Advances in Nanochemistry
Volume:1 Issue: 1, Winter and Spring 2019

In this study, we developed a selective and sensitive inner filter effect-based method by thioglycolic acid capping CdTe quantum dots (TGA-CdTe QDs) for the quantitative determination of Vitamin B12 (B12). The effect of all experimental parameters and possible interference agents for determination of B12 by TGA-CdTe, were individually investigated and optimized. In addition, the mechanism of this detection method was discussed in detailed. Under the optimum conditions, the fluorescence-quenching rate of the TGA-CdTe QDs showed a relative linear relationship against B12 concentration in the ranges of 0.02–0.4 and 1.5–70.0 μM B12 with a detection limit of 2.0×10-8 M. Furthermore, the accuracy, precision and the practical application of determination of B12 by this developed method, were studied in pharmaceutical formulations injection without any sample pretreatment process. The percentage recoveries for B12 determination in these real samples were obtained in the range of 95.0%–105.0%.

A modified electrode composed of horseradish peroxidase (HRP) trapped onto silica Sol-Gel/multi-walled carbon nanotubes (MWCNTs) matrix on carbon paste electrode (CPE) developed and applied for determination of methyldopa by electrocatalytic oxidation of methyldopa with HRP for the first time. The proposed biosensor showed linear response in two ranges of 1 μmol L-1 to 3.5 mmol L-1 and 3.5 mmol L-1 to 12 mmol L-1, and detection limit was obtained about 25.3 nmol L-1. The biosensor performance was much better than a lot of previously reported sensors and biosensors for methyldopa determination. This modified electrode was successfully used for accurate determination of methyldopa in urine and pharmaceutical samples. Using the developed biosensor provided an accurate, sensitive and repeatable method for methyldopa measurement in pharmaceutical and urine samples.

The model structures of the copper oxide (CuO) nanoparticles and the Victoria blue R (VBR) dye were drawn and optimized using density functional theory (DFT) methods. The orbital energy diagrams of CuO, VBR, and the VBR-sensitized CuO were calculated by means of DFT/B3LYP/6-31G* method. The study revealed the energy of the highest occupied molecular orbital (EHOMO), the lowest unoccupied molecular orbital (ELUMO), and the band gap (ΔEHOMO-LUMO) of the VBR molecule as -3.85, -2.77, and 1.08 eV, respectively. Same calculations on the model structure of CuO nanoparticles represented the band gap of 2.78 eV, which was decreased into 0.80 eV for the VBR-sensitized CuO. The ultraviolet-visible (UV-Vis), infrared (IR), and nuclear magnetic resonance (NMR) spectrums, as well as the effect of solvation on the molecular orbitals of the VBR molecule, were also calculated. The UV-Visible spectra of the dye display two broad absorption peaks in the visible region. In addition, the electrostatic potential and the local ionization potential maps of the modeled VBR-sensitized CuO photoanode were illustrated and discussed. This study successfully describes the potential of VBR-sensitized CuO to be used as a photoanode in dye-sensitized solar cells (DSCs).

Molecularly imprinted polymer nanoparticles (MIP NPs) were synthesized using a noncovalent molecular imprinting approach for the selective extraction of amoxicillin from wastewater samples. Solid-phase extraction (SPE) method based on the synthesized MIP NPs followed by high-performance liquid chromatography (HPLC) was used to avaluate the affinity of MIP NPs to amoxicillin. The effect of significant parameters on the extraction process such as sample solution flow rate, breakthrough volume, sample pH, type and volume of the elution solvent as well as the salt addition were investigated and optimized . Under the optimum conditions, the calibration graphs were linear in the range of 0.06–60 µg/L with a limit of detection (LOD) of 0.02 µg/L. The relative standard deviation (RSD, for 1.0 µg/L of amoxicillin in wastewater) was 4.1% (n=7). The SPE using the MIP NPs provided a high enrichment factor (1667) for amoxicillin. These data indicated that the MIP NPs had a perfect selectivity and affinity for amoxicillin and could be used for selective extraction and analysis of amoxicillin in wastewaters.

A graphite paste electrode modified with Multiwall Carbon Nanotube (MWCNT) was prepared and used for low level determination of anticancer drug idarubicin (IDA) in biological fluids. The measurement was made using differential pulse voltammetry (DPV). The influence of some experimental variables such as composition of carbon paste, pH of solution, scan rate and possible interferences were studied. The charge transfer property of the fabricated composite electrode was characterized by electrochemical impedance spectroscopy (EIS). Furthermore, the morphology of the electrode was characterized by scanning electron microscopy (SEM). Under optimum conditions, the proposed sensor provides two linear DPV responses toeard IDA over the concentration ranges of 1–100 nM and 100–1000 nM for with a detection limit of 0.2 nM. Finally, the constructed sensor was successfully applied for determination of IDA in human urine and serum samples.

In this report, the kinetic and equilibrium isotherm modeling for removal of malachite green dye with Fe3O4@SiO2-CPTS magnetic nanoparticles in aqueous solutions were investigated. The equilibrium adsorption data were fitted with Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich isotherm models. The adsorption equilibrium data fitted very well to Redlich-Peterson (D-R) isotherm models that predict accurately the adsorption experimental data on solid adsorbents in comparison to other models. Moreover, the adsorption kinetics data were fitted with the pseudo-second order model. Characterization of Fe3O4@SiO2-CPTS Magnetic nanoparticles was carried out by using scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The recovery tests were carried out to evaluate the reliability of the NPs for the adsorption and desorption of malachite green dye that showed excellent recoveries in both water solution at pH = 4 (recovery=95%).

In the current work, nickel oxide (NiO) and copper-doped nickel oxide (Cu-NiO) nanoparticles were prepared by co-precipitation method. The effect of Cu doping on the structural and optical features of NiO nanoparticles and the effect of solvent and temperature on the optical and structural properties of nickel oxide and Cu-doped nickel oxide nanoparticles were studided by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, fourier transform-infrared (FT-IR) spectroscopy and vibrating-sample magnetometer (VSM) technique. The XRD analysis condirmed that the Cu-doped nickel oxide have a cubical structure and showed that the crystalline size increased with the increase of temperature. The optical absorption spectra of the structures illusterated a blue-shift with decreasing in crystal size so that the energy gap of nickel oxide decreased with increasing temperature. Subsequently, in the presence of propranol and without ethylene glycol, the Cu-doped NiO band gap was the lowest and with the applying of ethanol and ethylene glycol was the highest amount. Magnetization property study of the nanoparticles performed at room temperature confirmed the weak ferromagnetic behavior of Cu-doped NiO nanoparticles before calcinations. The magnetization in the magnetic hysteresis loop indicated that nanoparticles have super paramagnetic property after calcination.