Ultrasensitively sensing acephate using molecular imprinting techniques on a surface plasmon resonance sensor.

An ultrathin molecularly imprinted polymer film was anchored on an Au surface for fabricating a surface plasmon resonance sensor sensitive to acephate by a surface-bound photo-radical initiator. The polymerization in the presence of acephate resulted in a molecular-imprinted matrix for the enhanced binding of acephate. Analysis of the SPR wavenumber changes in the presence of different concentrations of acephate gave a calibration curve that included the ultrasensitive detection of acephate by the imprinted sites in the composite, K(ass) for the association of acephate to the imprinted sites, 7.7×10(12) M(-1). The imprinted ultrathin film revealed impressive selectivity. The selectivity efficiencies for acephate and other structurally related analogues were 1.0 and 0.11-0.37, respectively. Based on a signal to noise ratio of 3, the detection limits were 1.14×10(-13) M for apple sample and 4.29×10(-14) M for cole sample. The method showed good recoveries and precision for the apple and cole samples spiked with acephate solution. This suggests that a combination of SPR sensing with MIP film is a promising alternative method for the detection of organophosphate compounds.