Ultrasensitive electrochemical detection of bile acids via ZIF-67-MOF-derived CoNi(OH)x/CeO2/COOH-MWCNTs composite electrodes

Scheme of CoNi(OH)x/CeO2/COOH-MWCNTs preparation and detection of bile acids. This protocol describes CoNi(OH)x/CeO2 nanomaterials that were synthesized in situ by a two-step reflux method with cobalt-containing metal–organic framework (ZIF-67) as precursor, and ultrasonically combined with MWCNTs-COOH. The composite suspension was then modified onto a glassy carbon electrode (GCE), and the resulting CoNi(OH)x/CeO2/COOH-MWCNTs was successfully used for the ultrasensitive detection of bile acids. [Display omitted] •CoNi(OH)x/CeO2 nanomaterials were synthesized in situ by a two-step reflux method with cobalt-containing metal–organic framework (ZIF-67) as precursor.•CoNi(OH)x/CeO2/COOH-MWCNTs sensor to detect bile acids for traditional Chinese medicines.•A linear range of (0.05–10.0 µM) and LOD (1.0 nM) for bile acids detection were achieved.•The sensors were used to sensitively determine bile acids in Shedan Chuanbei Liquid Oral traditional Chinese medicine.. Fast and ultra-sensitive assays are essential for the assessment of the efficacy of traditional Chinese medicines. Here, an ultrasensitive and rapid electrochemical detection of bile acid in traditional Chinese medicine using composite electrodes is presented. Cobalt-nickel hydroxide and cerium dioxide (CoNi(OH)x/CeO2) nanomaterials were synthesized in situ by a two-step reflux method with cobalt-containing metal–organic framework (ZIF-67), as precursor. It was ultrasonically complexed with carboxylated carbon nanotubes (COOH-MWCNTs) to form CoNi(OH)x/CeO2/COOH-MWCNTs composites, for facile direct detection of bile acids in traditional Chinese medicine. Characterization methods were used to verify the successful creation of the composite CoNi(OH)x/CeO2/COOH-MWCNTs, a material which demonstrated excellent electrochemical properties. The experimental results showed that the electrode responded well when bile acids, nicotinamide adenine dinucleotide, and 3α hydroxysteroid dehydrogenase were simultaneously present in the solution, and that the peak current had a good linear relationship (R2 = 0.988) with the concentration of bile acids (0.05–10.0 µM). The sensor has an outstanding detection limit of 1.0 nM, 2–3 orders of magnitude more sensitive than the concentration. Therefore, it can be used for rapid on-site detection of bile acids in real traditional Chinese medicines.