Pyrolytic Graphite Electrode Modified with Nano-diamonds Decorated with Silver Nanoparticles as an Efficient Sensor for Voltammetric Determination of Thioridazine N. Hosseininasab a, S. Shahrokhian a Department of Chemistry, Sharif University of Technology, Tehran 11155-9516, Iran, [email protected]

Nowadays, carbon-based nanomaterials have attracted enormous interest due to their excellent electrical, chemical and mechanical properties, which make them suitable for developing nanoelectronics and electrochemical sensors [1-3]. Recently, nano-crystalline diamond (also called nanodiamond, ND) as a novel carbon material, because of its special properties such as high surface area, biocompatibility and non- toxicity, can be used in fabrication of electrochemical sensors [4-5]. In this region, metal nanoparticles have attracted much attention too. As a result, interesting class of carbon nanostructures derivatives were formed by deposition of metallic nanoclusters on their surfaces. Furthermore, uniform dispersion of metallic nanoparticles decorated on their surfaces can yield ideal nanocatalysts for application in chemically modified electrodes [6-7]. In this work, nano-diamonds decorated with silver nanoparticles (AgNPs-NDs) was used as an effective and new modifier for electrode surface modification. The decoration of NDs with AgNPs improved colloidal dispersion of the decorated NDs in water, affording uniform and stable thin films for improving the surface properties of the working electrode. The resulting modified electrode was used for sensitive voltammetric determination of Thioridazine (TR). Because of enchantment of surface area peak current for TR increased significantly. The effect of different experimental parameters, such as deposited amount of the modifier suspension, pH, accumulation potential and time, and scan rate on the voltammetric response of TR was investigated using cyclic voltammetry. Under optimal conditions, the modified electrode showed a wide linear response to the concentration of TR in the range of 0.08–10 μM with a detection limit of 10 nM. The proposed method was successfully applied in determination of TR in biological samples with satisfactory results. The modified electrode showed excellent sensitivity, selectivity, long-term stability and remarkable reproducibility. Keywords: Thioridazine; Nanodiamond; Ag Nanoparticles; Modified Electrode; Cyclic Voltammetry References: [1] M. Musameh, J. Wang, A. Merkoci, Y. Lin, Electrochem. Commun. 4 (2002) 743. [2] J. Wang, M. Li, Z. Shi, N. Li, Z. Gu, Electrochim. Acta 47 (2001) 651. [3] I. Streeter, G.G. Wildgoose, L. Shao, R.G. Compton, Sens. Actuators B 133 (2008) 462. [4] W. Zhao, J.J. Xu, Q.Q. Qiu, H.Y. Chen, Biosens. Bioelectron. 22 (2006) 649. [5] N. Gibson, O. Shenderova, T.J.M. Luo, S. Moseenkov, V. Bondar, A. Puzyr, K.Purtov, Z.Fitzgerald, D.W. Brenner, Diamond Relat. Mater. 18 (2009) 620. [6] Huang, J., Liu, Y., Hou, H., You, T., Biosens. Bioelectron. 24 (2008) 632–637. [7] Tzitzios, V., Georgakilas, V., Oikonomou, E., Karakassides, M., Petridis, D., Carbon 44 (2006) 848–853.