Dopamine is an organic compound that plays a crucial role in many brain processes. Several neurological and neuropsychiatric disorders are associated to the deficiency of dopamine and for that reason the detection of this compound is a major concern. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conducting polymer whose properties depend on the method used for its deposition and of the counterions included in its structure during the deposition process. This polymer has been used with different dopants for the detection of many organic and inorganic compounds. Furthermore, nanostructures such as carbon nanotubes, metal oxides, reduced graphene oxide and metal particles have been used for the detection of dopamine [1,2].

In this work electrodeposition of PEDOT was carried out by scanning the working electrode (glassy carbon) potential between -0.3 and 1.1 V vs Ag/AgCl 3.5 M at 50 mV/s. After the electrodeposition, the films were reduced at -0.3 V for 10 minutes and then silver nanoparticles were deposited on the films at open circuit potential for 30 minutes. The morphology of the PEDOT/ClO₄ films with and without SDS modified with silver particles was analyzed by SEM. The nanoparticles are seen as bright spots in the SEM images. In both films there are isolated and conglomerated nanoparticles. In the PEDOT/ClO₄ films the nanoparticles are distributed mainly in the globules while in the PEDOT/ClO₄/SDS films silver nanoparticles are also placed a greater depth in the porous structure. The size of the nanoparticles in the PEDOT/ClO₄/SDS films is between 6 and 100 nm. The elemental composition of the modified electrodes was determined by EDX. The spectrums of PEDOT/ClO₄ films with and without SDS modified with silver nanoparticles confirmed the presence of carbon, sulfur and oxygen, the constituents of PEDOT in the films. In addition, the spectrums also showed the peak for silver which proves that silver nanoparticles were incorporated into the PEDOT films.

The prepared structures differ from films prepared in previous reports and exhibit a different electrochemical behavior [3,4]. The analytical performance of PEDOT/ClO4/SDS modified with the nanoparticles for the detection of dopamine was evaluated by differential pulse voltammetry. The sensitivity of the sensor was 0.03 +/-0.01 µA µM^-1.

[1] K. Liu, H. Pang, J. Zhang, H. Huang, Qing L. and Y. Chua. RSC Adv.4 (2014) 8415.

[2] C. L. Weaver H. Li, X. Luod and X. T. Cui. J. Mater. Chem. B. 2 (2014) 5209.

[3] V. Karabozhikova and V. Tsakova. Chem. Pap. 71 (2017) 339.

[4] E. Tolstopyatova, N. Pogulyaichenko, and V. Kondratiev. Russ J. Electrochem. 50 (2014) 510