Voltametric sensors formed by the combination of a sulfur-substituted zinc phthalocyanine (ZnPcRS) and gold nanoparticles capped with tetraoctylammonium bromide (AuNPtOcBr) have been developed. The influence of the nature of the interaction between both components in the response towards catechol has been evaluated. Electrodes modified with a mixture of nanoparticles and phthalocyanine (AuNPtOcBr/ZnPcRS) show an increase in the intensity of the peak associated with the reduction of catechol. Electrodes modified with a covalent adduct-both component are linked through a thioether bond-(AuNPtOcBr-S-ZnPcR), show an increase in the intensity of the oxidation peak. Voltammograms registered at increasing scan rates show that charge transfer coefficients are different in both types of electrodes confirming that the kinetics of the electrochemical reaction is influenced by the nature of the interaction between both electrocatalytic materials. The limits of detection attained are 0.9 × 10−6 mol∙L−1 for the electrode modified with the mixture AuNPtOcBr/ZnPcRS and 1.3 × 10−7 mol∙L−1 for the electrode modified with the covalent adduct AuNPtOcBr-S-ZnPcR. These results indicate that the establishment of covalent bonds between nanoparticles and phthalocyanines can be a good strategy to obtain sensors with enhanced performance, improving the charge transfer rate and the detection limits of voltammetric sensors.

Voltammetric sensors chemically modified with combinations of two electrocatalytic materials: tetraoctylammonium bromide capped gold nanoparticles (AuNP NBr ) and a sulphur containing zinc phthalocyanine derivative (ZnPc RS ) are reported. The electrocatalytic effects in the detection of catechol have been analyzed in sensors obtained by direct mixing (AuNP NBr /ZnPc RS ) and in sensors modified with an adduct where both components are linked covalently (AuNP NBr -S-ZnPc R ). Results demonstrate that the nature of the interaction between both components modifies the electrocatalytic properties. The AuNP NBr /ZnPc RS mixture improves the electron transfer rate of the catechol reduction, with limits of detection of 10 −6 M. The covalent adduct AuNP NBr -S-ZnPc R enhances the response rate of the oxidation of the catechol with limits of detection of 10 −7 M.