Bioconcentration of ionic cadmium and cadmium selenide quantum dots in zebrafish larvae

Quantum dots for bone tissue engineering

In confronting the global prevalence of bone-related disorders, bone tissue engineering (BTE) has developed into a critical discipline, seeking innovative materials to revolutionize treatment paradigms. Quantum dots (QDs), nanoscale semiconductor particles with tunable optical properties, are at the cutting edge of improving bone regeneration. This comprehensive review delves into the multifaceted roles that QDs play within the realm of BTE, emphasizing their potential to not only revolutionize imaging but also to osteogenesis, drug delivery, antimicrobial strategies and phototherapy. The customizable nature of QDs, attributed to their size-dependent optical and electronic properties, has been leveraged to develop precise imaging modalities, enabling the visualization of bone growth and scaffold integration at an unprecedented resolution. Their nanoscopic scale facilitates targeted drug delivery systems, ensuring the localized release of therapeutics. QDs also possess the potential to combat infections at bone defect sites, preventing and improving bacterial infections. Additionally, they can be used in phototherapy to stimulate important bone repair processes and work well with the immune system to improve the overall healing environment. In combination with current trendy artificial intelligence (AI) technology, the development of bone organoids can also be combined with QDs. While QDs demonstrate considerable promise in BTE, the transition from laboratory research to clinical application is fraught with challenges. Concerns regarding the biocompatibility, long-term stability of QDs within the biological environment, and the cost-effectiveness of their production pose significant hurdles to their clinical adoption. This review summarizes the potential of QDs in BTE and highlights the challenges that lie ahead. By overcoming these obstacles, more effective, efficient, and personalized bone regeneration strategies will emerge, offering new hope for patients suffering from debilitating bone diseases.

Kidney injury contributes to edema of zebrafish larvae caused by quantum dots

Edema represents a notable outcome in fishes exposed to aquatic pollutants, yet the underlying etiology remains inadequately understood. This investigation delves into the etiological factors of edema formation in 7 days post fertilization (dpf) zebrafish larvae following their exposure to InP/ZnS quantum dots (QDs), which was chosen as a prototypical edema inducer. Given the fundamental role of the kidney in osmoregulation, we used transgenic zebrafish lines featuring fluorescent protein labeling of the glomerulus, renal tubule, and blood vessels, in conjunction with histopathological scrutiny. We identified the pronounced morphological and structural aberrations within the pronephros. By means of tissue mass spectrometry imaging and hyperspectral microscopy, we discerned the accumulation of InP/ZnS QDs in the pronephros. Moreover, InP/ZnS QDs impeded the renal clearance capacity of the pronephros, as substantiated by diminished uptake of FITC-dextran. InP/ZnS QDs also disturbed the expression levels of marker genes associated with kidney development and osmoregulatory function at the earlier time points, which preceded the onset of edema. These results suggest that impaired fluid clearance most likely resulting from pronephros injury contributes to the emergence of zebrafish edema. Briefly, our study provides a perspective: the kidney developmental injury induced by exogenous substances may regulate edema in a zebrafish model.

A multiscale study of the effects of a diet containing CdSe/ZnS-COOH quantum dots on Salmo trutta fario L.: Potential feed-related nanotoxicity

Quantum dots (QDs) receive widespread attention in industrial and biomedical fields, but the risks posed by the use of nanoparticles to aquatic organisms and the associated toxicological effects are still not well understood. In this study, effects of the 7-day dietary exposure of Salmo trutta fario L. juveniles to CdSe/ZnS-COOH QDs were evaluated at molecular, cellular, physiological and whole-organism levels. Fish feeding with QDs-contaminated feed resulted in an increased somatic index of the liver, a genotoxic effect on peripheral blood erythrocytes, altered enzyme activity and decreased MDA level. Furthermore, Cd levels in the gills and liver tissues of the exposed fish were found to be significantly higher than in those of the control fish. Alpha diversity indexes of the gut microbiota of the QDs-exposed S. trutta fario L. individuals exhibited a decreasing trend. The principal coordinate analysis (PCoA) showed that the gut microbiota of the control fish was significantly different from that of the fish exposed to QDs (p < 0.05). Additionally, the linear discriminant analysis (LDA) performed using an effect size (LEfSe) algorithm unveiled 19 significant taxonomic differences at different taxonomic levels between the control group and the QDs-exposed group. In the QDs-exposed group, the relative abundance of the genus Citrobacter (Proteobacteria phylum) in the gut microbiota was found to be significantly increased whereas that of the genus Mycoplasma (Tenericutes phylum) significantly decreased compared to the control group. In summary, QDs-contaminated diet affects the gut microbiota of fish by significantly changing the relative abundance of some taxa, potentially leading to dysbiosis. This, together with morphophysiological, cytogenetic and biochemical changes, poses a risk to fish health.

Quantitative titanium imaging in fish tissues exposed to titanium dioxide nanoparticles by laser ablation-inductively coupled plasma-mass spectrometry

Imaging studies by laser ablation-inductively coupled plasma mass spectrometry have been successfully developed to obtain qualitative and quantitative information on the presence/distribution of titanium (ionic titanium and/or titanium dioxide nanoparticles) in sea bream tissues (kidney, liver, and muscle) after exposure assays with 45-nm citrate-coated titanium dioxide nanoparticles. Laboratory-produced gelatine standards containing ionic titanium were used as a calibration strategy for obtaining laser ablation-based images using quantitative (titanium concentrations) data. The best calibration strategy consisted of using gelatine-based titanium standards (from 0.1 to 2.0 μg g^-1) by placing 5.0-μL drops of the liquid gelatine standards onto microscope glass sample holders. After air drying at room temperature good homogeneity of the placed drops was obtained, which led to good repeatability of measurements (calibration slope of 4.21 × 10⁴ ± 0.39 × 10⁴, n = 3) and good linearity (coefficient of determination higher than 0.990). Under the optimised conditions, a limit of detection of 0.087 μg g^-1 titanium was assessed. This strategy allowed to locate prominent areas of titanium in the tissues as well as to quantify the bioaccumulated titanium and a better understanding of titanium dioxide nanoparticle spatial distribution in sea bream tissues.

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

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

Progress on the toxicity of quantum dots to model organism-zebrafish

In vivo toxicological studies are currently necessary to analyze the probable dangers of quantum dots (QDs) to the environment and human safety, due to the fast expansion of QDs in a range of applications. Because of its high fecundity, cost-effectiveness, well-defined developmental phases, and optical transparency, zebrafish has long been considered the "gold standard" for biosafety assessment of chemical substances and pollutants. In this review, the advantages of using zebrafish in QD toxicity assessment were explored. Then, the target organ toxicities such as developmental toxicity, immunotoxicity, cardiovascular toxicity, neurotoxicity, and hepatotoxicity were summarized. The hazardous effects of different QDs, including cadmium-containing QDs like CdTe, CdSe, and CdSe/ZnS, as well as cadmium-free QDs like graphene QDs (GQDs), graphene oxide QDs (GOQDs), and others, were emphasized and described in detail, as well as the underlying mechanisms of QDs generating these effects. Furthermore, general physicochemical parameters determining QD-induced toxicity in zebrafish were introduced, such as chemical composition and surface coating/modification. The limitations and special concerns of using zebrafish in QD toxicity studies were also mentioned. Finally, we predicted that the utilization of high-throughput screening assays and omics, such as transcriptome sequencing, proteomics, and metabolomics will be popular topic in nanotoxicology.

Facets of ICP-MS and their potential in the medical sciences-Part 2: nanomedicine, immunochemistry, mass cytometry, and bioassays

Inductively coupled-plasma mass spectrometry (ICP-MS) has transformed our knowledge on the role of trace and major elements in biology and has emerged as the most versatile technique in elemental mass spectrometry. The scope of ICP-MS has dramatically changed since its inception, and nowadays, it is a mature platform technology that is compatible with chromatographic and laser ablation (LA) systems. Over the last decades, it kept pace with various technological advances and was inspired by interdisciplinary approaches which endorsed new areas of applications. While the first part of this review was dedicated to fundamentals in ICP-MS, its hyphenated techniques and the application in biomonitoring, isotope ratio analysis, elemental speciation analysis, and elemental bioimaging, this second part will introduce relatively current directions in ICP-MS and their potential to provide novel perspectives in the medical sciences. In this context, current directions for the characterisation of novel nanomaterials which are considered for biomedical applications like drug delivery and imaging platforms will be discussed while considering different facets of ICP-MS including single event analysis and dedicated hyphenated techniques. Subsequently, immunochemistry techniques will be reviewed in their capability to expand the scope of ICP-MS enabling analysis of a large range of biomolecules alongside elements. These methods inspired mass cytometry and imaging mass cytometry and have the potential to transform diagnostics and treatment by offering new paradigms for personalised medicine. Finally, the interlacing of immunochemistry methods, single event analysis, and functional nanomaterials has opened new horizons to design novel bioassays which promise potential as assets for clinical applications and larger screening programs and will be discussed in their capabilities to detect low-level proteins and nucleic acids.

Assessment of the transfer of heavy metals in seawater, sediment, biota samples and determination the baseline tissue concentrations of metals in marine organisms

The majority of tissue-specific environmental quality standards (EQSs) considering metal tolerance are prior to the chemical-specific EQSs in aquatic organisms. However, metal baseline levels in marine organisms were very scarce. We explored the correlation between Hg, Cd, Pb, Cu, and Zn concentrations in water or sediments and those metal concentrations in marine organisms (crustacean, mollusc, and fish) by generalized additive models (GAMs) and executed a meta-analysis of Hg, Cd, Pb, Cu, and Zn contents in those three organisms by implementing cumulative frequency distribution analysis of individual metal distribution in a heavy metal-contaminated semi-enclosed Bay, China. Results showed that the average contents of Hg, Cd, Pb, Cu, and Zn were 0.042±0.01, 0.38±0.22, 1.72±0.65, 3.61±1.01, and 16.08±6.33 μg/L in water; 0.064±0.02, 0.42±0.04, 20.54±7.76, 28.97±3.90, and 96.74±35.11 μg/g dw in sediment; and 0.0049±0.0028, 0.52±0.28, 0.24±0.15, 11.05±6.95, and 21.12±4.47 μg/g dw in crustacean, 0.015±0.0087, 0.24±0.17, 0.08±0.02, 0.37±0.35, and 10.62±6.79 μg/g dw in mollusc; and 0.0038±0.0028, 0.065±0.05, 0.32±0.19, 2.01±0.59, and 16.04±4.97 μg/g dw in fish. The mercury content in mollusc presented a negative correlation with mercury content in sediment, while the content of other metals (Cd, Pb, Cu, and Zn) in organisms showed positive correlations with the content of those metals in water or sediment. We further obtained tissue-baseline-C5% in crustacean, mollusc, and fish which were 1.191, 3.341, and 0.014 μg/g dw for Cu; 0.013, 0.072, and 0.033 μg/g dw for Cd, 0.015, 0.027, and 0.052 μg/g dw for Pb; 9.515, 14.422, and 0.056 μg/g dw for Zn; and 0.0009, 0.004, and 0.0035 μg/g dw for Hg, respectively. However, there were no obvious relationships of the 4d-NOEC in laboratory toxicity tests with C5%, as well as C50% and 4d-LC50 or tolerance index a for Cu, Cd, Pb, Zn, and Hg in organisms. Our results pointed out the controversy of laboratory sensitive species toxicity results for deriving chemical-specific EQSs with field studies. We advocated to set up the metal concentration baselines in aquatic organisms and further served the tissue-specific EQSs, which are essential basis for geochemical recordings, bio-monitoring, and semi-enclosed bay management in the world.

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Imaging in Biology

Elemental imaging gives insight into the fundamental chemical makeup of living organisms. Every cell on Earth is comprised of a complex and dynamic mixture of the chemical elements that define structure and function. Many disease states feature a disturbance in elemental homeostasis, and understanding how, and most importantly where, has driven the development of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) as the principal elemental imaging technique for biologists. This review provides an outline of ICP-MS technology, laser ablation cell designs, imaging workflows, and methods of quantification. Detailed examples of imaging applications including analyses of cancers, elemental uptake and accumulation, plant bioimaging, nanomaterials in the environment, and exposure science and neuroscience are presented and discussed. Recent incorporation of immunohistochemical workflows for imaging biomolecules, complementary and multimodal imaging techniques, and image processing methods is also reviewed.

In-vitro and in-vivo evaluation of the molecular mechanisms involved in the toxicity associated to CdSe/ZnS quantum dots exposure

The use of different types of quantum dots is growing in recent times in both the technology and biomedical industries. Such is the extension of the use of these quantum dots that they have become potential emerging contaminants, which makes it necessary to evaluate their potential toxicity and the impact they may have on both health and the environment. Although studies already exist in this regard, the molecular mechanisms by which CdSe/ZnS quantum dots exert their toxic effects are still unknown. For this reason, in this study, a comprehensive proteomic approach has been designed, applying the SILAC strategy to an in-vitro model (hepatic cells) and the super-SILAC alternative to an in-vivo model, specifically zebrafish larvae. This integral approach, together with additional bioanalytical assays, has made it possible for the identification of proteins, molecular mechanisms and, therefore, biological processes that are altered as a consequence of exposure to CdSe/ZnS quantum dots. It has been demonstrated, on the one hand, that these quantum dots induce hypoxia and ROS generation in hepatic cells, which leads to apoptosis, specifically through the TDP-43 pathway. On the other hand, it has been shown that exposure to CdSe/ZnS quantum dots has a high impact on developing organisms, inducing serious neural and developmental problems in the locomotor system.

Assessing cadmium-based quantum dots effect on the gonads of the marine mussel Mytilus galloprovincialis

This study assesses the sex-specific effects induced by CdTe QDs, on the marine mussel Mytilus galloprovincialis in comparison to its dissolved counterpart. A 14 days exposure to CdTe QDs and dissolved Cd was conducted (10 μg Cd L^-1), analysing Cd accumulation, oxidative stress, biotransformation, metallothionein and oxidative damage in the gonads. Both Cd forms caused significant antioxidant alterations, whereby QDs were more pro-oxidant, leading to oxidative damage, being females more affected. Overall, biochemical impairments on gonads of M. galloprovincialis demonstrate that the reproductive toxicity induced by CdTe QDs in mussels are sex-dependent and mediated by oxidative stress and lipid peroxidation. It is crucial to acknowledge how gametes are affected by metal-based nanoparticles, such as Cd-based QDs. As well as understanding the potential changes they may undergo at the cellular level during gametogenesis, embryogenesis and larval development potentially leading to serious impacts on population sustainability and ecosystem health.

In vivo Comparison of the Biodistribution and Toxicity of InP/ZnS Quantum Dots with Different Surface Modifications

INTRODUCTION

Indium phosphide (InP) quantum dots (QDs) have shown a broad application prospect in the fields of biophotonics and nanomedicine. However, the potential toxicity of InP QDs has not been systematically evaluated. In particular, the effects of different surface modifications on the biodistribution and toxicity of InP QDs are still unknown, which hinders their further developments. The present study aims to investigate the biodistribution and in vivo toxicity of InP/ZnS QDs.

METHODS

Three kinds of InP/ZnS QDs with different surface modifications, hQDs (QDs-OH), aQDs (QDs-NH2), and cQDs (QDs-COOH) were intravenously injected into BALB/c mice at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively. Biodistribution of three QDs was determined through cryosection fluorescence microscopy and ICP-MS analysis. The subsequent effects of InP/ZnS QDs on histopathology, hematology and blood biochemistry were evaluated at 1, 3, 7, 14 and 28 days post-injection.

RESULTS

These types of InP/ZnS QDs were rapidly distributed in the major organs of mice, mainly in the liver and spleen, and lasted for 28 days. No abnormal behavior, weight change or organ index were observed during the whole observation period, except that 2 mice died on Day 1 after 25 mg/kg BW hQDs treatment. The results of H&E staining showed that no obvious histopathological abnormalities were observed in the main organs (including heart, liver, spleen, lung, kidney, and brain) of all mice injected with different surface-functionalized QDs. Low concentration exposure of three QDs hardly caused obvious toxicity, while high concentration exposure of the three QDs could cause some changes in hematological parameters or biochemical parameters related to liver function or cardiac function. More attention needs to be paid on cQDs as high-dose exposure of cQDs induced death, acute inflammatory reaction and slight changes in liver function in mice.

CONCLUSION

The surface modification and exposure dose can influence the biological behavior and in vivo toxicity of QDs. The surface chemistry should be fully considered in the design of InP-based QDs for their biomedical applications.

Different factors determined the toxicokinetics of organic chemicals and nanomaterials exposure to zebrafish (Danio Rerio)

Little is known about how the chemical properties (molecular structure, such as the hydrophobic and hydrophilic end group for organic chemical, and particle size for nanomaterials (NMs)) quantitatively affect the toxicokinetics (TK) in organisms especially in short-term, single-species studies. A novel method based on a first-order one compartment TK model which described the monophasic uptake pattern and two-compartment TK model which adequately described the biphasic metabolism pattern was used to determine the bioconcentration and TK rate constants of organic compounds (n = 17) and nanomaterials (NMs, n = 7) in zebrafish. For both one and two compartment model, the uptake (k_in) and elimination (k_out) rate constants were fitted using a one- and two-compartment first-order kinetic model, and bioconcentration factors (BCF) and 95% depuration times (t₉₅) for all tested chemicals were calculated, respectively. The results showed that there was significant difference in TK parameters k_in, k_out, and BCF between organic chemicals and nano metal oxides. For organic compounds, significant correlations were found between the k_in and BCF and the octanol-water partition coefficient (K_ow) and molecular mass. For nano metal oxides, there was a significant negative correlation between the k_in or BCF and particle size, but a positive correlation between k_in and Zeta potential of nanoparticles and also a significant positive correlation between k_out and particle size or specific surface area. Those findings indicated that NMs particle size does matter in biological influx and efflux processes. Our results suggest that the TK process for organic compound and NMs are correlated by different chemical properties and highlight that the K_ow, the absorption k_in, metabolism k₁₂ and k₂₁, elimination rate k_out, and all the parameters that enable the prediction and partitioning of chemicals need to be precisely determined in order to allow an effective TK modeling. It would therefore appear that the TK process of untested chemicals by a fish may be extrapolated from known chemical properties.

Bioaccumulation of Cadmium Affects Development, Mating Behavior, and Fecundity in the Asian Corn Borer, Ostrinia furnacalis

Heavy metal pollution is becoming an increasingly serious problem in agricultural ecosystems. Heavy metals such as cadmium (Cd) accumulate in the food chain and may lead to detrimental effects on the physiological functions of living organisms, including herbivorous insects. One such example is the Asian Corn Borer, Ostrinia furnacalis (Lepidoptera: Pyralidae). However, how Cd can affect the development and reproduction of O. furnacalis is largely unknown. In this study, we exposed larvae of O. furnacalis to a diet containing Cd and investigated the effects of Cd on the development, mating behavior, and fecundity of the insect. We showed that Cd accumulates in the larvae and inhibits development by extending larval and pupal duration and decreasing the survival rate. The excretion of Cd through multiple routes during the larval and pupal stages resulted in low levels of residual Cd in the adult insects, which were not fed with Cd. However, the mating behavior and fecundity of these insects were significantly affected, compared to control insects. This suggests that the bioaccumulation of heavy metals such as Cd has long lasting and detrimental effects on O. furnacalis over the entire life cycle, affecting fecundity, even when specimens are only exposed at an early life stage.

InP/ZnS Quantum Dots Cause Inflammatory Response in Macrophages Through Endoplasmic Reticulum Stress and Oxidative stress

Purpose

Quantum dots (QDs) are widely used semiconductor nanomaterials. Indium phosphide/zinc sulfide (InP/ZnS) QDs are becoming potential alternatives to toxic heavy metal-containing QDs. However, the potential toxicity and, in particular, the immunotoxicity of InP/ZnS QDs are unknown. This study aimed to investigate the impacts of InP/ZnS QDs on inflammatory responses both in vivo and in vitro.

Methods

Mice and mouse bone marrow-derived macrophages (BMMs) were exposed to polyethylene glycol (PEG) coated InP/ZnS QDs. The infiltration of neutrophils and the release of interleukin-6 (IL-6) were measured using a hematology analyzer and an enzyme-linked immunosorbent assay (ELISA) for the in vivo test. Cytotoxicity, IL-6 secretion, oxidative stress and endoplasmic reticulum (ER) stress were studied in the BMMs, and then, inhibitors of oxidative stress and ER stress were used to explore the mechanism of the InP/ZnS QDs.

Results

We found that 20 mg/kg PEG-InP/ZnS QDs increased the number of neutrophils and the levels of IL-6 in both peritoneal lavage fluids and blood, which indicated acute phase inflammation in the mice. PEG-InP/ZnS QDs also activated the BMMs and increased the production of IL-6. In addition, PEG-InP/ZnS QDs triggered oxidative stress and the ER stress-related PERK-ATF4 pathway in the BMMs. Moreover, the inflammatory response caused by the PEG-InP/ZnS QDs could be attenuated in the macrophages by blocking the oxidative stress or the ER stress with inhibitors.

Conclusion

InP/ZnS QDs can activate macrophages and induce acute phase inflammation both in vivo and in vitro, which may be regulated by oxidative stress and ER stress. Our present work is expected to help clarify the biosafety of InP/ZnS QDs and promote their safe application in biomedical and engineering fields.

Toxicological Potential of Cadmium Impact on Rainbow Trout (Oncorhynchus mykiss) in Early Development

Cadmium (Cd) is a toxic element widely distributed in the aquatic environment and producing a wide variety of harmful effects. In this study, the acute toxicity (96 h LC50) of Cd to rainbow trout Oncorhynchus mykiss embryos and larvae was determined. The obtained results showed that hatched larvae were the most sensitive to Cd exposure. After 4 days of exposure, embryos were found to have accumulated greater concentrations of Cd than larvae. Exposure to Cd at sublethal concentrations produced deleterious, exposure duration-related effects on biological parameters (mortality, heart rate and gill ventilation frequency) of larvae. Cd induced a significant elevation of all the studied geno- and cytotoxicity endpoints in larval erythroblasts.

Toxicokinetic and toxicodynamic (TK-TD) modeling to study oxidative stress-dependent toxicity of heavy metals in zebrafish

Adverse outcome pathways (AOP) have been proposed as a new method to improve the ecological risk assessment of pollutants, but it requires quantitation linkage between exposure, biomarker response and toxicity of pollutants. A toxicokinetic and toxicodynamic (TK-TD) model was used to quantify AOP of the toxicity of Cd and Pb to zebrafish, including the quantitative relationship between Cd and Pb accumulation in gill and oxidative damage level based on ROS or MDA, and LC₅₀ values at different times. Significant relationships were found between the oxidative damage level characterized by ROS and MDA content and Cd or Pb accumulation in gill (R² > 0.60), and the TK model could better simulate the Pb accumulation in the gills (R² > 0.60) than Cd. The increasing of Cd or Pb concentrations induced the generation of ROS and the formation of ROS initiated the fluctuation of MDA level in the cells as compared to controls (p < 0.05). For the individual level effect, the Damage Assessment Model (DAM) could successfully explain the change of LC_50-ROS and LC_50-MDA values at different times (R² > 0.99). Our findings suggested that the TK-TD model based on ROS and MDA could be used as a quantitative AOP to predict toxicity of metals to zebrafish.

Biodistribution and toxicity assessment of intratumorally injected arginine-glycine-aspartic acid peptide conjugated to CdSe/ZnS quantum dots in mice bearing pancreatic neoplasm

Quantum dots (QDs) conjugated with arginine-glycine-aspartic acid (RGD) peptides (which are integrin antagonists) are novel nanomaterials with the unique optical property of high molar extinction coefficient, and they have potential utility as photosensitizers in photodynamic therapy (PDT). Our group previously demonstrated significant benefits of using PDT with QD-RGD on pancreatic tumor cells. This study aimed to evaluate the biodistribution and toxicity of QD-RGD in mice prior to in vivo application. Mice with pancreatic neoplasms were intratumorally injected with varying doses of QD-RGD, and the biodistribution 0-24 h post injection was compared to that in control mice (intravenously injected with unconjugated QD). Various tissue samples were collected for toxicity analyses, which included inductively coupled plasma mass spectrometry (ICP-MS) to assess Cd²⁺ concentrations and hematoxylin-eosin staining for histopathological examination. Fluorescent imaging revealed relatively sufficient radiant efficiency in mice under specific conditions. The ICP-MS and HE data showed no significant signs of necrosis due to Cd²⁺ release by QDs. The mice survived well and had no apparent weakness or weight loss during the 4 weeks post injection. These findings provide novel insights into the biodistribution of QD-RGD and encourage profound in vivo studies regardless of safety concerns. These findings alleviate safety concerns and provide novel insights into the biodistribution of QD-RGD, offering a solid foundation for comprehensive in vivo studies.

InP/ZnS QDs exposure induces developmental toxicity in rare minnow (Gobiocypris rarus) embryos

We investigated the in vivo toxicity of InP/ZnS quantum dots (QDs) in Chinese rare minnow (Gobiocypris rarus) embryos. The 72 h post-fertilization (hpf) LC₅₀ (median lethal concentration) was 1678.007 nmol/L. Rare minnows exposed to InP/ZnS QDs exhibited decreased spontaneous movement, decreased survival and hatchability rates, and an increased malformation rate. Pericardial edema, spinal curvature, bent tails and vitelline cysts were observed. Embryonic Wnt8a and Mstn mRNA levels were significantly up-regulated after InP/ZnS QDs treatment at 48 hpf (200 nmol/L) (p < 0.05). The superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels at 96 hpf (800 nmol/L) had an increasing trend. Hsp70 mRNA expression was significantly changed at 48 hpf (200 nmol/L), but compared with the blank control, the different InP/ZnS QDs treatments did not significantly change the Olive tail moments (p > 0.05). Thus, InP/ZnS QDs caused teratogenic effects and death during the development of Chinese rare minnow embryos, but InP/ZnS QDs did not cause significant genetic toxicity during Chinese rare minnow development.

In vivo bioconcentration of a metal mixture by Danio rerio eleutheroembryos

Exposure to heavy metals has represented one of the most serious health risks of environmental pollution over the last 50 years. Most of the bioconcentration studies that have been carried out to date explored only individual contaminants, unlike the real situations that occur in the environment. In this work, zebrafish eleutheroembryos were exposed to a mixture of CH₃Hg(II), iAs(III), Ag(I) and Cd(II), and new BCFs were calculated and compared with those calculated from single metal exposures. In both cases, experimental conditions meet the OECD Test 305 conditions established for aquatic systems. In addition, spatial imaging obtained by laser ablation coupled to inductively plasma mass spectrometry (LA-ICP/MS), has been directly performed in these samples providing complementary information. The new BCF's have revealed some differences compared to single metal exposures when eleutheroembryos were exposed to the metal mixture, especially for iAs(III) and Cd(II). LA-ICP/MS images are in good agreement with the BFC's found, representing an interesting approach to get spatial distribution of metals that reinforces the toxicokinetic information.

Zebrafish models for functional and toxicological screening of nanoscale drug delivery systems: promoting preclinical applications

Preclinical screening with animal models is an important initial step in clinical translation of new drug delivery systems. However, establishing efficacy, biodistribution, and biotoxicity of complex, multicomponent systems in small animal models can be expensive and time-consuming. Zebrafish models represent an alternative for preclinical studies for nanoscale drug delivery systems. These models allow easy optical imaging, large sample size, and organ-specific studies, and hence an increasing number of preclinical studies are employing zebrafish models. In this review, we introduce various models and discuss recent studies of nanoscale drug delivery systems in zebrafish models. Also in the end, we proposed a guideline for the preclinical trials to accelerate the progress in this field.