Fullerene hollow microspheres prepared by bubble-templates as sensitive and selective electrocatalytic sensor for biomolecules

We developed an electrocatalytic sensor based on C(60) hollow microspheres for highly sensitive and selective detection of dopamine (DA) in the presence of ascorbic acid (AA), and uric acid (UA) in the presence of l-cysteine (RSH). The hollow microspheres of C(60) with a diameter controllable in the range of 0.5 to 1.5 μm and a thickness of 200 nm are synthesized by a high-temperature reprecipitation method with the assistance of alcohol bubbles. The superhydrophobicity of C(60) hollow microspheres makes them capable of forming a compact thin film at air/water interface, which can be readily transferred on the surface of gold or glassy carbon electrodes. This porous C(60) film made from C(60) hollow microspheres shows a specific surface area as high as 107 m(2) g(-1). In order to obtain a conducting film, the C(60)-modified electrode is pretreated by scanning the potential range from 0.0 to -1.5 V in 1 M KOH followed by potential cycling between 550 to -50 mV in a pH 7.2 phosphate buffer solution. On the basis of XPS and IR measurements, we found that surface oxides, such as -OH and C═O groups, are introduced on the surfaces of the conducting C(60) film. This, combined with the porosity that enhances the adsorption activity of C(60)-modified electrodes, enable the electrocatalytic analysis of target biomolecules with detection limit as low as 0.1 nM for DA in the presence of AA, and 1 μM for UA in the presence of RSH.