Desenvolvimento de imunossensor para detecção do hormônio tireoidiano L-triiodotironina (L-T3)

Abstract

In this work was developed a functionalized polymer nanocomposite platform with reduced graphene oxide/poly-tyramine (rGO/Poly-Tyr) deposited on graphite electrode to L-triiodothyronine detection (L-T3), a thyroid hormone. Initially, the GE/rGO/Poly-Tyr electrochemically platform was characterized by cyclic voltammetry, morphologically by AFM and SEM images and by FT-IR. After characterization, the antibody was immobilized on the surface of the matrix GE/ rGO/ Poly-Tyr and were standardized optimum conditions for immobilization of the probe, such as concentration, probe interaction time with the platform and pH, giving the following values: 6.0 ng mL-1; 45 minutes and 7.46 respectively. For blocking surface BSA solution was used at 0.5% and, after the L-T3 target was dripped on the electrode surface. The direct detection of anti L-T3 and L-T3 was performed by differential pulse voltammetry. It was observed that the target (L-T3) is electroactive in the platform developed, showing an oxidation peak at 0.6 V of low intensity current. When the L-T3 interacts with the probe, forming the antibody-antigen complex, a potential shift occurs at 0.7 V, and simultaneously there is an increase in intensity of electrical current, indicating that there was indeed the interaction. A calibration curve was constructed with linear response range of 0.001 ng mL-1 to 5.0 ng mL-1 L-T3, with R2 = 0.997342. The biosensor was characterized morphologically by AFM and SEM images. It was observed that there were morphological changes as it added the probe, BSA and target (L-T3) on the EG / ogre / PTir platform. These results are promising in the development of the immunosensor, once the analyte concentration detected, which was 0.001ng/mL is lower than the concentration of hormone (L-T3) exists in human blood ([L-T3total ] = 0.6 ng mL-1 to 1.81 ng mL-1). Keywords: reduced graphene oxide, poly-tyramine, nanocomposite, electropolymerization, immunosensor, L-triiodothyronine, thyroid.