Polimerização do ácido 4-hidroxibenzóico em eletrodos de carbono grafite visando o desenvolvimento de um biossensor enzimático

Abstract

The study of new biosensors is an area of science in full development due to the diversity of applications in the health, food and environmental sectors. The objective of this work was to modify, characterize and optimize a platform for biomolecule immobilization seeking a biosensor development using low-cost pencil carbon graphite electrodes. The monomer 4-hydroxybenzoic acid was chosen because it has the possibility to form a functionalized polymer with carboxyl groups. The formation of the polymer was performed through cyclic voltammetry. Electrochemical, morphological and spectroscopic experiments were performed for the material characterization. Allied to the data obtained by the pH study, it was proposed an electropolymerization mechanism. The system was optimized to be used in the immobilization of biomolecules and the best values were 5.0mM 4-hydroxybenzoic acid, 0.5M perchloric acid and 30 cycles. Two systems were constructed seeking the better biomolecule immobilization; a resine electrode and an enameled electrode. It was proved that the enameled presented easiness to assembly and better electrochemical responses. The immobilization of the enzyme alkaline phosphatase was performed and the substrate 4-nitrophenylphosphate was analyzed by the detection of the enzymatic reaction product, 4-nitrophenol. The system presents good response besides the possibility to develop a biosensor to detect organophosphate pesticides, as well the detection of the enzyme in solution for the analysis of bone and hepatic dysfunction in human organism.