Desenvolvimento de biossensor eletroquímico de baixo custo para identificação da deficiêcia da glicose 6-fosfato desidrogenase (G6PD)

Abstract

For the treatment of malaria caused by Plasmodium vivax, one of the drugs used is Primaquina an effective drug in combating the parasitic forms incubated in the liver. However, this drug may induce hemolysis in individuals with Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, which affects millions of people worldwide. G6PD deficiency is an erythroenzymepathy caused by blockage of the enzymatic pathway of the monophosphate hexoses. That leads to the accumulation of hydrogen peroxide causing oxidative damage to the erythrocyte, which is one of the most frequently known enzymopathies, ranging from an asymptomatic clinical picture to chronic or acute hemolytic anemia, cholecystitis, jaundice, and chronic granulomatosis. The use of biosensors (modified sensors with biological material closely linked to the surface of a transducer) for the detection of this disease has been of great applicability due to the advantages it offers, being able to highlight: sensitivity, rapid responses, and low cost. Considering these advantages and the need for detection devices, the present project was developed five types of electrochemical sensors based on polymeric composites for immobilization of the enzyme G6PD, to develop low-cost biosensors for the detection of enzymatic activity. For the execution of the work, gold and carbon were used as working electrodes, depositing on their surfaces a mixture of different composites, Dihexadecyl Phosphate (DHP), Graphene Oxide (OG), Nanoparticles (NPsAu): DHP-OG, DHP- NPsAu, DHP-OG-NPsAu which were characterized and studied the effects they exert on the immobilization of the enzyme. The biosensors were characterized using techniques such as cyclic voltammetry (VC), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIE), and the surface topography and its structure using techniques such as scanning electron microscopy (SEM), spectroscopy dispersive energy (EDS), infrared spectroscopy by Fourier transform variant attenuated total reflectance (FTIR-ATR) and ultraviolet-visible spectrophotometry (UV-Vis) combined with the contact angle technique to know the wettability.Analytical curves were performed by differential pulse voltammetry (DPV) and SWV with the parameters optimized for each technique and evaluated in PBS 0.1 mol L-1, pH= 7.6 with additions of C(NAD+) 3× 10-4 mol L-1 at different volumes in the electrolytic cell. Linearity ranged from 7.5×10-7 to 6.0×10-6mol L-1 with R2 between 98 and 99 %, detection limits LOD and LOQ in the order of 10-6 mol L-1. The biosensors were shown to be stable for six days.