Development of a new dopamine biosensor based on polythiophene/carbon nanotube composite

In this study, polythiophene/multi-walled carbon nanotube (PTh/MWCNT) composites were synthesized by chemical oxidative polymerization and their properties were investigated. The Fourier transform infrared spectrometry (FTIR) results of PTh, CNT and composites were supported the polymerization and formation of composites. Surface morphologies of the polymers were illuminated by scanning electron microscopy (SEM). Electrochemical characterization studies were carried out by using cyclic voltammetry (CV) method. The composites were attached to the glassy carbon electrode surface to develop a biosensor sensitive to dopamine. The working conditions of the biosensor were optimized by selecting the composite which gives the best response against dopamine (160 μL/16 mg) (PTh/MWCNT). Working pH, amount of composites and the effects of dopamine concentration on the electrode response were investigated. The effects of interferants were also studied. The response time was 4-5 seconds and the upper limit of the linear operating range for dopamine concentration was 0.98 mM. The detection limit of the biosensor was 0.08 mM and its sensitivity was 289 µA.nM-1. In addition, preparation method of the working electrode is quite simple and fast.