Effect of different modification by gold nanoparticles on the electrochemical performance of screen‑printed sensors with boron‑doped diamond electrode

Abstract

Screen-printed sensors with chemically deposited boron-doped diamond electrodes (BDDE) were modifed with diferent types of gold nanoparticles (AuNPs) according to a new original procedure. Physically and electrochemically deposited AuNPs had various sizes and also nanoporous character. They also difer in shape and density of surface coverage. The developed sensors were characterized using scanning electron microscopy and Raman spectroscopy. Their electrochemical properties were studied using cyclic voltammetry and electrochemical impedance spectrometry of selected outer sphere ([Ru(NH3)6]Cl3) and inner sphere (K3[Fe(CN)6], dopamine) redox markers. The application possibilities of such novel screen-printed sensors with BDDE modifed by AuNPs were verifed in the analysis of the neurotransmitter dopamine. The best analytical performance was achieved using printed sensors modifed with the smallest AuNPs. The achieved limit of detection values in nanomolar concentrations (2.5 nmol ­L−1) are much lower than those of unmodifed electrodes, which confrms the signifcant catalytic efects of gold nanoparticles on the surface of the working electrode. Sensors with the best electrochemical properties were successfully applied in the analysis of a model solution and spiked urine samples.