Electrochemical sensor based on MIP grafted on multi-walled carbon nanotubes for 17β-estradiol determination

The 17β -estradiol (E2) is a natural estrogenic hormone of great relevance in physiological process and for the development of sexual female features.1 For the determination of this compound in biological matrices, sensitive, cheap and low-cost methods have been developed, as electroanalytical techniques and the use of sensors.2 Aiming the increase of sensor selectivity, the use of molecularly imprinted polymers (MIPs) is investigated1. However, MIPs have an insulating property, and their synthesis supported in a conducting material as multi-walled carbon nanotubes (MWCNT) can be an interesting alternative.3 In this sense, the present work aims the development of a voltammetry sensor for the determination of E2, based on the modification of a bare glass carbon electrode (GCE) with the grafted MIP-MWCNT. Optimized voltammetric measurements were performed using the PalmSens potenciostat/galvanostat in cyclic voltametric mode with the parameters: potential: -1,0 to 1,0 V; step: 0,03 V; scan rate: 0,5 V/s; deposition time: 270 s at -1,5 V. Studies involving optimization of suspension and support electrolyte were developed. Results have been demonstrating higher anodic peak of estradiol compared with the GCE or oxidized MWCNT. For the suspension, the major peaks were obtained for concentration: MIP (2,0 mg)/ DHP (2,0 mg) in 2,0 mL of ethanol, where the support electrolyte with the best results was phosphate buffer in pH 7,0. Until now, the use of MIPMWCNT electrodes presents a great potential in application of E2 quantification and further studies will be developed.