Ultrasensitive electrochemical detection of bisphenol A using copper(ii) metal-organic framework ternary quantum dot...

A copper(ii) metal-organic framework (MOF) formulated as [Cu₄(NITA)₄(H₂O)₂(DMF)₄]·(DMF)₄ was prepared and characterized by single-crystal X-ray crystallography. The compound crystallized as a paddled wheel binuclear complex with each copper(ii) ion in a distorted square pyramidal geometry. The MOF was reacted with silver indium sulphide (AgInS₂) ternary quantum dots (TQDs), prepared using a hydrothermal technique, to construct a composite electrochemical sensor, formulated as {AgInS₂@[Cu₄(NITA)₄(H₂O)₂(DMF)₄]·(DMF)₄} with improved electrochemical performance. The composite was characterized by electron microscopy and spectroscopic techniques and used to fabricate modified gold electrodes as electrochemical sensors for bisphenol A determination. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for the determination of bisphenol A (BPA) at the surface of each of the modified gold electrodes. The composite-modified gold electrode performed better electrochemically than the MOFs and TQDs over a concentration range of 2-20 nM (S/N = 3). The process at the surface of the composite-modified electrode was found to be diffusion-controlled, with a limit of detection of 1.33 nM and a limit of quantitation of 4.03 nM. The composite-modified gold electrode was stable, reproducible and selective and could serve as a model for the development of electrochemical sensor to determine BPA in water sample from the environment.