صدیقه هاشم نیا

Nowadays, magnetic nanoparticles are one of interest because of the unique properties such as electrical and magnetic properties. They are widely used to improve the electron transfer of the electroactive species at electrode surfaces.Nanoparticle modified electrodes show an apparent increase in active surface area and signal to noise ratio in electrochemical systems. However, it is possible to increase the selectivity and sensitivity of the electrodes by using functionalized nanoparticles. In this way, the aim of the first part of this thesis was to synthesize of magnetic iron oxide nanoparticles functionalized with dopamine ( MNPs-APTES-DA) using co-precipitation method. Synthesized nanoparticles were characterized by scanning electron microscope (SEM), dynamic light scattering (DLS) and fourier transform infrared spectroscopy (FT-IR). In the second part of the present work, The electrochemical response of MNPs-APTES-DA was investigated using a carbon paste electrode modified with MNPs-APTES-DA via surface adsorption. The resultant film exhibited a pair of well-defined quasi-reversible cyclic voltammetric peaks corresponding to the dopamine (ox)/dopamine (red) redox with a formal potential (E??) = 0.33 V vs. Ag/AgCl, in 100 mM phosphate buffer solution at pH 6.5. The effect of different parameters such as pH, ionic strength, concentration of nanoparticles, electrode preparation time and scan rate were studied in order to obtain optimum conditions.The results showed that the modified electrode in aqueous solution ( pH6.5), can be applied for determination of copper ions in the concentration range of 2.0 to 7.0 nM with a detection limit of 0.454 nM.