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Camacho SA, Sobral-Filho RG, Aoki PHB, Constantino CJL, Brolo AG. Immunoassay quantification using surface-enhanced fluorescence (SEF) tags. Analyst 2017; 142:2717-2724. [DOI: 10.1039/c7an00639j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A fluorescence immunoassay based on surface-enhanced fluorescence (SEF) was introduced. The use of SEF tags may provide advantages over regular organic dyes for biomedical assays.
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Affiliation(s)
- S. A. Camacho
- São Paulo State University (UNESP)
- School of Technology and Applied Sciences
- Brazil
- University of Victoria
- Department of Chemistry
| | | | - P. H. B. Aoki
- University of Victoria
- Department of Chemistry
- Victoria
- Canada
- São Paulo State University (UNESP)
| | - C. J. L. Constantino
- São Paulo State University (UNESP)
- School of Technology and Applied Sciences
- Brazil
| | - A. G. Brolo
- University of Victoria
- Department of Chemistry
- Victoria
- Canada
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2
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Aoki PHB, Schroder AP, Constantino CJL, Marques CM. Bioadhesive giant vesicles for monitoring hydroperoxidation in lipid membranes. Soft Matter 2015; 11:5995-8. [PMID: 26067909 DOI: 10.1039/c5sm01019e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Osmotic stresses, protein insertion or lipid oxidation lead to area increase of self-assembled lipid membranes. However, methods to measure membrane expansion are scarce. Challenged by recent progress on the control of phospholipid hydroperoxidation, we introduce a method to quantitatively evaluate membrane area increase based on the bio-adhesion of Giant Unilamellar Vesicles.
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Affiliation(s)
- P H B Aoki
- Institut Charles Sadron, Université de Strasbourg, CNRS UP 22, F-67034 Strasbourg Cedex 2, France.
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Almeida GFB, Cardoso MR, Aoki PHB, Lima JJD, Costa LDF, Rodrigues CA, Constantino CJL, Mendoncal CR. Surface Morphology and Structural Modification Induced by Femtosecond Pulses in Hydrogenated Amorphous Silicon Films. J Nanosci Nanotechnol 2015; 15:2495-2500. [PMID: 26413695 DOI: 10.1166/jnn.2015.9820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This work investigates the modification, resulting from fs-laser irradiation (150 fs, 775 nm and 1 kHz), on the structure and surface morphology of hydrogenated amorphous silicon (a-Si:H) thin films. The sample morphology was studied by performing a statistical analyzes of atomic force microscopy images, using a specially developed software that identifies and characterizes the domains (spikes) produced by the laser irradiation. For a fluence of 3.1 MJ/m2, we observed formation of spikes with smaller average height distribution, centered at around 15 nm, while for fluencies higher than 3.7 MJ/m2 aggregation of the produced spikes dominates the sample morphology. On the other hand, Raman spectroscopy revealed that a higher crystalline fraction (73%) is obtained for higher fluences (> 3.1 MJ/m2), which is accompanied by a decrease in the size of the produced crystals. Therefore, such results indicate that there is a trade-off between the spike distribution, crystallization fraction and size of the nanocrystals attained by laser irradiation, which has to be taken into account when using such approach for the development of devices.
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Volpati D, Spada ER, Cid CCP, Sartorelli ML, Aroca RF, Constantino CJL. Exploring copper nanostructures as highly uniform and reproducible substrates for plasmon-enhanced fluorescence. Analyst 2015; 140:476-82. [DOI: 10.1039/c4an00889h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Towards reproducible and feasible large-area active substrates for the surface-enhanced phenomena, we report electrodeposited antidot copper nanostructures and employed them as active substrates for surface-enhanced fluorescence (SEF), which exhibit a relative great enhancement factor and reproducible signals.
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Affiliation(s)
- D. Volpati
- C. J. L Constantino. Faculdade de Ciências e Tecnologia
- UNESP Univ Estadual Paulista
- Presidente Prudente
- Brazil
- Instituto de Física de São Carlos
| | - E. R. Spada
- Instituto de Física de São Carlos
- Universidade de São Paulo
- São Carlos
- Brazil
| | - C. C. Plá Cid
- Laboratório Central de Microscopia Eletronica
- Universidade Federal de Santa Catarina
- Florianópolis
- Brazil
| | - M. L. Sartorelli
- Departamento de Física
- Universidade Federal de Santa Catarina
- Florianópolis
- Brazil
| | - R. F. Aroca
- Materials and Surface Science Group
- University of Windsor
- Windsor
- Canada
| | - C. J. L. Constantino
- C. J. L Constantino. Faculdade de Ciências e Tecnologia
- UNESP Univ Estadual Paulista
- Presidente Prudente
- Brazil
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Medina-Plaza C, Furini LN, Constantino CJL, de Saja JA, Rodri Guez-Mendez ML. Synergistic electrocatalytic effect of nanostructured mixed films formed by functionalised gold nanoparticles and bisphthalocyanines. Anal Chim Acta 2014; 851:95-102. [PMID: 25440670 DOI: 10.1016/j.aca.2014.08.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/28/2014] [Accepted: 08/25/2014] [Indexed: 10/24/2022]
Abstract
A synergistic electrocatalytic effect was observed in sensors where two electrocatalytic materials (functionalized gold nanoparticles and lutetium bisphthalocyanine) were co-deposited using the Langmuir-Blodgett technique. Films were prepared using a novel method where water soluble functionalised gold nanoparticles [(11-mercaptoundecyl)tetra(ethylene glycol)] (SAuNPs) were inserted in floating films of lutetium bisphthalocyanine (LuPc2) and dimethyldioctadecylammonium bromide (DODAB) as the amphiphilic matrix. The formation of stable and homogeneous mixed films was confirmed by π-A isotherms, BAM, UV-vis and Raman spectroscopy, as well as by SEM and TEM microscopy. The synergistic effect towards hydroquinone of the electrodes modified with LuPc2:DODAB/SAuNP was characterised by an increase in the intensity of the redox peaks and a reduction of the overpotential. This synergistic electrocatalytic effect arose from the interaction between the SAuNPs and the phthalocyanines that occur in the Langmuir-Blodgett films and from the high surface area provided by the nanostructured films. The sensitivity increased with the amount of LuPc2 and SAuNPs inserted in the films and limits of detection in the range of 10(-7)molL(-1) were attained.
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Affiliation(s)
- C Medina-Plaza
- Universidad de Valladolid, Department of Inorganic Chemistry, Engineers School, Spain
| | - L N Furini
- Universidad de Valladolid, Department of Inorganic Chemistry, Engineers School, Spain; Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, 19060-900 Presidente Prudente, SP, Brazil
| | - C J L Constantino
- Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, 19060-900 Presidente Prudente, SP, Brazil
| | - J A de Saja
- Universidad de Valladolid, Department of Condensed Matter Physics, Faculty of Sciences, Spain
| | - M L Rodri Guez-Mendez
- Universidad de Valladolid, Department of Inorganic Chemistry, Engineers School, Spain.
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Alessio P, Apetrei C, Rubira RJG, Constantino CJL, Medina-Plazal C, De Saja JA, Rodríguez-Méndez ML. Structural and electrochemical properties of lutetium bis-octachloro-phthalocyaninate nanostructured films. Application as voltammetric sensors. J Nanosci Nanotechnol 2014; 14:6754-6763. [PMID: 25924327 DOI: 10.1166/jnn.2014.9355] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Thin films of the bis[2,3,9,10,16,17,23,24-octachlorophthalocyaninate] lutetium(III) complex (LuPc2Cl32) have been prepared by the Langmuir-Blodgett and the Langmuir-Schaefer (LS) techniques. The influence of the chlorine substituents in the structure of the films and in their spectroscopic, electrochemical and sensing properties has been evaluated. The π-A isotherms exhibit a monolayer stability greater than the observed in the unsubstituted analogue (LuPc2), being easily transferred to solid substrates, also in contrast to LuPc2. The LB and LS films present a linear growth forming stratified layers, monitored by UV-VIS absorption spectroscopy. The latter also revealed the presence of LuPc2Cl32 in the form of monomers and aggregates in both films. The FTIR data showed that the LuPc2Cl32 molecules present a non-preferential arrangement in both films. Monolayers of LB and LS were deposited onto 6 nm Ag island films to record surface-enhanced resonance Raman scattering (SERRS), leading to enhancement factors close to 2 x 10(3). Finally, LB and LS films deposited onto ITO glass have been successfully used as voltammetric sensors for the detection of catechol. The improved electroactivity of the LB and LS films has been confirmed by the reduction of the overpotential of the oxidation of catechol. The enhancement of the electrocatalytic effect observed in LB and LS films is the result of the nanostructured arrangement of the surface which increases the number of active sites. The sensors show a limit of detection in the range of 10(-5) mol/L.
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Alessio P, de Oliveira RF, Aoki PHB, Pereira JDAS, Braunger ML, Furini LN, Vieira M, Teixeira SR, Job AE, Saenz CAT, Alves N, Olivati CA, Constantino CJL. Molecular architecture and electrical properties in evaporated films of cobalt phthalocyanine. J Nanosci Nanotechnol 2012; 12:7010-7020. [PMID: 23035427 DOI: 10.1166/jnn.2012.6583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Thin films of cobalt phthalocyanine (CoPc) were deposited onto solid substrates through physical vapor deposition (PVD) by thermal evaporation up to 60 nm thick to determine their molecular architecture and electrical properties. The growth was monitored using UV-Vis absorption spectroscopy, revealing a linear increase for absorbance versus thickness. PVD films were found in the crystalline alpha phase and with the CoPc molecules forming ca. 45 degrees in relation to the substrate surface. The film surface was fairly homogeneous at the micro and nanoscales, with the roughness at ca. 3 nm. DC and AC electrical measurements were carried out for devices built with distinct structures. Perpendicular contact was established by depositing 60 nm CoPc PVD films between indium tin oxide (ITO) and Al, forming a sandwich-type structure (ITO/CoPc/Al). The current versus DC voltage curve indicated a Schottky diode behavior with a rectification factor of 4.2. The AC conductivity at low frequencies increased about 2 orders of magnitude (10(-9) to 10(-7) S/m) with increasing DC bias (0 to 5 V) and the dielectric constant at 1 kHz was 3.45. The parallel contact was obtained by depositing 120 nm CoPc PVD film onto interdigitated electrodes, forming an IDE-structured device. The latter presented a DC conductivity of 5.5 x 10(-10) S/m while the AC conductivity varied from 10(-9) to 10(-1) S/m between 1 Hz and 1 MHz, respectively, presenting no dependence on DC bias. As proof-of-principle, the IDE-structured device was applied as gas sensor for trifluoroacetic acid (TFA).
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Affiliation(s)
- P Alessio
- DFQB, Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, Presidente Prudente, SP 19060-900, Brazil
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Rodriguez-Perez MA, Simoes RD, Constantino CJL, de Saja JA. Structure and physical properties of EVA/starch precursor materials for foaming applications. J Appl Polym Sci 2011. [DOI: 10.1002/app.33946] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pavinatto FJ, Fernandes EGR, Alessio P, Constantino CJL, de Saja JA, Zucolotto V, Apetrei C, Oliveira Jr ON, Rodriguez-Mendez ML. Optimized architecture for Tyrosinase-containing Langmuir–Blodgett films to detect pyrogallol. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm03864d] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Aoki PHB, Volpati D, Riul A, Caetano W, Constantino CJL. Layer-by-layer technique as a new approach to produce nanostructured films containing phospholipids as transducers in sensing applications. Langmuir 2009; 25:2331-2338. [PMID: 19161323 DOI: 10.1021/la802696j] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Phospholipids are widely used as mimetic systems to exploit interactions involving biological membranes and pharmacological drugs. In this work, the layer-by-layer (LbL) technique was used as a new approach to produce multilayered thin films containing biological phospholipids applied as transducers onto Pt interdigitated electrodes forming sensing units of an electronic tongue system. Low concentrations (nM level) of a phenothiazine compound were detected through impedance spectroscopy. Both negative 1,2-dipalmitoyl-sn-3-glycero-[phosphor-rac-(1-glycerol)] (DPPG) and zwitterionic l-alpha-1,2-dipalmitoyl-sn-3-glycero-phosphatidylcholine (DPPC) phospholipids were used to produce the LbL films, whose molecular architecture was monitored combining spectroscopy and microscopy at micro and nanoscales. The sensor array was complemented by Langmuir-Blodgett (LB) monolayers of DPPG and DPPC deposited onto Pt interdigitated electrodes as well. It was found that the distinct molecular architecture presented by both LbL and LB films plays a key role on the sensitivity of the sensor array with the importance of the LbL films being demonstrated by principal component analysis (PCA).
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Affiliation(s)
- P H B Aoki
- Faculdade de Ciencias e Tecnologia, UNESP, Presidente Prudente/SP, 19060-900 Brazil
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Volpati D, Alessio P, Zanfolim AA, Storti FC, Job AE, Ferreira M, Riul A, Oliveira ON, Constantino CJL. Exploiting Distinct Molecular Architectures of Ultrathin Films Made with Iron Phthalocyanine for Sensing. J Phys Chem B 2008; 112:15275-82. [DOI: 10.1021/jp804159h] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. Volpati
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - P. Alessio
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - A. A. Zanfolim
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - F. C. Storti
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - A. E. Job
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - M. Ferreira
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - A. Riul
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - O. N. Oliveira
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
| | - C. J. L. Constantino
- DFQB, FCT, UNESP, CP 467, 19060-900, Presidente Prudente, SP, Brazil, Universidade Federal de São Carlos, 18043-970, campus Sorocaba, SP, Brazil, and Instituto de Física de São Carlos, USP, 13560-970, São Carlos, SP, Brazil
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Aoki PHB, Caetano W, Volpati D, Riul A, Constantino CJL. Sensor array made with nanostructured films to detect a phenothiazine compound. J Nanosci Nanotechnol 2008; 8:4341-4348. [PMID: 19049023 DOI: 10.1166/jnn.2008.297] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The detection of trace amounts of phenothiazines with fast, direct methods is important for medical applications and the pharmaceutical industry. In this paper we explore the concept of an electronic tongue to detect methylene blue (MB), with a sensor array comprising 6 units. These units were a bare Pt electrode, and Pt electrodes coated with 1-layer LB films of dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG), a 5-layer LB film of stearic acid, and 10 nm PVD films of bis benzimidazo perylene (AzoPTCD) and iron phthalocyanine (FePc). The electrical response obtained with impedance spectroscopy varied with the sensing unit, in spite of the small film thickness, thus indicating good cross-sensitivity. Upon treating the capacitance data at 1 kHz with Principal Component Analysis (PCA), the sensor array was capable of distinguishing MB solutions from ultrapure water down to 1 nM. This unprecedented high sensitivity was probably due to strong interactions between MB and DPPC and DPPG, as the sensing units of these phospholipids gave the most important contributions to the PCA plots. Such strong interaction was not manifested in the surface pressure-area isotherms of co-spread monolayers of MB and DPPC or DPPG, which emphasizes the high sensitivity of the electrical measurements in ultrathin films in contact with liquids, now widely exploited in electronic tongues.
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Affiliation(s)
- P H B Aoki
- DFQB, Faculdade de Ciências e Tecnologia, UNESP, Presidente Prudente/SP, 19060-900, Brazil
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Volpati D, Job AE, Aroca RF, Constantino CJL. Molecular and morphological characterization of bis benzimidazo perylene films and surface-enhanced phenomena. J Phys Chem B 2008; 112:3894-902. [PMID: 18335918 DOI: 10.1021/jp077588h] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thin solid films of bis benzimidazo perylene (AzoPTCD) were fabricated using physical vapor deposition (PVD) technique. Thermal stability and integrity of the AzoPTCD PVD films during the fabrication ( approximately 400 degrees C at 10(-6) Torr) were monitored by Raman scattering. Complementary thermogravimetric results showed that thermal degradation of AzoPTCD occurs at 675 degrees C. The growth of the PVD films was established through UV-vis absorption spectroscopy, and the surface morphology was surveyed by atomic force microscopy (AFM) as a function of the mass thickness. The AzoPTCD molecular organization in these PVD films was determined using the selection rules of infrared absorption spectroscopy (transmission and reflection-absorption modes). Despite the molecular packing, X-ray diffraction revealed that the PVD films are amorphous. Theoretical calculations (density functional theory, B3LYP) were used to assign the vibrational modes in the infrared and Raman spectra. Metallic nanostructures, able to sustain localized surface plasmons (LSP) were used to achieve surface-enhanced resonance Raman scattering (SERRS) and surface-enhanced fluorescence (SEF).
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Affiliation(s)
- D Volpati
- DFQB, Faculdade de Ciências e Tecnologia, UNESP, Presidente Prudente/SP, 19060-900, Brazil
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Pereira AA, Martins GF, Antunes PA, Conrrado R, Pasquini D, Job AE, Curvelo AAS, Ferreira M, Riul A, Constantino CJL. Lignin from sugar cane bagasse: extraction, fabrication of nanostructured films, and application. Langmuir 2007; 23:6652-9. [PMID: 17489613 DOI: 10.1021/la063582s] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Four lignin samples were extracted from sugar cane bagasse using four different alcohols (methanol, ethanol, n-propanol, and 1-butanol) via the organosolv-CO2 supercritical pulping process. Langmuir films were characterized by surface pressure vs mean molecular area (Pi-A) isotherms to exploit information at the molecular level carrying out stability tests, cycles of compression/expansion (hysteresis), subphase temperature variations, and metallic ions dissolved into the water subphase at different concentrations. Briefly, it was observed that these lignins are relatively stable on the water surface when compared to those obtained via different extraction processes. Besides, the Pi-A isotherms are shifted to smaller molecular areas at higher subphase temperatures and to larger molecular areas when the metallic ions are dissolved into the subphase. The results are related to the formation of stable aggregates (domains) onto the water subphase by these lignins, as shown in the Pi-A isotherms. It was found as well that the most stable lignin monolayer onto the water subphase is that extracted with 1-butanol. Homogeneous Langmuir-Blodgett (LB) films of this lignin could be produced as confirmed by UV-vis absorption spectroscopy and the cumulative transfer parameter. In addition, FTIR analysis showed that this lignin LB film is structured in a way that the phenyl groups are organized preferentially parallel to the substrate surface. Further, these LB films were deposited onto gold interdigitated electrodes and ITO and applied in studies involving the detection of Cd+2 ions in aqueous solutions at low concentration levels through impedance spectroscopy and electrochemical measurements. FTIR spectroscopy was carried out before and after soaking the thin films into Cd+2 aqueous solutions, revealing a possible physical interaction between the lignin phenyl groups and the heavy metal ions. The importance of using nanostructured systems is demonstrated as well by comparing both LB and cast films.
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Affiliation(s)
- A A Pereira
- DFQB, Faculdade de Ciências e Tecnologia, UNESP, Presidente Prudente, SP, Brazil
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da Silva BA, Antunes PA, Pasquini D, Curvelo AAS, Aroca RF, Riul AJ, Constantino CJL. Nanostructured films employed as sensing units in an "electronic tongue" system. J Nanosci Nanotechnol 2007; 7:510-4. [PMID: 17450787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Nanostructured films of lignin (macromolecule extracted from sugar cane bagasse), polypyrrole (conducting polymer) and bis butylimido perylene (organic dye) were used in the detection of trace levels of fluorine (from H2SiF6), chlorine (from NaClO), Pb(+2), Cu(+2), and Cd(+2) in aqueous solutions. Langmuir monolayers on ultrapure water were characterised by surface pressure-mean molecular area (II-A) isotherms. Langmuir-Blodgett (LB) films were transferred onto gold interdigitated electrodes and used as individual sensing units of an electronic tongue system. Impedance spectroscopy measurements were taken with the sensor immersed into aqueous solutions containing the ions described above in different molar concentrations. Fourier transform infrared absorption (FTIR) was employed to identify possible interactions between the LB films and the analytes in solution, and no significant changes could be observed in the FTIR spectra of BuPTCD and Ppy. Therefore, the results for lignin point to an interaction involving the electronic cloud of the phenyl groups with the metallic ions.
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Affiliation(s)
- B A da Silva
- DFOB, FCT UNESFP, CP 457, 19060-900, Presidente Prudente, SP, Brazil
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Constantino CJL, Job AE, Simões RD, Giacometti JA, Zucolotto V, Oliveira ON, Gozzi G, Chinaglia DL. Phase transition in poly(vinylidene fluoride) investigated with micro-Raman spectroscopy. Appl Spectrosc 2005; 59:275-9. [PMID: 15901306 DOI: 10.1366/0003702053585336] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The phase transition from the non-polar alpha-phase to the polar beta-phase of poly(vinylidene fluoride) (PVDF) has been investigated using micro-Raman spectroscopy, which is advantageous because it is a nondestructive technique. Films of alpha-PVDF were subjected to stretching under controlled rates at 80 degrees C, while the transition to beta-PVDF was monitored by the decrease in the Raman band at 794 cm(-1) characteristic of the alpha-phase, along with the concomitant increase in the 839 cm(-1) band characteristic of the beta-phase. The alpha-->beta transition in our PVDF samples could be achieved even for the sample stretched to twice (2x-stretched) the initial length and it did not depend on the stretching rate in the range between 2.0 and 7.0 mm/min. These conclusions were corroborated by differential scanning calorimetry (DSC) and X-ray diffraction experiments for PVDF samples processed under the same conditions as in the Raman scattering measurements. Poling with negative corona discharge was found to affect the alpha-PVDF morphology, improving the Raman bands related to this crystalline phase. This effect is minimized for films stretched to higher ratios. Significantly, corona-induced effects could not be observed with the other experimental techniques, i.e., X-ray diffraction and infrared spectroscopy.
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Affiliation(s)
- C J L Constantino
- Faculdade de Ciências e Tecnologia--UNESP, 19060-900--Presidente Prudente, SP, Brazil.
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Wohnrath K, Constantino CJL, Antunes PA, dos Santos PM, Batista AA, Aroca RF, Oliveira ON. Molecularly Organized Langmuir−Blodgett Films from a Ruthenium Biphosphine Complex. J Phys Chem B 2005; 109:4959-64. [PMID: 16863154 DOI: 10.1021/jp048941b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Langmuir-Blodgett (LB) films from a ruthenium complex mer-[RuCl3 (dppb)(4-Mepy)] (dppb = PPh2 (CH2)4PPh2; 4-Mepy = 4-methylpyridine), termed Ru-Pic, display a distinct color, which is different from the coloration exhibited by cast films or chloroform solutions. The solution and cast films are red, while the LB films are green-bluish. The manifestation of the blue color in the LB film finds its explanation in a unique absorption band at 690 nm, which is associated with the oxidation of the phosphine moieties. Fluorescence emission and absorption-reflection infrared spectroscopy measurements revealed the molecular organization in the LB films. In contrast, cast films showed a random distribution of complexes. Surface-enhanced Raman scattering was also used in an attempt to identify the main interactions in Ru-Pic.
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Affiliation(s)
- K Wohnrath
- Departamento de Química, UEPG, Ponta Grossa/PR, Brazil.
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Camillo EC, Constantino CJL, Teruya MY, Alves N, Mattoso LHC, Job AE. Dependence of the electrical conductivity and elastomeric properties on sample preparation of blends of polyaniline and natural rubber. J Appl Polym Sci 2005. [DOI: 10.1002/app.21899] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Gaffo L, Constantino CJL, Moreira WC, Aroca RF, Oliveira ON. Surface-enhanced Raman scattering and micro-Raman imaging of Langmuir-Blodgett films of rhodium phthalocyanine. Spectrochim Acta A Mol Biomol Spectrosc 2004; 60:321-327. [PMID: 14670494 DOI: 10.1016/s1386-1425(03)00229-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Rhodium phthalocyanine (RhPc) was synthesized and ultra thin Langmuir-Blodgett (LB) films of RhPc were successfully fabricated. The LB film characterization was carried out using both UV-vis absorption spectra and Raman scattering. The Raman spectroscopy was carried out using 633 and 780 nm laser lines. LB films were deposited onto Ag nanoparticles to achieve the surface-enhanced pre-resonance Raman scattering (pre-SERRS) and surface-enhanced Raman scattering (SERS) for both laser lines, respectively, which allowed the characterization of the RhPc ultra thin films. The morphology of the LB RhPc neat film is extracted from micro-Raman imaging.
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Affiliation(s)
- L Gaffo
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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Constantino CJL, Lemma T, Antunes PA, Aroca R. Single molecular detection of a perylene dye dispersed in a Langmuir-Blodgett fatty acid monolayer using surface-enhanced resonance Raman scattering. Spectrochim Acta A Mol Biomol Spectrosc 2002; 58:403-409. [PMID: 11908494 DOI: 10.1016/s1386-1425(01)00459-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The Langmuir-Blodgett (LB) monolayer technique was used to fabricate single molecule LB monolayer containing bis(phenethylimido)perylene (PhPTCD), a red dye dispersed in arachidic acid (AA) with an average doping of 1 molecule per microm2. The monolayer was transferred onto Ag island films to obtain spatially resolved surface-enhanced resonance Raman scattering (SERRS) spectra. The mixed LB monolayers were fabricated with a concentration, on average, of 1, 6, 19 and 118 PhPTCD molecules per microm2 in AA. The AA provides a two-dimensional host matrix whose background signal does not interfere with the detection of the probe molecule's SERRS signal. The properties of the single molecule detection were investigated using micro-Raman with a 514.5-nm laser line. The Ag island surfaces coated with the LB monolayer were mapped with spatial steps of 3 microm and global chemical imaging of the most intense SERRS band in the spectrum was also recorded. The SERRS and surface-enhanced fluorescence (SEF) of the neat and single molecule LB monolayer were recorded in a temperature range from liquid nitrogen to + 200 degrees C. Neat PhPTCD LB monolayer spectra served as reference for the identification of characteristic signatures of the single molecule behavior. The spatial resolution of Raman-microscopy experiments, the multiplicative effect of resonance Raman and SERRS, and the high sensitivity of the new dispersive Raman instruments, allow SERRS to be part of the family of single molecular spectroscopies.
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Affiliation(s)
- C J L Constantino
- Materials and Surface Science Group, School of Physical Sciences, University of Windsor, Ont. Canada
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Constantino CJL, Aroca RF, Yang S, Zucolotto V, Li L, Oliveira ON, Cholli AL, Kumar J, Tripathy SK. RAMAN MICROSCOPY AND MAPPING OF SURFACE-RELIEF GRATINGS RECORDED ON AZOCELLULOSE FILMS. J of Macromolecular Sc , Part A 2001. [DOI: 10.1081/ma-100108404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Dhanabalan A, Mendonça CR, Balogh DT, Misoguti L, Constantino CJL, Giacometti JA, Zilio SC, Oliveira ON. Storage Studies of Langmuir−Blodgett (LB) Films of Methacrylate Copolymers Derivatized with Disperse Red-13. Macromolecules 1999. [DOI: 10.1021/ma9902495] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Dhanabalan
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - C. R. Mendonça
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - D. T. Balogh
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - L. Misoguti
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - C. J. L. Constantino
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - J. A. Giacometti
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - S. C. Zilio
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
| | - O. N. Oliveira
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil
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