Desenvolvimento de uma superfície bifuncional Pt/Au modificada com glicose oxidase para determinação de glicose em amostras alimentícias

Abstract

Glucose is a reducing sugar very important in the human diet and is abundant in many foods, such as fruit juices, honey, yogurt and soft drinks and can be easily ingested and metabolized. It provides the energy for the human body perform its healthy functioning. However, many metabolic imbalances associated with variations in the level of glucose in the blood, urine or saliva. Therefore it is necessary to develop methods cheap, simple and quick to allow the monitoring of this metabolite. Therefore, in the present work was developed and characterized an electrode composed of a bifunctional surface Pt/Au, where Au surface was modified with a selforganized monolayer of cystamine which was anchored in the enzyme glucose oxidase and the surface of Pt with ferrocene for the determination of glucose in food samples. The electrode was constructed using a platinum electrode, which was electrodeposited gold nanostructures, using the technique of linear voltammetry in a solution containing the anion tetrachloroauric. The gold nanostructures were modified with cystamine alkanethiol forming a self-organized layer to serve as a platform for anchoring the glucose oxidase. Hydrogen peroxide, which is a product of the enzyme reaction, was determined in the platinum modified with ferrocene. Therefore, the gold nanostructures serve as sites for specific enzymes, and platinum modified with ferrocene serve to quantify the product of the enzymatic reaction. For detection of glucose were built three electrodes, the electrode embedded (EE) for detecting glucose in soft drinks, the electrode by evaporating platinum (EEP) for detection of glucose in samples of yogurt and ultramicroelectrode (UME) for future sensing applications glucose through non-evasive. We found a detection limit of 2.4 µmol L -1 to the electrode EE, 2.2 µmol L -1 to the electrode EEP and 0.03 µmol L -1 for UME. Various statistical treatments were performed as relative error, standard deviation and uncertainties to check the response of the electrode. Finally, the electrodes developed were applied to the detection of glucose in samples of soft drinks, teas and yogurts, which gave a satisfactory response to the detection of the analyte in food samples.