Name: Rayssa Helena Arruda Pereira
Type: MSc dissertation
Publication date: 14/03/2016
Advisor:

Namesort descending Role
Marco Cesar Cunegundes Guimarães Advisor *

Examining board:

Namesort descending Role
André Romero da Silva External Examiner *
Daniela Amorim Melgaço Guimarães do Bem Internal Examiner *
Marco Cesar Cunegundes Guimarães Advisor *

Summary: Ochratoxins metabolites are secreted by the fungal species known as Aspergillus and Peniccillium. They are derived from a substituted phenylalanyl isocoumarin, and ochratoxin A (OTA) the most toxic among the two types of ochratoxin, A and B. Their similarity with the amino acid phenylalanine is the origin of their toxicity, which causes an effect inhibitory in various enzymes whose substrate is phenylalanine. The regulation of tolerable levels of ochratoxin in foods for human consumption and feed for animal consumption was defined in some countries. The European Union, for example, limited the maximum levels of ochratoxin in some foods, such as wine (2 ppb), coffee (5ppb) and cereals (5ppb). In order to meet these limits of detection, simpler analytical methods, safe and fast are being developed to make it accessible to use by unskilled people. In this context, nanotechnology has much to contribute, especially the branch of nanotechnology that uses the optical properties of materials. Those consisting of noble metal nanomaterials have a property capable of translating events of interaction between molecules in a measurable signal, the plasmon resonance surface located (LSPR). Furthermore, the possibility of adding selectivity sensitivity led to the conjugation of biological macromolecules and nanoparticles capable of recognizing specific antigens. In the present study, we used gold nanoparticles (AUNP) synthesized with trisodium citrate to evaluate the OTA detection potential. The nanoparticles were characterized by spectrophotometry in the UV-visible, infrared spectroscopy (FT-MIR), Raman spectroscopy, zeta potential and transmission electron microscopy. Anti-Ochratoxin A antibodies were adsorbed to colloidal nanoparticles. Detection assays occurred in an aqueous medium and the detection limit reached 1.10-7 OTA µg.ml-1. There was a decrease of the maximum absorbance to the OTA increase in increasing concentrations with a correlation of 0.98065. It was concluded that AUNP remained stabilized carboxylates after adsorption of antibodies and these remain active after adsorption, suggesting a second sphere coordination. The pH 9 proved important for maintaining antibody activity.

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