A sensitive electrochemical molecularly imprinted sensor based on catalytic amplification by silver nanoparticles for 3-indoleacetic acid determination

A novel strategy for improving the sensitivity of a molecularly imprinted sensor was proposed based on the amplification effect derived from the electrochemical stripping of copper produced by catalytic deposition by silver nanoparticles (AgNPs). Polypyrrole was electrochemically polymerized to prepare a molecularly imprinted polymer film using 3-indoleacetic acid (IAA) as a template. After the competitive reaction between IAA and thiolation-3-indoleacetic acid (IAA-S), IAA-S was labeled with AgNPs, and then copper was catalytically reduced and deposited onto the AgNP surface. The deposited copper was electrochemically dissolved, and the anodic stripping current was recorded using linear sweep voltammetry. The change in signal decreased when IAA-S was replaced by IAA in the samples. The peak current was proportional to the logarithm of the concentration of IAA in the range of 9   ×   10 −10 –6   ×   10 −7   mol/L, with a detection limit of 2.31   ×   10 −10   mol/L determined by the 3 σ rule. Samples were assayed, and the recoveries of the approach ranged within 99.7–104.2%.