Nanostructured Alpha-NiCe Mixed Hydroxide for Highly Sensitive Amperometric Prednisone Sensors

Nickel hydroxide nanoparticles with enhanced electrocatalytic activity and stability in the alpha phase were prepared by incorporation of 20 atom% of Ce(III) ions, that were shown to be oxidized to the catalytic active Ce(IV) species in the mixed hydroxide/oxide nanomaterial. Alpha-NiCe is constituted by smaller nanoparticles as compared with pure nickel hydroxide and can interact with prednisone, a widely prescribed medicine that is controlled by the International Anti-Doping Agency because of its use as anabolic agent. This compound is more or less easily hydroxilated by oxygen and then oxidized to the respective keto species, that was shown to be oxidized further by the modified electrodes upon loss of the alkyl side chain. Thus, a sensitive prednisone sensor was demonstrated exploring the electrocatalytic oxidation reaction instead of the reduction of prednisone to prednisolone, as previously reported in the literature. Sensitivity as high as 3.9 × 10−2 A mol−1 L/cm2 and limit of detection as low as 8.4 × 10−9 mol L−1 were achieved using flow injection analyses.