A Comparative Study of Modified Magnetic Nano-Particles Grafted to β-yclodextrin/Thermosensitive Polymer for Removal of Diazinon and Fenitrothion from Aqueous Solution

Organophosphate pesticides such as diazinon and fenitrotion are fat-soluble, so delayed toxicity occurs if significant amounts of them are stored in adipose tissues.  These insecticides have been classified by the World Health Organization (WHO) as class II, having a moderate hazard. Therefore the preparation and use of grafted β-cyclodextrin/thermo-sensitive polymer/modified Fe3O4/SiO2 nano-particles was investigated for the removal of fenitrothion and diazinon from aqueous solution. Modified MNPs were synthesized due to increase of removal efficiency and applicability in different condition. MNPs were synthesized and characterized by using FTIR, SEM, CHN, TGA, and TEM. The effect of some operational parameters, such as pH, adsorption isotherms, sorption kinetics, concentration, reusability, adsorption/desorption temperature, and ultrasound effect on desorption were examined. The results showed that the best sorption of pesticides on the MNPs-AGENVC-CD took place at 20 °C and optimum pH of 6. The initial concentration and nano-sorbent dosage were 100 mg/L and 0.01 g, respectively. The kinetic study showed that the best time for the pesticides sorption was 90 min. Also, the Pseudo-Second-Order model used fitted the adsorption kinetics well, thus exhibiting high correlation coefficients. Pesticides sorption capacity was found to be 34 and 29 mg/g. The equilibrium data of pesticides modified by the MNPs-sorbent were correctly shown by Langmuir, Freundlich, Redlich-Peterson, and Temkin models. The data was well-fitted to Langmuir equation. The findings showed that the proposed method was very impressive, providing a significant adsorption capacity, appropriate reusability and control functions along with temperature variations

Electrostatic attraction between DNA and a cationic surfactant aggregate. The screening effect of salt

Anionic DNA and cationic surfactants form charge neutral complexes that contain finite amounts of water. There is a strong electrostatic attraction between the oppositely charged species, and the finite swelling is caused by an opposing repulsive force. Adding NaCl to the complexes provides an opportunity to modulate the strength of the electrostatic attraction. The thermodynamics of the isothermal swelling process has been experimentally characterized using a calorimetric technique monitoring both the free energy and the enthalpy. The experimental results are quantitatively analyzed in calculations using the Poisson-Boltzmann equation to describe the electrostatic effects. The main findings are as follows: (i) Addition of salt results in an increased swelling at a given water activity. (ii) The effect of the salt can be quantitatively modeled on the basis of the Poisson-Boltzmann equation with a dielectric description of the water. (iii) There exists a short-range repulsive force between DNA double helices and surfactant aggregates. (iv) Solid NaCl dissolves in the complex at water activities in the range 0.5-0.6 rather than at 0.74 as in a saturated aqueous solution. (v) The heat of solution of NaCl in the complexes is around +1.6 +/- 0.5 kJ/mol, surprisingly close to the values found for the dissolution into bulk aqueous solutions

Green biosynthesis of magnetic iron oxide nanoparticles using Mentha longifolia for imatinib mesylate delivery

Abstract In this work, the rapid, facile, and eco‐friendly green process was introduced in the preparation of β‐cyclodextrin/magnetic iron oxide nanoparticles by using the aqueous Mentha longifolia extracts of Mentha longifolia. The obtained nanoparticles were characterised by Fourier transform infrared spectroscopy, x‐ray powder diffraction, field emission scanning electron microscope, and thermogravimetric analysis. Also, effective factors on the synthesis of magnetic nanocomposites including temperature, concentration of the Mentha longifolia extract, and concentration of FeSO4 solution were optimised by Taguchi design. Moreover, important effective parameters on the adsorption efficiency; such as adsorbent dosage, pH, contact time, and temperature were investigated. The prepared magnetic nanocomposite was applied as a nanocarrier for imatinib mesylate delivery. In vitro studies confirmed imatinib mesylate release over 6 h. The nanocarrier showed pH‐dependent imatinib mesylate release with higher drug release at simulated cancer fluid (pH = 5.6) compared to neural fluid (pH = 7.4). Moreover, the sorption isotherms and kinetics for the magnetic nanocomposite were fitted into Langmuir and pseudo‐second order models, respectively. Based on the thermodynamic results, the adsorption of imatinib mesylate onto the nanoadsorbent was found to be spontaneous and exothermic

Microstructural characterization and antibacterial activity of carbon nanotube decorated with Cu nanoparticles synthesized by a novel solvothermal method

In this research, carbon nanotube decorated with Cu nanoparticles (CNT/Cu) was synthesized by a new solvothermal process. Solvothermal treatment of CuSO4 and NaOH was completed in ethanol containing ultrasonically dispersed CNTs at 160 degrees C for 3 h. In the solvothermal process, Cu nanoparticles were heterogeneously deposited on the surface of COOH-functionalized CNTs through the reduction of the Cu+2 ions. Cu nanoparticles with the size of approximate to 8 nm on CNTs (and some in the solution) and strong bonding between Cu and CNT were obtained by the used process. Microstructural characterization revealed that the solvothermal method is an appropriate method for producing homogenous CNT/Cu nanostructure. Also, the antibacterial activity of the synthesized powder was investigated by disc diffusion, direct contact and colony counting methods. CNT/Cu nanopowder inhibited bacteria growth within the tested concentration range, while CNTs did not show any considerable antibacterial response. Minimum inhibitory concentration and minimum bactericidal concentration of CNT/Cu nanopowder were 500 mu g/ml and 250 mu g/ml against E. coli, and 250 mu g/ml and 125 mu g/ml against S. aureus, respectively. S. aureus was more sensitive than E. Coli to CNT/Cu nanopowder which can be attributed to the absence of a cell wall in gram positive bacteria