A sensitive and selective molecularly imprinted electrochemical sensor based on Pd-Cu bimetallic alloy functionalized graphene for detection of amaranth in soft drink.

A special electrochemical sensor was developed based on molecularly imprinted polymer (MIP), which was formed by the dopamine (DA) self-polymerization on the surface of Pd-Cu bimetallic alloy functionalized poly (diallyldimethylammonium chloride) -dispersed graphene (PDDA-Gr). This sensor takes advantages of molecularly imprinted technique and nanocomposite to realize the application of amaranth determination with high selectivity and sensitivity. In this study, the nanocomposite PDDA-Gr-(Pd-Cu) characterized by various techniques provides large surface area and accelerates the electron transfer process. The imprinted composite deposited on the surface of PDDA-Gr-(Pd-Cu), not only provides abundant specific cavities to amaranth, but also decreases the thickness of molecularly imprinted polymer leading to high conductivity. The electrochemical behavior of amaranth on the modified electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). After optimization, the anodic peak current showed a linear relationship with the concentration of amaranth in the range of 0.006-10 μM, and the limit of detection (LOD) was 2 nM. The proposed sensor distinguished amaranth from other structurally similar substances such as sunset yellow and tartrazine with good results. In addition, the molecularly imprinted sensor proposed in this study was successfully applied to determine amaranth in the soft drink with satisfactory recoveries.