Capacitive Detection of Morphine via Cathodically Electropolymerized, Molecularly Imprinted Poly(p-aminostyrene) Films

Highly sensitive and selective detection of morphine is exhibited using a capacitive transducer coated with cathodically electropolymerized and molecularly imprinted poly(p aminostyrene). Through molecular imprinting, morphine‐specific recognition sites have been fabricated throughout the film, which shows exceptional binding activity toward morphine based from electrochemical capacitance measurements. The thin film sensor has a linear response to morphine solutions with 20–40 × 10−6 m concentrations and a detection limit of 5.95 × 10−6 m. It demonstrates high selectivity toward morphine as compared to other analog molecules including nicotine and cholesterol. The formation of the polymer film is facilitated and monitored using electrochemical‐quartz crystal microbalance and characterized by X‐ray photoelectron spectroscopy. Infrared spectroscopy confirms the loading and removal of the analyte from the film. Based on molecular modeling calculations, strong hydrogen‐bonding interactions between the monomer, cross‐linker, and analyte form a stable pre‐polymerization complex, which is critical in successfully imprinting morphine into the film and effective sensing of the analyte. Capacitive sensing of morphine with high sensitivity and selectivity is demonstrated using a cathodically electropolymerized and molecularly imprinted poly(p‐aminostyrene) films. The resulting film sensor exhibits a linear sensing ranging from 20 to 40 × 10−6 m morphine concentrations and a limit of detection of 5.95 × 10−6 m. It also possesses high selectivity as determined from interference experiments with nicotine and cholesterol.