Navegando por Palavras-chave "Langmuir-Blodgett films"

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    Algal polysaccharides on lipid Langmuir-Blodgett films and molecular effects upon metal ion contact
    (Elsevier B.V., 2013-05-01) Brito, Audrey Kalinouski de [UNIFESP]; Caseli, Luciano [UNIFESP]; Nordi, Cristina S. F. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The capability of extracellular polysaccharides released from microorganisms to bind to metal ions is a potential molecular biotechnological tool to produce biosorbents as an alternative for the removal of heavy metals from aquatic environments. in this paper, we exploit the ability of polysaccharides from extracellular polymeric substances produced by phytoplankton adsorbed on lipid monolayers as Langmuir-Blodgett films to interact with silver ions in aqueous environments. the properties of the biomacromolecules after the interaction were investigated with polarisation modulation infrared reflection-absorption spectroscopy and atomic force microscopy. the vibrational spectroscopy technique applied to the Langmuir-Blodgett films before and after contact with silver ions indicated significant changes for the bands related to the chemical groups present in polypeptides and polysaccharides. These changes point to the influence of the metal interaction on the molecular organisation and on the structure of the Langmuir-Blodgett film. Therefore, the behaviour of these biomacromolecules adsorbed at bioinspired interfaces is better understood in terms of properties at the molecular level. This understanding leads to a model in which metal incorporation affects the molecular structure of the ultrathin film. (C) 2013 Elsevier B.V. All rights reserved.
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    Block copolymers of o-PPV organized at the molecular scale as Langmuir and Langmuir-Blodgett films
    (Elsevier B.V., 2014-08-01) Ferreira, Gabriel Cervoni [UNIFESP]; Caseli, Luciano [UNIFESP]; Peres, Laura Oliveira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The control over the molecular architecture of polymeric films can be useful to enhance the properties of polymeric devices. in this paper, poly(o-phenylene vinylene) was spread on the air-water interface in order to form stable Langmuir monolayers. These films were investigated with measurements of surface pressure, surface potential, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). They were transferred from the air-water interface to solid supports through the Langmuir-Blodgett (LB) technique, and characterized with PM-IRRAS and atomic force microscopy, with the viability of the film as an optical device investigated with fluorescence spectroscopy. the immobilization of polymeric chains on solid supports as LB films may provide a high control of their molecular properties, which may enable such molecular architecture to be applied as an optoelectronic device. (C) 2014 Elsevier B.V. All rights reserved.
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    Carbon Nanotubes Arranged As Smart Interfaces in Lipid Langmuir-Blodgett Films Enhancing the Enzymatic Properties of Penicillinase for Biosensing Applications
    (Amer Chemical Soc, 2017) Scholl, Fabio A. [UNIFESP]; Morais, Paulo V.; Gabriel, Rayla C.; Schoening, Michael J.; Siqueira, Jose R., Jr.; Caseli, Luciano [UNIFESP]
    In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir-Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air-water interface was investigated by surface pressure-area isotherms, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by I quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy. Enzyme activity was studied with UV-vis spectroscopy and the feasibility of the supramolecular device nanostructured as ultrathin films were essayed in a capacitive electrolyte-insulator-semiconductor (EIS) sensor device. The presence of CNTs in the enzyme-lipid LB film not only tuned the catalytic activity of penicillinase but also helped conserve its enzyme activity after weeks, showing increased values of activity. Viability as penicillin sensor was demonstrated with capacitance/voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results may be related not only to the nanostructured system provided by the film, but also to the synergism between the compounds on the active layer, leading to a surface morphology that allowed a fast analyte diffusion because of an adequate molecular accommodation, which also preserved the penicillinase activity. This work therefore demonstrates the feasibility of employing LB films composed of lipids, CNTs, and enzymes as EIS devices for biosensing applications.
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    Celulase e álcool desidrogenase imobilizadas em filmes de Langmuir -Blodgett para identificação de celulose e etanol no nível molecular
    (Universidade Federal de São Paulo, 2013-01-07) Rodrigues, Dilmer [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In this study, we investigated at the molecular level the incorporation of cellulase and alcohol dehydrogenase (ADH) in Langmuir and Langmuir-Blodgett (LB) films of dipalmitoylphosphatidylcholine (DPPC). The mixed DPPC-enzyme films were then investigated upon contact with cellulose and ethanol. The changes at the molecular level in the properties of the films were analyzed by optical and tensiometric techniques. We aim to obtain information on the production of ethanol in a more efficient manner. The first evidence that enzymes adsorbed at the films in the lipid-water interface was through adsorption kinetic curves, wherein upon insertion of the enzyme in the aqueous subphase for monolayers of DPPC, an increase in the surface pressure values for the phospholipid matrix was observed. The second evidence was the analysis of the surface pressure-area isotherms, which showed that the presence of the enzymes caused the expansion of the lipid monolayer to higher areas. The third evidence was observed with polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS), studied in Langmuir films, which revealed bands in the regions between 1500 cm-1 and 1800 cm-1, related to protein groups, namely amide II ( CN and NH bendings) and amide I (C = O stretch). In the sequence, the films were transferred to solid matrices as LB films. The PM-IRRAS analysis confirmed the successful transfer of enzyme and phospholipids. The molecular interaction between the mixed LB film (DDPC / ADH / cellulase) and cellulose was observed through PM-IRRAS since in the regions between 1500 cm-1 and 3500 cm-1, changes were observed revealing alterations in the secondary structure of the protein, related to beta-sheet, alpha-helix, beta-turn, and unordered structures. Also for the regions between 2800 cm-1 and 3500 cm-1, the symmetric and asymmetric stretches for CH in CH2 CH3 groups, as well as the stretching of amines (NH2) and OH groups could be investigated. All these factors indicate the sensitivity of the enzymes when placed in contact with cellulose dissolved in ionic liquid.
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    Controlling the luminescence properties of poly(p-phenylene vinylene) entrapped in Langmuir and Langmuir-Blodgett films of stearic acid
    (Elsevier B.V., 2011-08-01) Sakai, Andrei [UNIFESP]; Wang, Shu H.; Peres, Laura O. [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Properties of hybrid films can be enhanced if their molecular architecture is controlled. in this paper, poly (p-phenylene vinylene) was mixed with stearic acid in order to form stable hybrid Langmuir monolayers. Surface properties of these films were investigated with measurements of surface pressure, and also with polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). the films were transferred from the air-water interface to solid supports through the Langmuir-Blodgett technique, and the viability of the film as optical device was investigated with fluorescence spectroscopy. Comparing the fluorescent spectra for the polymer in solution, as a casting film, and as an LB film, the emission bands for LB films were narrower and appeared at lower wavelengths. the interactions between the film components and the design for the LB film may take advantage of the method to immobilize luminescent polymers in mixed ultrathin films adsorbed in solid matrices. (C) 2011 Elsevier B.V. All rights reserved.
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    Controlling the molecular architecture of lactase immobilized in Langmuir-Blodgett films of phospholipids to modulate the enzyme activity
    (Elsevier Science Bv, 2017) Ayoub, Fabio de Paula [UNIFESP]; Caseli, Luciano [UNIFESP]
    In this present work, the adsorption of the enzyme lactase onto Langmuir monolayers of the phospholipid dimyristoylphosphatidic acid (DMPA) was investigated and characterized with surface pressure-area isotherms, surface potential-area isotherms and polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS). The adsorption of the enzyme at the air-water interface expanded the lipid monolayer and increased the film compressibility at high surface pressures. Amide bands in the PM-IRRAS spectra were identified, with the C-N and C=O dipole moments lying parallel to the monolayer plane, revealing that the structuring of the enzyme into beta-sheets was kept in the mixed monolayer. The enzyme-lipid films were transferred from the floating monolayer to solid supports as Langmuir-Blodgett (LB) films and characterized with fluorescence spectroscopy and atomic force microscopy. The catalytic activity of the films was measured and compared to the homogenous medium. The enzyme accommodated in the LB films preserved more than 80% of the enzyme activity after 20 days, in contrast for the homogeneous medium, which preserved less than 60% of the enzyme activity. The method presented in this present work not only allows for an enhanced catalytic activity toward lactose, but also can help explain why certain film architectures exhibit better performance. (C) 2016 Elsevier B.V. All rights reserved.
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    Estudos sobre complexos de Európio em Filmes de Langmuir e Langmuir -Blodgett
    (Universidade Federal de São Paulo, 2022-11-21) Frare, Isadora Mangini [UNIFESP]; Ceridório, Lucinéia Ferreira [UNIFESP]; http://lattes.cnpq.br/1469862511079434
    O objetivo desse trabalho foi estudar e reunir o conhecimento a respeito dos complexos de Európio em filmes de Langmuir e Langmuir Blodgett e apresentar o panorama desse contexto. O estudo foi dividido em duas etapas, a primeira consistiu na parte prática, experimentos para a formação de filmes de Langmuir com complexos de Európio e bases de Shift e a segunda realizar um levantamento bibliográfico qualitativo dos complexos de Eu(III) aplicados em filmes de Langmuir e Langmuir-Blodgett. O levantamento bibliográfico foi utilizado a partir da seleção de artigos obtidos base de dados internacional – Web of Science (WoS), publicados entre 2001 a 2021. Para a parte experimental foi verificado a solubilidade dos complexos em clorofórmio, realizado a análise espectroscópica de infravermelho (FTIR) e isotermas de pressão superficial em filmes de Langmuir. Com a análise de 12 artigos separados em categorias foi evidente que há uma diversidade de complexos de Eu empregados em filmes de Langmuir e LB e que a escolha do ligante tem fortes influencias tanto nas propriedades físico-química das monocamadas formadas (estabilidade e transferência), quanto nas propriedades de luminscência. A análise das espectroscopias FTIR do ligante e do complexo permitem confirmar a síntese dos complexos [Eu(Br2-salophen), [Eu-salophen] e [Eu(NO2)2-salophen)] e as curvas de presssão de superfície x área molecular dos filmes de Langmuir confirmam a formação desses complexos com a mistura de ácido esteárico.
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    Immbolization of uricase enzyme in Langmuir and Langmuir-Blodgett films of fatty acids: Possible use as a uric acid sensor
    (Elsevier B.V., 2012-05-01) Zanon, Nathaly Crystyna Muriel [UNIFESP]; Oliveira, Osvaldo Novais; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Preserving the enzyme structure in solid films is key for producing various bioelectronic devices, including biosensors, which has normally been performed with nanostructured films that allow for control of molecular architectures. in this paper, we investigate the adsorption of uricase onto Langmuir monolayers of stearic acid (SA), and their transfer to solid supports as Langmuir Blodgett (LB) films. Structuring of the enzyme in beta-sheets was preserved in the form of 1-layer LB film, which was corroborated with a higher catalytic activity than for other uricase-containing LB film architectures where the beta-sheets structuring was not preserved. the optimized architecture was also used to detect uric acid within a range covering typical concentrations in the human blood. the approach presented here not only allows for an optimized catalytic activity toward uric acid but also permits one to explain why some film architectures exhibit a superior performance. (C) 2011 Elsevier Inc. All rights reserved.
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    Implications of the structure for the luminescence properties of NBR-PF blend devices nanostructured as Langmuir-Blodgett films
    (Elsevier B.V., 2014-01-20) Barbosa, Camila G. [UNIFESP]; Faez, Roselena [UNIFESP]; Caseli, Luciano [UNIFESP]; Peres, Laura O. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de São Carlos (UFSCar)
    Properties of polymers in blends can be enhanced if molecular control is achieved. in this paper, we spread nitrile rubber (NBR) and polyfluorene (PF) on the air-water interface to form stable monolayers, as observed with surface pressure-area isotherms and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). Mixed monolayers showed that the isotherms were shifted to lower areas in relation to the areas predicted for an ideal mixture, which indicates attractive interactions between the polymeric constituents. Also, the transfer of the polymeric films to solid supports was possible using the Langmuir-Blodgett (LB) technique and the optical properties of the films were evaluated with infrared, UV-vis and fluorescence spectroscopies. Molecular-level interactions between the components lead to marked changes in the properties of the films, which exhibited optical (photoluminescence) properties that could be controlled at the molecular level. (C) 2013 Elsevier B.V. All rights reserved.
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    Interaction of oligonucleotide-based amphiphilic block copolymers with cell membrane models
    (Elsevier B.V., 2010-07-01) Caseli, L. [UNIFESP]; Pascholati, C. P.; Teixeira, F.; Nosov, S.; Vebert, C.; Mueeller, A. H. E.; Oliveira, O. N.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Basel; Univ Bayreuth
    Oligonucleotides have unique molecular recognition properties, being involved in biological mechanisms such as cell-surface receptor recognition or gene silencing. for their use in human therapy for drug or gene delivery, the cell membrane remains a barrier, but this can be obviated by grafting a hydrophobic tail to the oligonucleotide. Here we demonstrate that two oligonucleotides, one consisting of 12 guanosine units (G(12)), and the other one consisting of five adenosine and seven guanosine (A(5)G(7)) units, when functionalized with poly(butadiene), namely PB-G(12) and PB-A(5)G(7), can be inserted into Langmuir monolayers of dipalmitoyl phosphatidyl choline (DPPC), which served as a cell membrane model. PB-G(12) and PB-A(5)G(7) were found to affect the DPPC monolayer even at high surface pressures. the effects from PB-G(12) were consistently stronger, particularly in reducing the elasticity of the DPPC monolayers, which may have important biological implications. Multilayers of DPPC and nucleotide-based copolymers could be adsorbed onto solid supports, in the form of Y-type LB films, in which the molecular-level interaction led to lower energies in the vibrational spectra of the nucleotide-based copolymers. This successful deposition of solid films opens the way for devices to be produced which exploit the molecular recognition properties of the nucleotides. (C) 2010 Elsevier Inc. All rights reserved.
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    Interaction of polysaccharide-protein complex from Agaricus blazei with Langmuir and Langmuir-Blodgett films of phospholipids
    (Elsevier B.V., 2009-02-01) Schmidt, Thais F.; Pavinatto, Felippe J.; Caseli, Luciano [UNIFESP]; Gonzaga, Maria L. C.; Soares, Sandra A.; Ricardo, Nagila M. P. S.; Oliveira, Osvaldo N.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Fed Ceara
    The use of natural substances in health applications may be hampered by the difficulties in establishing the mechanisms of action, especially at molecular-level. the protein-polysaccharide complex extracted from the mushroom Agaricus blazei Murill, referred to as CAb, has been considered for treating various diseases with probable interaction with cell membranes. in this study, we investigate the interaction between CAb and a cell membrane model represented by a Langmuir monolayer of dimyristoyl phosphatidic acid (DMPA). CAb affects the structural properties of DMPA monolayers causing expansion and increasing compressibility. in addition, interaction with DMPA polar heads led to neutralization of the electrical double layer, yielding a zero surface potential at large areas per molecule. CAb remained at the interface even at high surface pressures, which allowed transfer of Langmuir-Blodgett (LB) films onto solid supports with the CAb-DMPA mixture. the mass transferred, according to quartz crystal microbalance (QCM) measurements, increased linearly with the number of deposited layers. With UV-vis absorption, fluorescence and FTIR spectroscopies, we confirmed that the LB films contain polysaccharides, proteins and DMPA. Therefore, the CAb biological action must be attributed not only to polysaccharides but also to proteins in the complex. (C) 2008 Elsevier Inc. All rights reserved.
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    Langmuir and Langmuir-Blodgett films of a quinoline-fluorene based copolymer
    (Elsevier B.V., 2012-01-20) Correia, Fabio Conte; Wang, Shu H.; Peres, Laura O. [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    The fabrication of Langmuir-Blodgett (LB) films of synthetic polymers allows the control of molecular architecture in order to optimize physical properties. in this paper, the surface chemistry of a quinoline-fluorene based copolymer spread on the air-water interface is investigated. Surface pressure-area isotherms as well as Polarization-Modulation Infrared Reflection-Absorption Spectroscopy (PM-IRRAS) were employed to characterize the films, which could be transferred to solid supports by the LB technique. Atomic force microscopy as well as UV-Vis and fluorescence spectroscopies have shown a regular deposition of the polymers, and the luminescence properties could be controlled with the number of layers deposited on the solid support. As a result, the photoluminescence of the LB films was considerably higher than that observed for the spin coated film, and the maximum emission peak was shifted to higher energies, which is attributed to the molecular-level interactions within the layer-ordered structure of the LB film. the luminescence response would possibly be tuned to approach the highest level, which allows the films to be employed in future applications in efficient optical devices such as organic light-emitting diodes (OLEDs). (C) 2011 Elsevier B.V. All rights reserved.
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    Langmuir and Langmuir-Blodgett films of Cl-PPV mixed with stearic acid: implication of the morphology on the surface and spectroscopy properties
    (Springer, 2015-03-01) Sakai, Andrei [UNIFESP]; Peres, Laura O. [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The molecular architecture of polymeric films can be changed in order to obtain enhanced properties for the fabrication of optoelectronic devices. in this paper, poly(2-chloro-p-phenylenevinylene) was spread on the air-water interface and mixed with stearic acid in order to form stable Langmuir monolayers. These films were transferred from the air-water interface to solid supports as Langmuir-Blodgett (LB) films. the influence of Cl in the polymer chain was investigated with measurements of surface pressure, polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS), Brewster angle microscopy (BAM), atomic force microscopy (AFM), and fluorescence spectroscopy. the immobilization of this polymer on solid supports as LB films provided a high control of its morphological and luminescence properties, which may be useful tomanipulate structures at the molecular level to be applied as optoelectronic devices.
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    Langmuir and Langmuir-Blodgett films of di-ureasil hybrid compounds containing phosphotungstic acid
    (Elsevier Science Bv, 2017) Teles Rossini, Cabo Vinicius [UNIFESP]; Molina, Celso [UNIFESP]; Caseli, Luciano [UNIFESP]
    The search for new molecular architectures to improve the efficiency of sensors and optoelectronic devices is fundamental to enhance the effectiveness of nanostructured materials. In this present work, a di-ureasil hybrid compound (DUPTS) was spread at the air-water interface in order to form Langmuir monolayers. Phosphotungstic acid, H3PW12O40, PWA inserted in the aqueous subphase stabilized the formation of DUPTS as a stable Langmuir film, as showed with surface pressure and surface potential-area isotherms, rheological measurements, polarization modulation reflection-absorption spectroscopy, and Brewster angle microscopy. The monolayers were transferred to solid supports as Langmuir-Blodgett films and presented different patterns of heterogeneity as observed with atomic force microscopy, with the morphology dependent on the presence of PWA and on the kind of solid support surface.
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    Langmuir-Blodgett films based on poly(p-phenylene vinylene) and protein-stabilised palladium nanoparticles: Implications in luminescent and conducting properties
    (Elsevier B.V., 2013-07-01) Goto, Thiago E. [UNIFESP]; Sakai, Andrei [UNIFESP]; Iost, Rodrigo M.; Silva, Welter C.; Crespilho, Frank N.; Peres, Laura O. [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Fed Piaui
    In this paper, poly(p-phenylene vinylene) block copolymers (PPV) were immobilised in stearic acid (HSt) Langmuir-Blodgett (LB) films, and their conducting and luminescent properties were enhanced by the incorporation of palladium nanoparticles stabilised by glucose oxidase (GOx-PdNPs). the nanobiocomposite, based on HSt, PPV, and GOx-PdNPs, was transferred from the air-water interface onto solid supports using the LB technique. the films were characterised by surface pressure-area isotherms, polarisation modulation infrared reflection-absorption spectroscopy, fluorescence spectroscopy, and conductivity measurements. the results indicated that the incorporation of GOx-PdNPs in PPV-HSt LB films enhances the luminescence and conducting properties of the PPV. Based on the higher conductivity and emission obtained with the hybrid LB films and the ability to tune the molecular-level interactions between the film components by changing the experimental conditions, thus allowing for further optimisation, one may envisage applications for these films in optical and electronic devices, such as organic light-emitting diodes. (C) 2013 Elsevier B.V. All rights reserved.
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    Organization of polythiophenes at ultrathin films mixed with stearic acid investigated with polarization-modulation infrared reflection-absorption spectroscopy
    (Elsevier Science Bv, 2017) da Silva, Edilene Assuncao; Caseli, Luciano [UNIFESP]; Olivati, Clarissa de Almeida
    In this present work, the polymers poly(3-alkylthiophene)s, regioregular poly(3-butylthiophene), poly(3-hexylthiophene) and poly(3-octylthiophene) were spread at the air-water interface to form Langmuir monolayers. They formed stable films by mixing them with Stearic Acid (SA), as confirmed with surface pressure-area isotherms and polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The floating monolayers were transferred from the liquid interface to solid supports by using the Langmuir-Blodgett (LB) and Langmuir-Schaeffer (LS) techniques, and characterized with PM-IRRAS. Surface pressure-area isotherms showed that SA monolayers are expanded upon polymer incorporation altering the rheological properties of the monolayer since the monolayer became less elastic at higher pressures and presented first-order transitions at lower pressures. PM-IRRAS showed that the organization of the films is affected at the molecular level depending on the chemical structure of the polymer chosen. Among the polymers analysed, the poly(3-butylthiophene) shows a more irregular conformational behaviour depending on the amount of stearic acid. The conformation of the films when transferred to solid support changes and is dependent on the type of deposition (LB or LS). The importance of this paper relies on the fact that SA can be employed to help the formation of stable floating monolayers of these polythiophenes at the air-water interface, and the successful transfer to solid supports may provide nanostructured films with a high control of their molecular properties, which may enable a molecular architecture to be applied as electronic devices of interest.
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    Properties of lipophilic nucleoside monolayers at the air-water interface
    (Elsevier B.V., 2010-06-01) Montanha, E. A.; Pavinatto, F. J.; Caseli, L. [UNIFESP]; Kaczmarek, O.; Liebscher, J.; Huster, D.; Oliveira, O. N.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Humboldt Univ; Univ Leipzig
    The capability of self-assembly and molecular recognition of biomolecules is essential for many nanotechnological applications, as in the use of alkyl-modified nucleosides and oligonucleotides to increase the cellular uptake of DNA and RNA. in this study, we show that a lipophilic nucleoside, which is an isomer mixture of 2'-palmitoyluridin und 3'-palmitoyluridin, forms Langmuir monolayers and Langmuir-Blodgett films as a typical amphiphile, though with a smaller elasticity. the nucleoside may be incorporated into dipalmitoyl phosphatidyl choline (DPPC) monolayers that serve as a simplified cell membrane model. the molecular-level interactions between the nucleoside and DPPC led to a remarkable condensation of the mixed monolayer, which affected both surface pressure and surface potential isotherms. the morphology of the mixed monolayers was dominated by the small domains of the nucleoside. the mixed monolayers could be deposited onto solid substrates as a one-layer Langmuir Blodgett film that displayed UV-vis absorption spectra typical of aggregated nucleosides owing to the interaction between the nucleoside and DPPC. the formation of solid films with DNA building blocks in the polar heads may open the way for devices and sensors be produced to exploit their molecular recognition properties. (C) 2010 Elsevier B.V. All rights reserved.
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    Ultrathin films of poly(2,5-dicyano-p-phenylene-vinylene)-co-(p-phenylene-vinylene) DCN-PPV/PPV: A Langmuir and Langmuir-Blodgett films study
    (Elsevier B.V., 2015-02-20) Soares, Cecilia Goncalves [UNIFESP]; Caseli, Luciano [UNIFESP]; Bertuzzi, Diego Luan; Santos, Fabio Santana; Garcia, Jarem Raul; Peres, Laura Oliveira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Estadual de Ponta Grossa (UEPG)
    Manipulation of polymeric films at the molecular level can be appropriate to improve the properties of optoelectronic devices. in this paper, the copolymer poly(2,5-dicyano-p-phenylene-vinylene)-co-(p-phenylene- vinylene) (DCN-PPV/PPV) was spread on the air-water interface forming Langmuir films. the monolayers were investigated with surface pressure-area isotherms, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). the monomolecular films were then transferred to solid supports through the Langmuir-Blodgett (LB) technique, and characterized by PM-IRRAS and atomic force microscopy, with the viability of the film as an optical device investigated with fluorescence spectroscopy. the immobilization of this copolymer on solid supports as LB films provided a molecular architecture with control of their molecular properties, which may have applications for the production of optoelectronic devices. (C) 2014 Elsevier B.V. All rights reserved.