High-Performance Novel MoS2@Zeolite X Nanocomposite-Modified Thin-Film Nanocomposite Forward Osmosis Membranes: A Study of Desalination and Antifouling Performance

Novel thin-film nanocomposite (TFN) membranes modified by the MoS2@Zeolite X nanocomposite were made and studied for desalination by the forward osmosis (FO) method. Herein, MoS2@Zeolite X nanocomposite (MoS2@Z) and zeolite X particles are integrated into the polyamide (PA) selective layer of the TFN membranes, separately. The aim of this study is the synthesis of nanocomposites containing hydrophilic zeolite X particles with a modified surface and pore and improvement of their effective properties on desalination and antifouling performance. For this purpose, MoS2 nanosheets with a high hydrophilicity were selected. The existence of polymer-matrix-compatible MoS2@Z inside the PA active layer caused the formation of a defect-free smooth surface with further channels within this layer that could increase the water flux and fouling resistance of the TFN membranes. The TFN-MZ2 membrane (containing 0.01 wt % MoS2@Z) showed the top desalination performance in the FO process. In contrast to the pristine thin-film composite (TFC) and TFN-Z2 membrane (containing 0.025 wt % zeolite X, the most optimal membrane among the zeolite-modified membranes), its water flux has increased by 2.6 and 1.8 times, respectively. Furthermore, in the fouling test, this optimal TFN-MZ2 membrane with a flux decrement of 19.6% revealed an ∼2.2- and 1.8-fold enhancement in antifouling tendency compared to the TFC and TFN-Z2, respectively. Also, based on the antibiofouling test, the water flux drop of 48.6% for the TFC membrane has reached 36.9% for the optimal membrane. Hence, this high-performance TFN-MZ2 membrane shows good capability for commercial employment in FO desalination application.

Fabrication of a magnetic alginate-silk fibroin hydrogel, containing halloysite nanotubes as a novel nanocomposite for biological and hyperthermia applications

In this study, the main focus was on designing and synthesizing a novel magnetic nanobiocomposite and its application in hyperthermia cancer treatment. Regarding this aim, sodium alginate (SA) hydrogel with CaCl₂ cross-linker formed and modified by silk fibroin (SF) natural polymer and halloysite nanotubes (HNTs), followed by in situ Fe₃O₄ magnetic nanoparticles preparation. No important differences were detected in red blood cells (RBCs) hemolysis, confirming the high blood compatibility of the treated erythrocytes with this nanobiocomposite. Moreover, the synthesized SA hydrogel/SF/HNTs/Fe₃O₄ nanobiocomposite does not demonstrate toxicity toward HEK293T normal cell line after 48 and 72 h. The anticancer property of SA hydrogel/SF/HNTs/Fe₃O₄ nanobiocomposites against breast cancer cell lines was corroborated. The magnetic saturation of the mentioned magnetic nanobiocomposite was 15.96 emu g⁻¹. The specific absorption rate (SAR) was measured to be 22.3 W g⁻¹ by applying an alternating magnetic field (AMF). This novel nanobiocomposite could perform efficiently in the magnetic fluid hyperthermia process, according to the obtained results.

Curcumin-reduced graphene oxide sheets and their effects on human breast cancer cells

Curcumin (as a natural reductant material) was utilized for green reduction and functionalization of chemically exfoliated graphene oxide (GO) sheets. The π-π attachment of the curcumin molecules onto the curcumin-reduced graphene oxide (rGO) sheets was confirmed by Raman and Fourier transform infrared spectroscopies. Zeta potential of the GO sheets decreased from about -40 mV to -20 mV, after the green reduction and functionalization. The probable cytotoxicity of the curcumin-rGO sheets was studied through their interactions with two human breast cancer cell lines (MDA-MB-231 and SKBR3 cell lines) and a normal cell line (mouse fibroblast L929 cell line). The curcumin-rGO sheet with concentrations <70 μg/mL in the cell culture medium, not only exhibited no significant toxicity and/or cell morphological changes, but also caused some cell growths (~25% after 48 h incubation time). Nevertheless, at 70 μg/mL, initiation of some cell morphological changes was observed. At higher concentrations (e.g., 100 μg/mL), some slight cytotoxic effects (resulting in ~15-25% cell destruction) were detected by MTT assay. In addition, the interaction of the rGO sheets and cells resulted in apoptosis as well as morphological transformation of the cells (from elongated to roundup morphology). These results indicated the concentration-dependent toxicity of functionalized-rGO nanomaterials (here, curcumin-rGO) at the threshold concentration of ~100 μg/mL.

Mechanical properties of graphene cantilever from atomic force microscopy and density functional theory

We have studied the mechanical properties of a few-layer graphene cantilever (FLGC) using atomic force microscopy (AFM). The mechanical properties of the suspended FLGC over an open hole have been derived from the AFM data. Force displacement curves using the Derjaguin-Müller-Toporov (DMT) and the massless cantilever beam models yield a Young modulus of E(c) approximately 37, E(a) approximately 0.7 TPa and a Hamakar constant of approximately 3 x 10( - 18) J. The threshold force to shear the FLGC was determined from a breaking force and modeling. In addition, we studied a graphene nanoribbon (GNR), which is a system similar to the FLGC; using density functional theory (DFT). The in-plane Young's modulus for the GNRs were calculated from the DFT outcomes approximately 0.82 TPa and the results were compared with the experiment. We found that the Young's modulus and the threshold shearing force are dependent on the direction of applied force and the values are different for zigzag edge and armchair edge GNRs.

Synthesis and photocatalytic activity of WO(3) nanoparticles prepared by the arc discharge method in deionized water

In this paper, we discuss the synthesis and characterization of tungsten trioxide nanoparticles prepared by the arc discharge method in deionized (DI) water. The size and morphology of WO(3) nanoparticles prepared using different arc currents (25, 35 and 45 A) were studied. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) results indicate that at an arc current of 25 A, the size of the particles is about 30 nm, and this increases to 64 nm by increasing the arc current. This size increase caused a decrease of optical band gap from 2.9 to 2.6 eV. X-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) spectra demonstrate the formation of the WO(3) phase. Photodegradation of Rhodamine B shows that samples prepared at the lowest current have more photocatalytic activity due to having the smallest particle size and highest surface area. The results demonstrate the ability of the arc discharge method for direct formation of WO(3) nanoparticles in DI water medium.