Electrochemical detection of dopamine using streptavidin-coated magnetic particles and carbon nanotube wiring

Magnetic particles (MP) and carbon nanotubes (CNT) have been extensively exploited in biosensor development. It has been recently suggested that combining MP binding of electroactive molecules with CNT wiring of the MP surface could provide novel sensing formats. Here, we demonstrate the validity of this approach using as a model dopamine (DA). As we show, DA can be electrostatically bound and concentrated using commercially available streptavidin-coated MP. Electrochemical detection of MP-bound DA is then accomplished by CNT wiring using cheap and disposable screen printed electrodes of different sizes and materials. The parameters potentially affecting DA binding, CNT wiring and electrochemical detection have been studied and optimized. The resulting assay takes 45 min, displays LOD of 2 nM DA in saline solution, is unaffected by ascorbic acid and uric acid, and can be operated in diluted urine human samples. Our results confirm that CNT wiring allows efficient detection of electroactive species after MP binding and is compatible with the study of complex real samples. © 2014 Elsevier B.V.