Alternative approach for highly sensitive and free-interference electrochemical dopamine sensing

Abstract

In biological fluids, the concentration of dopamine (DA) provides an important information about neurodegenerative disorders such as Parkinson's disease, schizophrenia and other DA-related ailments like hyperprolactinemia. Therefore, its accurate determination is crucial for the early diagnosis and monitoring of these syndromes. Herein we report a new approach that enables highly sensitive and free-interference of DA electroanalysis. The electrocatalytic properties of silver nanoparticles (AgNPs) towards DA and their ability to limit, in-situ, the uric acid (UA) oxidation were successfully combined with the electron transfer properties of pristine MWCNTs in a nanocomposite (AgNPs@MWCNTs). This nanomaterial showed complete elimination of UA interference and enhanced electron transfer kinetics. Subsequently, AgNPs@MWCNTs properties were successfully synergized with the great ability of graphene oxide (GO) to attract DA while repelling ascorbic acid (AA) and UA via electrostatic interactions, to carry out an electrode material (GO-AgNPs@MWCNTs). AgNPs@MWCNTs were characterized by XRD, Raman spectroscopy, HR-TEM and EDX. The successful GO synthesis was confirmed by XRD, Raman spectroscopy and XPS while its exfoliation and uniform distribution of AgNPs@MWCNTs on its layer surfaces were evidenced by FE-SEM and HR-TEM. The resulting DA sensor showed high sensitivity and complete suppression of UA and AA interferences. Calibration in the concentration range of 0.5–6.5 μM in the presence of 300 μM of AA and 500 μM of UA showed a linear response (R2 = 0.99944) with a detection limit of 2.58 nM (S/N = 3). Moreover, the prepared sensor showed good repeatability, reproducibility, long-term stability and satisfactory recoveries in human serum samples.