Neurotoxic and behavioral deficit in Drosophila melanogaster exposed to photocatalytic products of Paraquat.

The Advanced Oxidative Processes have demonstrated potential for application in the degradation of organic pollutants, such as Paraquat (PQ) from water and wastewater, due to their low price, high efficiency, and non-toxic properties. In this study, we investigated whether the photodegradation of PQ with TiO2 nanotubes reduced its toxicity in Drosophila melanogaster. However, dietary ingestion of degradation products PQ for larvae resulted in a low axial ratio (pupal volume). In the adults, products of photodegradation of PQ exposure markedly diminished climbing ability in a time-dependent manner after 10 days of feeding. In addition, exposure of D. melanogaster to photodegradation of PQ reduced acetylcholinesterase and citrate synthase activities but improved oxidative stress, as evidenced by oxide nitric, protein carbonyl, and lactate production. These results suggest that the photodegradation of PQ with TiO2 nanotubes produced PQ fragments with higher toxicity than PQ, while the precise mechanism of its action needs further investigation.

Effects of multi-walled carbon nanotubes and halloysite nanotubes on plasma lipid profiles and autophagic lipolysis pathways in mouse aortas and hearts.

Multi-walled carbon nanotubes (MWCNTs) and halloysite nanotubes (HNTs) are widely used tubular-structured nanomaterials (NMs), but their cardiovascular effects are not clear. This study compared the effects of MWCNTs and HNTs on lipid profiles in mouse plasma and gene expression profiles in aortas and hearts. Mice were intravenously injected with 50 µg NMs, once a day, for 5 days. Then, the plasma was collected for lipidomics analysis, and aortas and hearts were collected for RNA-sequencing analysis. While MWCNTs or HNTs did not induce obvious pathological changes in aortas or hearts, the lipid profiles in mouse plasma were altered. Further analysis revealed that MWCNTs more effectively upregulated sphingolipids and sterol lipids, whereas HNTs more effectively upregulated glycerophospholipids and fatty acyls. Consistently, RNA-sequencing data indicated that MWCNTs and HNTs altered signaling pathways related with lipid synthesis and metabolism, as well as those related with endoplasmic reticulum, lysosomes and autophagy, more significantly in aortas than in hearts. We further verified the changes of proteins involved in autophagic lipolysis, that MWCNTs were more effectively to suppress the autophagic biomarker LC3, whereas HNTs were more effectively to affect lipid metabolism proteins. These results may provide novel understanding about the influences of MWCNTs and HNTs on lipid profiles and lipid signaling pathways in cardiovascular systems. Importantly, previous studies considered HNTs as biocompatible materials, but the results from this study suggested that both MWCNTs and HNTs were capable to affect lipid profiles and autophagic lipolysis pathways in cardiovascular systems, although their exact influences were different.

Biodistribution and Toxicological Effects of Ultra-Small Pt Nanoparticles Deposited on Au Nanorods (Au@Pt NRs) in Mice with Intravenous Injection.

Purpose: Pt-based nanostructures are one of the promising nanomaterials for being used in catalysts, sensors, and therapeutics. However, their impacts on the health and biological systems are not adequately understood yet. Methods: In this work, nanorods composed of ultrasmall platinum (Pt) nanoparticles deposited on the surface and gold nanorod as the core (Au@Pt NRs) were synthesized, and the distribution and toxic effects of Au@Pt NRs were investigated in C57BL/6 mice with intravenous injection by using atomic absorption spectroscopy (AAS), transmission electron microscope (TEM), hematoxylin-eosin (HE) staining and blood cell analyzer. Results: At the time point of Day 1, Day 8 and Day 16 post injection of Au@Pt NRs (6 mg/kg of Pt atom), Au@Pt NRs were mainly accumulated in the liver and spleen. The energy dispersive spectrometer mapping images showed Au@Pt NRs experienced quick corrosion and Au released faster than Pt in the physiological environments. The catalase (CAT) activity in tissues increased slightly in the early stage of the Au@Pt NRs exposure and went down to the normal level. With HE staining, inflammatory cells infiltration could be seen in the tissues, while no significant influences were detected on the blood biochemistry and the function of liver and kidney. Conclusion: In conclusion, intravenously injected Au@Pt NRs mainly distributed in the liver and spleen with comparable levels, and did not exert any significant toxic effects on the organs' function within two weeks; meanwhile, Au@Pt NRs were able to degrade, which indicated acceptable safety to the mice and potentials of biomedical application.

Influence of Impurities from Manufacturing Process on the Toxicity Profile of Boron Nitride Nanotubes.

The toxicity of boron nitride nanotubes (BNNTs) has been the subject of conflicting reports, likely due to differences in the residuals and impurities that can make up to 30-60% of the material produced based on the manufacturing processes and purification employed. Four BNNTs manufactured by induction thermal plasma process with a gradient of BNNT purity levels achieved through sequential gas purification, water and solvent washing, allowed assessing the influence of these residuals/impurities on the toxicity profile of BNNTs. Extensive characterization including infrared and X-ray spectroscopy, thermogravimetric analysis, size, charge, surface area, and density captured the alteration in physicochemical properties as the material went through sequential purification. The material from each step is screened using acellular and in vitro assays for evaluating general toxicity, mechanisms of toxicity, and macrophage function. As the material increased in purity, there are more high-aspect-ratio particulates and a corresponding distinct increase in cytotoxicity, nuclear factor-κB transcription, and inflammasome activation. There is no alteration in macrophage function after BNNT exposure with all purity grades. The cytotoxicity and mechanism of screening clustered with the purity grade of BNNTs, illustrating that greater purity of BNNT corresponds to greater toxicity.

Prokaryotic and eukaryotic toxicity of halloysite decorated with photoactive nanoparticles.

The development of new approaches to treat the growing antibiotic resistance of pathogenic bacterial species is an important task to ensure the future safety of society. Utilization of irradiation of different wavelengths together with nanostructured materials based on metal containing nanoparticles may result in synergetic antibacterial effects. In this paper we aim to show the main conceptions of light-assisted bacteria deactivation techniques and prospects of application of natural clay nanotubes as a carrier for scalable photoactive antibacterial nanomaterials. Halloysite aluminosilicate nanotubes (ca 50 nm diameter, ca. 1.0 µm length) are safe and biocompatible natural materials produced in tons. Their application as a template or a carrier for metal nanoparticles, QDs and organic compounds has already found application in biomedical research, cosmetics, polymers, coatings, catalysis and related applications. Here, we show the toxicity of halloysite decorated with photoactive nanoparticles on prokaryotic and eukaryotic cells. The formation of light active nanostructured materials with this clay as the base is a promising tool for solving the problem of the antibiotic resistance of microorganisms.

Toxicity of titanate nanotubes in earthworm (Eisenia fetida): Growth inhibition and integrated biomarker response.

Widely use of Titanate Nanotubes (TNTs) as remediation materials for heavy metal polluted water and soil lead to their release into the soil environment, persistently threatening faunal biodiversity and the entire environment. Growth inhibition rates (GIR) and specific growth rates (SGR) are used to evaluate the effect of TNTs on earthworm growth, and the integrated biomarker response (IBR) index is used to comprehensively evaluate the toxicity of eight biomarkers (Protein-body mass ratio, MDA, SOD, CAT, POD, Cellulase, AChE, and Na+/K+-ATPase) on earthworms exposed to TNTs contaminated soil by concentrations of CK, 50, 250, 500 and 2500 mg TNTs/kg dry soil. Results show that TNTs significantly inhibit the growth of earthworms (p < 0.05), and GIR reaches up to 52.34 % at 2500 mg TNTs/kg dry soil for 28 days. IBR index has a dose-time relationship, which indicates that exposure time and concentration of TNTs contaminated soil affect the toxicity degree of contaminant to earthworms.

Mechanism of MnO2 nanorods toxicity in marine microalgae Chlorella sorokiniana during long-term exposure.

Due to the increasing production and use of nanomaterials (NMs), their potential toxic impacts on the environment should be considered for a safe application of NMs. In this regard, the potential hazards of MnO2 nanorods (NRs) on the green microalgae Chlorella sorokiniana during long-term exposure were investigated. Exposure to the high concentration of MnO2 NRs (100 and 200 mg L-1) significantly reduced the cell number of C. sorokiniana over 20 days of the experiment. The different concentrations of MnO2 NRs (25-200 mg L-1) induced the remarkable increase in the chlorophyll (a+b) content of algal cells due to the shading effect of NRs. For more than 72 h, the chlorophyll content of microalgae decreased due to the aggregation of NRs and the possible effects of oxidative stress. Long-term exposure to high concentrations of NRs caused a significant decrease in the primary and secondary metabolites of microalgae, including carotenoids, phenolic compounds, proteins, lipids, and carbohydrates. Oxidative stress was one of the possible toxic mechanisms of MnO2 NRs to microalgae validated by an increase in lipid peroxidation induced by exposure to NRs. The algal cells increased the catalase activity and the amount of extracellular polymeric substances in response to NRs toxicity. The low level of Mn ions in the culture media indicated that MnO2 NRs dissolution was not the cause of the observed reduction in the microalgae growth. Moreover, the bulk form of MnO2 was not involved in the toxic impact of MnO2, which was documented by an insignificant decrease in the growth, pigment, and lipid peroxidation of C. sorokiniana. These results may provide an additional insight into the potential hazards of MnO2 NRs on the aquatic ecosystem.

In vitro and in vivo MRI imaging and photothermal therapeutic properties of Hematite (α-Fe2O3) Nanorods.

Herein we report synthesis of hematite (α-Fe2O3) nanorods by calcinating hydrothermally synthesized goethite nanorods at 5000C. The structural, optical and MRI imaging guided cancer therapeutic properties of fabricated nanorods have been discussed in this manscript. FESEM and TEM imaging techniques were used to confirm the nanorod like morphology of as prepared materials. As we know that Fe2O3 nanorods with size in the range of 25-30 nm exhibit super magnetism. After coating with the PEG, the as prepared nanorods can be used as T2 MR imaging contrast agents. An excellent T2 MRI contrast of 38.763 mM-1s-1 achieved which is highest reported so far for α-Fe2O3. Besides the as prepared nanorods display an excellent photothermal conversion efficiency of 39.5% thus acts as an excellent photothermal therapeutic agent. Thus, we envision the idea of testing our nanorods for photothermal therapy and MR imaging application both in vitro and in vivo, achieving an excellent T2 MRI contrast and photothermal therapy effect with as prepared PEGylated nanorods.

Preparation, toxicity reduction and radiation therapy application of gold nanorods.

Gold nanorods (GNRs) have a broad application prospect in biomedical fields because of their unique properties and controllable surface modification. The element aurum (Au) with high atomic number (high-Z) render GNRs ideal radiosensitive materials for radiation therapy and computed tomography (CT) imaging. Besides, GNRs have the capability of efficiently converting light energy to heat in the near-infrared (NIR) region for photothermal therapy. Although there are more and more researches on GNRs for radiation therapy, how to improve their biocompatibility and how to efficiently utilize them for radiation therapy should be further studied. This review will focuse on the research progress regarding the preparation and toxicity reduction of GNRs, as well as GNRs-mediated radiation therapy.

Magnetic α-Fe2O3/Fe3O4 Heterostructure Nanorods: Fabrication and Cytotoxicity to A549 Cells.

The magnetic α-Fe2O3/Fe3O4 heterostructure nanorods were fabricated by an alcohol-solution direct combustion method. The influence of the calcination temperature on the composition and properties of the nanorods was investigated. When the calcination temperature was not greater than 400 °C, the magnetic α-Fe2O3/Fe3O4 heterostructure nanorods were obtained, and the saturation magnetization (Ms) of the magnetic α-Fe2O3/Fe3O4 heterostructure nanorods decreased with the calcination temperature increasing from 250 °C to 400 °C; when the calcination temperature was equal or greater than 450 °C, α-Fe2O3 nanorods were obtained. In addition, the effects of nanorods' concentration, nanorods' constituent, incubation time and magnetic field on A549 cytotoxicity were investigated. The cytotoxicity of the heterostructure nanorods appeared time-dependent and concentration-dependent, and the magnetic field could enhance the cytotoxicity of nanorods to A549.