Nitrogen-doped graphene–poly(hydroxymethylated-3,4-ethylenedioxythiophene) nanocomposite electrochemical sensor for ultrasensitive determination of luteolin

Abstract

A sensitive and selective electrochemical sensor was constructed by one-step co-electropolymerization of hydroxymethylated-3,4-ethylenedioxythiophene and nitrogen-doped graphene for the trace-level analysis of luteolin in Thymus vulgaris , Lonicera japonica , and Lamiophlomis rotata . An ultrasensitive luteolin electrochemical sensor was constructed by co-electropolymerization of nitrogen-doped graphene (N-GR) and hydroxymethylated-3,4-ethylenedioxythiophene (EDOT-MeOH) using cyclic voltammetry (CV). Because of the synergistic effects of the large surface area, superior electrical conductivity, and large amount of chemically active sites of N-GR together with the satisfactory water solubility and high conductivity of poly(hydroxymethylated-3,4-ethylenedioxythiophene) (PEDOT-MeOH), the N-GR–PEDOT-MeOH nanocomposite sensor exhibited high electrochemical sensitivity towards luteolin with a wide linear range of 0.005–10.06 μM and low detection limit of 0.05 nM. Satisfactory reproducibility, selectivity, and stability were exhibited by this electrochemical sensor. Additionally, the proposed sensor was employed for trace-level analysis of luteolin in actual samples of herbal medicines (thyme ( Thymus vulgaris L.), honeysuckle ( Lonicera japonica Thunb.), and Tibetan Duyiwei ( Lamiophlomis rotata (Benth.) Kudo)) with satisfactory results.