Surface plasmon resonance sensor for profenofos detection using molecularly imprinted thin film as recognition element

A surface plasmon resonance (SPR) sensor that uses molecularly imprinted polymer (MIP) ultrathin film as sensing material was developed for detecting profenofos in tap water . The MIP ultrathin film was anchored on a gold chip by surface-initiated radical polymerization . The gold surface was first modified by 11-mercaptoundecanoic acid to form a self-assembled monolayer (SAM). To easily graft 2,2-azobis (2-amidinopropane) hydrochloride onto the SAM, the carboxyl of SAM was activated using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N -hydroxysuccinimide. Then, the MIP film was synthesized by thermal-initiated polymerization using methacrylic acid as functional monomer and trimethylolpropane trimethacrylate as cross-linker. On the basis of this principle, two methods for ultrathin film preparation were studied and the most suitable technique was adopted. The prepared ultrathin film was characterized by atomic force microscopy . The MIP-SPR sensor was used to detect profenofos in tap water spiked with 0.001–0.1   μg   mL −1 of the insecticide. The sensor showed high sensitivity, selectivity and good stability. The recoveries and repeatability (RSD, n   =   4) of the sensor were 89.81–100.99% and 3.69–5.76%, respectively, while the detection limit based on a signal-to-noise ratio of 3 (S/N   =   3) was 3.6   ×   10 −4   μg   mL −1 .