Desenvolvimento de imunossupressores eletroquímicos baseado em nanocristais de óxido de zinco dopados com cobre com cobre ou estrutura metal-orgânica (MOF) para detecção de alfa-amilase salivar humana

Abstract

This work describes the importance of electrochemical biosensors for the detection of human salivary alpha-amylase (HSA). The central theme of the presented doctoral thesis is based on the description of a detection methodology that refers to the development of an electrochemical immunosensor decorated with nanomaterials for the detection of HSA in saliva. ZnO, CuO and ZnO x Cu (0.1, 0.4, 1.0, 4.0 and 12.0) nanocrystals (Ncs) metal-organic framework (MOF) nanomaterials were used. The incorporation of Cu2+ into the ZnO structure and the formation of nanocomposite were demonstrated in the chemical characterizations. Graphite electrodes were used, which showed a 40% increase in the electrochemical signal when using ZnO: 1.0Cu and 4.0Cu (0.25mg/mL- 1), in immunosensor (0.372mg/mL-1 anti- HSA and 1% casein). Different interactions between biomolecules and NCs were observed before and after the addition of saliva (4 μL). The immunosensor changed its specificity due to the interaction of copper. The ZnO:1Cu and ZnO:4Cu samples received 50% interference in detection when used before the addition of saliva. The electrochemical properties were evaluated by cyclic voltammetry (CV) (0.1 V.s- 1). The redox couple Ferri/Potassium Ferrocyanide allowed the analysis of anodic and cathodic current peaks. The results were obtained by the EmStat1 potentiostat/PsTrace8 software. The immunosensor showed 100% specificity and 0.00196U/mL-1 sensitivity. The results showed that the order of addition of NCs in the sensors should be tested and evaluated in order to avoid misinterpretations. Therefore, this sensor can be presented as a promising device for the detection of HSA, present in saliva. During the construction of the doctoral thesis, other works involving the theme of electrochemical biosensors were also developed and will be included in this material.