Banca de QUALIFICAÇÃO: Marylene Sousa Guimarães Roma

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Marylene Sousa Guimarães Roma
DATE: 23/05/2023
TIME: 09:30
LOCAL: Auditório do IB
TITLE:

"DEVELOPMENT OF A SALIVA CORTISOL SENSOR WITH AN INTERDIGITATED ELECTRODE PLATFORM BASED ON BARIUM TITANATE NANOPARTICLES."

KEY WORDS:

Titanium; Nanoparticles; Electrode; Cortisol; Point-of-Care

PAGES: 97
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

The stress caused by our lifestyle affects more than 90% of the global population, and induces restrictive physiological and/or psychosomatic responses in patients. The hormone cortisol, which is essential for maintaining homeostasis, is recognized as a potential biomarker for stress detection . There is an increase in patient self-monitoring technologies such as point-of-care devices, which apply sensors for the detection of cortisol by nanoparticles and capacitive arrangements of interdigitated electrode arrays (IDEAs), and thereby enable noninvasive, accurate diagnosis and screening in complex fluids. This study aims to quantify the cortisol dosage in saliva samples using mesoporous titanium oxide and complex impedance spectroscopy. The characteristic barium titanate oxide (TiBaO3) material with a high dielectric constant, was incorporated onto the surface of an IDEA. The mesoporous TiBaO3 particles were synthesized according to the colloidal precipitation method using titanium tetraisopropoxide (TTIP) and barium chloride, as well as the nonionic copolymer Pluronic® P123 as a structure-directing agent, to obtain the mesoporous SBA-15 structure. The TTIP precursor was subjected to hydrothermal treatment, which comprises hydrolysis and condensation reactions, under chemical reflux, followed by calcination at different temperatures. Subsequently, the surfactant P123 was removed at temperatures above 270 °C. The TiBaO3 nanoparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy coupled with attenuated total reflectance (FTIR-ATR), and X-ray diffraction (XRD). A unique gold interdigitated electrode platform composed of the semiconducting mesoporous TiBaO3 nanoparticles was developed. To increase the cortisol binding specificity in complex samples, albumin was attached onto the surface of the mesoporous particles as a surface antibinding agent. For the electrochemical cell fabrication, the IDEA was used as a support material for the TiBaO3 powder. Different analytical cortisol standard samples were prepared and measured at a constant voltage of 5 mV; the nominal current of 40 nA was generated at 1 kHz. The complex impedance spectra were measured using a sinusoidal input voltage in the frequency range of 100 Hz to 2 kHz. Principal component analysis was used for data processing, and cortisol levels as low as 40 ng/mL were detected. Further studies are being conducted to use this method for cortisol quantification in complex human saliva samples.

BANKING MEMBERS:
Presidente - 1547480 - JOSE ANTONIO HUAMANI COAQUIRA
Externo ao Programa - 331970 - JOSE FELICIO DA SILVA
Externo ao Programa - 1892565 - LEONARDO GIORDANO PATERNO
Externo à Instituição - Alessandro Pinheiro - IFB