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 CNTwiring of the MP surface could provide novel sensing formats. Here, we demonstrate the validity of thisapproach using as a model dopamine (DA). As we show, DA can be electrostatically bound and concentrated using commercially availablestreptavidincoated MP. Electrochemical detection of MP-bound DA is then accomplished by CNT wiringusing cheap and disposable screen printed electrodes of different sizes and materials. The parameterspotentially 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 byascorbic 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 bindingand is compatible with the study of complex real samples. (C) 2014 Elsevier B. V. All rights reserved.