Au–Ru Composite for Enzyme-Free Epinephrine Sensing

We report the synthesis and investigation of Au–Ru composite with highly developed specific surface area exhibiting excellent electrocatalytic performance suitable for detection of such hydrophobic metabolites as epinephrine in the physiological environment. This electrode material was fabricated using two-stage laser-assisted metal deposition technique. The morphological and structural studies of Au–Ru were performed using methods of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The voltammetric methods, including cyclic voltammetry (CV), differential pulse voltammetry (DPV) and direct amperometry, were used to analyze the composite’s electrochemical properties. The Au–Ru sensor exhibited two linear ranges of the non-enzymatic epinephrine detection: 0.01–10 μM and 10–1000 μM. The calculated sensitivities within these two ranges were 32.8 and 3.3 μA μM−1 cm−2, whereas the corresponding limits of detection were 9 and 20 nM, respectively. The Au–Ru sensor also revealed good stability and reproducibility, as well as high selectivity towards epinephrine detection in the presence of a number of the interfering species.