Banca de DEFESA: RENATA SOARES TEIXEIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : RENATA SOARES TEIXEIRA
DATA : 14/12/2020
HORA: 13:30
LOCAL: Sala de defesas do PGQUIM
TÍTULO:

Quantum dots immobilization into agarose discs for water analysis devices development

PALAVRAS-CHAVES:

Quantum dots; DGT; water analysis

PÁGINAS: 65
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Métodos Óticos de Análise
RESUMO:

Quantum dots (QD) are widely used as luminescent probes due to the high quantum yield, high photostability and narrow emission bands. However, the potential toxicity associated to metallic species and radical species photo-generation, raise questions about their application as probes for in situ analysis of water. Therefore, different strategies were evaluated for QD immobilization into agarose films aiming to the development of devices for in situ analysis of metals in waters based on the diffusion gradient in thin films. Thus, CdTe capped with glutathione (GSH-CdTe) and carbon (CQD; N-CQD) quantum dots were synthesized by hydrothermal and pyrolysis approaches, respectively. Solid supports such as aminated glass beads (SiO₂-NH₂), silica (SiO₂) and polymers (aminopropyltriethoxysilane - APTES) were studied for luminescent composite synthesis. The synthesized QD composites were tested on thin agarose gel discs (h = 1.6 mm; Φ = 2.0 cm) and immersed in purified water for periods of up to 24 h. The fluorescent intensity of thin QD/agarose discs and their diffusion into water was monitored by molecular fluorescence spectroscopy and image analysis. The QD direct addition to agarose films led to probe diffusion with visible increase water luminescence after 30 min of immersion. In addition, contamination of water samples by N-CQD@APTES was observed with an emission decay of 70% in 24 h. For QDs linked to substrates by covalent bonding (GSH-CdTe @ APTES) migration to water was not observed and a low variation in fluorescence was observed (<20%), except for the CQD@SiO₂ and GSH-CdTe@SiO₂-NH₂ composites, whose fluorescence decay levels were superior to 90%. Finally, the response of thin agarose discs doped with GSH-CdTe@APTES against Hg²⁺, Cd²⁺, Pb²⁺ and Cr³⁺ (50 μg L^-1) were observed (ΔF≥90%).

MEMBROS DA BANCA:
Presidente - 282814 - MARIA DAS GRACAS ANDRADE KORN
Interno - 2356272 - ARTUR JOSE SANTOS MASCARENHAS
Interno - 1190574 - RODOLFO DE MELO MAGALHAES SANTANA
Interno - 318.201.155-34 - WALTER NEI LOPES DOS SANTOS - UFBA
Externo à Instituição - CLEBER GALVAO NOVAES - UESB
Externo à Instituição - MARCO TADEU GRASSI - UFPR