Co Single-Atom Nanozymes for the Simultaneous Electrochemical Detection of Uric Acid and Dopamine in Biofluids

The development of enzyme-like electrochemical sensors with atomic-level catalytic activity sites is essential for the accurate and sensitive detection of active molecules in biological fluids. In this study, a sensitive signal amplification platform for simultaneous analysis of dopamine (DA) and uric acid (UA) was prepared on a screen-printed carbon electrode (SPCE). The sensing platform combines polypyrrole (Ppy) with high electrical conductivity and cobalt single-atom nanozymes of tubular bis-paraben nitrogen-carbon (Co-NNC) with excellent strong oxidase activity, named Ppy-Co-NNC/SPCE. The single-atom catalytic process and detection mechanism were investigated by using density functional theory. DA and UA were simultaneously detected in the ranges of 1-50 and 2-500 mu M with detection limits as low as 0.025 and 0.411 mu M, respectively. In addition, real-time detection of uric acid in sweat under resting and exercising conditions was achieved using a poly(vinyl alcohol) hydrogel as a sweat collector in combination with Ppy-Co-NNC/SPCE. Moreover, the simultaneous detection of UA and DA in human urine was also achieved. The method provides a new strategy for the detection of small molecules in biofluids, which is promising for sensing and personalized medicine.