The influence of copper-doped mesoporous bioactive nanospheres on the temperature rise during polymerization, polymer cross-linking density, monomer release and embryotoxicity of dental composites.

OBJECTIVES: Composites with copper-doped mesoporous bioactive nanospheres (Cu-MBGN) were developed to prevent secondary caries by imparting antimicrobial and ion-releasing/remineralizing properties. METHODS: Seven experimental composites containing 1, 5 or 10 wt% Cu-MBGN, the corresponding inert controls (silica) and bioactive controls (bioactive glass 45S5) were prepared. The temperature rise during light curing, cross-linking density by ethanol softening test, monomer elution and their potential adverse effects on the early development of zebrafish Danio rerio was investigated. RESULTS: Materials combining Cu-MBGN and silica showed the highest resistance to ethanol softening, as did the bioactive controls. Cu-MBGN composites showed significant temperature rise and reached maximum temperature in the shortest time. Bisphenol A was not detected, while bis-GMA was found only in the control materials and TEGDMA in the eluates of all materials. There was no increase in zebrafish mortality and abnormality rates during exposure to the eluates of any of the materials. CONCLUSIONS: The composite with 5 wt% Cu-MBGN combined with nanosilica fillers showed the lowest ethanol softening, indicating the polymer's highest durability and cross-linking density. Despite the TEGDMA released from all tested materials, no embryotoxic effect was observed.

Synthesis, Characterization and Biosafety Evaluation of Hollow Gold Nanospheres.

OBJECTIVES: In order to assess the biosafety of HAuNS using zebrafish models and the cancer cell lines HepG2, HEK293, and A549, this study prepared HAuNS in a variety of sizes and alterations. METHODS: By oxidizing cobalt nanoparticles encased in gold shells, HAuNS were created. In the meantime, PEG- and PEI-coated HAuNS were created. The diameters of the HAuNS that were produced were 30~40 nm, 50~60 nm, and 70~80 nm. MTT assay was used to assess the toxicity of HAuNS on HepG2, HEK293, and A549 cells. For the investigation of their toxicities, HAuNS (50~60 nm) of various concentrations were incubated with zebrafish embryos. Then, cell death was determined using acridine orange staining. RESULTS: In a cell line model, it was demonstrated that purified HAuNS exhibit lower toxicity than unpurified HAuNS. Meanwhile, it was discovered that surface-modified HAuNS was less hazardous than unmodified HAuNS. Unpurified HAuNS (50.60 nm) exposure to embryos caused deformity and increased mortality. Moreover, embryos exposed to HAuNS displayed an increase in cell death, showing that HAuNS can put zebrafish under physiological stress. CONCLUSION: The possible toxicity of HAuNS is now more understood thanks to this investigation. The details could improve our comprehension of the nanotoxicity of medication delivery systems. Comparing HAuNS (50~60 nm) to the other two particle sizes, its toxicity was quite low. Compared to unpurified HAuNS, purified HAuNS displayed less toxicity. Comparing PEI-HAuNS and HAuNS to PEG-HAuNS, cytotoxicity was found to be lower. Our data support the use of pure HAuNS, HAuNS-PEG, and HAuNS (50~60 nm) as possible photothermal conductors when seen as a whole.

Spindle-shaped Cu-Ru mesoporous nanospheres with enhanced enzyme-like activity for visual differentiation of toxic o-/m-aminophenol and recognition mechanisms.

To effectively differentiate toxic aminophenol isomers, a kind of spindle-shaped Cu-Ru bimetal mesoporous nanozyme (Cu-Ru MPNZ) with high specific surface was developed by one-pot homogeneous reduction method, directed by hexadecyl trimethyl ammonium bromide (CTAB) in this work. By virtue of the distinctive microstructure, Cu-Ru MPNZ expressed superior bi-functional oxidase- and peroxidase-mimic activity to catalyze the oxidation of 3,3',5,5,'-tetramethylbenzidine (TMB) and 2,2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) with low Michaelis-Menten constants and quick reaction rates. Especially, toxic aminophenol isomers could exclusively react with the oxydates of TMB or ABTS to express differentiable signals in color. Under the optimal conditions, Cu-Ru MPNZ was successfully applied for visual differentiation of toxic aminophenol isomers in real aqueous, juices and medicinal samples with low detection limits (1.60 × 10-8 mol/L for o-aminophenol and 3.25 × 10-8 mol/L for m-aminophenol) and satisfactory recoveries (96.6-103.5%). The different recognition mechanisms of Cu-Ru MPNZ to toxic o- and m-aminophenol isomers were proposed for the first time as far as we known. This work will provide a potential way to monitor different organic isomer pollution in future.

Hazard of polystyrene micro-and nanospheres to selected aquatic and terrestrial organisms.

Plastics contamination in the environment is a major concern. Risk assessment of micro- and nanoplastics (MPL and NPL) poses significant challenges due to MPL and NPL heterogeneity regarding compositional polymers, particle sizes and morphologies in the environment. Yet, there exists considerable toxicological literature on commercial polystyrene (PS) micro- and nanospheres. Although such particles do not directly represent the environmental MPL and NPL, their toxicity data should be used to advance the hazard assessment of plastics. Here, toxicity data of PS micro- and nanospheres for microorganisms, aquatic and terrestrial invertebrates, fish, and higher plants was collected and analyzed. The evaluation of 294 papers revealed that aquatic invertebrates were the most studied organisms, nanosized PS was studied more often than microsized PS, acute exposures prevailed over chronic exposures, the toxicity of PS suspension additives was rarely addressed, and ∼40 % of data indicated no organismal effects of PS. Toxicity mechanisms were mainly studied in fish and nematode Caenorhabditis elegans, providing guidance for relevant studies in higher organisms. Future studies should focus on environmentally relevant plastics concentrations, wide range of organisms, co-exposures with other pollutants, and method development for plastics identification and quantification to fill the gap of bioaccumulation assessment of plastics.

Dual-modified starch nanospheres encapsulated with curcumin by self-assembly: Structure, physicochemical properties and anti-inflammatory activity.

Pullulanase debranching and subsequent hydroxypropylation were applied to prepare a series of dual-modified starches (Hydroxypropylated debranched starch, HPDS) with different degrees of hydroxypropyl substitution. Their structural and physicochemical properties varied with the degree of hydroxypropyl substitution, and all HPDS exhibited the ability to self-assemble into well-shaped nanospheres (100-150 nm, PDI < 0.2). These HPDS nanospheres were attempted to encapsulate curcumin with the aim of improving the bioavailability, solubility and stability of curcumin. Their structural characteristics, thermal stability, iodine staining, morphology, safety, encapsulation efficiency, in vitro gastrointestinal release behavior, and anti-inflammatory activity were evaluated. The results showed that curcumin could be effectively encapsulated into the HPDS nanospheres, and the encapsulation efficiency, water solubility and physical stability were positively correlated with the degree of hydroxypropyl substitution. After encapsulation, the water solubility and physical stability of curcumin could be increased up to 226-fold and 6-fold, respectively. The HPDS nanospheres also exhibited good safety (including hemolysis and cytotoxicity) and sustainable release of curcumin. Evaluation of anti-inflammatory activity showed that the activity of curcumin-encapsulated HPDS was enhanced by 170% compared to unencapsulated curcumin. These suggest that HPDS nanospheres encapsulation may be a more suitable option for the development of functional foods containing bioactive compounds.

Magnetic Nanostructure-Loaded Bicontinuous Nanospheres Support Multicargo Intracellular Delivery and Oxidation-Responsive Morphological Transitions.

Magnetic nanostructures (MNS) have a wide range of biological applications due to their biocompatibility, superparamagnetic properties, and customizable composition that includes iron oxide (Fe3O4), Zn2+, and Mn2+. However, several challenges to the biomedical usage of MNS must still be addressed, such as formulation stability, inability to encapsulate therapeutic payloads, and variable clearance rates in vivo. Here, we enhance the utility of MNS during controlled delivery applications via encapsulation within polymeric bicontinuous nanospheres (BCNs) composed of poly(ethylene glycol)-block-poly(propylene sulfide) (PEG-b-PPS) copolymers. PEG-b-PPS BCNs have demonstrated versatile encapsulation and delivery capabilities for both hydrophilic and hydrophobic payloads due to their unique and highly organized cubic phase nanoarchitecture. MNS-embedded BCNs (MBCNs) were thus coloaded with physicochemically diverse molecular payloads using the technique of flash nanoprecipitation and characterized in terms of their structure and in vivo biodistribution following intravenous administration. Retention of the internal aqueous channels and cubic architecture of MBCNs were verified using cryogenic transmission electron microscopy and small-angle X-ray scattering, respectively. MBCNs demonstrated improvement in magnetic resonance imaging (MRI) contrast enhancement (r2 relaxivity) as compared to free MNS, which in combination with scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy evidenced the clustering and continued access to water of MNS following encapsulation. Furthermore, MBCNs were found to be noncytotoxic and able to deliver their hydrophilic and hydrophobic small-molecule payloads both in vitro and in vivo. Finally, the oxidation sensitivity of the hydrophobic PPS block allowed MBCNs to undergo a unique, triggerable transition in morphology into MNS-bearing micellar nanocarriers. In summary, MBCNs are an attractive platform for the delivery of molecular and nanoscale payloads for diverse on-demand and sustained drug delivery applications.

An ultrasmall chitosan nanosphere encapsulating carbon dots and rhodamine B as a ratiometric probe for the determination of Hg2.

Hg2+-sensitive carbon dots (CDs) were synthesized by microwave-assisted pyrolysis of citric acid, sodium fluoride, and urea. The CDs as a signal report unit and rhodamine B (RhB) as a reference were then encapsulated in a nanosphere of chitosan assembled by a nonsolvent-induced chitosan colloidal formation and in situ cross-linking to construct a ratiometric probe for Hg2+ (chitosan-CDs-RhB). Interestingly, without any assistance from acids to improve the solubility of chitosan, the nanosphere containing CDs and RhB had an ultrasmall size of 9.7 nm with only approximately 1.1-nm-thick layers of chitosan enclosing one dot. In order to keep the residual functional groups on the nanosphere from compromising the fluorescence response of CDs to Hg2+, Co2+ was used as a fluorescently intact metal ion to saturate the functional groups. The saturated chitosan-CDs-RhB was thus potentially developed for determining Hg2+ in the fruit bodies and mycelia of edible and medicinal fungi. Limits of detection (LODs) of 2.24, 5.29, and 2.03 µM and recoveries in the ranges 98.3 to 101.8%, 99.5 to 104.6%, and 97.4 to 100.9% were estimated for the determination of Hg2+ in the fruit bodies of Pleurotus ostreatus, Lentinus edodes, and Hypsizygus marmoreus, respectively. Chitosan-CDs-RhB was further developed as a fluorescent ratiometric probe for quantitatively determining intracellular Hg2+ in fungal mycelia with a linear calibration curve of RIgreen/Ired = - 0.145c + 1.69 within the range 0.013 to 0.356 µg g-1. Graphical abstract An ultrasmall chitosan nanosphere encapsulating carbon dots and rhodamine B as a ratiometric probe for the determination of Hg2+.

An in vivo study of nanorod, nanosphere, and nanowire forms of titanium dioxide using Drosophila melanogaster: toxicity, cellular uptake, oxidative stress, and DNA damage.

The biological impact of nanomaterials (NMs) is determined by several factors such as size and shape, which need to be taken into consideration in any type of analysis. While investigators often prefer to conduct in vitro studies for detection of any possible adverse effects of NMs, in vivo approaches yield more relevant data for risk assessment. For this reason, Drosophila melanogaster was selected as a suitable in vivo model to characterize the potential risks associated with exposure nanorods (NRs), nanospheres (NSs), nanowires (NWs) forms of titanium dioxide (TiO2), and their microparticulated (or bulk) form, as TiO2. Third instar larvae (72 hr old larvae) were fed with TiO2 (NRs, NSs, or NWs) and TiO2 at concentrations ranging from 0.01 to 10 mM. Viability (toxicity), internalization (cellular uptake), intracellular reactive oxygen species (ROS) production, and genotoxicity (Comet assay) were the end-points evaluated in hemocyte D. melanogaster larvae. Significant intracellular oxidative stress and genotoxicity were noted at the highest exposure concentration (10 mM) of TiO2 (NRs, NSs, or NWs), as determined by the Comet assay and ROS analysis, respectively. A concentration-effect relationship was observed in hemocytes exposed to the NMs. Data demonstrated that selected forms of TiO2.-induced genotoxicity in D. melanogaster larvae hemocytes indicating this organism is susceptible for use as a model to examine in vivo NMs-mediated effects.

DNAzyme-functionalized porous carbon nanospheres serve as a fluorescent nanoprobe for imaging detection of microRNA-21 and zinc ion in living cells.

The present study shows that a dual-signal nanoprobe consisting of DNAzyme-functionalized porous carbon nanospheres (PCNs) responds to microRNA-21 and zinc ion (Zn2+). The fluorescent probe undergoes an increase in the fluorescence intensity of fluorescein isothiocyanate (FITC) (with excitation/emission wavelengths at 488/517 nm) and the fluorescence intensity of cyanine-5 (Cy5) (with excitation/emission wavelengths at 633/670 nm) in the presence of microRNA-21 and Zn2+. The recognition between microRNA-21 and its complementary strand in the PCNs induces the separation of Zn2+-specific DNAzyme from PCNs, thus resulting in the increase of green fluorescence, and the exogenous Zn2+ triggers the rupture of cleavage strand of DNAzyme and recovery of red fluorescence. This nanoprobe allows us to acquire in vitro the determination of microRNA-21 in the range of 2-300 nM with a detection limit of 0.57 nM and the determination of Zn2+ in the range 2-100 nM with a detection limit of 0.43 nM, and in situ simultaneous imaging in MCF-7 breast cancer cells. Therefore, this strategy permits to obtain the expression levels of different biomarkers in living cells, providing a useful tool for diagnosis of cancers and understanding their biological process. Graphical abstract Schematic representation of the DNAzyme-functionalized porous carbon nanospheres for the imaging analysis of microRNA-21 and Zn2+ in living cells.

Hollow Mesoporous Tantalum Oxide Based Nanospheres for Triple Sensitization of Radiotherapy.

Radiotherapy (RT) is one of the most widely used cancer treatments in the clinical setting, while hypoxia-associated resistance often occurs. Herein, a PEGylated TaOx-based oxygen-carrying nanoplatform was constructed for triple sensitizing tumor radiotherapy. The high-Z element based hollow mesoporous TaOx nanospheres were prepared following the in situ growth of ultrasmall CuS nanocrystals and then packaged with O2-saturated perfluoropentane (PFP). NIR laser-triggered mild hyperthermia would lead to the increase of intratumoral blood flow, together with the release of O2, the radiotherapeutic efficiency would be enhanced. Alternatively, radiant energy would be deposited inside the tumor by the Ta element, therefore triple sensitization of radiotherapy could be achieved. The in vivo studies showed that the as-prepared nanospheres could achieve almost total inhibition of tumor growth without obvious side effects, which provides new possibilities for multisensitizing tumor radiotherapy.

An anti-inflammatory nanoagent for tumor-targeted photothermal therapy.

We developed an anti-inflammatory nanoagent by combining polydopamine nanospheres with aspirin and cancer cell membrane coating, which can effectively kill cancer cells and simultaneously eliminate photothermal therapy-induced inflammation.

Effect of bovine serum albumin on tartrate-modified manganese ferrite nano hollow spheres: spectroscopic and toxicity study.

The emerging category of magneto-fluorescent tartrate-modified MnFe2O4 nano hollow spheres (T-MnFe2O4 NHSs) can be considered as promising candidates for biomedical applications. The interaction of bovine serum albumin (BSA) with T-MnFe2O4 NHSs has been studied using several spectroscopic techniques, which suggest that the interaction occurs by an electrostatic mechanism. Furthermore, BSA enhances the charge transfer transition from the tartrate ligand to the metal ions along with the d-d transition of Fe3+ ions on NHSs surfaces at different pH. Very strong salt bridge formation occurs between the lysine of the BSA surface and the tartrate in basic medium (pH 10), followed by the acidic (pH 3) and neutral medium (pH 7), respectively. Systematic fluorescence microscopic analysis reveals that BSA significantly enhances the contrast of T-MnFe2O4 NHSs in UV and blue light excitation because of the extended charge transfer from BSA to T-MnFe2O4 NHSs. Our report demonstrates great potential in the field of nanotechnology and biomedical applications. In vitro toxicity analysis using RAW 264.7 celline and in vivo studies on Wister rats revealed that the T-MnFe2O4 NHSs are benign. Furthermore, T-MnFe2O4 NHSs also appear to be an antimicrobial agent. Therefore, T-MnFe2O4 NHSs can be explored for future therapeutic applications.

Polymer-Coated Gold Nanospheres Do Not Impair the Innate Immune Function of Human B Lymphocytes in Vitro.

Gold nanoparticles (GNPs) are intended for use within a variety of biomedical applications due to their physicochemical properties. Although, in general, biocompatibility of GNPs with immune cells such as macrophages and dendritic cells is well established, the impact of GNPs on B lymphocyte immune function remains to be determined. Since B lymphocytes play an important role in health and disease, the suitability of GNPs as a B cell-targeting tool is of high relevance. Thus, we provide information on the interactions of GNPs with B lymphocytes. Herein, we exposed freshly isolated human B lymphocytes to a set of well-characterized and biomedically relevant GNPs with distinct surface (polyethylene glycol (PEG), PEG/poly(vinyl alcohol) (PEG/PVA)) and shape (spheres, rods) characteristics. Polymer-coated GNPs poorly interacted with B lymphocytes, in contrast to uncoated GNPs. Importantly, none of the GNPs significantly affected cell viability, even at the highest concentration of 20 µg/mL over a 24 h suspension exposure period. Furthermore, none of the nanosphere formulations affected the expression of activation markers (CD69, CD86, MHC II) of the naive B lymphocytes, nor did they cause an increase in the secretion of pro-inflammatory cytokines ( i.e. , IL-6, IL-1ß). However, the absence of polymer coating on the sphere GNPs and the rod shape caused a decrease in IL-6 cytokine production by activated B lymphocytes, suggesting a functional impairment. With these findings, the present study contributes imperative knowledge toward the safe-by-design approaches being conducted to benefit the development of nanomaterials, specifically those as theranostic tools.

Systematic in vivo study of NiO nanowires and nanospheres: biodegradation, uptake and biological impacts.

High aspect ratio nanomaterials (NM) have a promising future in medicine and industry as a unique category of NM. Consequently, it is important to evaluate their potential biological side-effects before crediting their use. To understand the mechanisms of degradation, internalisation, and interaction with different biological targets, we used the in vivo model Drosophila melanogaster to obtain a systematic and complete study on high aspect ratio Ni nanowires (NiNW), compared with low aspect ratio Ni nanospheres (NiNS), and NiSO4 as a model of agent releasing nickel ions. The distinguished shape of nanowires showed changes in their characteristics after oral administration until they reached the intestinal lumen, where their diameter decreased significantly. For the first time, we confirmed the internalization of needle-shaped materials via perforation of the intestinal barrier. Moreover, the results showed that D. melanogaster is a valid and effective tool in studies related to magnetic resonance imaging (MRI). Additionally, NiNM induced DNA damage and molecular changes at the gene expression level, in association with increase in oxidative stress levels. Notably, the observed negative effects were related to nickel as a metal rather than to its shape, since the effects induced by the three Ni forms were notably similar. In addition, independent of their form, Ni compounds did not induce toxic or mutagenic impacts. Our Drosophila model can be used to understand different phenomena related to high aspect ratio NM exposure, such as degradation, internalization and interaction with different targets.

Effects of differently shaped TiO2NPs (nanospheres, nanorods and nanowires) on the in vitro model (Caco-2/HT29) of the intestinal barrier.

BACKGROUND: The biological effects of nanoparticles depend on several characteristics such as size and shape that must be taken into account in any type of assessment. The increased use of titanium dioxide nanoparticles (TiO2NPs) for industrial applications, and specifically as a food additive, demands a deep assessment of their potential risk for humans, including their abilities to cross biological barriers. METHODS: We have investigated the interaction of three differently shaped TiO2NPs (nanospheres, nanorods and nanowires) in an in vitro model of the intestinal barrier, where the coculture of Caco-2/HT29 cells confers inherent intestinal epithelium characteristics to the model (i.e. mucus secretion, brush border, tight junctions, etc.). RESULTS: Adverse effects in the intestinal epithelium were detected by studying the barrier's integrity (TEER), permeability (LY) and changes in the gene expression of selected specific markers. Using Laser Scanning Confocal Microscopy, we detected a different behaviour in the bio-adhesion and biodistribution of each of the TiO2NPs. Moreover, we were able to specifically localize each type of TiO2NPs inside the cells. Interestingly, general DNA damage, but not oxidative DNA damage effects, were detected by using the FPG version of the comet assay. CONCLUSIONS: Results indicate different interactions and cellular responses related to differently shaped TiO2NPs, nanowires showing the most harmful effects.

Mesoporous silica nanorods for improved oral drug absorption.

Mesoporous silica nanoparticles (MSNs) have been widely used in biomedical applications. However, most studies have been limited to spherical MSNs, while non-spherical MSNs have never been rigorously studied. In this study, we fabricated mesoporous silica nanospheres (MSNSs) and mesoporous silica nanorods (MSNRs), with different aspect ratios (ARs) but identical surface chemistries to explore the shape effects of MSNs on oral delivery. The results of cellular studies demonstrated that MSNRs exhibited a higher cellular uptake than MSNSs. Mechanistic studies showed that caveolae-mediated endocytosis was involved in the uptake of MSNRs, while the clathrin-dependent pathway contributed to the endocytosis of MSNSs. Meanwhile, the apparent permeability coefficient value (Papp) of doxorubicin hydrochloride (Dox)-loaded MSNRs was approximately 1.8-, 3.2- and 6.3-fold higher than that of Dox-loaded MSNS1, Dox-loaded MSNS2 and Dox solution, respectively. The in vivo pharmacokinetics study showed that the area under the plasma concentration-time curve (AUC) achieved by Dox-loaded MSNRs was 1.9-, 3.4- and 5.7-fold higher than the corresponding values for Dox-loaded MSNS1, MSNS2 and Dox solution, respectively. Taken together, our results demonstrated that tuning nanoparticle shape potentially determines the biological fate of nanoparticles with higher delivery efficiency, such as enhanced cellular uptake and oral bioavailability.

Facile synthesis of highly biocompatible folic acid-functionalised SiO2 nanoparticles encapsulating rare-earth metal complexes, and their application in targeted drug delivery.

Mesoporous silica core-shell nanospheres encapsulating a rare-earth metal complex (RC) were first synthesised through a facile W/O (water in oil) inverse microemulsion method. In order to achieve targeted complex delivery, folic acid (FA) was used as the targeting component due to its high affinity for over-expressed folate receptors (FRs) in cancer cells. The RC2@SiO2-FA nanospheres were characterised via ultraviolet-visible light absorption spectroscopy (UV-vis spectroscopy), dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A microwave method was used to synthesise five RC cores based on 4-chlorophenoxyacetic acid, and their crystal structures were further confirmed using X-ray diffraction. The five RC cores have the following chemical formulae: [Er2(p-CPA)6(H2O)6] RC1, [Ho2(p-CPA)6(H2O)6] RC2, [Sm(p-CPA)3(H2O)] RC3, [Pr(p-CPA)3(H2O)]·3H2O RC4 and [Ce(p-CPA)3(H2O)2]·2H2O RC5. The carboxyl groups showed two kinds of coordination modes, namely µ2-η1:η1 and µ2-η1:η2, among RC1-RC5. The flexible -OCH2COO- spacer group, which can undergo rotation of its C-O and C-C bonds, offered great potential for structural diversity. In vivo experiments revealed that the nanospheres exhibited no obvious cytotoxicity on HepG2 cells and 293 T cells, even at concentrations of up to 80 µg mL-1. Nevertheless, all of the RC cores showed a certain degree of anti-tumour efficacy; in particular, RC2 showed the strongest cytotoxicity against HepG2 cells. Interestingly, the cytotoxicity of all of the RC2@SiO2-FA nanospheres was higher than that of lone RC2. These types of FA-targeted mesoporous silica nanocarriers can be used for the delivery of anti-tumour RC, and provide a basis for the further study of affordable non-platinum-based complexes.

Acute and long-term effects of trophic exposure to silver nanospheres in the central nervous system of a neotropical fish Hoplias intermedius.

Nanotechnologies are at the center of societal interest, due to their broad spectrum of application in different industrial products. The current concern about nanomaterials (NMs) is the potential risks they carry for human health and the environment. Considering that NMs can reach bodies of water, there is a need for studying the toxic effects of NMs on aquatic organisms. Among the NMs' toxic effects on fish, the interactions between NMs and the nervous system are yet to be understood. For this reason, our goal was to assess the neurotoxicity of polyvinylpyrrolidone coated silver nanospheres [AgNS (PVP coated)] and compare their effects in relation to silver ions (Ag+) in carnivorous Hoplias intermedius fish after acute and subchronic trophic exposure through the analysis of morphological (retina), biochemical (brain) and genetic biomarkers (brain and blood). For morphological biomarkers, damage by AgNS (PVP coated) in retina was found, including morphological changes in rods, cones, hemorrhage and epithelium rupture, and also deposition of AgNS (PVP coated) in retina and sclera. In the brain biomarkers, AgNS (PVP coated) did not disturb acetylcholinesterase activity. However, lowered migration of the DNA tail in the Comet Assay of blood and brain cells was observed for all doses of AgNS (PVP coated), for both acute and subchronic bioassays, and in a dose-dependent manner in acute exposure. Ag+ also reduced the level of DNA damage only under subchronic conditions in the brain cells. In general, the results demonstrated that AgNS (PVP coated) do not cause similar effects in relation to Ag+. Moreover, the lowered level of DNA damage detected by Comet Assay suggests that AgNS (PVP coated) directly interacts with DNA of brain and blood cells, inducing DNA-DNA or DNA-protein crosslinks. Therefore, the AgNS (PVP coated) accumulating, particularly in the retina, can lead to a competitive disadvantage for fish, compromising their survival.

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

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

Evaluation of silver nanospheres on viability and innate cellular parameters of gilthead seabream (Sparus aurata L.) head-kidney leucocytes.

The increasing use of nanomaterials, e.g. nanosilver, has lead to concerns about environmental contamination and possible toxic effects on aquatic organisms. Here, we present evidence for the impact of silver nanospheres (AgNSs) on fish innate immune cells after in vitro exposure. AgNSs of 20, 50 or 100 nm in diameter were tested with the smallest ones (20 nm) clearly having the most deleterious effects, after an exposure period of 30 min, followed by the medium-sized ones; the NSs of 100 nm had no impact. The effective concentration was determined at 10 µg ml-1 while lower concentrations (1, 2.5 or 5 µg ml-1) were ineffective. Head-kidney mixed leucocyte population showed significant viability reduction which was attributable to diminished viability of macrophages/monocytes and lymphocytes only whereas granulocytes' viability was not affected at the above exposure regime. Furthermore, cellular respiratory burst activity, phagocytic capacity and phagocytic ability were all reduced, with the first two parameters exhibiting the sharper reductions. Finally, transmission electron microscopy revealed that the AgNSs' internalization was brought about via phagocytosis, pinocytosis, receptor-mediated endocytosis and macropinocytosis; also, that cell death could be effected in either an apoptotic or a necrotic manner. It is concluded that AgNSs are potentially very noxious for the teleost fish immune system as they can adversely affect the function and viability of the head-kidney leucocytes.