Banca de QUALIFICAÇÃO: BRUNA GOMES MACIEL

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : BRUNA GOMES MACIEL
DATE: 12/01/2022
LOCAL: Google Classroom
TITLE:

APPLICATION OF NANOSTRUCTURES FOR DNA EXTRACTION, ENVIRONMENTAL REMEDIATION, AND LEISHMANIA SENSING

KEY WORDS:

Magnetic nanocomposite. DNA extraction. Dye removal. Gold nanoparticles. Diagnostic tests.

PAGES: 106
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

In the present work, we describe the continuity of a project, which started during the Master's
period, in which an iron oxide/chitosan magnetic nanocomposite (NCM) coated with polyaniline
(Pani) was used for the extraction of dissolved DNA in aqueous media. (model system) and
human blood samples (real system). To better investigate the possibilities of applying these
NCM in real systems, several optimizations of the system were carried out for different
parameters, such as the amount of NCM to be used and the volume of buffer solution used to
promote desorption and the comparison of the results obtained with those resulting from the use
of commercial kits based on column systems (membranes) and particles. As part of the doctoral
work, we developed in parallel two additional works, which are still in progress. The first
concerns the optimization of the polymeric coating of the γ-Fe2O3/Qui/Pani NCM, which was
properly characterized by Fourier Transform Infrared Spectroscopy (FTIR), magnetization
curves, and X-ray diffraction (XRD). This nanocomposite was then applied to remove dyes
(methyl orange (AM), indigo carmine (IC), and rhodamine B (RB)) dispersed in aqueous media.
For this, we analyzed the effect of variations in parameters such as the pH value of the medium,
the dye concentration, and the interaction time, which allowed us to adjust the data to different
models used in the description of isotherms and the kinetics of the process. adsorption of
contaminants. This NCM exhibited an adsorption capacity of 147 mg [126 mg] of the AM dye
[IC], and 80 mg RB per gram of material, values that can be considered promising compared to
the performance of others adsorbent materials described in the literature. As part of these studies,
we also examined the influence of temperature variation on the adsorption process to perform
thermodynamic calculations that indicated that the process occurs spontaneously and is
endothermic in nature. We also started an additional work, which was dedicated to the
development of a platform to be used for diagnostic tests, using thiolated probes labeled with
fluorescent dyes. For this, we implemented functionalization studies of glass substrates by vapor
deposition of thiolated and amine groups, to be then coated with gold nanoparticles (NPs) to
form a nanostructured film. In this investigation, we evaluated the film formation time using the
techniques of ultraviolet and visible spectroscopy (UV-Vis), scanning electron microscopy
(SEM-STEM), and atomic force microscopy (AFM). Thus, we could verify that the time
required for functionalization to occur is 2h, with the formation of a uniform film of Au NPs
occurring in 6h. The deposited Au nanoparticles have a uniform size distribution between 19 and
23 nanometers. After optimizing the platform, we should start the application in the sensing of
Leishmania Infantum through the immobilization of thiolated DNA probes, subsequent addition
of spacer or blocker groups, and, finally, insertion of complementary probes to evaluate
parameters such as sensitivity and selectivity.

BANKING MEMBERS:
Externa à Instituição - ANA CLAUDIA VAZ DE ARAUJO - UFRPE
Presidente - 2199290 - BEATE SAEGESSER SANTOS
Externa à Instituição - MARIA TEREZA CARTAXO MUNIZ