Copper-based metal–organic framework decorated by CuO hair-like nanostructures: Electrocatalyst for oxygen evolution reaction

We report a Cu-based metal–organic framework (MOF) decorated by CuO nanostructures as an efficient catalyst for the oxygen evolution reaction (OER). MIL-53(Cu) was synthesized by a hydrothermal approach using 1,4-bezenedicarboxylic acid as organic precursor and further annealed at 300°C to form CuO nanostructures on its surface. The produced electrocatalyst, CuO@MIL-53(Cu), was characterized using various techniques. Under alkaline conditions, the developed electrocatalyst exhibited an overpotential of 801 and 336 mV versus RHE at 10 and 1 mA cm⁻², respectively. The reproducibility of the catalytic performance was validated using several electrodes. It was confirmed that the CuO hair-like nanostructures grown on MIL-53(Cu) using thermal treatment exhibit high OER activity, good kinetics and durability. CuO@MIL-53(Cu) is an economic noble-metal-free OER electrocatalyst. It has potential for application as anode material for sustainable energy technologies like batteries, fuel cells and water electrolysis.     

Alizarin-modified sulfonate carbon nanoparticles in vanadium sensing

The adsorption processes of alizarin onto hydrophilic carbon nanoparticles (Emperor 2000?) are investigated. The significant increase in voltammetric responses for pre-adsorbed alizarin compared with those for solution confirms high affinity of alizarin to carbon nanoparticles (possibly due to π–π stacking interaction between aromatic rings of alizarin and surface-sulfonated carbon nanoparticles). To obtain the optimum of adsorption conditions, the effects of pH, agitation rate, and adsorption time are investigated. Under square wave voltammetry conditions, the peak current for the reduction of alizarin shows a linear relationship with concentration in the range from 2.0 to 10.0 nM. The limit of detection is estimated 5.8?×?10^?9 mol L^?1. Next, alizarin is applied as a receptor for sensing of trace vanadium in acetate buffer pH 5. Linear calibration curves are obtained for vanadium in the range of 1.0?×?10^?6 to 1.0?×?10^?4 mol L^?1 and the limit of detection is estimated 9.6?×?10^?8 mol L^?1. Determination of vanadium in real samples such as sea and tap water is demonstrated.     

Iron Oxychloride/Bovine Serum Albumin Nanosheets as Chemodynamic Therapy Agents

Iron oxychloride (FeOCl) is known for reactive oxygen species (ROS) generation through Fenton chemistry. The activity of FeOCl is preserved in the slightly acidic pH value of the tumor microenvironment (pH 6.5−6.9). Such property can be advantageous in biobased systems, where ROS generation can be modulated in slightly acidic conditions, which is characteristic of the solid tumor microenvironment. In the present study, BSA-stabilized FeOCl nanosheets (NSs) are synthesized and characterized by transmission electron microscope, Fourier transform infrared spectroscopy, zeta potential analysis, dynamic light scattering, and UV–vis spectroscopy. The morphology of the nanoparticles is flake-like, and their hydrodynamic diameter is around 200 nm. MTT, apoptosis assay, and trypan blue staining evaluate the toxicity of FeOCl NSs toward the 4T1 cell line. It is found that the toxicity of the NSs is higher in physiological conditions of solid tumors (pH 6.5, H₂O₂ 100 × 10⁻⁶ m ) than in the conditions of healthy organs (pH 7.4). Specifically, cancer cells are in their late apoptotic stage by more than eight times higher at pH 6.5 than pH 7.4. The toxicity results are in agreement with the in vitro catalytic assay of the NSs. Therefore, the FeOCl NSs can be the building blocks for constructing chemodynamic therapy agents.     

Catalytic effect of lucunary heteropolyanion containing molybdenum and tungsten atoms on decolorization of direct blue 71

In this research,a lucunary Keggin structure,[PMo₂W₉O₃₉]^7- was selected as an efficient homogenous catalyst for degradation of an azo dye（direct blue 71） and a simple method was developed for degradation of DB71.The method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates,K₇[PMo₂W₉O₃₉]? 19H₂O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H₂O₂,pH and reaction time were investigated and optimized. Results show that K₇[PMo₂W₉O₃₉]? 19H₂O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H₂O₂ could lead to the disappearance approximately 65%of dye after 60 min.But degradation for the same experiment performed in the absence of catalyst or in the absence of H₂O₂ was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H₂O₂ and optimize conditions(0.6 g/L of K₇[PMo_2- W₉O₃₉H₉H₂O,0.08 mol/L hydrogen peroxide and room temperature).     

Effect of silicon oxidation on long-term cell selectivity of cell-patterned Au/SiO2 platforms

Cellular patterning on silicon platforms is the basis for development of integrated cell-based biosensing devices, for which long-term cell selectivity and biostability remain a major challenge. We report the development of a silicon-based platform in a metal-insulator format capable of producing uniform and biostable cell patterns with long-term cell selectivity. Substrates patterned with arrays of gold electrodes were surface-engineered such that the electrodes were activated with fibronectin to mediate cell attachment and the silicon oxide background was passivated with PEG to resist protein adsorption and cell adhesion. Three types of oxide surfaces, i.e., native oxide, dry thermally grown oxide, and wet thermally grown oxide, were produced to illustrate the effect of oxide state of the surface on long-term cell selectivity. Results indicated that the cell selectivity over time differed dramatically among three patterned platforms and the best cell selectivity was found on the dry oxide surface for up to 10 days. Surface analysis results suggested that this enhancement in cell selectivity may be related to the presence of additional, more active oxide states on the dry oxide surface supporting the stability of PEG films and effectively suppressing the cell adhesion. This research offers a new strategy for development of stable and uniform cell-patterned surfaces, which is versatile for immobilization of silane-based chemicals for preparation of biostable interfaces.     

Lattice Boltzmann simulation of particles agglomeration and rheology in a particulate flow

The dynamics and rheology of particles in a Newtonian fluid subjected to shear are simulated using Lattice Boltzmann Method. A computationally-efficient Smoothed Profile Method is used to resolve fluid-solid interactions, and the Lennard-Jones inter-particle potential is implemented to account for inter-particle forces. The use of a bi-periodic computational domain with Lees-Edward boundary conditions allows simulation for systems consisting of a large number of particles under shear. The method is validated for single and dual particle problems and an analysis is performed for multi-particle problems under a range of shear rates and particle fractions. The introduction of particle-particle interactions, which are physically important in many engineering processes, is found to have a considerable impact on the dynamics, agglomeration and rheology. The total stress exhibits high unsteadiness primarily due to the solid component contribution, at higher particle fractions. The simulations underscore the complex interplay between shear, interparticle forces and agglomeration and the complex dependencies of the rheological properties.