Desenvolvimento de um biossensor de transistor de efeito de campo baseado em grafeno para detectar aflatoxina B1

• Ano de defesa: 2019
• Autor(a) principal: Paulo Alexandre Alves de Almeida Neves
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ICB - INSTITUTO DE CIÊNCIAS BIOLOGICAS; Programa de Pós-Graduação em Bioquímica e Imunologia; UFMG
• Palavras-chave em Português: Aflatoxina B1; Grafeno; Biossensor; GFET; Bioquímica; Técnicas Biossensoriais
• Link de acesso: http://hdl.handle.net/1843/31003

Aflatoxicosis is an intoxication caused by ingestion of aflatoxin through contaminated food and ration. There is great interest from both academia and industry in the use of relatively inexpensive miniaturized sensors for the detection of aflatoxin B1. The development of diagnostic biosensors has been the subject of much research and graphene is a model for this application due to its unique physicochemical properties. The realization of this proposed project is justified by the scarcity of information about the effective exposure sensors to aflatoxin B1, given the absence of biosensors that allow this diagnosis and aims to develop a method to be used as a point-of-care device to detect and quantify aflatoxin B1-N7-guanine from dietary ingestion of aflatoxin B1. The graphene used was grown by chemical vapor deposition method. An electrochemical transfer method was used to remove graphene from its growth substrate. The device was constructed containing a closed silicon channel with openings solely for the input of reaction solutions and the measuring electrode. The area of graphene was delimited by photolithography to small microscopic rectangles on gold contacts. Graphene was functionalized with a solution containing a linker, 1-pyrenobutanoic acid N-hydroxysuccinimide ester, a molecule capable of interacting with graphene and proteins. The intrinsic condition of the graphene built on each chip manufactured was electrically characterized by source and drain voltage curves (ISD × VSD) for all electrode assemblies produced. Samples obtained from the growth performed in the laboratory have resistances of 800 to 3 kΩ. To verify that the graphene produced was composed of a monolayer, some Raman spectroscopy measurements were performed and fluorescence microscopy assays were performed to determine the adhesion of anti-aflatoxin antibodies to the graphene. In order to use graphene as a biosensor, its behavior and response to the field effect were evaluated by checking the ISD × VSD curves. An atomic force microscopy analysis was performed to visualize the nanometer level distribution of the linker and protein assembly. The data illustrate a linear relationship within the range of 0 to 50 nmol / L with R² = 0.977. The detection limit of aflatoxin B1-N7-guanine was calculated at 3.26 nmol / L. This paper presents the prospects of employing graphene sensors for the detection of aflatoxin B1-N7-guanine, providing reliability in the rapid diagnosis of aflatoxin B1 poisoning and exposure.