A gold nanoparticle-loaded molecularly imprinted switch sensor with high sensitivity to ethephon

Abstract A highly sensitive molecularly imprinted ethephon sensor based on the amplification effect of gold nanoparticle (Au NPs) was designed in this study. An ethephon molecularly imprinted polymer (MIP) was prepared on a surface by electropolymerisation with Au NPs as the carriers and ethephon as the template molecule. Elution of the template molecule gave an MIP sensor that retains imprinted sites for specific recognition of ethephon. The sensor forms a current switch through adsorption of different concentrations of ethephon molecules to obtain different current responses, thereby establishing a new method for ethephon detection. The results indicated that using Au NPs as a carrier in the ethephon imprinted sensor could permit the loading of more MIP and increase the electron-transfer rate. The sensitivity of the sensor prepared with Au NPs was increased by three orders of magnitude compared to conventional MIP sensors without a carrier. Using potassium ferricyanide as a probe, the oxidation peak intensity of the probe molecule and the negative logarithm of the ethephon concentration exhibited a linear relationship within the concentration range from 1.0 × 10−13 to 1.0 × 10−9 mol L−1. The linear equation was ΔI (10−5 A) = −1.7838 × (−lg c) + 26.1216, and the detection limit was 2.78 × 10−14 mol L−1. In addition, the sensor successfully measured the ethephon content in apples.