Detection of uric acid at reversibly nanostructured thin-film microelectrodes

Nanomaterials such as carbon nanotubes (CNT) are extensively used to produce electrodes of enhanced performance. However, since their incorporation tends to be irreversible, nanostructured electrodes are used only once or have to be extensively treated for their reutilization. Accordingly, nanostructuration has been seldom exploited onto microfabricated electrodes, which are too expensive to be disposable and cannot be treated aggressively for regeneration. Here, we show a fast and simple method for the reversible nanostructuration of thin-film devices, which is based on production of a magnetic CNT composite, its magnetic confinement onto the sensor, and composite release after magnet removal. Following this procedure, thin-film electrodes could be submitted to more than 10 successive rounds of nanostructuration and regeneration without any performance loss. In order to demonstrate the utility of the method reported, we show that when applied to uric acid (UA) monitoring, the modified sensors produced lower limit of detection (LOD 0.86 μM) than bare devices (38 μM) and effective detection of endogenous uric acid (UA) in diluted urine with minimal risk of sample crossed-contamination. These results suggest that magnetic co-entrapment is a simple and versatile strategy for the reversible modification of thin-film devices with nanocomposite materials.