Synthesis and Characterization of Nickel Oxide Nanostructures for Electrochemical Analysis of Methotrexate

Metal oxide nanoparticles have found numerous applications in different fields. In this paper, the preparation of nickel oxide nanostructures is given. The nanostructures were synthesized by using the hydrothermal method. The characterization was done with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The newly synthesized nanostructures were utilized as a modifier of the working electrode, i.e., glassy carbon electrode (GCE). The modified GCE exhibited an excellent response towards methotrexate (MTX) anticancer drug. The modified GCE, as compared to bare GCE, showed an increased response towards MTX. In this study, BrittonRobinson buffer (BRB) was selected as a supporting electrolyte having pH 5. By using electrochemical impedance spectroscopy (EIS), the method was found linear in the range of 5-40 µM with a limit of detection and quantification values of 2.4 µM and 7.28 µM, respectively. The method developed by this way was successfully applied for the analysis of MTX from injection formulations. The interference studies were also carried out to check the method's selectivity.

Electrochemical Synthesis of Zinc Oxide Nanostructures on Flexible Substrate and Application as an Electrochemical Immunoglobulin-G Immunosensor

Immunoglobulin G (IgG), a type of antibody, represents approximately 75% of serum antibodies in humans, and is the most common type of antibody found in blood circulation Consequently, the development of simple, fast and reliable systems for IgG detection are of considerable interest which can be achieved using electrochemical sandwich-type immunosensors. In this study we have developed an immunosensor sub-strate using an inexpensive and very simple fabrication method based on ZnO nanorods obtained through the electrodeposition of ZnO. The ZnO nanorods were treated by electrodepositing a layer of reduced gra-phene oxide to ensure an easy immobilization of the antibodies. On this substrate, the sandwich configura-tion of the immunosensor was built through different incubation steps, that were all optimized. The im-munosensor is electrochemically active thanks to the presence of gold nanoparticles tagging the secondary antibody, therefore it has been used to measure the current density of the hydrogen development reaction which is indirectly linked to the concentration of H-IgG antigens. In this way the calibration curve was constructed obtaining a linear range of 1-100 ng / ml with a detection limit of few ng / mL and good sensi-tivity.