An electrochemical sensor based on Au/poly(ortho-aminophenol-co-ortho-phenylenediamine)/TiO2 nanocomposite ((Au/P(OAP-co- OPD)/TiO2)) to detect ampicillin (AMP) antibiotic was developed. The thin films of poly(ortho-aminophenol) (POAP), poly(orthophenylenediamine) (POPD), P(OAP-co-OPD), POAP/TiO2, POPD/TiO2 and (P(OAP-co-OPD)/TiO2)) nanocomposites were synthesized on gold electrodes by in situ electrocopolymerization method and characterized by CV, FT-IR, SEM, EIS, in situ resistivity measurements and in situ UV-visible spectroelectrochemistry. Two mechanism for copolymerization of OAP and OPD were suggested. In order to achieve a reproducible state of the sensing, the current changes were recorded for nanocomposites electrodes over time using the double chronoamperometric technique. Between the modified electrodes, Au/(POAP-co-POPD)/TiO2 nanocomposite exhibited high conductivity and sensitivity, excellent activity and long-term stability for detecting AMP antibiotic with a limit of detection down to 0.28 nM. The reproducibility of the Au/Cop. A/TiO2 nanocomposites sensors to lowest AMP concentration contents was observed approximately 6%–8% changes. The interference effects of four selected antibiotics on AMP for Au/Cop. A/TiO2 nanocomposites electrode were investigated. The response signal indicating that the sensor can not detect the target molecules within the different concentration range solutions. The results in the analysis of AMP on Au/P(OAP-co-POPD)/TiO2 sensor demonstrates that the obtain electrode is suitable as a promising candidates for electrochemical sensor applications.
