Applications of surface plasmon resonance and quartz crystal microbalance in the investigation of interface processes intending the sensors development

Orientador: Lauro Tatsuo KubotaTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: O presente trabalho descreve as aplicações da ressonância de plásmon de superfície (surface plasmon resonance-SPR) e da microbalança de cristal de quartzo (quartz crystal microbalance-QCM) na investigação de processos interfaciais, visando o melhor entendimento e aplicação dos sistemas investigados bem como o estabelecimento das aplicações da técnica SPR aliada à eletroquímica. Neste sentido são apresentadas investigações do comportamento óptico-eletroquímico da molécula de azul de metileno (sistema 1), polímeros condutores (sistema 2) e monocamadas auto-organizadas (sistema 3). A escolha de tais sistemas, embora distintos, tem a finalidade de exploração ampla da técnica SPR na investigação de processos superficiais e interfaciais. O uso da técnica SPR na investigação do sistema 1 mostra a sua aplicabilidade no monitoramento do intumescimento de filmes em dimensões nanométricas e a investigação de processos adsortivos e difusionais com elevada sensibilidade. Assim sendo, a técnica SPR foi aplicada na investigação de processos de formação de filmes finos de polímeros condutores, bem como os processos de dopagem destes filmes. Neste sentido, foi investigada a eletropolimerização do pirrol e da polianilina bem como o efeito de dopantes aniônicos sobre as propriedades ópticas e eletroquímicas destes materiais. As medidas ópticas obtidas foram correlacionadas aos processos de dopagem e desdopagem dos filmes confeccionados mediante um estudo comparativo destes processos por QCM tendo em vista a consolidação da mesma na investigação de tais processos. Por fim, com o propósito de explorar a sensibilidade da técnica SPR a sistemas de dimensões sub-nanométricas, foram investigadas monocamadas auto-organizadas de ácido 11-mercapto-undecanóico e mono(6-deoxi-6-mercapto)-b-ciclodextrina. Neste sentido, foram determinadas a espessura e a constante dielétrica destes filmes, assim como a cinética de adsorção destes empregando um modelo de adsorção fundamentado na adsorção, desorção e re-arranjo molecularAbstract: The present work describes the applications of surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) in the investigation of interface processes in the attempt to improve the understanding and application of the investigated systems as well as the establishment of the applications of the SPR allied with electrochemical techniques. In this sense, are presented the investigation of the electrochemical behavior of the methylene blue molecule (system 1), conducting polymers (system 2) and self-assembled monolayers (system 3). The selection of these systems, although distinct, has a focus on the exploration of the SPR technique in the investigation of surface and interface processes. The use of SPR technique in the investigation of the system 1 shows its applicability in the monitoring of swelling of films in nanometric size as well as the investigation of adsorptive and diffusional processes with high sensitivity. Thus, SPR was applied in the investigation of construction of thin conducting polymer films as well as its doping processes. In this sense, were investigated pyrrole and aniline electropolymerization as well as the effects of anionic dopants on its optical and electrochemical properties. The optical measurements were correlated with the doping and dedoping processes of the films by means of a comparative study of these processes by QCM due to the better establishment of this technique in the investigation of these processes. Finally, with the purpose of explore the sensitivity of the SPR technique in sub-nanometric size systems, the SPR technique was applied in the investigation of selfassembled monolayers of 11-mercapto-undecanoic acid and mono(6-deoxy-6-mercapto)-b- cyclodextrin. In this sense, were determined the thickness and dielectric constant of these films as well as the adsorption kinetic by using a kinetic model based on adsorption, desorption and re-arrangement of moleculesDoutoradoFísico-QuímicaMestre em Químic

Aplicações de QCM, EIS e SPR na investigação de superfícies e interfaces para o desenvolvimento de (bio)sensores

The use of the quartz crystal microbalance process, electrochemical impedance spectroscopy and surface plasmon resonance for characterizing thin films and monitoring interfaces is presented. The theorical aspects of QCM, EIS and SPR are introduced and the main application areas are outlined. Future prospects of the combined applications of QCM, EIS and SPR methods in the studies of interfacial processes at surfaces are also discussed

Applications of QCM, EIS and SPR in the investigation of surfaces and interfaces for the development of (bio)sensors

The use of the quartz crystal microbalance process, electrochemical impedance spectroscopy and surface plasmon resonance for characterizing thin films and monitoring interfaces is presented. The theorical aspects of QCM, EIS and SPR are introduced and the main application areas are outlined. Future prospects of the combined applications of QCM, EIS and SPR methods in the studies of interfacial processes at surfaces are also discussed.97097

Cobalt Tetrasulphonated Phthalocyanine Immobilized On Poly-l-lysine Film Onto Glassy Carbon Electrode As Amperometric Sensor For Cysteine.

The present work describes the development of a simple and efficient method for the amperometric determination of cysteine (CySH) in wild medium at an applied potential of 0.150 V versus Ag/AgCl. In this sense, the electrocatalytic oxidation of cysteine (CySH) was carried out on a glassy carbon electrode modified with cobalt tetrasulphonated phthalocyanine (CoTSPc) and poly-L-lysine (PLL) film. The immobilization of CoTSPc in PLL film was performed by a simple evaporation of the solvent. The CoTSPc/PLL film, formed on the GC electrode showed an electrocatalytic activity to the CySH oxidation. The sensor presented its best performance in 0.1 mol l(-1) Pipes at pH 7.5. Under optimized operational conditions, the sensor provided a wide linear response range for CySH from 0.50 up to 216.0 micromol l(-1) with a sensitivity and detection limit of 157 nA cm(-2) l micromol(-1) and 150 nmol l(-1), respectively. The proposed sensor presented higher sensitivity when compared to the other modified electrodes described in the literature and showed a stable response for at least 200 successive determinations. The repeatability of the measurements with the same sensor and different sensors, evaluated in term of relative standard deviation, were 4.1 and 5.2%, respectively, for n=10. The developed sensor was applied for the CySH determination in food supplement samples and the results were statistically the same to those obtained by a comparative method described in the literature at a confidence level of 95%.42184-9

Electrocatalytic Determination Of Reduced Glutathione In Human Erythrocytes.

The determination of reduced glutathione (GSH) in human erythrocytes using a simple, fast and sensitive method employing a glassy carbon electrode modified with cobalt tetrasulfonated phthalocyanine (CoTSPc) immobilized in poly(L: -lysine) (PLL) film was investigated. This modified electrode showed very efficient electrocatalytic activity for anodic oxidation of GSH, decreasing substantially the anodic overpotentials for 0.2 V versus Ag/AgCl. The modified electrode presented better performance in 0.1 mol l(-1) piperazine-N,N'-bis(2-ethanesulfonic acid) buffer at pH 7.4. The other experimental parameters, such as the concentration of CoTSPc and PLL in the membrane preparation, pH, type of buffer solution and applied potential, were optimized. Under optimized operational conditions, a linear response from 50 to 2,160 nmol l(-1) was obtained with a high sensitivity of 1.5 nA l nmol(-1) cm(-2). The detection limit for GSH determination was 15 nmol l(-1). The proposed sensor presented good repeatability, evaluated in terms of the relative standard deviation (1.5%) for n = 10. The modified electrode was applied for determination of GSH in erythrocyte samples and the results were in agreement with those obtained by a comparative method described in the literature The average recovery for these fortified samples was 100 +/- 1)%. Applying a paired Student's-t test to compare these methods, we could observe that, at the 95% confidence level, there was no statistical difference between the reference and the proposed methods.3871891-

Highly sensitive p-nitrophenol determination employing a new sensor based on N-Methylphenazonium methyl sulfate and graphene: analysis in natural and treated waters

This paper describes a rapid and highly sensitive method for determination of p-nitrophenol (p-NP) in water samples employing a glassy carbon electrode modified with N-Methylphenazonium methyl sulfate (NMP) adsorbed on graphene. This modified electrode presented very efficient capability toward p-NP reduction, decreasing substantially its oxidation potential to -0.6V vs Ag/AgCl. Electrochemical impedance spectroscopy and FTIR spectroscopy measurements were also carried out in characterizing of the modification process. It has been found that the electrode modification with NMP and graphene has significantly enhanced the electrode response toward p-NP reduction. Linear response range from 1 nmol L-1 up to 1170 nmol L-1 (or 0.001-1.17 mu mol L-1) by differential pulse voltammetry and from 500 nmol L-1 up to 5600 nmol L-1 (or 0.50-5.60 mu mol L-1) by amperometry were obtained with sensitivities of 42.42 mu AL mu mol(-1) and 28.84 mu AL mu mol(-1), respectively. The proposed method was effectively applied for the determination of p-NP in samples of natural and treated waters and recovery tests to the analyte presented satisfactory results. (C) 2015 Elsevier B.V. All rights reserved.This paper describes a rapid and highly sensitive method for determination of p-nitrophenol (p-NP) in water samples employing a glassy carbon electrode modified with N-Methylphenazonium methyl sulfate (NMP) adsorbed on graphene. This modified electrode pr221740749FAPEMA - FUNDAÇÃO DE AMPARO A PESQUISA E AO DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO DO MARANHÃOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçãoThe authors are grateful to Fundação de Amparo à Pesquisa e Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and INCTBi

Sensitive electroanalytical detection on GCE: the case of lipoic acid and its interaction with N ‐acetylcysteine and glutathione

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A simple and sensitive electrochemical method was developed for the determination of N-Acetylcysteine (NAC) and Glutathione (GSH), on glassy carbon electrode. The results indicate that -lipoic acid (LipS(2)) is oxidized at the electrode, but is regenerated by thiols, suggesting a redox catalytic effect. Under optimized conditions, the analytical curves for NAC and GSH were obtained in the range of 1 up to 10 mu M and 1 up to 60 mu M, respectively. The quantification can be performed in a single assay with high sensitivity, reproducibility and low detection limit of 0.27 and 0.67 mu M for NAC and GSH, respectively. This method was successfully applied to the determination of NAC and GSH in artificial saliva and human urine samples, with excellent recovery results.A simple and sensitive electrochemical method was developed for the determination of N ‐Acetylcysteine (NAC) and Glutathione (GSH), on glassy carbon electrode. The results indicate that α‐lipoic acid (LipS2) is oxidized at the electrode, but is regenerate281128182826CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPEAL - FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DE ALAGOASConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)4840044/2011‐3, 407963/2013‐8, 458114/2014‐63004–20142009‐09‐006The authors are grateful to CNPq, CAPES and FAPEAL through grants from the CNPq (4840044/2011‐3, 407963/2013‐8, 458114/2014‐6), PRONEX/FAPEAL/CNPq/2009‐09‐006 and PROCAD/CAPES/3004–2014. The authors also gratefully acknowledge support from INCT‐Bioanalit

Development of a label-free immunosensor based on surface plasmon resonance technique for the detection of anti-Leishmania infantum antibodies in canine serum.

In this work ,a surface Plasmon resonance (SPR) immune sensor was developed using an 11-mercaptoundecanoic acid (11-MUA) modified gold SPR sensor chip for the detection of anti- Leishmania infantum antibodies. The soluble antigens of L. infantum were securely immobilized on an SPR gold disk byan 11-MUA self-assembled monolayer. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) techniques were employed in the characterization of the antigenim mobilization. After the immune sensor construction, canine serum positive for visceral leishmaniasis was added to its surface and showed significant variation in the SPR angle, indicating excellent sensitivity of the technique for antigen–antibody interaction detection. Moreover, the addition of negative serum was accompanied by as maller response, demonstrating that the immunosensor shows good specificity against anti-L. infantum antibodies. Therefore, this work demonstrates the success ful development of an SPR sensor for anti- L. infantum antibodies detection in short time, showing a great perspective as asensing system of visceral leishmania sisinende micregions