Flexible electroactive membranes for the electrochemical detection of dopamine

In addition of a key catecholamine neurotransmitter, dopamine is is the metabolite predominantly produced by specific types of tumors (e.g. paragangliomas and neuroblastomas), which cannot be diagnosed using conventional sensitive tests. Within this context, development of flexible electrochemical sensors to monitor dopamine levels in physiological fluids for the early diagnosis and control of diseases related to abnormal levels of such compound, is necessary. In this work, a flexible self-supported membrane, which acts directly as electrode, has been developed to detect dopamine. The membrane consists of three nanoperforated polylactic acid (PLA) layers, which provide flexibility and mechanical integrity, separated by two layers of an electroactive copolymer, which are obtained by electrochemical copolymerization of 3,4-ethylenedioxythiophene and aniline. The sensitivity and detection limit provided by the electroactive copolymer, which is accessible to dopamine molecules through the nanoperforations of the PLA outer layers, is 1.846 µA/(cm2·µM) and 1.7 µM, respectively, in a urea-rich environments that mimics urine. These values allow us to propose the self-standing flexible electrodes developed in this study for the detection of dopamine in patients affected by paragangliomas and neuroblastomas tumors, which typically present dopamine concentrations between 2 and 7 μM.