Banca de DEFESA: PRISCILA DIAS MENDONCA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : PRISCILA DIAS MENDONCA
DATE: 27/10/2021
TIME: 09:00
LOCAL: Google Meet
TITLE:

Immunosensor platform for the diagnosis of dengue fever and zika

KEY WORDS:

Dengue; Zika; NS1; Immunosensor; carbon nanotubes

PAGES: 82
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

Arboviruses diseases are recognized by the World Health Organization as a global health
problem, generating relevant social and economic impacts. In the tropics and intertropical zones
of the terrestrial globe, dengue infection has been the most endemically prevalent, although
other infections, such as Zika, have had devastating effects, such as congenital fetal syndrome.
Considering that the clinical differential diagnosis is a difficult task, the search for new
biomarkers that identify arboviruses in a laboratory manner and in large scale is desirable. Non-
structural protein 1 (NS1) has been observed in infections by Dengue (DENV) and Zika (ZIKV)
viruses, circulating in the bloodstream of the infected individual during the entire viremia, with
higher levels in the initial phase of the disease, having been detected in serum and urine
samples. Because the NS1 protein is considered sensitive among non-structural proteins and
more specific for diagnosis, it is important in the clinical phase of these infections, several
studies for the development of immunosensors were carried out, using different types of
transduction, such as: fluorescence, impedance, surface plasmon resonance, amperometry.
However, the amperometric transduction, as it is easy to be portable and can be used in
emergency care, has proven to be the most attractive. In this thesis, an immunosensor platform
was developed, constituted by the electrosynthesis of polyethylenediamine (poly-EDA), from the
oxidation of ethylenediamine, providing a controlled thickness and good electrochemical
properties. The poly-EDA film rich in amino-reactive groups was used to strategically anchor
carbon nanotubes (CNT) that increase the electron transfer as well as the electroactive area of
the sensor surface. The incorporation of CNT carboxylated provided an oriented immobilization
of the anti-NS1 monoclonal antibodies by covalent bonds, allowing a high stability during the
measurements. All steps of electrode surface modifications were characterized by
electrochemical, structural and morphological techniques using cyclic voltammetry, Fourier
Transform Infrared with Attenuated Total Reflectance (ATR FTIR) and scanning electron
microscopy, respectively. A quartz crystal microbalance system was used to control the
thickness of the electrosynthesized poly-EDA in nanoscale order (~100nm). The analytical
responses of immunosensor to the NS1 protein were obtained by differential pulse voltammetry
technique showing a linear range between 20 and 800 ng/mL; with a limit of detection 6.8 ng/mL
and reproducibility of 97.0%. This immunosensor was able to detect the NS1 protein at clinical
levels, in serum and spiked urine samples collected from individuals with Dengue and Zika.
Thus, it is suggested that the polymer synthesized and constituted with NTCs (poly-EDA/NTC)
has potential for the development of new methodologies, providing a faster, more accurate and
sensitive diagnosis compared to existing techniques, and may enable clinical data of individuals
infected as well as epidemiological studies to assist in the sanitary approach of endemic regions
of the world.

BANKING MEMBERS:
Interna - 1257300 - JACIANA DOS SANTOS AGUIAR
Externo à Instituição - MARCOS VINÍCIUS FOGUEL
Externa à Instituição - MARLI TENÓRIO CORDEIRO - Fiocruz - PE
Externa à Instituição - PATRICIA MUNIZ MENDES FREIRE DE MOURA - UPE
Interna - 1836797 - ROSA AMALIA FIREMAN DUTRA