Contribuição para o desenvolvimento de biossensores eletroquímicos para detecção de hapatopatias

Abstract

Modified electrodes can be used in selective interactions, pre-concentration, electrocatalysis, permselective membranes and incorporation of biomolecules, contributing, in this way, to increase the sensibility and selectivity of an analytical measurement. Polymeric films represent an alternative in the modification of an electrode. Non-conducting polymers presents high resistivity, which limits the films growing, offering a low diffusional barrier. These polymers are used as permselective membranes avoiding the approach of interferent species on the electrode surface. Conducting polymers presents unusual properties as electric conductivity, low energy of optical transmission, low ionization potential and high electronic affinity. These polymers are called synthetical metals because they have electronic properties similar to that one from metals. The use of conducting and non-conducting polymeric films has attracted considerable interest on the development of amperometric biosensors, due to its unique properties. Biosensor is a device that employs a biological recognition element attached to a transducer. Biosensors offers some advantages as high sensibility and selectivity, response in real time, potential to be miniaturized, possibility to an in situ monitoration, easily handed, which justify its employ in analytical measurements. Biosensors represents a promising tool in the detection of hepatopaties due to its unique characteristics as the possibility of the construction of simple and portable devices to an fast on site monitoration. In this way, the use of biosensors enables a precocious diagnosis of hepatopaties, belonging in a group of illnesses that causes a great number of deaths. This work proposes to contribute to the development of a biosensor to the detection of diseases that attacks the liver. This biosensor will be constructed as a modified electrode with a polymeric film from 4-aminophenol, electrochemically deposited, in which will be incorporated L-alanine and α-ketoglutarate as recognition elements of alanine aminotransferase (ALT), enzyme presents in a great amount in human blood attacked by any kind of hepatic injury.