Banca de DEFESA: VANESSA ERIKA ABRANTES COUTINHO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : VANESSA ERIKA ABRANTES COUTINHO
DATE: 07/07/2023
TIME: 14:30
LOCAL: FAMED
TITLE:

LECTINS FROM Ganoderma applanatum AND Canavalia ensiformis AS ELEMENTS IN ELECTROCHEMICAL BIORECOGNITION 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, being important in
mechanisms of intercellular recognition and interaction and for health. Different ways of
controlling glucose levels have been the subject of much research aimed at facilitating and/or
improving the detection of this monosaccharide in biological fluids, foods and commercial
formulations. Due to their ability to reversibly and specifically bind carbohydrates, lectins are
proteins that have been gaining ground as a recognition star in the development of
electrochemical glucose biosensors. Legume lectins are widely studied and characterized,
with the basic lectin from Canavalia ensiformes (ConA) being the best-known of this group.
Due to the diversity of properties according to the source of production, fungal lectins also
show biotechnological potential. The species Ganoderma applanatum, for example, has a
lectin (GAL) with an affinity for glucose and which is moderately resistant to variations in pH
(4 - 8) and temperature (20 – 60 ºC), although with a hemagglutinating activity that is 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 hexacyanometalate Prussian Blue (PB) which, in addition to being a
semiconductor material, has heterogeneous electron density regions and suitable for the
adsorption of proteins, through intermolecular bonds. The results obtained by different
techniques proved that the problem of PB instability at physiological pH can be solved by
thermal treatment at 100 ºC for 1h, leading to the electrode support of ta-PB/GCE. The use of
artificial intelligence associated with electrochemical parameters allowed structural studies
and the collection of data on biocompatible and electrostatically favorable conditions for
immobilization of GAL in 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 ‒1 cm ‒2 . The performance obtained with ConA/ta-PB/GCE was satisfactory,
reaching a detection limit of 0.96 µM and sensitivity of 3.94×10 3 µA µM ‒1 cm ‒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 surface
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 was successfully applied for the analysis of total
sugars in a soft drink sample. Each device presented particular 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 electrochemical biosensors based on
lectins for carbohydrates of biological relevance.

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