Simultaneous and selective measurement of dopamine and uric acid using glassy carbon electrodes modified with a complex of gold nanoparticles and multiwall carbon nanotubes

Abstract

Abnormal levels of dopamine and uric acid are closely relative to some diseases of human body and can serve as key indicators for human health monitoring. As the primary products of purine metabolism, dopamine and uric acid generally coexist in the extracellular fluid of central nervous system and serum. The sensitive and simultaneous analysis of dopamine and uric acid is urgent in clinical diagnosis of some diseases. Herein, carboxylated-multiwall carbon nanotubes (MWCNTs) were functionalized with N-acetyl-l-cystein (NAC) stabilized Au clusters to generate Au@NAC- MWCNTs complex. By drop-coating the complex on glassy carbon electrode (GCE) surface, the complex-modified GCE was fabricated and used for a new working electrode for electrochemical sensing applications. Using cyclic voltammetry and differential pulse voltammetry measurements, the complex-modified GCE showed the capacity of highly sensitive, individual, and simultaneous electrochemical sensing of dopamine and uric acid. The linear detection ranges of dopamine and uric acid were 0.1–250μM and 0.1–300μM, respectively, accompanied by low detection limits of 30nM of dopamine and 40nM uric acid. In real human serum and urine samples, the complex- modified GCE exhibited a high performance for simultaneous and selective detection of dopamine and uric acid, together with high detection recoveries of 96.9–104.7% and low relative standard deviation of 1.1–3.7%.