Dendrimer─Gold Nanocomposite-Based Electrochemical Aptasensor for the Detection of Dopamine

Dopamine is an important neurotransmitter and biomarker that plays a vital role in our neurological system and body. Thus, it is important to monitor the concentration levels of dopamine in our bodies. We report an aptamer-based sensor fabricated through an electro-co-deposition of a generation 3 poly(propylene imine) (PPI) dendrimer and gold nanoparticles (AuNPs) on a glassy carbon (GC) electrode by cyclic voltammetry. Through self-assembly, a single-stranded thiolated dopamine aptamer was immobilized on the GC/PPI/AuNPs electrode to prepare an aptasensor. Voltammetry and electrochemical impedance spectroscopy (EIS) were used to characterize the modified electrodes. The readout for the biorecognition event between the aptamer and various dopamine concentrations was attained from square wave voltammetry and EIS. The aptasensor detected dopamine from the range of 10–200 nM, with a limit of detection of 0.26 and 0.011 nM from SWV and EIS, respectively. The aptasensor was selective toward dopamine when different amounts of epinephrine and ascorbic acid were present. The aptasensor was applicable in a more complex matrix of human serum.