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 μM with detection limits as low as 0.025 and 0.411 μM, 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.