Gold Electrodes Modified with Molecular Imprinted Acrylate Polymer for Impedimetric Determination of Testosterone

A moleculary imprinted polymer (MIP) sensor was developed for impedimetric detection of testosterone. 4,4’-azobis(4-cyanovaleric acid) initiator was first grafted onto a gold electrode modified by a self-assembled monolayer of thiolamine (11-amino-1-undecanethiol). Methacrylic acid and ethylene glycol dimethacrylate were prepolymerized by photo-polymerization in presence of testosterone as template and then spincoated and polymerized on the functionalized electrode surface. The different steps of MIP sensor fabrication were controlled using electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy and time of flight-secondary ion mass spectrometry. After template removal, the biosensor response, expressed as the variation of charge transfer resistance at the electrode/electrolyte interface measured by EIS, increased linearly with testosterone concentration up to 50 µg.L-1. The sensitivity was 0.28 per log C for testosterone, while it was only 0.0085 and 0.020 for methyltestosterone and 17b-estradiol, respectively. A very good limit of detection (103 ng.L-1) was achieved for testosterone. The sensitivity of the non imprinted polymer sensor, prepared the same way but in absence of template, was 18 times lower than that obtained with the MIP