The performance of a modified electrode of nanocomposite films consisting of polypyrrole–chitosan–titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1–14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.

Nitrogen-doped reduced graphene oxide (NrGO) sheets decorated with Co(OH)2 nanoflakes were prepared by a single-step hydrothermal process. The morphological and structural characterizations of as synthesized NrGO@Co(OH)2 nanoflakes were performed by field emission scanning electron microscopy (FESEM), EDX-mapping and X-ray diffraction (XRD). NrGO@Co(OH)2 nanoflakes modified glassy carbon electrode (GCE) was used for electrochemical sensing of dopamine in neutral medium. The nanocomposite modified electrode showed enhanced electrochemical sensing ability for the detection of dopamine and the limit of detection (LoD) was found to be 0.201 μM with a sensitivity value of 0.0286 ± 0.002 mA mMâ1. Interference studies revealed that NrGO@Co(OH)2âGCE endow excellent selectivity for DA detection even in the presence of higher concentration of common co-existing physiological interfering analytes. Additionally, proposed sensor demonstrated excellent performance in urine samples with promising reproducibility and stability. Keywords: Nitrogen doped graphene, Dopamine, Electrochemical sensor, Amperometric detectio

The Schiff base sodium pyruvate thiosemicarbazone (SPTSC) was synthesized from the condensation of sodium pyruvate and thiosemicarbazide hydrochloride in aqueous medium. This molecule coordinates to a variety of divalent metal ions M²⁺ (M = Fe, Co, Ni, Cu or Cd) and one type of complexes was obtained with general formulae [M (SPTSC)₂]. The modes of bonding and overall geometry of the complexes were determined through physicochemical and spectroscopic methods. These studies revealed octahedral geometry of all prepared complexes. Thermal analyses (TG and DTG) of (SPTSC) and all complexes have been carried out to confirm the final molecular structures of free ligand and its metal complexes and also to study their thermal stability. This study confirms that the complexes have been formed by the coordination of metal ion to the (SPTSC) donor atoms only (there is no coordinate and hydrate solvents). Also the study shows that the prepared complexes have more thermal stability than free ligand (SPTSC) and the thermal stability of (SPTSC) has been enhanced by the coordination to metal ions.

Sol–gel technique was applied to synthesis TiO2 with SnO2 nanoparticles in relatively acidic media. X-ray diffraction measurements showed that TiO2/SnO2 nanoparticles were polycrystalline at the anatase phase. TiO2/SnO2 nanoparticles were examined using atomic force microscopy, scanning electron microscopy and Fourier transform infrared analysis. The band gap for the TiO2/ SnO2 nanoparticle estimated from UV–vis spectroscopy was 3.69 eV and also varied in order to investigate the effects of these parameter such as nanoparticle loading, pH, initial p-NT concentration , and temperature, on the reaction kinetics. The TiO2-coupled SnO2 nanoparticles in general showed higher photocatalytic activities than the pure ones.Kinetic studies that the reaction is pseudo first order, and the rate of reaction decreased with increasing p-Nitrotoluene initial concentration, and the used different light source showed the visible light was most Efficiency.