Electrochemical sensing interface of copper-coordinated polyhistidine/functionalized multi-walled carbon nanotubes for shikonin determination

A copper-coordinated poly-L-histidine/carboxylated multi-walled carbon nanotube (Cu-HIS/ f -MWCNTs) sensing interface was constructed using electropolymerization and self-assembly methods. The electrochemical response of shikonin (SHI) on this sensing interface was analyzed using cyclic voltammetry (CV) and chronoamperometry (CC). The results showed that the interface had a large effective surface area, and the imidazole groups on histidine exhibited good recognition and electrocatalytic oxidation of shikonin. At optimal conditions, the differential pulse voltammetry (DPV) peak current demonstrated a linear dependence on shikonin concentration within the range of 2 × 10 −4 to 10 µmol/L, achieving a detection limit of 0.07 nmol/L. The sensing interface demonstrated a broad detection range, along with excellent stability, selectivity, and reproducibility. It was successfully employed for the analysis of shikonin in real samples, yielding a spiked recovery rate from 98.4 to 104.8%.