Molecularly imprinted nanoparticles based potentiometric sensor with a nanomolar detection limit

A novel molecularly imprinted nanoparticles based potentiometric sensor with a nanomolar detection limit has been described. Uniform-sized molecularly imprinted nanoparticles are utilized as a recognition receptor to provide a higher affinity since they have a larger binding capability and can be well dispersed in the polymeric membrane of an ion-selective electrode (ISE). The asymmetric membrane rotating ISE configuration is introduced to improve the detection sensitivity by enhancing the nonequilibrium steady-state potential response at the sample-membrane interface. It has been found that the proposed electrode shows a remarkably improved sensitivity over conventional potentiometric sensors based on molecularly imprinted polymers (MIPs). By using triclosan as a model, the new concept offers a low detection limit of 1.9 × 10−9 mol L−1 in 0.2 M NaHCO3/Na2CO3 of pH 10.1, which is at least two orders of magnitude lower than those of conventional MIPs based potentiometric sensors. The practical application of the proposed sensor has been carried out for the detection of trace levels of triclosan in toothpaste samples.