QCM sensing of a chemical nerve agent analog via electropolymerized molecularly imprinted polythiophene films

The highly selective and sensitive detection of a chemical nerve agent analog pinacolyl methylphosphonate (PMP) was demonstrated using an electrochemically molecularly imprinted polymer (MIP) polythiophene film onto a quartz crystal microbalance (QCM) transducer surface. The fabrication and optimization of the sensor film was monitored by in situ electrochemistry-QCM (EC-QCM) measurements, which determined the change in mass and simultaneous change in redox properties of the polymer film. The film deposition, template loading, and template removal were evidenced by a combination of surface characterization techniques such as the attenuated total reflection infrared spectroscopy and high-resolution X-ray photoelectron spectroscopy. The fabricated MIP film demonstrated a limit of detection and a limit of quantification of ~60 and ~197 µM, respectively. The linear sensing range is between 125 and 250 µM concentration of PMP. Finally, theoretical modeling (AM1 semiempirical quantum calculations) studies revealed that a stable prepolymerization complex is formed in solution with the existence of H-bonding interactions using the 2:1 monomer-to-template ratio