Modificación de superficies de oro con tiourea como herramienta para la inmovilización y detección de vitamina K 3

Abstract

Immobilizing molecules of vitamin K3 was performed by modification of gold surfaces by chemisorption of thiourea, to form self-assembled monolayers of thiols uniformly oriented. Gold over other materials presents the advantage of not having a stable oxide, allowing handle under atmospheric conditions, this makes this metal is one of the materials mostly used in the modification with self-assembled monolayers of thiols. Thus, after immersing the clean gold surface in a solution of 5mM thiourea and vitamin K3 100mM thiourea packed monolayer (Au/SAM/TOU-Vit.K3) and immobilized simultaneously vitamin K3 is obtained. The immobilization of vitamin K3 was not achieved by modifying the gold surface with 5mM thiourea and subsequent incubation in vitamin K3. To check if the formation of monolayers occurs, cyclical voltammetries were made in 0.5M KOH under N2 (with modified electrodes), in the window of potential between -0.2V to -1.2V vs Ag/AgCl, where a wave is shown next to -0.9V characteristic of sulfur compounds adsorbed on gold. For detection of vitamin K3 cyclic voltammetries in 0.1M KCl and potential window from -0.2V they were performed to -0.8V, resulting signals corresponding to vitamin K3 (Epc?-0.45V and Epa?-0.35V). Conditions of pH, concentration of vitamin K3, incubation times thiourea and vitamin K3, and the detection limit for cyclic voltammetry (50mM) was also optimized.