism's cuticle, but atomic force microscopy shows no difference in cuticle structure from exposure. Importantly, TOPO ligand alone is as toxic as TOPO QDs, and our data suggests that TOPO may impact neuromuscular function, perhaps upon displacement from the QD surface. This study demonstrates the importance of examining ligand-specific impacts of hydrophobic ENMs and indicates OA-functionalized QDs as a potential alternative to TOPO QDs for reduced toxicity.

Systematic evaluation of CdSe/ZnS quantum dots toxicity on the reproduction and offspring health in male BALB/c mice

Increased applications of quantum dots (QDs) in the biomedical field have aroused attention for their potential toxicological effects. Although numerous studies have been carried out on the toxicity of QDs, their effects on reproductive and development are still unclear. In this study, we systematically evaluated the male reproductive toxicity and developmental toxicity of CdSe/ZnS QDs in BALB/c mice. The male mice were injected intravenously with CdSe/ZnS QDs at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively, and the survival status, biodistribution of QDs in testes, serum sex hormone levels, histopathology, sperm motility and acrosome integrity was measured on Day 1, 7, 14, 28 and 42 after injection. On Day 35 after treatment, male mice were housed with non-exposed female mice, and then offspring number, body weight, organ index and histopathology of major organs, blood routine and biochemical tests of offspring were measured to evaluate the fertility and offspring health. The results showed that CdSe/ZnS QDs could rapidly distribute in the testis, and the fluorescence of QDs could still be detected on Day 42 post-injection. QDs had no adverse effect on the structure of testis and epididymis, but high-dose QDs could induce apoptosis of Leydig cells in testis at an early stage. No significant differences in survival of state, body weight organ index of testis and epididymis, sex hormones levels, sperm quality, sperm acrosome integrity and fertility of male mice were observed in QDs exposed groups. However, the development of offspring was obviously influenced, which was mainly manifested in the slow growth of offspring, changes in organ index of main organs, and the abnormality of liver and kidney function parameters. Our findings revealed that CdSe/ZnS QDs were able to cross the blood-testis barrier (BTB), produce no discernible toxic effects on the male reproductive system, but could affect the healthy growth of future generations to some extent. In view of the broad application prospect of QDs in biomedical fields, our findings might provide insight into the biological safety evaluation of the reproductive health of QDs.

Physiological effect of colloidal carbon quantum dots on Bursaphelenchus xylophilus

Bursaphelenchus xylophilus (B. xylophilus) is a dangerous plant pest which could result in Pine Wild Disease (PWD).

In vivo percutaneous permeation of gold nanomaterials in consumer cosmetics: implication in dermal safety assessment of consumer nanoproducts

The increasing emergence of nano-cosmetics in the marketplace provokes safety concerns with respect to percutaneous permeation and toxicity of nanomaterials inside the human body. In this study, in vivo percutaneous permeation and dermal safety of cosmetic cream containing Au nanosheets and extracted Au nanosheets from cosmetic creams are investigated with guinea pigs. Quantitative percutaneous permeation data suggests that Au nanosheets in cosmetic creams permeate into the skin epidermis, dermis, and subcutaneous layer after 10 d cutaneous exposure, but cannot enter the systemic circulation. However, more Au nanosheets are accumulated in the skin and the permeation of Au nanosheets increased after embedded into the cream matrix. Synchrotron radiation X-ray fluorescence (SRXRF) imaging reveals that Au nanosheets in cosmetics penetrate mainly through hair follicles in a time-dependent manner. Cosmetic creams rather than extracted Au nanosheets decrease the cell viability of keratinocytes and slightly induce apoptosis/necrosis of keratinocytes and skin dermal fibroblasts. Intriguingly, the growth of hair is inhibited by the cosmetic cream and the extracted Au nanosheets revealed by HE staining and immunohistochemistry (IHC) assay. Altogether this study provides insights into the comprehensive understanding of percutaneous permeation and dermal safety of cosmetic creams containing Au nanosheets. This work provides reliable methods to study the skin permeation, biodistribution, and dermal safety of nano-cosmetics and reminds the community of the crucial need to combine the assays at molecular, cellular, and organ levels in nanotoxicology research.

In Vitro and In Vivo Models for Evaluating the Oral Toxicity of Nanomedicines

Toxicity studies for conventional oral drug formulations are standardized and well documented, as required by the guidelines of administrative agencies such as the US Food & Drug Administration (FDA), the European Medicines Agency (EMA) or European Medicines Evaluation Agency (EMEA), and the Japanese Pharmaceuticals and Medical Devices Agency (PMDA). Researchers tend to extrapolate these standardized protocols to evaluate nanoformulations (NFs) because standard nanotoxicity protocols are still lacking in nonclinical studies for testing orally delivered NFs. However, such strategies have generated many inconsistent results because they do not account for the specific physicochemical properties of nanomedicines. Due to their tiny size, accumulated surface charge and tension, sizeable surface-area-to-volume ratio, and high chemical/structural complexity, orally delivered NFs may generate severe topical toxicities to the gastrointestinal tract and metabolic organs, including the liver and kidney. Such toxicities involve immune responses that reflect different mechanisms than those triggered by conventional formulations. Herein, we briefly analyze the potential oral toxicity mechanisms of NFs and describe recently reported in vitro and in vivo models that attempt to address the specific oral toxicity of nanomedicines. We also discuss approaches that may be used to develop nontoxic NFs for oral drug delivery.

Ru/CdS Quantum Dots Templated on Clay Nanotubes as Visible-Light-Active Photocatalysts: Optimization of S/Cd Ratio and Ru Content

A nanoarchitectural approach based on in situ formation of quantum dots (QDs) within/outside clay nanotubes was developed. Efficient and stable photocatalysts active under visible light were achieved with ruthenium-doped cadmium sulfide QDs templated on the surface of azine-modified halloysite nanotubes. The catalytic activity was tested in the hydrogen evolution reaction in aqueous electrolyte solutions under visible light. Ru doping enhanced the photocatalytic activity of CdS QDs thanks to better light absorption and electron-hole pair separation due to formation of a metal/semiconductor heterojunction. The S/Cd ratio was the major factor for the formation of stable nanoparticles on the surface of the azine-modified clay. A quantum yield of 9.3 % was reached by using Ru/CdS/halloysite containing 5.2 wt % of Cd doped with 0.1 wt % of Ru and an S/Cd ratio of unity. In vivo and in vitro studies on the CdS/halloysite hybrid demonstrated the absence of toxic effects in eukaryotic cells and nematodes in short-term tests, and thus they are promising photosensitive materials for multiple applications.

Molecular Mechanisms, Characterization Methods, and Utilities of Nanoparticle Biotransformation in Nanosafety Assessments

It is a big challenge to reveal the intrinsic cause of a nanotoxic effect due to diverse branches of signaling pathways induced by engineered nanomaterials (ENMs). Biotransformation of toxic ENMs involving biochemical reactions between nanoparticles (NPs) and biological systems has recently attracted substantial attention as it is regarded as the upstream signal in nanotoxicology pathways, the molecular initiating event (MIE). Considering that different exposure routes of ENMs may lead to different interfaces for the arising of biotransformation, this work summarizes the nano-bio interfaces and dose calculation in inhalation, dermal, ingestion, and injection exposures to humans. Then, five types of biotransformation are shown, including aggregation and agglomeration, corona formation, decomposition, recrystallization, and redox reactions. Besides, the characterization methods for investigation of biotransformation as well as the safe design of ENMs to improve the sustainable development of nanotechnology are also discussed. Finally, future perspectives on the implications of biotransformation in clinical translation of nanomedicine and commercialization of nanoproducts are provided.

Proteomic Analysis Identifies Markers of Exposure to Cadmium Sulphide Quantum Dots (CdS QDs)

The use of cadmium sulphide quantum dot (CdS QD)-enabled products has become increasingly widespread. The prospect of their release in the environment is raising concerns. Here we have used the yeast model Saccharomyces cerevisiae to determine the potential impact of CdS QD nanoparticles on living organisms. Proteomic analyses and cell viability assays performed after 9 h exposure revealed expression of proteins involved in oxidative stress and reduced lethality, respectively, whereas oxidative stress declined, and lethality increased after 24 h incubation in the presence of CdS QDs. Quantitative proteomics using the iTRAQ approach (isobaric tags for relative and absolute quantitation) revealed that key proteins involved in essential biological pathways were differentially regulated over the time course of the experiment. At 9 h, most of the glycolytic functions increased, and the abundance of the number of heat shock proteins increased. This contrasts with the situation at 24 h where glycolytic functions, some heat shock proteins as well as oxidative phosphorylation and ATP synthesis were down-regulated. It can be concluded from our data that cell exposure to CdS QDs provokes a metabolic shift from respiration to fermentation, comparable to the situation reported in some cancer cell lines.

Quantum dots functionalized with gH625 attenuate QDs oxidative stress and lethality in Caenorhabditis elegans: a model system

Nanomaterials have revolutionized many scientific fields and are widely applied to address environmental problems and to develop novel health care strategies. However, their mechanism of action is still poorly understood. Several nanomaterials for medical applications are based on quantum dots (QDs). Despite their amazing physico-chemical properties, quantum dots display significant adverse effects. In the present study, the effects of QDs on the motor nervous system of nematodes Caenorhabditis elegans have been investigated as a non-mammalian alternative model. We also explored the possibility of modifying the toxicity of QDs by coating with a cell-penetrating peptide gH625 and thus we analysed the effects determined by QDs-gH625 complexes on the nematodes. With this work, we have demonstrated, by in vivo experiments, that the peptide gH625 is able to reduce the side effects of metallic nanoparticle making them more suitable for medical applications.

Antibacterial Carbon-Based Nanomaterials

The emergence and global spread of bacterial resistance to currently available antibiotics underscore the urgent need for new alternative antibacterial agents. Recent studies on the application of nanomaterials as antibacterial agents have demonstrated their great potential for management of infectious diseases. Among these antibacterial nanomaterials, carbon-based nanomaterials (CNMs) have attracted much attention due to their unique physicochemical properties and relatively higher biosafety. Here, a comprehensive review of the recent research progress on antibacterial CNMs is provided, starting with a brief description of the different kinds of CNMs with respect to their physicochemical characteristics. Then, a detailed introduction to the various mechanisms underlying antibacterial activity in these materials is given, including physical/mechanical damage, oxidative stress, photothermal/photocatalytic effect, lipid extraction, inhibition of bacterial metabolism, isolation by wrapping, and the synergistic effect when CNMs are used in combination with other antibacterial materials, followed by a summary of the influence of the physicochemical properties of CNMs on their antibacterial activity. Finally, the current challenges and an outlook for the development of more effective and safer antibacterial CNMs are discussed.

Glyco-functionalised quantum dots and their progress in cancer diagnosis and treatment

Despite all major breakthroughs in recent years of research, we are still unsuccessful to effectively diagnose and treat cancer that has express and metastasizes. Thus, the development of a novel approach for cancer detection and treatment is crucial. Recent progress in Glyconanotechnology has allowed the use of glycans and lectins as bio-functional molecules for many biological and biomedical applications. With the known advantages of quantum dots (QDs) and versatility of carbohydrates and lectins, Glyco-functionalised QD is a new prospect in constructing biomedical imaging platform for cancer behaviour study as well as treatment. In this review, we aim to describe the current utilisation of Glyco-functionalised QDs as well as their future prospective to interpret and confront cancer.

Exposure to MPA-capped CdTe quantum dots causes reproductive toxicity effects by affecting oogenesis in nematode Caenorhabditis elegans

Quantum dots (QDs), considered as a type of excellent semiconductor nanomaterial, are widely employed and have a number of important applications. However, QDs have the potential to produce adverse effects and toxicity with the underlying molecular mechanisms not well understood. Herein, Caenorhabditis elegans was used for in vivo toxicity assessment to detect the reproductive toxicity of CdTe QDs. We found that exposure to CdTe QDs particles (≥ 50 mg/L) resulted in a defect in reproductive capacity, dysfunctional proliferation and differentiation, as well as an imbalance in oogenesis by reducing the number of cells in pachytene and diakinesis. Further, we identified a SPO-11 and PCH-2 mediated toxic mechanism and a GLP-1/Notch mediated protective mechanism in response to CdTe QDs particles (≥ 50 mg/L). Taken together, these results demonstrate the potential adverse impact of CdTe QDs (≥ 50 mg/L) exposure on oogenesis and provide valuable data and guidelines for evaluation of QD biocompatibility.

Caenorhabditis elegans as a complete model organism for biosafety assessments of nanoparticles

The number of biosafety evaluation studies of nanoparticles (NPs) using different biological models is increasing with the rapid development of nanotechnology. Thus far, nematode Caenorhabditis elegans (C. elegans), as a complete model organism, has become an important in vivo alternative assay system to assess the risk of NPs, especially at the environmental level. According to results of qualitative and quantitative analyses, it can be concluded that studies of nanoscientific research using C. elegans is persistently growing. However, the comprehensive conclusion and analysis of toxic effects of NPs in C. elegans are limited and chaotic. This review focused on the effects, especially sublethal ones, induced by NPs in C. elegans, including the development, intestinal function, immune response, neuronal function, and reproduction, as well as the underlying mechanisms of NPs causing these effects, including oxidative stress and alterations of several signaling pathways. Furthermore, we presented some factors that influence the toxic effects of NPs in C. elegans. The advantages and limitations of using nematodes in the nanotoxicology study were also discussed. Finally, we predicted that the application of C. elegans to assess long-term impacts of metal oxide NPs in the ecosystem would become a vital part of the nanoscientific research field, which provided an insight for further study.

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.

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.

Biocompatible protamine sulfate@silicon nanoparticle-based gene nanocarriers featuring strong and stable fluorescence

The development of biocompatible and fluorescent gene carriers is of particular importance in the gene-delivery field. Taking advantage of the unique optical properties (e.g., strong and robust fluorescence) of silicon nanoparticles (SiNPs), as well as the excellent biocompatibility of silicon and protamine sulfate (PS, approved by the U.S. Food and Drug Administration (FDA) for clinical use), we herein present a type of PS-modified SiNP (PS@SiNP)-based gene carrier. Plasmid DNA (pDNA) with negative charges can be effectively bound onto the surface of the as-prepared fluorescent PS@SiNP-based gene carriers via electrostatic interactions. In particular, such resultant gene carriers possess stable and high fluorescence (photoluminescent quantum yield (PLQY): ∼25%). In addition, the PS@SiNP-based gene carriers show minimal toxic effects on normal mitochondrial metabolic activity (e.g., human retinal pigment epithelial (ARPE-19) cells preserve ∼90% of their cell viability after a 48 h incubation with the resultant carriers). Based on tracking the strong and stable fluorescence signals of SiNPs, the dynamic behavior of the PS@SiNP-based gene carriers in live cells (e.g., clathrin-mediated endocytosis, lysosomal escape, pDNA release, etc.) is investigated in a long-term manner, providing valuable information for understanding the intracellular behavior of gene vectors and designing high-efficacy gene carriers.

Walking the line: The fate of nanomaterials at biological barriers

Biological systems have developed an efficient multi-tiered defense system to block foreign substances such as engineered nanomaterials (NMs) from causing damage. In a pathological scenario, the disease itself may also pose additional barriers due to the imbalance between abnormal cells and their surrounding microenvironment, and NMs could behave similarly or differently to classic foreign substances, depending on their unique characteristics. Thus, understanding the mechanisms that govern the fate of NMs against these biological barriers, including the strategies that can be used to shift their fate between access and blockage, become key information for NMs design. In this manuscript, we first describe the biological barriers that NMs may encounter, and further discuss how these biological barrier interactions could shift the fate of NMs between toxicity and therapeutic potential. A list of effects that may influence NMs access at nano/bio interface are presented and discussed, followed by personal insights on the important nano/bio topics that require additional research for a better understanding of NM/biological barrier interactions.

Quantum dots cause acute systemic toxicity in lactating rats and growth restriction of offspring

The in vivo toxicity of QDs in animals has been broadly studied; however, their reproductive toxicity towards lactating rodents is currently unknown. This study therefore aims to assess the potential toxicity against dams and offspring after postnatal QD exposure at two doses (5 and 1 nmol per rat) and unravel whether QDs can translocate to pups via breastfeeding. The dose-dependent systemic toxicity of QDs in dams was observed by examining the body weight, hematology, biochemistry, histopathological changes, and sex hormone levels. It was found that the QDs primarily accumulated in the liver and spleen of dams at 1 day post injection (dpi), but the highest concentrations were found in the kidneys at 18 dpi. A few QDs were detected in breast milk and stomach and intestine of pups; this suggested that the QDs were transmitted to breast milk via blood circulation and then transferred to pups via breastfeeding. High-dose QDs induced severe growth inhibition and a 71.08% offspring mortality, while pups showed growth restriction within 90 dpi in the low-dose group. Moreover, the hematology, biochemistry, and histology results showed limited chronic toxicity against offspring in the long term. This study provides a theoretical foundation for the exposure assessment of nanomaterials in lactating animals and for the advancement of QDs in the biomedical field.

Advanced Nuclear and Related Techniques for Metallomics and Nanometallomics

Metallomics, focusing on the global and systematic understanding of the metal uptake, trafficking, role, and excretion in biological systems, has attracted more and more attention. Metal-related nanomaterials, including metallic and metal-containing nanomaterials, have unique properties compared to their macroscale counterparts and therefore require special attention. The absorption, distribution, metabolism, excretion (ADME) behavior of metal-related nanomaterials in the biological systems is influenced by their physicochemical properties, the exposure route, and the microenvironment of the deposition site. Nanomaterials not only may interact directly or indirectly with genes, proteins, and other molecules to bring genotoxicity, immunotoxicity, DNA damage, and cytotoxicity but may also stimulate the immune responses, circumvent tumor resistance, and inhibit tumor metastasis. Because of their advantages of absolute quantification, high sensitivity, excellent accuracy and precision, low matrix effects, and nondestructiveness, nuclear and related analytical techniques have been playing important roles in the study of metallomics and nanometallomics. In this chapter, we present a comprehensive overview of nuclear and related analytical techniques applied to the quantification of metallome and nanometallome, the biodistribution, bioaccumulation, and transformation of metallome and nanometallome in vivo, and the structural analysis. Besides, metallomics and nanometallomics need to cooperate with other -omics, like genomics, proteomics, and metabolomics, to obtain the knowledge of underlying mechanisms and therefore to improve the application performance and to reduce the potential risk of metallome and nanometallome.

Intensive epidermal adsorption and specific venous deposition of carboxyl quantum dots in zebrafish early-life stages

To properly assess the environmental risk of quantum dots (QDs), it is necessary to determine their fate in living organisms, including adsorption, distribution and bioaccumulation under representative environmental or physiological conditions. We comprehensively investigated the fate of QDs with carboxyl terminal functional groups (carboxyl-QDs) in zebrafish (Danio rerio) embryo and larvae subjected to either waterborne exposure or cardiovascular system microinjection. On waterborne exposure, carboxyl-QDs exhibited an intensive adsorption and accumulation in the chorion of embryos, and their predominate target organs were the gill and intestinal tract in larvae. On microinjection, carboxyl-QDs were rapidly delivered into the cardiovascular system and specifically deposited in veins and the capillary network system of zebrafish larvae, but not in the arterial system. Taken together, we found that the exact tissue condition including epidermal structures, mucus secretion and vascular microstructures strongly affected the adsorption, uptake and distribution of carboxyl-QDs in zebrafish. This work highlights the intensive tissue epidermal adsorption and accumulation of carboxyl-QDs and their specific vein and capillary deposition in the cardiovascular system in zebrafish early-life stages.

Toxicity of Nanoparticles on the Reproductive System in Animal Models: A Review

In the last two decades, nanotechnologies demonstrated various applications in different fields, including detection, sensing, catalysis, electronics, and biomedical sciences. However, public concerns regarding the well-being of human may hinder the wide utilization of this promising innovation. Although, humans are exposed to airborne nanosized particles from an early age, exposure to such particles has risen dramatically within the last century due to anthropogenic sources of nanoparticles. The wide application of nanomaterials in industry, consumer products, and medicine has raised concerns regarding the potential toxicity of nanoparticles in humans. In this review, the effects of nanomaterials on the reproductive system in animal models are discussed. Females are particularly more vulnerable to nanoparticle toxicity, and toxicity in this population may affect reproductivity and fetal development. Moreover, various types of nanoparticles have negative impacts on male germ cells, fetal development, and the female reproductive system. These impacts are associated with nanoparticle modification, composition, concentration, route of administration, and the species of the animal. Therefore, understanding the impacts of nanoparticles on animal growth and reproduction is essential. Many studies have examined the effects of nanoparticles on primary and secondary target organs, with a concentration on the in vivo and in vitro effects of nanoparticles on the male and female reproductive systems at the clinical, cellular, and molecular levels. This review provides important information regarding organism safety and the potential hazards of nanoparticle use and supports the application of nanotechnologies by minimizing the adverse effects of nanoparticles in vulnerable populations.