An electrochemical sensor based on synergistic enhancement effects between nitrogen-doped carbon nanotubes and copper ions for ultrasensitive determination of anti-diabetic metformin

Metformin (MET) is the primary medicine for type II diabetes, which produces carcinogenic byproducts during chlo-rine disinfection, so the detection of MET in aqueous environment is crucial. In this work, an electrochemical sensor based on nitrogen-doped carbon nanotubes (NCNT) has been constructed for ultrasensitive determination of MET in the presence of Cu(II) ions. The excellent conductivity and rich pi-conjugated structure of NCNT facilitate the electron transfer rate of fabricated sensor and benefit the adsorption of cation ions. Cu(II) ions can chelate with MET to form MET-Cu(II) complex, which are easily accumulated on the surface of NCNT through cation-pi interaction. Attributing to the synergistic enhancement effects of NCNT and Cu(II) ions, the fabricated sensor exhibits excellent analytical per-formances with a low detection limit of 9.6 nmol L-1, high sensitivity of 64.97 A mol-1 cm-2 and wide linear range of 0.3-10 mu mol L-1. The sensing system has been successfully applied for rapid (20 s) and selective determination of MET in real water samples with satisfactory recoveries (90.2 %-108.8 %). This study provides a robust strategy for MET de-tection in aqueous environment and holds great promise for rapid risk assessment and early warning of MET.

Automated summary

An electrochemical sensor based on nitrogen-doped carbon nanotubes (NCNT) was developed for ultrasensitive determination of metformin (MET) in the presence of Cu(II) ions. The sensor showed excellent analytical performances with a low detection limit, high sensitivity, and wide linear range. It was successfully applied for rapid and selective determination of MET in real water samples. This study provides a reliable strategy for MET detection in aqueous environments with promising applications in risk assessment and early warning.