PEDOT-Au nanocomposite film for electrochemical sensing J. Mathiyarasu ⁎ , S. Senthilkumar, K.L.N. Phani, V. Yegnaraman Electrodics & Electrocatalysis Division, Central Electrochemical Research Institute, Karaikudi-630 006 India Received 19 June 2006; accepted 1 June 2007 Available online 9 June 2007 Abstract In this work, conducting polymer incorporated gold nanoparticles are synthesized through a sequence of chemical and electrochemical routes. These materials are characterized using TEM and FE-SEM techniques. The advantages of these films are demonstrated for sensing biologically important compounds such as dopamine and uric acid in presence of excess ascorbic acid. The PEDOT matrix is recognized to be responsible for the peak separation (selectivity) while also favouring catalytic oxidation of the above compounds and the nanometer-sized gold particles allow nanomolar sensing of DA and UA (sensitivity). Thus, it is possible to detect nanomolar levels of DA and UA in presence of excess of AA. © 2007 Elsevier B.V. All rights reserved. Keywords: Nanocomposites; Nanoparticles; Sensor; Polymer 1. Introduction Conducting polymer incorporated metallic or semiconduct- ing nanoparticles provides an exciting system and these materials hold potential application in electronics, sensors and catalysis [1–6]. They have synergistic chemical and physical properties based on the constituent polymer and introduced metal. By tuning the polymer backbone with nanoscale materials, realization of nano-electronic sensor devices with superior performance is possible. Sensors fabrication based on nanoparticle-incorporated polymeric matrices are of recent technological interest [7,8]. Metal nanoparticles can be grown inside the polymer matrix by simultaneous electrodeposition of polymer along with metal nanoparticles. Arrays of gold (Au) nanoparticles have been utilized for electrochemical sensors as they exhibit excellent catalytic activity towards various reactions [9,10]. In this work, Au nanoparticles incorporated poly(3,4- ethylenedioxythiophene) (PEDOT) film was utilized as the sensing matrix by demonstrating sensitivity at nanomolar levels. This is a one-component system where the polymer matrix offers the selectivity from the complex environment and the nanoparticles offer the required sensitivity, which is lacking in the polymer matrix alone. The sensitivity of the nanocompo- site film was demonstrated in detecting the biomolecules such as dopamine (DA) and uric acid (UA) at nanomolar levels. 2. Experimental methods For voltammetric studies, a glassy carbon (φ 3 mm, BAS, Inc.) working electrode (GCE), a platinum wire auxiliary electrode and an Ag|AgCl (3 M NaCl) reference electrode were used. Phosphate (0.1 M) buffer solution (PBS) of pH: 7.4 were employed as the electrolytic medium in electroanalysis experiment. Electrochemical experiments were carried out using a Po- tentiostat/Galvanostat Autolab PGSTAT-30 (Eco-Chemie B.V., The Netherlands) at ambient temperature (25+1 °C). To record the differential pulse voltammograms (DPV), the following input parameters were used: scan rate: 30 mV s − 1 , sample-width: 17 ms, pulse-amplitude: 50 mV, pulse-width (modulation time): 50 ms, pulse–period (interval): 200 ms and quiet-time: 2 s. Transmission electron microscope (TEM) measurements were made using a Philips CM 200 machine using 400-mesh ultra thin carbon type-A copper grid. Field emission scanning electron microscope (FE-SEM) measurements were made using Hitachi Model S 4700 with an acceleration voltage of 10 kV. Available online at www.sciencedirect.com Materials Letters 62 (2008) 571 – 573 www.elsevier.com/locate/matlet ⁎ Corresponding author. E-mail address: al_mathi@yahoo.com (J. Mathiyarasu). 0167-577X/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2007.06.004