Direct electrochemical detection of Estriol in serum by polymer brushes reinforced with carbon nanotubes

The aim of this study was the development a simple and sensitive sensor for estriol detection in serum based on the combination of multiwalled carbon nanotubes with polymer brushes that provides a nanocomposite with high electrochemical response. Scanning electron microscopy was applied for characterization of the surface morphology of the modified electrodes and cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy were used to investigate the electrochemical properties of the proposed electrode. Linearity between oxidation peak current and estriol concentration was obtained ranging from 2.0 × 10-6 M to 15 × 10-6 M with a detection limit of 90 nM and sensitivity was calculated to be 0.15 μA/μM. The polymer reinforced carbon nanotube displayed high selectivity, good stability and reproducibility, making it suitable for the routine analysis of estriol in clinical use.