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 mu m 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 mu M for UA in the presence of RSH.