Banca de QUALIFICAÇÃO: VANESSA ERIKA ABRANTES COUTINHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : VANESSA ERIKA ABRANTES COUTINHO
DATE: 31/03/2023
TIME: 14:30
LOCAL: Remoto
TITLE:

Use of Ganoderma applatum and Canavalia ensiformis lectins as electrochemical biorecognition elements for glucose

KEY WORDS:

Legume lectins; Fungal lectins; Canavalia ensiformis; Ganoderma applanatum; Glucose; Electrochemical biosensors.

PAGES: 104
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Carbohydrates are the most abundant organic molecules on the planet. In the cell, these compounds participate in molecular recognition and interaction mechanisms and are also used as a primary source of energy. Carbohydrates are also important for health and uncontrolled levels in the body can lead to metabolic diseases, such as diabetes mellitus and obesity. The control of glucose has been investigated to facilitate and/or improve the detection of this monosaccharide in biological fluids, food, and commercial formulations. Due to their ability to reversibly and specifically bind carbohydrates, lectins are proteins that have been gaining ground as recognition molecules in the development of electrochemical glucose biosensors. Legume lectins are widely studied and characterized, with the lectin isolated from Canavalia ensiformis (ConA) being the best known of this group and used for its specificity for glucose. Due to the diversity of properties according to the source obtained, fungal lectins also attract researchers interested in investigating the biotechnological potential of these proteins. The species Ganoderma appalanatum, for example, has a lectin (GAL) with an affinity for glucose, moderately resistant to variations in pH (4-8) and temperature (20-60ºC), but with hemagglutinating activity better preserved under physiological conditions. In this work, two biorecognition systems for glucose were developed with ConA and GAL, using a glassy carbon electrode (GCE) modified with Prussian Blue (PB) that, in addition to being a semiconductor material, it also has heterogeneous regions of electronic density for the suitable adsorption of proteins through intermolecular bonds. The results obtained by different techniques proved that the problem of instability of this material at physiological pH can be solved by thermal treatment at 100 ºC for 1h, leading to the electrode suport named ta-PB/GCE. The use of artificial intelligence associated with electrochemical parameters allowed perform structural studies to obtain biocompatible and electrostatically conditions for immobilizing GAL on ta-PB/GCE, which were also useful in studies with ConA. The GAL/ta-PB/GCE biosensor showed excellent electrochemical performance for glucose quantification under ideal conditions, reaching a detection limit of 10.2 pM and sensitivity of 0.012 µA µM^‒1cm^‒2. The performance obtained with ConA/ta-PB/GCE was also satisfactory, reaching a detection limit of 0.56 µM and sensitivity of 3.94×10³ µA µM^‒1cm^‒2. The selectivity of the assays was influenced by other carbohydrates, including fructose, maltose, and sucrose, probably due to the moderately low regioselectivity achieved with superficial interaction sites of these proteins, but without compromising the viability of the devices for the electroanalysis of glucose in complex samples. Both biosensors were tested for glucose quantification in pharmaceutical formulations, achieving recovery values between 98.0% and 100.5%. The ConA/ta-PB/GCE biosensor has also been successfully applied for the analysis of total sugars in soft drink samples. Each device presented advantages and challenges that still require further studies, but the set of figures of merit obtained in each system proved that the platforms developed are truly efficient for the analysis of glucose in different samples, stimulating further research with the development of lectin-based electrochemical biosensors for biologically relevant carbohydrates.

BANKING MEMBERS:
Externa à Instituição - TATIANE SANTI GADELHA
Externo à Instituição - FRANCISCO ADRIANO DE OLIVEIRA CARVALHO
Interno - FRANCISCO NASCIMENTO PEREIRA JUNIOR
Presidente - THIAGO MIELLE BRITO FERREIRA OLIVEIRA