High selectivity, ultra-sensitivity, and ultra-distinguishability of electrochemical sensing platform for simultaneous detection of dopamine, uric acid, and ascorbic acid

Dopamine (DA), uric acid (UA), and ascorbic acid (AA), three similar electroactive biological small molecules, generally coexist in human serum, causing serious interference when detected separately. In order to realize the simultaneous detection of DA, UA, and AA, three similar electroactive biomolecules, through the electrochemical sensing platform based on 2D Cu-TCPP MOFs nanofilms, DA molecules were successfully detected and optimized the detection conditions according to our previous detection methods for UA and AA. The results displayed the perfect electrochemical response signal of DA, excellent linear correlation between current intensity and DA concentration, LODs, repeatability, and stability. The electrochemical potential (E_pa) of UA oxidation peak was intermediate between E_pa of AA and DA oxidation peak, the response current intensity of UA oxidation peak continuously decreases with increases of UA concentration. The response current intensity of DA and AA oxidation peak on both sides of UA gradually increases with the increase of DA and AA concentration. On the other hand, there is a significant difference in the oxidation potential difference between adjacent substances DA, UA, and AA (ΔE_AA-UA = 141 mV, ΔE_UA-DA = 167 mV, and ΔE_AA-DA = 308 mV), which will play a decisive role in the simultaneous detection of DA, UA, and AA based on 2D Cu-TCPP MOFs/GCE electrochemical sensing platform. Therefore, the electrochemical platform based on 2D Cu-TCPP MOFs nanofilms is more conducive to the simultaneous detection of DA, UA, and AA with high selectivity, ultra-sensitivity, and ultra-distinguishability.