Comparative Toxicity of TiO2 and Sn-Doped TiO2 Nanoparticles in Zebrafish After Acute and Chronic Exposure.

This study was conducted to assess the toxicological potential of synthesized pure and Sn-doped TiO2 NPs (Sn-TiO2 NPs) in zebrafish after acute and chronic exposure. The pure TiO2 NPs, 4%, and 8% Sn-TiO2 NPs were synthesized and characterized using X-ray diffraction, Scanning Electron Microscope, diffuse reflectance spectra, dynamic light scattering, and zeta potential analyses. The pure TiO2 NPs, 4%, and 8% Sn-TiO2 NPs were spherical with average sizes of about 40, 28, and 21 nm, respectively, indicating significant size reduction of TiO2 NPs following Sn doping. According to our results, the LC50-96h increased in the order of 8% Sn-TiO2 NPs (45 mg L-1) < 4% Sn-TiO2 NPs (80.14 mg L-1) < pure TiO2 NPs (105.47 mg L-1), respectively. Exposure of fish to Sn-TiO2 NPs after 30 days resulted in more severe histopathological alterations in gills, liver, intestine, and kidneys than pure TiO2 NPs. Furthermore, Sn-doping significantly elevated malondialdehyde levels and micronuclei frequency, indicating increased oxidative stress and genotoxicity. Expression analysis revealed altered expression of various genes, including upregulation of pro-apoptotic Bax gene and downregulation of anti-apoptotic Bcl-2 gene, suggesting potential induction of apoptosis in response to Sn-doped NPs. Additionally, antioxidant genes (Gpx, Sod, Cat, and Ucp-2) and stress response gene (Hsp70) showed altered expression, suggesting complex cellular responses to mitigate the toxic effects. Overall, this study highlights the concerning impact of Sn-doping on the toxicity of TiO2 NPs in zebrafish and emphasizes the need for further research to elucidate the exact mechanisms underlying this enhanced toxicity.

Toxicological effects of Ag2O and Ag2CO3 doped TiO2 nanoparticles and pure TiO2 particles on zebrafish (Danio rerio).

In this study, the toxic effects of silver oxide and silver carbonate doped TiO2 nanoparticles (Ag2O-TiO2 NPs and Ag2CO3-TiO2NPs), TiO2 nanoparticles (TiO2 NPs), and bulk TiO2 on gene expression, lipid peroxidation, genotoxicity, and histological alterations in zebrafish (Danio rerio) was assessed. The physicochemical properties of the synthesized nanoparticles were evaluated by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), diffuse reflectance spectroscopy (DRS), dynamic light scattering (DLS), and Zeta potential analyses. TiO2NPs after doping with Ag showed shift to higher wavelengths and decrease of band gap energy. Also, remarkable reduction in the size of Ag-doped TiO2NPs in comparison with the TiO2 NPs was observed. According to our results, acute toxicity increased in the order of bulk TiO2 < TiO2 NPs < Ag2O-TiO2NPs < Ag2CO3-TiO2NPs, respectively. Results of sub-lethal experiments after 30 days of exposure, showed higher expression of Gpx, Hsp70, Ucp-2, and Bax genes, and lower expression of Bcl-2 gene in Ag-doped TiO2NPs than pure TiO2 particles (TiO2 NPs and bulk TiO2) treatments (p < 0.05). However, the mRNA levels of SOD and CAT genes were significantly higher in pure TiO2 particles than doped TiO2NPs (p < 0.05). Moreover, levels of malondialdehyde, abnormalities of peripheral blood cells and severity of histological lesions in liver, gill, intestine and kidney tissues were more evident in Ag-dopedTiO2 NPs than pure TiO2 particles. It can be concluded that Ag doping of TiO2 NPs significantly increased their toxicity and resulted in more histological lesions, apoptosis and oxidative stress than pure TiO2 particles in adult zebrafish.

Approach to the Synthesis of Unsymmetrical/Symmetrical Maleimides via Desulfitative Arylation at Different Temperatures.

New routes toward selective synthesis of both mono- and diaryl maleimides have been innovated. The mere requirement to this end is through the increase of temperature. The method works effectively for maleic anhydride and maleic acid as well. Also, the first expedient synthesis of 2-arylnaphthoquinones via the reaction of naphthoquinone with arenesulfonyl chlorides is revealed.

A metal-catex composite electrode for determination of paraquat in various samples by Ad-differential pulse cathodic stripping voltammetry.

In this work, a novel kind of metal-catex composite electrode for determination of paraquat (PQ) by adsorptive differential pulse voltammetry is introduced. The metal-catex composite electrode was fabricated by cathodic electropolymerization of p-nitrophenol and p-nitrobenzoic acid in the presence of tin (II) chloride as a scaffold for composite structure on prepared glassy carbon electrode. Electropolymerization was carried out in sodium acetate medium. The surface of the fabricated electrode was characterized with field emission scanning electron microscope and energy-dispersive X-ray spectrometry. The obtained results show that there are Sn nanoparticles in the structure of the catex-composite. Chemical structure of metal-catex composite electrode was investigated using FTIR (ATR), 13C NMR, H NMR and a suitable mechanism for electropolymerization has been proposed. This metal-catex composite electrode was applied for determinations of PQ using sodium acetate buffer solutions at pH = 6.5 as an electrolyte solution. All parameters influencing the performance of the fabricated electrode were studied and optimized. The proposed electrode exhibits good linearity versus PQ concentration in the range of 3.8 × 10-8 to 7.7 × 10-7 mol L-1 and shows a manifold increase in sensitivity (more than 30 times) as compared to the glassy carbon electrode. The LOQ of this electrode was 7.78 × 10-9 mol L-1, which is comparable with that of other electrochemical methods. The mean, standard deviation and relative standard deviation for seven repetitive determinations of paraquat (7.78 × 10-8 mol L-1) were measured to be 7.75 × 10-8 mol L-1, ±0.29 × 10-8 mol L-1, and 3.75% respectively. This electrode was applied for the determination of paraquat in natural water, natural juice, potatoes and onions. The introduced electrode shows good stability with repeated use and over long periods (about 20 days). There is a good agreement between the results for water analysis by this method and the standard method.

C-H Activation under the Guise of Diels-Alder Reaction: Annulation toward the Synthesis of Benzo[e]isoindole-1,3-diones.

A new paradigm in the coupling of external alkenes with internal electron-deficient alkenes has been investigated in which an unprecedented annulation of vinylarenes on maleimides takes place. The reaction is carried out via a tandem in situ activation of both olefinic and aromatic C-H bonds of styrenes driving the reaction in a pseudo-Diels-Alder mode.

Experimental study of the removal of copper ions using hydrogels of xanthan, 2-acrylamido-2-methyl-1-propane sulfonic acid, montmorillonite: Kinetic and equilibrium study.

In this paper, removal of copper ions from aqueous solution using novel xanthan gum (XG) hydrogel, xanthan gum-graft-2-acrylamido-2-methyl-1-propane sulfonic acid (XG-g-P(AMPS)) hydrogel and xanthan gum-graft-2-acrylamido-2-methyl-1-propane sulfonic acid/montmorillonite (XG-g-P(AMPS)/MMT) hydrogel composite were studied. The structure and morphologies of the xanthan-based hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Adsorbents comprised a porous crosslink structure with side chains that carried carboxyl, hydroxyl and sulfonate. Maximum adsorption was observed in the pH=5.2, initial concentrations of Cu(2+)=321.8 mg/L, Temperature=45 °C, contact time=5 h with 0.2 g/50 mL of the hydrogels. Adsorption process was found to follow Langmuir isotherm model with maximum adsorption capacity of 24.57, 39.06 and 29.49 mg/g for the XG, XG-g-P(AMPS) and XG-g-P(AMPS)/MMT, respectively. Adsorption kinetics data fitted well with pseudo second order model. The negative ΔG° values and the positive ΔS° confirmed that the adsorption was a spontaneous process. The positive ΔH° values suggested that the adsorption was endothermic in nature.

The synthesis and spectroscopic characterization of nano calcium fluorapatite using tetra-butylammonium fluoride.

Pure homogeneous nano sized biocompatible fluorapatite (FAp) particles were synthesized by a wet chemical procedure using water soluble tetra-butylammonium fluoride (TBAF) without using high temperatures and any purification processes. Combination of the Bragg's law and the plane-spacing equation for the two high intensity lines, namely, (002) and (300), gives a=9.3531 Å, c=6.8841 Å, confirms the identity of the highly crystalline synthetic material as well as its purity. The effect of various pH's in crystal formation and on their size was also evaluated. The calculated crystallinities were excellent with a rate around 5.0. The synthesized nano FAp was fully characterized by spectroscopic techniques (XRD, SEM, EDS, BET, FT-IR and ICP-AES). The nitrogen adsorption-desorption isotherm showed a type IV diagram and calculation of the surface area was investigated as well.