Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol

Detalhes bibliográficos
Autor(a) principal: Dibo, Vitória Soares
Data de Publicação: 2019
Tipo de documento: Trabalho de conclusão de curso
Idioma: por
Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
dARK ID: ark:/83112/0013000011srm
Texto Completo: http://www.repositorio.ufc.br/handle/riufc/43785
Resumo: The Self-Assembled Monolayer (SAM), which is formed by spontaneous adsorption of chemical species on a surface, when combined with gold nanoparticles (AuNPs) can be used to build electrochemical biosensors destinated to detect biomolecules. This work had the intention to develop a chemically modified electrode, which is a platform, that might be used to build an electrochemical biosensor. Thus, the SAM modification method was used immerging a polycrystalline gold electrode in 1,4-bezenedithiol (BDT) solution, to form the modified electrode Au/BDT. After this procedure, the Au/BDT was immersed in gold colloidal solution (AuNPs) for 2 hours, resulting on the Au/BDT/AuNPs electrode. So, correlating the vibrational SERS (Surface-Enhanced Raman Scattering) and Raman spectra, particularly related to the S–H bend and stretching modes, it was possible to infer the adsorption process of the BDT molecules onto gold occurs through one of the sulfur atoms. The monitoring of the formation of the BDT monolayer was performed by cyclic voltammetry and impedance in solution containing [Fe(CN)6]3-/4- ions as redox species. With the increase in the modification time, the voltammetric curves presented an increase in the peak potential difference (Ep) and the Nyquist diagrams obtained showed similar trend presenting an increase in the heterogeneous charge transfer resistance (RCT). Have proven that the sulfur atom was responsible to adsorb on gold, the modified electrode was used in a linear sweep voltammetry in alkaline medium to determine the desorption potential (-0.88 V vs Ag/AgCl) and the surface coverage (Γ = 1.62 x 10-10 mol cm-2). The AuNPs synthesized presented a band assigned to the surface plasmon resonance (SPR) with maximum at 534 nm being consistent with an average diameter of 56 nm. The addition of the AuNPs on the Au/BDT electrode was followed by cyclic voltammetry and impedance in solution containing [Fe(CN)6]3-/4- ions as redox species. The electrochemical and impedimetric results showed that the addition of the nanoparticles decreases the separation between the peak potentials as well as the heterogeneous charge transfer resistance on the interface Au/BDT/AuNPs with the redox species. In addition, the SERS spectra obtained for Au/BDT/AuNPs confirmed that the interaction of the nanoparticles with the SAM of BDT occurred through the terminal sulfur atom.
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spelling Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiolMonocamada automontadaBenzenoditiolNanopartículas de ouroThe Self-Assembled Monolayer (SAM), which is formed by spontaneous adsorption of chemical species on a surface, when combined with gold nanoparticles (AuNPs) can be used to build electrochemical biosensors destinated to detect biomolecules. This work had the intention to develop a chemically modified electrode, which is a platform, that might be used to build an electrochemical biosensor. Thus, the SAM modification method was used immerging a polycrystalline gold electrode in 1,4-bezenedithiol (BDT) solution, to form the modified electrode Au/BDT. After this procedure, the Au/BDT was immersed in gold colloidal solution (AuNPs) for 2 hours, resulting on the Au/BDT/AuNPs electrode. So, correlating the vibrational SERS (Surface-Enhanced Raman Scattering) and Raman spectra, particularly related to the S–H bend and stretching modes, it was possible to infer the adsorption process of the BDT molecules onto gold occurs through one of the sulfur atoms. The monitoring of the formation of the BDT monolayer was performed by cyclic voltammetry and impedance in solution containing [Fe(CN)6]3-/4- ions as redox species. With the increase in the modification time, the voltammetric curves presented an increase in the peak potential difference (Ep) and the Nyquist diagrams obtained showed similar trend presenting an increase in the heterogeneous charge transfer resistance (RCT). Have proven that the sulfur atom was responsible to adsorb on gold, the modified electrode was used in a linear sweep voltammetry in alkaline medium to determine the desorption potential (-0.88 V vs Ag/AgCl) and the surface coverage (Γ = 1.62 x 10-10 mol cm-2). The AuNPs synthesized presented a band assigned to the surface plasmon resonance (SPR) with maximum at 534 nm being consistent with an average diameter of 56 nm. The addition of the AuNPs on the Au/BDT electrode was followed by cyclic voltammetry and impedance in solution containing [Fe(CN)6]3-/4- ions as redox species. The electrochemical and impedimetric results showed that the addition of the nanoparticles decreases the separation between the peak potentials as well as the heterogeneous charge transfer resistance on the interface Au/BDT/AuNPs with the redox species. In addition, the SERS spectra obtained for Au/BDT/AuNPs confirmed that the interaction of the nanoparticles with the SAM of BDT occurred through the terminal sulfur atom.A monocamada automontada (SAM – Self-Assembled Monolayer), que é formada pela adsorção espontânea de espécies químicas sobre uma superfície, quando combinada a nanopartículas de ouro (AuNPs) pode ser utilizada na construção de biossensores eletroquímicos destinados a detecção de moléculas de interesse. Este trabalho teve o intuito de desenvolver uma plataforma de eletrodo modificado quimicamente com a possível proposta de formar um biossensor eletroquímico. Assim, foi utilizado o método de modificação da SAM em que o eletrodo de ouro policristalino foi imerso em uma solução de 1,4-benzenoditiol (BDT), a fim de formar o substrato modificado Au/BDT. Com o eletrodo modificado com a espécie sulfurada, o Au/BDT foi imerso em solução coloidal de AuNPs por 2 horas, resultando no eletrodo Au/BDT/AuNPs. Dessa forma, através da correlação entre os espectros vibracionais SERS (Surface-Enhanced Raman Scattering) e Raman normal, particularmente em relação aos modos de deformação e estiramento S–H, foi possível inferir que o processo de adsorção das moléculas de BDT sobre ouro ocorreu através de pelo menos um dos átomos de enxofre. O acompanhamento da formação da monocamada de BDT foi realizado por voltametria cíclica e impedância em solução contendo íons [Fe(CN)6]3-/4- como espécies redox. Com o aumento do tempo de modificação, as curvas voltamétricas apresentaram um aumento na separação de potencial de pico (Ep), e os diagramas de Nyquist obtidos apresentaram a mesma tendência mostrando um aumento da resistência de transferência heterogênea de carga (RCT). Tendo-se o enxofre como átomo responsável pela adsorção sobre o ouro, utilizou-se a dessorção redutiva alcalina para determinar o potencial de dessorção (-0,88 V vs Ag/AgCl) e o recobrimento superficial (Γ = 1,62 x 10-10 mol cm-2). As nanopartículas de ouro sintetizadas apresentaram uma banda ao plasmon de superfície (SPR, do inglês Surface Plasmon Resonance) com máximo em 534 nm correspondendo a um diâmetro médio de 56 nm. A incorporação das AuNPs foi monitorada por voltametria cíclica e impedância em solução contendo íons [Fe(CN)6]3-/4- como espécies redox. Os resultados eletroquímicos e impedimétricos mostraram que a adição das nanopartículas diminui a separação entre os potenciais de pico e a resistência de transferência heterogênea de carga na interface do eletrodo Au/BDT/AuNPs com a solução de espécies redox. Adicionalmente, os espectros de SERS do eletrodo Au/BDT/AuNPs confirmaram a interação das nanopartículas com a SAM de BDT através do átomo de enxofre terminal.Diógenes, Izaura Cirino NogueiraFurtado, Roselayne FerroDibo, Vitória Soares2019-07-19T17:23:33Z2019-07-19T17:23:33Z2019info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/bachelorThesisapplication/pdfDIBO, Vitória Soares. Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol. 2019. 40 f. Trabalho de Conclusão de Curso (Graduação em Química Bacharelado) - Universidade Federal do Ceará, Fortaleza, 2019.http://www.repositorio.ufc.br/handle/riufc/43785ark:/83112/0013000011srmporreponame:Repositório Institucional da Universidade Federal do Ceará (UFC)instname:Universidade Federal do Ceará (UFC)instacron:UFCinfo:eu-repo/semantics/openAccess2019-07-19T17:23:33Zoai:repositorio.ufc.br:riufc/43785Repositório InstitucionalPUBhttp://www.repositorio.ufc.br/ri-oai/requestbu@ufc.br || repositorio@ufc.bropendoar:2024-09-11T18:22:26.666643Repositório Institucional da Universidade Federal do Ceará (UFC) - Universidade Federal do Ceará (UFC)false
dc.title.none.fl_str_mv Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
title Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
spellingShingle Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
Dibo, Vitória Soares
Monocamada automontada
Benzenoditiol
Nanopartículas de ouro
title_short Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
title_full Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
title_fullStr Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
title_full_unstemmed Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
title_sort Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol
author Dibo, Vitória Soares
author_facet Dibo, Vitória Soares
author_role author
dc.contributor.none.fl_str_mv Diógenes, Izaura Cirino Nogueira
Furtado, Roselayne Ferro
dc.contributor.author.fl_str_mv Dibo, Vitória Soares
dc.subject.por.fl_str_mv Monocamada automontada
Benzenoditiol
Nanopartículas de ouro
topic Monocamada automontada
Benzenoditiol
Nanopartículas de ouro
description The Self-Assembled Monolayer (SAM), which is formed by spontaneous adsorption of chemical species on a surface, when combined with gold nanoparticles (AuNPs) can be used to build electrochemical biosensors destinated to detect biomolecules. This work had the intention to develop a chemically modified electrode, which is a platform, that might be used to build an electrochemical biosensor. Thus, the SAM modification method was used immerging a polycrystalline gold electrode in 1,4-bezenedithiol (BDT) solution, to form the modified electrode Au/BDT. After this procedure, the Au/BDT was immersed in gold colloidal solution (AuNPs) for 2 hours, resulting on the Au/BDT/AuNPs electrode. So, correlating the vibrational SERS (Surface-Enhanced Raman Scattering) and Raman spectra, particularly related to the S–H bend and stretching modes, it was possible to infer the adsorption process of the BDT molecules onto gold occurs through one of the sulfur atoms. The monitoring of the formation of the BDT monolayer was performed by cyclic voltammetry and impedance in solution containing [Fe(CN)6]3-/4- ions as redox species. With the increase in the modification time, the voltammetric curves presented an increase in the peak potential difference (Ep) and the Nyquist diagrams obtained showed similar trend presenting an increase in the heterogeneous charge transfer resistance (RCT). Have proven that the sulfur atom was responsible to adsorb on gold, the modified electrode was used in a linear sweep voltammetry in alkaline medium to determine the desorption potential (-0.88 V vs Ag/AgCl) and the surface coverage (Γ = 1.62 x 10-10 mol cm-2). The AuNPs synthesized presented a band assigned to the surface plasmon resonance (SPR) with maximum at 534 nm being consistent with an average diameter of 56 nm. The addition of the AuNPs on the Au/BDT electrode was followed by cyclic voltammetry and impedance in solution containing [Fe(CN)6]3-/4- ions as redox species. The electrochemical and impedimetric results showed that the addition of the nanoparticles decreases the separation between the peak potentials as well as the heterogeneous charge transfer resistance on the interface Au/BDT/AuNPs with the redox species. In addition, the SERS spectra obtained for Au/BDT/AuNPs confirmed that the interaction of the nanoparticles with the SAM of BDT occurred through the terminal sulfur atom.
publishDate 2019
dc.date.none.fl_str_mv 2019-07-19T17:23:33Z
2019-07-19T17:23:33Z
2019
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/bachelorThesis
format bachelorThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv DIBO, Vitória Soares. Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol. 2019. 40 f. Trabalho de Conclusão de Curso (Graduação em Química Bacharelado) - Universidade Federal do Ceará, Fortaleza, 2019.
http://www.repositorio.ufc.br/handle/riufc/43785
dc.identifier.dark.fl_str_mv ark:/83112/0013000011srm
identifier_str_mv DIBO, Vitória Soares. Incorporação de nanopartículas de ouro sobre monocamada automontada de benzenoditiol. 2019. 40 f. Trabalho de Conclusão de Curso (Graduação em Química Bacharelado) - Universidade Federal do Ceará, Fortaleza, 2019.
ark:/83112/0013000011srm
url http://www.repositorio.ufc.br/handle/riufc/43785
dc.language.iso.fl_str_mv por
language por
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositório Institucional da Universidade Federal do Ceará (UFC)
instname:Universidade Federal do Ceará (UFC)
instacron:UFC
instname_str Universidade Federal do Ceará (UFC)
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institution UFC
reponame_str Repositório Institucional da Universidade Federal do Ceará (UFC)
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repository.name.fl_str_mv Repositório Institucional da Universidade Federal do Ceará (UFC) - Universidade Federal do Ceará (UFC)
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