Banca de DEFESA: ANDRE OLIVEIRA SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDRE OLIVEIRA SANTOS
DATE: 13/08/2024
TIME: 09:00
LOCAL: Google meet
TITLE:

Photoelectrochemical biosensors for lactose developed with the lectin of the macrofungus Agaricus bisporus

KEY WORDS:
PAGES: 123
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Diets rich in lactose-based products provide important nutrients for our health, but people with lactose intolerance face serious adverse effects. Rigorous quality control of these products is important for adherence to lactose-free diets. Lectin-based biosensors for carbohydrate analysis are among the biotechnological applications of these macromolecules. The mushroom Agaricus bisporus contains a lectin (ABL) with biotechnological potential, featuring interaction sites for carbohydrates, including lactose, allowing the development of photoelectrochemical biosensors for this carbohydrate. In this study, lactose biosensors containing ABL were developed. The high lectin activity found in extracts from this macrofungus (640 UH mL⁻¹), even at critical pH values (4–10) and temperatures (20–100 °C), enabled its direct use as a source of ABL. In the first biosensor, a glass electrode coated with fluorine-doped tin oxide, modified with poly(methylene blue) and ABL, was used, resulting in the ABL/PMB/FTO biosensor. The poly(methylene blue) enhanced the photoactivity of the device, allowing the identification of lectin-carbohydrate interactions with even greater sensitivity. The dose-response curves studied by electrochemical impedance spectroscopy were well-fitted by the Hill equation, expanding the dynamic working range (lactose from 15–540 nM; detection limit of 20.2 pM). This device exhibited signal stability, precision, specificity, and selectivity for lactose analysis. In the second biosensor, glassy carbon modified with poly(beta-cyclodextrin), nanocellulose, cerium molybdate nanoparticles, and ABL was used, resulting in the GCE/β-CD/CeMo/ABL biosensor. Additionally, the principal component analysis (PCA) method was adopted to select data from multiple frequencies for the association curves. Computational data for the immobilization of ABL from its extract showed that this procedure also contributed to reducing the flat band potential to a magnitude equivalent to that obtained with GCE/β-CD/CeMo irradiation. For PCA analyses, normalized impedance modulus data provided the best separation between lactose levels and the least data dispersion. The association curves for frequencies between 3.1 and 31.6 Hz were fitted by the biphasic association model. By associating these data, those obtained with the ABL/PMB/FTO biosensor and PCA analysis, three association events were found with dissociation constants equals to . The GCE/β-CD/CeMo biosensor exhibited high sensitivity (detection limit of 0.4 pM), even in atypical pH and temperature conditions for protein materials, without compromising the selectivity for lactose.

COMMITTEE MEMBERS:
Externa à Instituição - SIMONE BARREIRA MORAIS
Externa à Instituição - ADRIANA NUNES CORREIA
Interno - HEBERTY DI TARSO FERNANDES FACUNDO
Externo ao Programa - 1549914 - MARCELO OLIVEIRA SANTIAGO - nullExterna ao Programa - 1151160 - MARIA APARECIDA SANTIAGO DA SILVA - nullPresidente - THIAGO MIELLE BRITO FERREIRA OLIVEIRA
Externa à Instituição - VANESSA ERIKA ABRANTES COUTINHO