Synthesis of conducting molecularly imprinted polymer nanoparticles for estriol chemosensing

Herein, electrochemically active molecularly imprinted polypyrrole nanoparticles (PPy NPs) were synthesized with the aid of micelles. Iron(III) p-toluenesulfonate induced polymerization of pyrrole resulting in the imprinting of estriol in growing NPs. Two separate imprinted NPs were prepared with pristine and derivatized pyrrole monomers. Techniques such as scanning electron microscopy (SEM), and transmission electron micro-scopy (TEM), confirmed the synthesis of imprinted PPy NPs of ~60 nm in size. NPs prepared with pristine pyrrole showed an imprinting factor of 4.2, while NPs prepared with derivatized pyrrole showed no imprinting. The electrochemical-based transduction allowed for the determination of estriol in the concentration range of 0.5–5 μM and 10–100 μM with the 0.16 μM limit of detection (LOD). Furthermore, the selectivity of the MIP NP-coated electrode toward estriol and its structural analogs, namely β-estradiol and estrone, was satisfactory.