Banca de QUALIFICAÇÃO: MÔNICA RODRIGUES DE SÁ

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MÔNICA RODRIGUES DE SÁ
DATE: 28/06/2023
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

SELF-ASSEMBLY LATEX SYSTEMS FOR USE IN SERS-TYPE SENSORS

KEY WORDS:

látex, self-assembly, SERS.

PAGES: 84
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Latex nanoparticles have been highlighted as an alternative for the preparation of more stable self-assembled substrates for use in SERS-type devices due to their high monodispersity, a very relevant feature in the spontaneous formation of self-assembled macrocrystals that can be used in optical applications. Thus, this work aimed to prepare self-ordered substrates of latex nanoparticles (PS and (P(SHEMA)) containing AgNPs for use in SERS-type devices, combined with the incorporation of luminescent molecules in order to to evaluate its possible influence on the signal intensity and detection magnification. The latices were obtained by polymerization process in surfactant-free emulsion, being this process used in the production of synthetic latices for the formation of nanoparticles. Methods for the preparation of films self-organized were: aqueous surface method, spin coating and spontaneous selfordering method. The size and morphology of the latex particles were evaluated by SEM, which allowed identifying the PS nanoparticles with spherical morphology and mean diameter of 759 ± 31, 87 nm and P(S-HEMA) particles with a diameter of 500 ± 18.50 nm and DLS analysis showing 870 ± 2.5 nm (PS) and 580 ± 1.5 nm (P(S-HEMA) which pointed an excellent monodispersity of the particles. The PZ of the nanoparticles was negative with values of -37.34 ± 2.8 for PS and 53.50 ± 3.4 for P(S-HEMA), indicating good stability. The contact angle measurement showed good wettability of the particles on the glass substrate with values of 59.90° and 39.80° for PS and P(S-HEMA), respectively. The self-assembled films were characterized by SEM, which showed the formation of self-assembled systems of hexagonal array of particles, through the proposed methodologies. The micrographs also made it possible to identify the incorporation of the dye into the latex particles, by changing the sizes and morphology after the insertion of the R6G, combined with the luminescence spectroscopy technique and the use of UV light, which showed the presence of luminescent characteristics in the latex nanoparticles doped. Measurements by backscattered electrons and EDS showed the presence of addition of AgNPs in the substrate with an average size of 9.5 ± 4.2 nm and DLS analysis with a value of 20.88 ± 0.50 nm and PZ of 46.69 ± 1.27 mV. Preliminary testing of the SERS substrate containing the analyte, through Raman spectra, indicated an increase in signal intensity, promoting a self-assembled system with improved intensity. In this way, these results demonstrate the possibility of the system in the use of sensors of the SERS type, which can contribute significantly to analyzes of a single molecule and of low concentration of the analyte.

COMMITTEE MEMBERS:
Interno - 1129726 - CID BARTOLOMEU DE ARAUJO
Interna - 1857515 - GIOVANNIA ARAUJO DE LIMA PEREIRA
Presidente - 1354207 - SEVERINO ALVES JUNIOR