Cathodic deposition of CoNi-ZIFs on molecularly imprinted polymers for synergistically enhanced electrochemical detection of rutin.

Abstract

Rutin often coexists with other flavonoids possessing similar electroactive sites in natural plants, resulting in poor selectivity in electrochemical detection. An efficient electrochemical sensor was developed by cathodically depositing CoNi-Zeolitic Imidazolate Frameworks (ZIFs) onto molecularly imprinted polymer (MIP) films to improve the detection selectivity for rutin. The deposition conditions of the CoNi-ZIFs/MIP composite electrode were systematically optimized and the morphology, structure and electrocatalytic performance of CoNi-ZIFs/MIP composite electrodes using different deposition times were investigated. Results showed that the composite electrode presented two distinct morphologies-granular and block-like-which featured different Co/Ni atomic ratios. The electrode prepared with the deposition time of 250 s exhibited higher current, smaller charge transfer resistance, larger effective specific surface area, higher area ratios of Co2+/Co3+ and Ni2+/Ni3+, and higher content of oxidized nitrogen species, thereby enhancing electrocatalytic activity for rutin. CoNi-ZIFs incorporated onto MIP/GCE further amplified potential differences (ΔE) and current ratios between rutin and three structurally similar flavonoids, synergistically enhancing rutin selectivity, presumably due to their electrocatalytic discrimination of flavonoids with varied C-ring substitutions. This sensor exhibited low detection limit (i.e. 2.4 nM) and wide detection range (i.e. 0.01-1 µM and 1-100 µM). Furthermore, the sensor demonstrated good repeatability, reproducibility, and anti-interference ability, and was successfully applied for accurate determination of rutin in real Flos Sophorae Immaturus samples.

Abstract as supplied by the indexing source. © the authors / publisher.