Investigation on cathodic electrochemiluminescence of luminol at cucurbit[8]uril modified electrode and its application in the detection of vecuronium bromide

Abstract

In the past few decades, anodic electrochemiluminescence (ECL) of luminol attracted many interests in biosensing field. Nevertheless, its cathodic ECL was extremely weak and not suitable for fabricating ECL sensor. In this work, strong and stable cathodic luminol ECL was obtained at a cucurbit[8]uril (Q[8]) modified electrode under neutral condition. The effects of potential scanning direction, switch potential, and scanning laps on ECL emission were investigated to elucidate the possible ECL mechanism. The larger cavity of Q[8] is facile for the immobilization of oxygen on the electrode surface, as a result, more O2•− were generated during the electrochemical reduction of dissolved oxygen, which could further react with luminol to generate strong cathodic ECL. Based on the host–guest recognition role of Q[8], a sensor for monitoring small molecule was proposed. Vecuronium bromide (VMBM) can enter the cavity of the Q[8] through host–guest recognition to form an inclusion complex, leading to the decrease of ECL intensity. Under the optimal conditions, the change of its concentration and the ECL intensity showed a good linear relationship in the range of 1–1000 nM, and the detection limit was 0.167 nM. The low detection limit and excellent anti-interference ability proved that Q[8] has great application prospects in the detection of various drugs.