Highly sensitive and doubly orientated selective molecularly imprinted electrochemical sensor for Cu2+

Studies on molecularly imprinted electrochemical sensors for metal ions determination have been widely reported. However, the sensitivity and selectivity of the sensors needs to be improved urgently. In the current work, a novel molecularly imprinted electrochemical sensor was originally developed for selective determination of ultratrace Cu2+ by combining the metal-ligand chelate orientated recognition with enzyme amplification effect. The detection relied on a competition reaction between Cu2+-glycine (Cu-Gly) and horse radish peroxidase (HRP)-labeled Cu-Gly on the imprinted polymer membrane modified electrode. The sensitivity of this sensor was promoted by enzyme amplification. Selectivity was improved by the double-specificity derived from ligand-to-metal ion and metal-ligand chelate orientated recognition of 3D imprinted cavities. This technique was quantitatively sensitive to Cu2+ concentrations ranging from 0.5 nmol/L to 30 nmol/L, with a detection limit of 42.4 pmol/L. which was lower than those in most of the reported methods. The allowable amounts of interference ions were higher when it compared to other common molecularly imprinted sensors. Moreover, the results of assaying several real samples have proven its feasibility for practical applications.