Desenvolvimento de eletrodos de pasta de carbono modificados com nanopartículas de óxido de silício e ouro como biossensores para detecção de 17-beta-estradiol

Abstract

The objective of this work was the synthesis of gold (NpAu) and silicon oxide (NpSiO2) nanoparticles for the manufacture of modified carbon paste (EPC) electrodes for the electroanalytical detection of 17-β-estradiol. Seeking then to obtain devices with high sensitivity, selectivity and specificity, aiming to improve the detection limit and quantification limit levels (LD and LQ), established within the regulations by the National Water and Basic Sanitation Agency (ANA) and by the Ministry of Health, of traditional techniques, such as liquid chromatography and gas chromatography. In this work, modified carbon paste electrodes with the insertion of NpAu and NpSiO2 were prepared for electroanalytical detection of Estradiol Valerate (EV), a synthetic derivative homologous to the function of 17-β-estradiol. Electroanalytical detection was performed in electrolyte solutions containing or not the anionic surfactant Sodium Dodecyl Sulfate (SDS). The results presented demonstrate that these electrodes can be used to build biosensors for this hormone without the need to incorporate markers that are difficult to access and/or processes with higher added cost to obtain the sensor surface. It could be observed that the insertion of Np in the carbon paste significantly improved the analytical detection limit parameters. For carbon paste electrodes in the solution without SDS: without modification, NpAu and NpSiO2, 0.397 µmol/L; 0.179 µmol/L and 1.30 µmol/L, respectively. For the limit of quantification of the electrodes in the solution without SDS: without modification, NpAu and NpSiO2, of 1.20 µmol/L; 0.542 µmol/L and 3.95 µmol/L, respectively. For EPCs in the solution containing 1.00 mmol/L SDS: no modification, for electrodes modified with NpAu and NpSiO2, 0.0975mol/L; 0.299 µmol/L and 0.0186 µmol/L, respectively. For the limit of quantification of electrodes for carbon paste electrodes: without modification, NpAu and NpSiO2, 0.297 µmol/L; 0.905 µmol/L, 0.0563 µmol/L, respectively. The addition of SDS surfactant in the electrolyte solution amplified the analytical signal of the current relative to the LV oxidation, thus enabling the improvement of the noise signal and the detection of smaller amounts of analyte in the samples. Among the electrodes tested for the method developed in this work, it is important to emphasize that the best results were obtained when it was the EPC modified with NpSiO2, where the LD and LQ for this electrode, both in the solution with SDS and in the solution without SDS were given within the limit established for regulation by the ANA and the Ministry of Health.