Electrochimica Acta 78 (2012) 422–429 Contents lists available at SciVerse ScienceDirect Electrochimica Acta j ourna l ho me pag e: www.elsevier.com/locate/electacta Electrochemical deposition of gold nanoparticles on carbon nanotube coated glassy carbon electrode for the improved sensing of tinidazole Saeed Shahrokhian a,b,∗ , Shokoufeh Rastgar a a Department of Chemistry, Sharif University of Technology, Tehran 11155-9516, Iran b Institute for Nanoscience and Technology, Sharif University of Technology, Tehran, Iran a r t i c l e i n f o Article history: Received 1 April 2012 Received in revised form 6 June 2012 Accepted 8 June 2012 Available online 18 June 2012 Keywords: Gold nanoparticles Multi-walled carbon nanotube Tinidazole Voltammetry a b s t r a c t The electrochemical reduction of tinidazole (TNZ) is studied on gold-nanoparticle/carbon-nanotubes (AuNP/CNT) modified glassy carbon electrodes using the linear sweep voltammetry. An electrochem- ical procedure was used for the deposition of gold nanoparticles onto the carbon nanotube film pre-cast on a glassy carbon electrode surface. The resulting nanoparticles were characterized by scanning electron microscopy and cyclic voltammetry. The effect of the electrodeposition conditions, e.g., salt concentra- tion and deposition time on the response of the electrode was studied. Also, the effect of experimental parameters, e.g., potential and time of accumulation, pH of the buffered solutions and the potential sweep rate on the response is examined. Under the optimal conditions, the modified electrode showed a wide linear response toward the concentration of TNZ in the range of 0.1–50 M with a detection limit of 10 nM. The prepared electrode was successfully applied for the determination of TNZ in pharmaceutical and clinical samples. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction The integration of nanotechnology with electrochemistry is expected to produce major advances in the field of electrochem- ical sensors. There is growing interest in developing new enhanced materials and designing novel sensors with controlled features on a nanometric scale. The unique properties of metal nanopar- ticles (enhanced mass transport, high surface area and improved signal-to-noise ratio) can often be advantageous in electroan- alytical techniques [1,2]. Carbon nanotubes (CNTs) are gaining popularity in the electrochemistry as a viable nanomaterial due to their extraordinary electronic, chemical and structural character- istics. CNTs display intrinsic properties that include high surface areas, high electrical conductivities, and their inherent size and hollow geometry, which make them extremely attractive as sub- strates for heterogeneous catalysis [3–5]. Furthermore, uniform dispersion of metallic nanoparticles on CNT surfaces can offer new opportunities for the development of new sensors with high ana- lytical performances [6–9]. Taking account of the advantages of gold nanoparticles (AuNPs) and CNTs, AuNP/CNT has more poten- tial applications in the generation of the electrochemical sensors, because of the greatly promoted electron transfer rate and elec- trocatalytic ability [10–16]. Controlling the size and distribution ∗ Corresponding author. Tel.: +98 21 66005718; fax: +98 21 66002983. E-mail address: shahrokhian@sharif.edu (S. Shahrokhian). of nanoparticles on a substrate remains one of the main chal- lenges of materials science, due to tuning their morphology and response characteristics. Electrodeposition offers many advantages over high temperature metal deposition for the metal nanopar- ticle formation on CNTs. One of the most significant advantages of electrochemical deposition is the ability to controlling size and distribution of nanoparticles by varying potential, time or solution concentration [2,17–19]. Tinidazole (TNZ) (Scheme 1) is an antibacterial, anti-protozoa and anticancer drug that belongs to a class of antibiotics known as nitroimidazole developed in 1972. It is widely known through- out Europe and the developing world as treatment for a variety of amoebic and parasitic infections. TNZ is used to treat certain infections caused by bacteria, such as infection of the intestines or vagina. This drug is used for the treatment of trichomoniasis (sexually transmitted disease (STD)) that affects both women and men, although symptoms are more common in women are increas- ing among the African women. It is known that trichomoniasis facilitates the spread of HIV infection [20,21]. The mechanism of the action of nitroimidazoles, as the cited drugs, involved interfer- ence with DNA by a metabolite in which, the nitro group had been reduced. The free nitro-radical generated as a result of this reduc- tion may be responsible for the cytotoxity activity [22]. Because of its important role in numerous pathological processes, detection and quantification of TNZ is important in pharmaceutical and clini- cal procedures. Several methods are reported for the determination of TNZ, including spectrophotometry [23–26] and chromatography 0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2012.06.035