Simultaneous Determination of Paracetamol,Ascorbic Acid and Codeine by Differential Pulse Voltammetry on the Aluminum Electrode Modified by Thin Layer of Palladium

In the present work an aluminum electrode was modified with thin layer of metallic palladium. The ability of the electrode for electrooxidation and subsequent differential pulse voltammetric determination of paracetamol (PCT), ascorbic acid (AA) and codeine (CO) was evaluated. The results obtained indicated that a linear range from 0.1–3 mM and a detection limit of 5 μM for both three compounds is accessible. The peak separation of AA, PCT and CO is more than 300 mV large enough, allowed simultaneous determination of these compounds. The proposed method was applied for determination of AA, PCT and CO in some real samples.     

Simultaneous Determination of Nitrite and Hydrogen Peroxide Using Hemoglobin Modified Pencil Lead Electrode as a Novel Biosensor: Application to the Analysis of Mother’s Milk

In the present paper simultaneous determination of nitrite and hydrogen peroxide using hemoglobin modified pencil lead electrode (Hb/PLE) prepared by a simple and rapid electroless method was described. In the first part of the work the reduction of NO₂ and H₂O₂ at the modified electrode was investigated by cyclic voltammetry. Then under optimal conditions using differential pulse voltammetry, the biosensor could be used for the determination of H₂O₂ at concentration ranging from 5 to 240 M and NO₂ at concentration ranging from 10 to 240 M. The detection limits were 3×10^?6 and 5×10^?6 M, for NO₂ and H₂O₂ respectively. Differential pulse voltammetry also used for the simultaneous determination of NO₂ and H₂O₂. This modified electrode successfully used for the determination of NO₂ and H₂O₂ in tap water and mother’s milk samples.     

Hollow Zn/Co Zeolitic Imidazolate Framework (ZIF) and Yolk–Shell Metal@Zn/Co ZIF Nanostructures

Metal–organic frameworks (MOFs) feature a great possibility for a broad spectrum of applications. Hollow MOF structures with tunable porosity and multifunctionality at the nanoscale with beneficial properties are desired as hosts for catalytically active species. Herein, we demonstrate the formation of well‐defined hollow Zn/Co‐based zeolitic imidazolate frameworks (ZIFs) by use of epitaxial growth of Zn‐MOF (ZIF‐8) on preformed Co‐MOF (ZIF‐67) nanocrystals that involve in situ self‐sacrifice/excavation of the Co‐MOF. Moreover, any type of metal nanoparticles can be accommodated in Zn/Co‐ZIF shells to generate yolk–shell metal@ZIF structures. Transmission electron microscopy and tomography studies revealed the inclusion of these nanoparticles within hollow Zn/Co‐ZIF with dominance of the Zn‐MOF as shell. Our findings lead to a generalization of such hollow systems that are working effectively to other types of ZIFs.     

Modification of WS2 nanosheets with beta-cyclodextrone and N-isopropylacrylamide polymers for tamoxifen adsorption and investigation of in vitro drug release

In this research, tungsten disulfide (WS₂) nanosheets were modified with beta-cyclodextrone (βCD) N-isopropylacrylamide polymers (NIPAAP) for adsorption of tamoxifen (TAM) drug. The synthesized WS₂/βCD/NIPAAP samples were characterized by field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) analyses. The adsorption experiments of TAM on WS₂/βCD/NIPAAP were performed as a function of pH, reaction contact time, temperature and drug concentration. The adsorption kinetic data were well fitted to the pseudo-second-order model. Also, the equilibrium data were well described by Langmuir isotherm model. The maximum adsorption capacity of WS₂/βCD/NIPAAP for TAM drug was found to be 62.0 mg/g. The results of regeneration tests showed that the synthesized WS₂/βCD/NIPAAP adsorbent can be easily reused after 6 cycles of adsorption–desorption. Furthermore, TAM drug release was investigated in a simulated system with pH 7.4 at different temperatures. The results showed that the release of TAM drug from WS₂/βCD/NIPAAP carrier at 50 °C and 37 °C was greater than TAM release at 25 °C. Also, the experimental data of drug release were studied by Higuchi, Ritger-Peppas, zero-order and first-order models. The release data were well fitted to the zero-order model indicating a case II transport. The results showed a high stability for TAM drug.