Biological application of RuO2 nanorods grown on a single carbon fiber for the real-time direct nitric oxide sensing

This paper reports the application of single crystalline RuO2 nanorods grown on a single carbon fiber (RuO2 nanorods-CF) as a microsensing device for in vivo NO measurement. The electrocatalytic activity of RuO2 nanorods-CF, synthesized via simple thermal annealing process, toward electrochemical NO oxidation is studied by linear sweep voltammetry. RuO2 nanorods-CF shows highly enhanced and facilitated NO oxidation activity compared to bare carbon fiber (CF). The amperometric responses to varying concentration of NO verifies that RuO2 nanorods-CF exhibited ca. 40-fold higher sensitivity than bare CF and sufficient selectivity to NO over common biological interfering species (ascorbic acid, dopamine, nitrite, acetaminophen, and hydrogen peroxide) at greater concentrations than their physiological levels. The observed high sensitivity and selectivity of RuO2 nanorods-CF are rationally attributed to the substantial real surface area as well as the inherent electroactivity of RuO2 nanorods. As prepared RuO2 nanorods-CF is successfully applied for real-time direct NO measurements at the cortical surface of a living rat brain.