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Nanociência & Nanotecnologia: Príncipios e Aplicações, Nov 2014

Journal Articles by Guedmiller S Oliveira

Neste trabalho esta sendo proposto a construcao de uma balanca com materiais de baixo custo pa... more Neste trabalho esta sendo proposto a construcao de uma balanca com materiais de baixo custo para determinacao da tensao super cial de lquidos. A con abilidade das medidas foi comprovada comparando os resultados
obtidos com aqueles apresentados na literatura para lquidos simples, e empregando o metodo da ascensao capilar
para o caso de outros lquidos. Por este metodo, os erros sistematicos dos resultados obtidos foram reduzidos
consideravelmente. O princpio de funcionamento do dispositivo consiste na medida da forca necessaria para
desprender uma l^amina de vidro parcialmente imersa em um lquido. Os valores da tens~ao super cial sao calculados
com base nos conceitos de momento de forcas, e considera as interacoes intermoleculares entre a lamina e
a superfcie do lquido.

The herbicide residue from intensive agricultural activity provokes environmental disturbances an... more The herbicide residue from intensive agricultural
activity provokes environmental disturbances and human health
injuries. Among the enzymatic disruptor herbicides, mesotrione
is able to inhibit 4-Hydroxyphenylpyruvate dioxygenase (HPPD),
which plays a key role in the carotenoid synthesis. Therefore,
enzyme-based sensors are innovative options for monitoring
herbicides used in agriculture. Compared to the standard
sensors, biosensors have assorted advantages, such as
practicality, quick response, low cost, and high sensitivity. A
nanobiosensor was developed herein based on HPPD for
mesotrione detection. Theoretically, the Molecular Docking and
Molecular Dynamics Simulation estimated the interacting regions
of HPPD with mesotrione. Experimentally, the AFM tip
functionalization with HPPD immobilized in self-assembled
monolayers was confirmed by fluorescence microscopy and
atomic force spectroscopy. The cross-linker EDC, which stands
for N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide
hydrochloride, was responsible for properly preserve of the
enzyme on the tip. The nanobiosensor proposed here was
successfully able to detect mesotrione molecules. Such
effectiveness in the development of nanobiosensors promises
reliable, precise, low cost techniques, which apply to a broad
range of issues, from ecology to medicine.

Journal of Molecular Graphics and Modelling, Jul 23, 2014

A stochastic simulation of adsorption processes was developed to simulate the coverage of an atom... more A stochastic simulation of adsorption processes was developed to simulate the coverage of an atomic force microscope (AFM) tip with enzymes represented as rigid polyhedrons. From geometric considerations of the enzyme structure and AFM tip, we could estimate the average number of active sites available to interact with substrate molecules in the bulk. The procedure was exploited to determine the interaction force between acetyl-CoA carboxylase enzyme (ACC enzyme) and its substrate diclofop, for which steered molecular dynamics (SMD) was used. The theoretical force of (1.6 ± 0.5) nN per enzyme led to a total force in remarkable agreement with the experimentally measured force with AFM, thus demonstrating the usefulness of the procedure proposed here to assist in the interpretation of nanobiosensors experiments.

IEEE Sensors Journal, 2014

Highly sensitive and selective functional nanobiobreaksensors are being developed because they ha... more Highly sensitive and selective functional nanobiobreaksensors are being developed because they have significant applications in the sustenance and conservation of natural resources and can be used in projects to identify degraded and contaminated areas (of both soil and water) and as environmental quality indicators. In the present study, a nanobiosensor was developed based on using theoretical models (molecular docking and molecular dynamics simulations) based on biomimicry of the action mechanism of herbicides in plants coupled with atomic force microscopy (AFM) tools. The herbicide molecules were detected at very low concentrations using a unique sensor construction: the AFM probes and the substrate were chemically functionalized to favor covalent bonding and promote molecular flexibility, as well as to achieve reproducible and accurate results. Computational methods were used to determine the binding energies associated with the enzyme-herbicide interactions, which were compared with experimental results for adhesion forces. The theoretical results showed that the diclofop herbicide could be assembled and attached onto the mica substrate surface and the ACCase enzyme on the AFM probe without damaging the diclofop molecule. The experimental results showed that using a specific agrochemical target molecule was more efficient than using other nonspecific agrochemicals. On average, there was a 90% difference between the values of specific recognition (diclofop) and nonspecific recognition (imazaquin, metsulfuron, and glyphosate). This result validated the selectivity and specificity of the nanobiosensor. The first evidence of diclofop detection by the AFM probe sensors has been presented in this paper.

Journal of Molecular Graphics and Modelling, Aug 16, 2013

The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step ... more The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step in the development of nanobiosensors to be used in detection process. In this work, an atomistic modeling of the attachment of the acetyl coenzyme A carboxylase (ACC enzyme) on a functionalized AFM tip surface is proposed. Using electrostatic considerations, suitable enzyme–surface orientations with the active sites of the ACC enzyme available for interactions with bulk molecules were found. A 50 ns molecular dynamics trajectory in aqueous solution was obtained and surface contact area, hydrogen bonding and protein stability were analyzed. The enzyme–surface model proposed here with minor adjustment can be applied to study antigen–antibody interactions as well as enzyme immobilization on silica for chromatography applications.

Journal of Photochemistry and Photobiology. A, Chemistry

The solvatochromism and other spectroscopic and photophysical characteristics of four azo dispers... more The solvatochromism and other spectroscopic and photophysical characteristics of four azo disperse dyes, derived from 2-amino-5-nitrothiazole, were evaluated and interpreted with the aid of experimental data and quantum mechanical calculations. For the non-substituted compound two conformers, E and Z, were proposed for the isolated molecules, being the second one considerably less stable. The optimization of these structures in combination with a SCRF methodology (IEFPCM, simulating the molecules in a continuum dielectric with characteristics of methanol), suggests that the Z form is not stable in solution. This same behaviour is expected for the substituted compounds, which is corroborated by experimental data presented in previous investigations [A.E.H. Machado, L.M. Rodrigues, S. Gupta, A.M.F. Oliveira-Campos, A.M.S. Silva, J. Mol. Struct. 738 (2005) 239-245].

Horticultura Brasileira, 2009

Content, yield and chemical composition of the essential basil oil under chicken manure levels

Ciência Florestal , 2007

Neste estudo, foram analisados os principais componentes químicos da madeira da Moquinia polymorp... more Neste estudo, foram analisados os principais componentes químicos da madeira da Moquinia polymorpha (LESS.) DC., conhecida como candeia ou cambará, nativa da região Sul de Minas Gerais. A composição química dessa madeira foi: 47,5% de α-celulose, 25,4% de hemiceluloses A e B, 24,0% de lignina, 73,2% de holocelulose, 3,82% de extrativos em etanol:cicloexano (1:1, v v -1 ), 3,21% em etanol e 4,04% em água quente. Nos compostos voláteis identificados, destacaram-se: α-curcumeno, αdiidroturmerona, β-diidroturmerona, cedranol, 1-ciclopentil-3-[2,4-dimetil-fenil]propano. A análise dos fenóis totais foi conduzida com base nos extratos metanol-água (MA) e acetona-água (AA), em que esse último apresentou maior rendimento. O teor de fenóis totais foi determinado pelos métodos Folin-Ciocalteau e Azul da Prússia modificado. No método Folin-Ciocalteau, foram encontrados 0,93 mg g -1 de madeira para o extrato MA e 1,56 para o extrato AA e no método azul da Prússia modificado, foram determinados 2,74 mg g -1 de madeira para o extrato MA e 4,42 para o extrato AA. O teor de proantocianidinas foi determinado pelos métodos da vanilina e n-butanol:ácido. No método n-butanol:ácido, foram encontrados 0,012 mg g -1 de madeira para o extrato MA e 0,017 para o extrato AA e, no método da vanilina, foram determinados 0,29 mg g -1 de madeira para o extrato MA e 0,58 para o extrato AA. Não foram detectados 3-deoxi-proantocianidinas.

Papers by Guedmiller S Oliveira

Sensors

Here, we describe 4-dimethylaminoantipyrine (4-DMAA)-mediated interfacing as a broad biochemical ... more Here, we describe 4-dimethylaminoantipyrine (4-DMAA)-mediated interfacing as a broad biochemical indicator to stabilize and promote the higher response of electrodes for immunological detection. We hypothesized that the improved biological interactions of 4-DMAA with electrodes and biological samples may be due to the interaction properties of the benzene and pyrazole chemical groups with graphite and proteins, respectively. In order to demonstrate that 4-DMAA could be used as a general indicator in electrochemical immunoassays, we used peptides as probes for the diagnosis of four neglected tropical infectious diseases Tegumentary leishmaniasis, Visceral leishmaniasis, Strongyloidiasis, and Leprosy on commercial graphite screen-printed electrodes. 4-DMAA oxidation was used to indicate specific biological recognition between the epitope-based peptide and serum immunoglobulin G (IgG) from infected patients. We demonstrated that 4-DMAA should be incorporated into the electrodes prior t...

Revista Brasileira de Ensino de Física, 2015

Journal of molecular graphics & modelling, 2014

A stochastic simulation of adsorption processes was developed to simulate the coverage of an atom... more A stochastic simulation of adsorption processes was developed to simulate the coverage of an atomic force microscope (AFM) tip with enzymes represented as rigid polyhedrons. From geometric considerations of the enzyme structure and AFM tip, we could estimate the average number of active sites available to interact with substrate molecules in the bulk. The procedure was exploited to determine the interaction force between acetyl-CoA carboxylase enzyme (ACC enzyme) and its substrate diclofop, for which steered molecular dynamics (SMD) was used. The theoretical force of (1.6±0.5) nN per enzyme led to a total force in remarkable agreement with the experimentally measured force with AFM, thus demonstrating the usefulness of the procedure proposed here to assist in the interpretation of nanobiosensors experiments.

Journal of Molecular Graphics and Modelling, 2013

The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step ... more The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step in the development of nanobiosensors to be used in detection process. In this work, an atomistic modeling of the attachment of the acetyl coenzyme A carboxylase (ACC enzyme) on a functionalized AFM tip surface is proposed. Using electrostatic considerations, suitable enzyme-surface orientations with the active sites of the ACC enzyme available for interactions with bulk molecules were found. A 50 ns molecular dynamics trajectory in aqueous solution was obtained and surface contact area, hydrogen bonding and protein stability were analyzed. The enzyme-surface model proposed here with minor adjustment can be applied to study antigen-antibody interactions as well as enzyme immobilization on silica for chromatography applications.

IEEE Sensors Journal, 2014

Fonte referencial de informação para a Pesquisa Apoiada pela FAPESP (Referência obtida automatica... more Fonte referencial de informação para a Pesquisa Apoiada pela FAPESP (Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.

IEEE Sensors Journal, 2021

The study of the interaction of the herbicide glyphosate with zinc oxide (ZnO) nanocrystals (NCs)... more The study of the interaction of the herbicide glyphosate with zinc oxide (ZnO) nanocrystals (NCs) was investigated under controlled pH conditions. These changes alter the various chemical groups’ vibrational frequencies of the glyphosate molecule according to the infrared spectra. Scanning electron microscopy (SEM), and atomic force microscopy (AFM) images suggest that the pH changes promote specific conformational changes due to the protonation of glyphosate. Then, the glyphosate is organized as a mycelium around ZnO NCs at neutral pH. Also, as the pH varies from acidic to alkaline, new crystal structures occur, which goes from star-like to volcano-like shapes. For an efficient quantification of glyphosate using ZnO NCs, it is essential to correlate the pH to its method. The acidic medium is recommended for optical methods, while the basic medium is more suitable for gravimetric methods, and neutral pH is ideal for spectroscopic analysis in FTIR and Raman. Therefore, in this study, we demonstrated that tuning pH could change the identification method to improve accuracy.

Grandes áreas Da Nanociência e Suas Aplicações, 2015

ABSTRACT Nanociência e Nanotecnologia: Princípios e Aplicações é uma coletânea de três volumes de... more ABSTRACT Nanociência e Nanotecnologia: Princípios e Aplicações é uma coletânea de três volumes dedicada a estudantes de graduação e pós-graduação de diversos cursos, além de técnicos e profissionais de várias indústrias. Os livros contêm capítulos direcionados a temas de vanguarda em novas áreas de pesquisa, além de capítulos de caráter técnico-científico, em que são descritas estruturas e ferramentas para a ciência e tecnologia em escala nanométrica. A coleção tem o objetivo principal de orientar o leitor com relação aos conceitos e fundamentos teóricos da nanociência, para permitir o entendimento dos fenômenos e das propriedades da matéria em nível atômico-molecular. Propriedades de nanoestruturas, síntese, processamento, caracterização, manipulação e modelamento computacional foram temas abordados nos diversos capítulos. Pretende-se com esta obra ensinar alunos de diversas áreas os tópicos essenciais para iniciar pesquisas em nanociência e nanotecnologia. O texto é intrinsecamente interdisciplinar, já que os autores possuem formação acadêmica diversificada. Os capítulos são didáticos tanto na descrição dos modelos quanto nas suas possíveis utilizações. O aprofundamento em cada tema pode ser adquirido por intermédio da extensa lista de referências disponibilizadas pelos autores em seus capítulos.O segundo volume aborda as principais aplicações do nanomundo, integrando grandes áreas da ciência de forma multidisciplinar. O entendimento, controle e exploração de materiais e sistemas em nível molecular fornecem propriedades e fenômenos físicos, químicos e biológicos significativamente novos. O objetivo principal dos nanocientistas é explorar estas novas propriedades para futuras aplicações tecnológicas, compreendendo os fenômenos da natureza e suas respectivas implicações no bem-estar humano e no desenvolvimento da nossa civilização.

New Journal of Chemistry, 2021

Monometallic [RuCl2(η6-p-cymene)(pipNH2)] (mono-Ru) and heterobimetallic [RuCl2(η6-p-cymene)][(μ-... more Monometallic [RuCl2(η6-p-cymene)(pipNH2)] (mono-Ru) and heterobimetallic [RuCl2(η6-p-cymene)][(μ-Schiff-pip)Ni(PPh3)Cl] (Ru–Ni) complexes were successfully synthesized. They were fully characterized by FTIR, UV-Vis, and NMR spectroscopic studies, elemental analysis, cyclic voltammetry and computational studies. Complex Ru–Ni was additionally characterized by MALDI-TOF mass spectrometry. The polynorbornene (polyNBE) syntheses via ROMP using mono-Ru and Ru–Ni as pre-catalysts in the presence of ethyl diazoacetate (EDA) were evaluated at different [EDA]/[Ru] ratios, time periods (5–60 min) and temperatures (25 and 50 °C). Higher yields of polyNBE were obtained using [NBE]/[Ru] = 5000 and 5 μL of EDA at 50 °C for 60 min. Under these conditions, mono-Ru exhibited higher catalytic activity than Ru–Ni, reaching 50 and 40% yield, respectively. Hence, a strong steric influence of Ru–Ni on the catalytic activity was demonstrated. The order of magnitude of 105 g mol−1 was measured by SEC for M...

Nanociência & Nanotecnologia: Príncipios e Aplicações, Nov 2014

Neste trabalho esta sendo proposto a construcao de uma balanca com materiais de baixo custo pa... more Neste trabalho esta sendo proposto a construcao de uma balanca com materiais de baixo custo para determinacao da tensao super cial de lquidos. A con abilidade das medidas foi comprovada comparando os resultados
obtidos com aqueles apresentados na literatura para lquidos simples, e empregando o metodo da ascensao capilar
para o caso de outros lquidos. Por este metodo, os erros sistematicos dos resultados obtidos foram reduzidos
consideravelmente. O princpio de funcionamento do dispositivo consiste na medida da forca necessaria para
desprender uma l^amina de vidro parcialmente imersa em um lquido. Os valores da tens~ao super cial sao calculados
com base nos conceitos de momento de forcas, e considera as interacoes intermoleculares entre a lamina e
a superfcie do lquido.

The herbicide residue from intensive agricultural activity provokes environmental disturbances an... more The herbicide residue from intensive agricultural
activity provokes environmental disturbances and human health
injuries. Among the enzymatic disruptor herbicides, mesotrione
is able to inhibit 4-Hydroxyphenylpyruvate dioxygenase (HPPD),
which plays a key role in the carotenoid synthesis. Therefore,
enzyme-based sensors are innovative options for monitoring
herbicides used in agriculture. Compared to the standard
sensors, biosensors have assorted advantages, such as
practicality, quick response, low cost, and high sensitivity. A
nanobiosensor was developed herein based on HPPD for
mesotrione detection. Theoretically, the Molecular Docking and
Molecular Dynamics Simulation estimated the interacting regions
of HPPD with mesotrione. Experimentally, the AFM tip
functionalization with HPPD immobilized in self-assembled
monolayers was confirmed by fluorescence microscopy and
atomic force spectroscopy. The cross-linker EDC, which stands
for N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide
hydrochloride, was responsible for properly preserve of the
enzyme on the tip. The nanobiosensor proposed here was
successfully able to detect mesotrione molecules. Such
effectiveness in the development of nanobiosensors promises
reliable, precise, low cost techniques, which apply to a broad
range of issues, from ecology to medicine.

Journal of Molecular Graphics and Modelling, Jul 23, 2014

A stochastic simulation of adsorption processes was developed to simulate the coverage of an atom... more A stochastic simulation of adsorption processes was developed to simulate the coverage of an atomic force microscope (AFM) tip with enzymes represented as rigid polyhedrons. From geometric considerations of the enzyme structure and AFM tip, we could estimate the average number of active sites available to interact with substrate molecules in the bulk. The procedure was exploited to determine the interaction force between acetyl-CoA carboxylase enzyme (ACC enzyme) and its substrate diclofop, for which steered molecular dynamics (SMD) was used. The theoretical force of (1.6 ± 0.5) nN per enzyme led to a total force in remarkable agreement with the experimentally measured force with AFM, thus demonstrating the usefulness of the procedure proposed here to assist in the interpretation of nanobiosensors experiments.

IEEE Sensors Journal, 2014

Highly sensitive and selective functional nanobiobreaksensors are being developed because they ha... more Highly sensitive and selective functional nanobiobreaksensors are being developed because they have significant applications in the sustenance and conservation of natural resources and can be used in projects to identify degraded and contaminated areas (of both soil and water) and as environmental quality indicators. In the present study, a nanobiosensor was developed based on using theoretical models (molecular docking and molecular dynamics simulations) based on biomimicry of the action mechanism of herbicides in plants coupled with atomic force microscopy (AFM) tools. The herbicide molecules were detected at very low concentrations using a unique sensor construction: the AFM probes and the substrate were chemically functionalized to favor covalent bonding and promote molecular flexibility, as well as to achieve reproducible and accurate results. Computational methods were used to determine the binding energies associated with the enzyme-herbicide interactions, which were compared with experimental results for adhesion forces. The theoretical results showed that the diclofop herbicide could be assembled and attached onto the mica substrate surface and the ACCase enzyme on the AFM probe without damaging the diclofop molecule. The experimental results showed that using a specific agrochemical target molecule was more efficient than using other nonspecific agrochemicals. On average, there was a 90% difference between the values of specific recognition (diclofop) and nonspecific recognition (imazaquin, metsulfuron, and glyphosate). This result validated the selectivity and specificity of the nanobiosensor. The first evidence of diclofop detection by the AFM probe sensors has been presented in this paper.

Journal of Molecular Graphics and Modelling, Aug 16, 2013

The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step ... more The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step in the development of nanobiosensors to be used in detection process. In this work, an atomistic modeling of the attachment of the acetyl coenzyme A carboxylase (ACC enzyme) on a functionalized AFM tip surface is proposed. Using electrostatic considerations, suitable enzyme–surface orientations with the active sites of the ACC enzyme available for interactions with bulk molecules were found. A 50 ns molecular dynamics trajectory in aqueous solution was obtained and surface contact area, hydrogen bonding and protein stability were analyzed. The enzyme–surface model proposed here with minor adjustment can be applied to study antigen–antibody interactions as well as enzyme immobilization on silica for chromatography applications.

Journal of Photochemistry and Photobiology. A, Chemistry

The solvatochromism and other spectroscopic and photophysical characteristics of four azo dispers... more The solvatochromism and other spectroscopic and photophysical characteristics of four azo disperse dyes, derived from 2-amino-5-nitrothiazole, were evaluated and interpreted with the aid of experimental data and quantum mechanical calculations. For the non-substituted compound two conformers, E and Z, were proposed for the isolated molecules, being the second one considerably less stable. The optimization of these structures in combination with a SCRF methodology (IEFPCM, simulating the molecules in a continuum dielectric with characteristics of methanol), suggests that the Z form is not stable in solution. This same behaviour is expected for the substituted compounds, which is corroborated by experimental data presented in previous investigations [A.E.H. Machado, L.M. Rodrigues, S. Gupta, A.M.F. Oliveira-Campos, A.M.S. Silva, J. Mol. Struct. 738 (2005) 239-245].

Horticultura Brasileira, 2009

Content, yield and chemical composition of the essential basil oil under chicken manure levels

Ciência Florestal , 2007

Neste estudo, foram analisados os principais componentes químicos da madeira da Moquinia polymorp... more Neste estudo, foram analisados os principais componentes químicos da madeira da Moquinia polymorpha (LESS.) DC., conhecida como candeia ou cambará, nativa da região Sul de Minas Gerais. A composição química dessa madeira foi: 47,5% de α-celulose, 25,4% de hemiceluloses A e B, 24,0% de lignina, 73,2% de holocelulose, 3,82% de extrativos em etanol:cicloexano (1:1, v v -1 ), 3,21% em etanol e 4,04% em água quente. Nos compostos voláteis identificados, destacaram-se: α-curcumeno, αdiidroturmerona, β-diidroturmerona, cedranol, 1-ciclopentil-3-[2,4-dimetil-fenil]propano. A análise dos fenóis totais foi conduzida com base nos extratos metanol-água (MA) e acetona-água (AA), em que esse último apresentou maior rendimento. O teor de fenóis totais foi determinado pelos métodos Folin-Ciocalteau e Azul da Prússia modificado. No método Folin-Ciocalteau, foram encontrados 0,93 mg g -1 de madeira para o extrato MA e 1,56 para o extrato AA e no método azul da Prússia modificado, foram determinados 2,74 mg g -1 de madeira para o extrato MA e 4,42 para o extrato AA. O teor de proantocianidinas foi determinado pelos métodos da vanilina e n-butanol:ácido. No método n-butanol:ácido, foram encontrados 0,012 mg g -1 de madeira para o extrato MA e 0,017 para o extrato AA e, no método da vanilina, foram determinados 0,29 mg g -1 de madeira para o extrato MA e 0,58 para o extrato AA. Não foram detectados 3-deoxi-proantocianidinas.

Sensors

Here, we describe 4-dimethylaminoantipyrine (4-DMAA)-mediated interfacing as a broad biochemical ... more Here, we describe 4-dimethylaminoantipyrine (4-DMAA)-mediated interfacing as a broad biochemical indicator to stabilize and promote the higher response of electrodes for immunological detection. We hypothesized that the improved biological interactions of 4-DMAA with electrodes and biological samples may be due to the interaction properties of the benzene and pyrazole chemical groups with graphite and proteins, respectively. In order to demonstrate that 4-DMAA could be used as a general indicator in electrochemical immunoassays, we used peptides as probes for the diagnosis of four neglected tropical infectious diseases Tegumentary leishmaniasis, Visceral leishmaniasis, Strongyloidiasis, and Leprosy on commercial graphite screen-printed electrodes. 4-DMAA oxidation was used to indicate specific biological recognition between the epitope-based peptide and serum immunoglobulin G (IgG) from infected patients. We demonstrated that 4-DMAA should be incorporated into the electrodes prior t...

Revista Brasileira de Ensino de Física, 2015

Journal of molecular graphics & modelling, 2014

A stochastic simulation of adsorption processes was developed to simulate the coverage of an atom... more A stochastic simulation of adsorption processes was developed to simulate the coverage of an atomic force microscope (AFM) tip with enzymes represented as rigid polyhedrons. From geometric considerations of the enzyme structure and AFM tip, we could estimate the average number of active sites available to interact with substrate molecules in the bulk. The procedure was exploited to determine the interaction force between acetyl-CoA carboxylase enzyme (ACC enzyme) and its substrate diclofop, for which steered molecular dynamics (SMD) was used. The theoretical force of (1.6±0.5) nN per enzyme led to a total force in remarkable agreement with the experimentally measured force with AFM, thus demonstrating the usefulness of the procedure proposed here to assist in the interpretation of nanobiosensors experiments.

Journal of Molecular Graphics and Modelling, 2013

The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step ... more The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step in the development of nanobiosensors to be used in detection process. In this work, an atomistic modeling of the attachment of the acetyl coenzyme A carboxylase (ACC enzyme) on a functionalized AFM tip surface is proposed. Using electrostatic considerations, suitable enzyme-surface orientations with the active sites of the ACC enzyme available for interactions with bulk molecules were found. A 50 ns molecular dynamics trajectory in aqueous solution was obtained and surface contact area, hydrogen bonding and protein stability were analyzed. The enzyme-surface model proposed here with minor adjustment can be applied to study antigen-antibody interactions as well as enzyme immobilization on silica for chromatography applications.

IEEE Sensors Journal, 2014

Fonte referencial de informação para a Pesquisa Apoiada pela FAPESP (Referência obtida automatica... more Fonte referencial de informação para a Pesquisa Apoiada pela FAPESP (Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.

IEEE Sensors Journal, 2021

The study of the interaction of the herbicide glyphosate with zinc oxide (ZnO) nanocrystals (NCs)... more The study of the interaction of the herbicide glyphosate with zinc oxide (ZnO) nanocrystals (NCs) was investigated under controlled pH conditions. These changes alter the various chemical groups’ vibrational frequencies of the glyphosate molecule according to the infrared spectra. Scanning electron microscopy (SEM), and atomic force microscopy (AFM) images suggest that the pH changes promote specific conformational changes due to the protonation of glyphosate. Then, the glyphosate is organized as a mycelium around ZnO NCs at neutral pH. Also, as the pH varies from acidic to alkaline, new crystal structures occur, which goes from star-like to volcano-like shapes. For an efficient quantification of glyphosate using ZnO NCs, it is essential to correlate the pH to its method. The acidic medium is recommended for optical methods, while the basic medium is more suitable for gravimetric methods, and neutral pH is ideal for spectroscopic analysis in FTIR and Raman. Therefore, in this study, we demonstrated that tuning pH could change the identification method to improve accuracy.

Grandes áreas Da Nanociência e Suas Aplicações, 2015

ABSTRACT Nanociência e Nanotecnologia: Princípios e Aplicações é uma coletânea de três volumes de... more ABSTRACT Nanociência e Nanotecnologia: Princípios e Aplicações é uma coletânea de três volumes dedicada a estudantes de graduação e pós-graduação de diversos cursos, além de técnicos e profissionais de várias indústrias. Os livros contêm capítulos direcionados a temas de vanguarda em novas áreas de pesquisa, além de capítulos de caráter técnico-científico, em que são descritas estruturas e ferramentas para a ciência e tecnologia em escala nanométrica. A coleção tem o objetivo principal de orientar o leitor com relação aos conceitos e fundamentos teóricos da nanociência, para permitir o entendimento dos fenômenos e das propriedades da matéria em nível atômico-molecular. Propriedades de nanoestruturas, síntese, processamento, caracterização, manipulação e modelamento computacional foram temas abordados nos diversos capítulos. Pretende-se com esta obra ensinar alunos de diversas áreas os tópicos essenciais para iniciar pesquisas em nanociência e nanotecnologia. O texto é intrinsecamente interdisciplinar, já que os autores possuem formação acadêmica diversificada. Os capítulos são didáticos tanto na descrição dos modelos quanto nas suas possíveis utilizações. O aprofundamento em cada tema pode ser adquirido por intermédio da extensa lista de referências disponibilizadas pelos autores em seus capítulos.O segundo volume aborda as principais aplicações do nanomundo, integrando grandes áreas da ciência de forma multidisciplinar. O entendimento, controle e exploração de materiais e sistemas em nível molecular fornecem propriedades e fenômenos físicos, químicos e biológicos significativamente novos. O objetivo principal dos nanocientistas é explorar estas novas propriedades para futuras aplicações tecnológicas, compreendendo os fenômenos da natureza e suas respectivas implicações no bem-estar humano e no desenvolvimento da nossa civilização.

New Journal of Chemistry, 2021

Monometallic [RuCl2(η6-p-cymene)(pipNH2)] (mono-Ru) and heterobimetallic [RuCl2(η6-p-cymene)][(μ-... more Monometallic [RuCl2(η6-p-cymene)(pipNH2)] (mono-Ru) and heterobimetallic [RuCl2(η6-p-cymene)][(μ-Schiff-pip)Ni(PPh3)Cl] (Ru–Ni) complexes were successfully synthesized. They were fully characterized by FTIR, UV-Vis, and NMR spectroscopic studies, elemental analysis, cyclic voltammetry and computational studies. Complex Ru–Ni was additionally characterized by MALDI-TOF mass spectrometry. The polynorbornene (polyNBE) syntheses via ROMP using mono-Ru and Ru–Ni as pre-catalysts in the presence of ethyl diazoacetate (EDA) were evaluated at different [EDA]/[Ru] ratios, time periods (5–60 min) and temperatures (25 and 50 °C). Higher yields of polyNBE were obtained using [NBE]/[Ru] = 5000 and 5 μL of EDA at 50 °C for 60 min. Under these conditions, mono-Ru exhibited higher catalytic activity than Ru–Ni, reaching 50 and 40% yield, respectively. Hence, a strong steric influence of Ru–Ni on the catalytic activity was demonstrated. The order of magnitude of 105 g mol−1 was measured by SEC for M...

Aplicações de química teórica no estudo de materiais: métodos in silico para nanomateriais, 2018

All the contents of this work, except where otherwise noted, is licensed under a Creative Commons... more All the contents of this work, except where otherwise noted, is licensed under a Creative Commons Attribution 4.0 International license. Todo o conteúdo deste trabalho, exceto quando houver ressalva, é publicado sob a licença Creative Commons Atribição 4.0. Todo el contenido de esta obra, excepto donde se indique lo contrario, está bajo licencia de la licencia Creative Commons Reconocimento 4.0. 4-Desenvolvimento de nanodispositivos baseados em biomoléculas: abordagens computacionais

Agradeço aos meus pais, Herculano e Sonia, e aos meus irmãos Juliano e Natália pelo apoio incondi... more Agradeço aos meus pais, Herculano e Sonia, e aos meus irmãos Juliano e Natália pelo apoio incondicional e presença na minha vida a todo o momento. Agradeço aos meus mentores e amigos Fábio, Eduardo, Gomide e Osvaldo por toda confiança e ensinamentos de vida e profissionais. Agradeço aos meus amigos e companheiros de grupo Jéssica, Pâmela, Ariana, Guilherme e Guedmiller por todo trabalho e conhecimento compartilhado. Agradeço a todo grupo de NanoNeuroBioFísica por todo apoio e tutoria. Agradeço aos meus professores do IFSC/USP e da UFSCar-SOR pelos conhecimentos transmitidos, apoio e confiança depositada. Agradeço aos meus amigos e companheiros de estudos Jorge e Tiago por todo trabalho e conhecimento compartilhado. Agradeço a todos os meus amigos que estiveram comigo nesse período tão importante da minha vida.

Journal of Nanomedicine Research, 2016

Submit Manuscript | http://medcraveonline.com A thunderous deep inside advancement in medicine sc... more Submit Manuscript | http://medcraveonline.com A thunderous deep inside advancement in medicine science has impacted all fields in the last decades. Nanotechnology (Nt) has consolidated their progress in biology, physics, mathematics and chemistry. In human diseases, Nt introduces new perspectives to the investigation of the mechanisms pathways involved in neurodegenerative diseases, (e.g, multiple sclerosis, Parkinson’s and Alzheimer’s disease) [5,6]. Additionally, the development and characterization of nanostructured materials simplify disease investigation.

In the present work, the compounds 1-(3",4",5"-trimethoxiphenil)-2-(2"tienyl)-5-(4""-nitrophenyla... more In the present work, the compounds 1-(3",4",5"-trimethoxiphenil)-2-(2"tienyl)-5-(4""-nitrophenylazo) pirrol (compound 1) and 5"-dicianovinyl-5piperidine-5,2":5":2"-tertiophene (compound 2), were characterized using a combination of spectroscopic measurements and quantum mechanical calculation, aiming to evaluate if they present the necessary requisites for application no photonic technologies. Both compounds present acceptable polarizability and first polarizability values, and high values of dipole moment, which tend to be higher for the relaxed S 1 state, probably influenced by solvent interactions. These estimates were done using a theoretical methodology under development in Laboratório de Fotoquímica (IQUFU). These compounds present a solvatochromic behavior desirable for NLO ones, confirmed by theoretical estimates. Besides they possess asymmetry and electron delocalization important requisites to favor the intramolecular charge transfer (ICT) along the molecular structure, also possessing expressive values of dipole moment. These characteristics tend to facilitate the orientation of such compounds under conditions of electric field polarization. Both compounds also presents a low energy gap between the first excited electronic state and the ground state, considerable oscillator strengths, and expressive differences for the dipole moment between the first excited electronic state and the ground state, also expected requisites for compounds with potential application in photonics. Based on the collected information, compounds derived from these ones were proposed, which present increased NLO properties relative to their precursors.

1.4.5 A reação CH 3 ONO 2 + OH − : seletividade dirigida pela dinâmica 48 1.4.6 Resultados da sup... more 1.4.5 A reação CH 3 ONO 2 + OH − : seletividade dirigida pela dinâmica 48 1.4.6 Resultados da superfície de energia potencial combinados com cálculos RRKM 50 1.4.7 Resultados das simulações BOMD 51 1.4.8 Comportamento fora das condições estatísticas na reação CH 3 ONO 2 + OH-55 1.4.9 Conclusão e perspectivas 55 referêncIaS 56 2 ALGORITMOS PARA O MÉTODO MONTE CARLO QUÂNTICO: O AJUSTE VARIACIONAL 63 Rogério Custodio 2.1 Introdução 65 2.2 deScrIção geral do mcv 67 2.3 utIlIzando o algorItmo de metropolIS 70 2.4 defInIndo a função de onda tentatIva 73 2.5 conStruIndo determInanteS de Slater 76 2.6 funçõeS de correlação explícItaS 78 2.7 expreSSõeS para o cálculo da energIa cInétIca 80 2.8 o gradIente e o laplacIano de um determInante de Slater 84 2.9 métodoS de otImIzação de parâmetroS daS funçõeS de onda 86 2.10 perSpectIvaS e aplIcaçõeS do mcv 90 referêncIaS 93 3 ESTUDO DE ESTRUTURA DE LÍQUIDOS PELO MÉTODO EPSR 99 João Manuel Marques Cordeiro 3.1 Introdução 101 3.2 empIrIcal potentIal Structure refInement 103 3.3 epSr em n-metIlformamIda 107 3.4 epSr na mIStura n-metIlformamIda-dImetIlSulfóxIdo 111 3.5 concluSão e perSpectIvaS 115 referêncIaS 115

Nanoscience and its Applications, 2017

Molecular modeling is an important tool for the study and development of new nanotechnologies. Th... more Molecular modeling is an important tool for the study and development of new nanotechnologies. This technique is widely applied in the description and characterization of biological systems, aiding the research and development of new health-related technologies. This chapter provides the reader with basic—but fundamental—principles of computer simulation and the use of online biomolecule data repositories. The main programs for molecule manipulation and visualization and the theory underlying the main computational methods discussed are presented.

Journal of Molecular Graphics and Modelling

Experimental results for the antibody known as immunoglobulin G - IgG interacting with phenobarbi... more Experimental results for the antibody known as immunoglobulin G - IgG interacting with phenobarbital were obtained via atomic force microscopy (AFM) and thereafter investigated using computer simulation modeling tools. Using molecular dynamics simulation and docking calculations, the energetically stable configurations of an immobilized antibody over a silicon surface were searched. Six stable configurations of the immobilized antibody over the silicon nitride surface covered by linker molecules were found. Although, only three of them (P1, P2, P5) maintained the Fragment antigen binding available for antigen interaction. Therefore, these configurations were equilibrated after reaching 100 ns molecular dynamics trajectory. The average interaction energy between the surface and the immunoglobulin G - IgG antibody in the P1, P2 and P5 configurations were -62.4 ± 2.4 kcal/mol; -54.3 ± 5.7 kcal/mol, and -360.9 ± 4.2 kcal/mol respectively. Phenobarbital was docked within the Fab domain o...

Journal of Electroanalytical Chemistry

Nanomaterials

Glyphosate detection and quantification is still a challenge. After an extensive review of the li... more Glyphosate detection and quantification is still a challenge. After an extensive review of the literature, we observed that Fourier transform infrared spectroscopy (FTIR) had practically not yet been used for detection or quantification. The interaction between zinc oxide (ZnO), silver oxide (Ag2O), and Ag-doped ZnO nanocrystals (NCs), as well as that between nanocomposite (Ag-doped ZnO/AgO) and glyphosate was analyzed with FTIR to determine whether nanomaterials could be used as signal enhancers for glyphosates. The results were further supported with the use of atomic force microscopy (AFM) imaging. The glyphosate commercial solutions were intensified 10,000 times when incorporated the ZnO NCs. However, strong chemical interactions between Ag and glyphosate may suppress signaling, making FTIR identification difficult. In short, we have shown for the first time that ZnO NCs are exciting tools with the potential to be used as signal amplifiers of glyphosate, the use of which may be ...