Electroanalytical method for determination of shikonin based on the enhancement effect of cyclodextrin functionalized carbon nanotubes

A simple and sensitive electroanalytical method for determination of shikonin, a widely used anti-tumoral agent, using β-cyclodextrin-functionalized multiwalled carbon nanotubes composite modified glassy carbon electrodes (MWCNTs/β-CD/GCE) was presented. CDs are water-soluble and environmentally friendly and can improve the dispersibility of MWCNTs/β-CD functional materials, which was confirmed by SEM. The electrochemical behaviors of shikonin on different electrodes were investigated by cyclic voltammetry (CV) and differential pulse voltammograms (DPVs). The results demonstrated that the redox peak currents of shikonin obtained at MWCNTs/β-CD/GCE were much higher than those at the β-CD/GCE and MWCNTs/GCE, which can be attributed to the combination of the excellent electrocatalytic properties of MWCNTs and the molecular recognition ability of β-CD. At MWCNTs/β-CD/GCE, the response current exhibits a linear range from 5.0 nmol/L to 10.0 μmol/L with a detection limit of 1.0 nmol/L (S/N = 3). As a practical application, the proposed method was applied to quantitatively determine shikoninin urine samples with satisfying results.