Construction and Evaluation of a Graphene Oxide Functionalized Aminopropyltriethoxy Silane Surface Molecularly Imprinted Polymer Potentiometric Sensor for Dipyridamole Detection in Urine and Pharmaceutical Samples

A dipyridamole (DIP) based surface molecularly imprinted polymer (MIP) was synthesized and applied as a sensing agent in a sensing layer of a new modified potentiometric carbon paste electrode (CPE). The potentiometric modified CPEs (GO@SiO2-NH2-MIP/MWCNTs/CPE, where GO is graphene oxide and MWCNTs is multi-walled carbon nanotubes) showed an improved performance in term of Nernstian slope, selectivity and response time compared to the unmodified CPE. The response time of the sensor in the range of 2.5 × 10-8-1.1 × 10-2 M DIP was 20 s. The obtained DIP sensor showed low limit of detection (1 × 10-8 M), and satisfactory long-term stability (higher than 4 months). The practical application of the sensor was demonstrated by the determination of DIP concentration in urine samples and pharmaceutical preparations, with good precision and acceptable recoveries (96.0-103.0%). The prepared sensor showed high selectivity for DIP over a number of common species (aspirin, caffeine, ascorbic acid, glucose, urea, bipyridine, Na+, Fe3+, Mg2+, Ca2+ and K+).