Banca de DEFESA: ANA ELISA FERREIRA DE OLIVEIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANA ELISA FERREIRA DE OLIVEIRA
DATE: 09/02/2022
TIME: 13:00
LOCAL: São João del Rei
TITLE:

Development of Printed Paper-based Electrochemical Sensors for Determination of Breast Cancer Biomarker CA 15-3 in Biological Samples
Thesis

KEY WORDS:

CA 15-3; Electrochemical Sensor; Paper-based Sensors; Blood Serum; Saliva

PAGES: 358
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Eletroanalítica
SUMMARY:

In this work, it was developed two sensitives, simple and low-costs printed paper-based electrochemical sensors as an effective alternative for the determination of the breast cancer biomarker CA 15-3 in human serum and saliva samples. The electrodes were fabricated using different techniques, conductive inks and modifications. The first one was the graphite sensor. Initially, graphite and silver/silver chloride inks were fabricated using nail polish and acetone. The silver/silver chloride ink includes an additional step called chlorination where the AgCl layer is deposited on top of Ag ink with bleach solution. Next the graphite sensor was fabricated by screen-printing method. The graphite ink was used to print the working and counter electrodes, and silver/silver chloride ink in the development of the reference electrode. Then the sensor was modified with gold nanoparticles, antibody anti-human CA 15-3 and bovine serum albumin, resulting in the immunosensor SPE/AuNP/BSA. The immunosensor presented a sensitivity of 0.01231 μA/U mL-1, LOD of 0.5626 U mL-1 and LOQ of 1.8755 U mL-1. The interfering substances did not affect significantly the current signal, with response variation of 4.94%, and the reproducibility showed a relative standard deviation of 5.65%. The immunosensor was used to determine the CA 15-3 concentration in human serum and saliva samples using the standard addition method. The applications showed satisfactory recoveries, demonstrating good precision and potential application of the SPE/AuNP/BSA in clinical analysis. Next, the carbon nanotube sensor was fabricated. For that a carbon nanotube ink was fabricated using multi-wall carbon nanotube (MWCNT) and both covalent and non-covalent functionalization. The covalent functionalization was performed in acid medium using H2SO4/HNO3 and the non-covalent functionalization used SDS and ultrasonication. The ink formulation combines the insertion of functional groups and absorption of the SDS hydrophobic tail in the CTN surface. The silver nanoparticle ink was synthesized using the polyol method, with silver nitrate, ethylene glycol and polyvinylpyrrolidone. Then the material was dried and re-dispersed the in methanol. The carbon nanotube sensor was fabricated using carbon nanotube ink in marker pen to print the working electrode, graphite pencil to print the counter electrode and graphite/silver nanoparticle ink in rollerball pen to print the quasi-reference electrode. The CNT sensor was printed in a paper substrate using handwriting technique. The carbon nanotube sensor was electropolymerized with o-phenylenediamine in presence of CA 15-3 to form imprinted sites. First, a layer of AuNP was applied, serving as a platform for incubation of CA 15-3. While the oPD was used as the monomer on the construction of the polymeric film. After the protein was extracted, leaving vacant sites for subsequent rebinding. The developed sensor, called CNE/AuNP/MIP, provided a sensitivity of 0.013936 μA/U mL-1, limits of detection of 1.16 U mL-1 and quantification of 3.87 U mL-1. The interference studies showed that the sensor can be specific for CA 15-3. While the reproducibility exhibited a RSD of the current response for CA 15-3 detection of 2.77%, indicating the precision of the sensor. Then the sensor was applied in determination of CA 15-3 in samples of serum and saliva. The use in serum presented good recovery, but the application in saliva was not satisfactory. Therefore, the sensor CNE/AuNP/MIP should be used in the determination of CA 15-3 in serum samples only.

BANKING MEMBERS:
Interno - 1727278 - LUIZ GUSTAVO DE LIMA GUIMARAES
Interno - 1677150 - ARNALDO CESAR PEREIRA
Externa à Instituição - MARIA DEL PILAR TABOADA SOTOMAYOR - UNESP
Externo à Instituição - LUCAS FRANCO FERREIRA - UFVJM
Externo à Instituição - CESAR RICARDO TEIXEIRA TARLEY - UEL