Desenvolvimento de biossensor enzimático e eletroquímico para detecção de ureia.

Abstract

The diseases caused by the malfunction of the kidneys and urinary tract vary with the type of pathology and the part of the affected system, with renal failure being one of the diseases that causes the increase of toxins in the blood, such as urea. The clinical method for quantifying urea in the body is performed only in laboratories, has costs and is a relatively time-consuming procedure. Devices that reduce costs, time and increase patient access to rapid diagnosis, such as biosensors is a necessity of society. In view of the above, the objective of this research was to develop enzymatic and electrochemical biosensor for the detection of urea. For that, antimony and graphite paint were produced, enzyme immobilization was performed and the screen printing technique was used to produce the biosensor. It is characterized by X-ray diffraction, scanning electron microscopy, adhesion evaluation, electrical conductivity, pH evaluation, sensitivity and linearity range and clinical sample testing. X-ray diffraction confirmed the crystalline phases present in the inks produced. Scanning electron microscopy showed the morphology of the particles and that the particle size was between 1 and 40 μm in size. The adhesion evaluation showed that the antimony ink particles such as graphite have a good interaction with the support. The conductivity of the antimony paint is less than that of graphite, however, they are well suited for the desired application. The pH of the serum solutions with different urea concentrations varied between (6.3 and 6.88), and that during the bioresponse measures these values vary between (7.56 and 8.88). The biosensor presented sensitivity at concentrations of 0 to 20 mmol / L, however, for concentrations between 10 and 20 mmol / L, the values were not significant. The range of linearity of the biosensor is 0 to 10mmol / L and that the clinical tests by the standard method were similar to those obtained with the developed biosensors. In the clinical samples tests using whole blood, the biosensors showed satisfactory responses, obtaining urea conversion values similar to those presented in the traditional clinical tests, proving the efficacy and the possibility of using the biosensor with a whole blood sample without any preparation.