RESUMO

An electrochemical impedimetric immunosensor was developed for the detection of the neuropeptide Corticotropin Releasing Hormone (CRH) based on the immobilization of half-antibody fragments on gold nanoparticles (AuNp). Then, the optimal conditions for the obtainment of AuNp through electroplating on a bare gold electrode were studied. The results showed that the obtainment of AuNp at a fixed potential of -0.2 V for 330 s, at 80 °C and 2·10-3 mol·L-1 of HAuCl4 generates an adequate nanostructured surface and is a highly reproducible method. Also, the optimal conditions for immobilizing the half-antibody on AuNp were studied. The interaction of the CRH with the recognition layer of the immobilized half-antibody on the nanostructured surface was carried out by incubation at 4 °C for 2 h. A dissolution of [Fe(CN)6]4-/[Fe(CN)6]3- as a redox probe was used to study the electrochemical responses of the nanostructured surface and the immobilization processes of the half-antibody and detection of CRH, using cyclic voltammetry and electrochemical impedance spectroscopy. An immunosensor was obtained for the specific detection of CRH, within a range of 10.0-80.0 µg mL-1, with a limit of detection of 2.7 µg mL-1 and a limit of quantification of 9.2 µg mL-1. Additionally, the association constant between the CRH and the immobilized half-antibody was calculated at 1.96·105 M-1.

Assuntos

Técnicas Biossensoriais , Hormônio Liberador da Corticotropina/isolamento & purificação , Espectroscopia Dielétrica , Fragmentos de Imunoglobulinas/química , Anticorpos/química , Anticorpos/imunologia , Anticorpos Imobilizados/química , Hormônio Liberador da Corticotropina/química , Hormônio Liberador da Corticotropina/imunologia , Técnicas Eletroquímicas , Humanos , Imunoensaio , Fragmentos de Imunoglobulinas/imunologia , Limite de Detecção , Nanopartículas Metálicas/química , Nanoestruturas