Melamine-derived N-rich C-entrapped Au nanoparticles for sensitive and selective monitoring of dopamine in blood samples

Several neurological disorders, including Parkinson's disease, schizophrenia, human immunodeficiency virus infection, and restless leg syndrome, majorly result from disruption in the dopamine (DA) level. Thus, useful information about the treatment and prevention of various genetic majorly mental health problems can be obtained through precise and real-time monitoring of DA. Herein, we report the fabrication of novel N-rich carbon-coated Au nanoparticles (NC@Au-NPs) by deriving from melamine-crosslinked citrate-stabilized Au NPs. NC@Au-NPs offer fast electro-oxidation efficacy towards DA, because of strong electrostatic attraction between negatively charged NC@Au-NPs and positively charged DA. The catalytic efficacy and shelf life of the designed system were further boosted by applying a mixture of polydopamine (PDA) and benzimidazolium-1-acetate ionic liquid (IL) as a sandwich between the working electrode surface (graphitic pencil electrode: GPE) and the designed nanohybrid NC@Au-NPs as a redox mediator. The results indicate that the designed novel NC@Au/PDA–IL/GPE exhibits excellent sensitivity, selectivity, and reproducibility over a wide linear range (50–1000 nm) and a low detection limit of 0.002 μM ± 0.001 as well. The developed sensor was successfully applied to monitor DA in the blood of COVID-19 quarantined patients and pharmaceutical samples with high accuracy, thus suggesting a powerful tool for the diagnosis of mental problems.