Polypyrrole (Ppy) is one of the conducting polymers that has been used to create various kinds of sensors [1]. Chemical [2], enzymatic [3], electrochemical [4], or other methods are simple ways to synthesize Ppy. In our case, Ppy was used to create coatings on the indium tin oxide (ITO) electrode. The deposition of coatings on an ITO electrode presents many challenges. This study analysed the conditions under which the layer should be prepared and stored. The stability of the layer over time was also observed.
The first and one of the most important steps is proper electrode preparation and washing. Using a specific procedure, the electrode is pre-treated and can be modified later. The modification of the glass/ITO surface with silane could be performed in a 4% (v/v) solution of TEMS in acetone overnight and correspondingly TEMS modified structure (glass/ITO(TEMS)) could be formed. [5]
The possibility to cover electrodes with layers of conductive polymers and/or their composites with high conductivity is one of the benefits of electrochemical polymerization. By controlling the synthesis conditions, the physical properties of chemically synthesized conductive polymers, such as particle size and shape, can be managed [6]. The thickness can be partially controlled by changing the concentration of the monomer, the number of potential pulses, number of potential cycles. It was observed that the thicker the layer obtained, the more difficult it is to keep it mechanically attached to the electrode surface. Also, the use of heparin in the polymerization mixture improves adhesion to the surface.
This study aimed to evaluate the Ppy layer stability on the electrode when layers were stored in air, Britton-Robinson buffer (pH 3), or water.
In summary, it can be stated that the layer kept in the air, covered with the thinnest possible layer and modified with diverse substances, such as heparin or phenothiazine derivatives, has the best stability properties and can be used for the creation of various sensors.