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M. Barros JL, Nunes MM, Alves OC, Franchini CA, Corat EJ, Silva AM. Evaluation of Al2O3 and ZrO2 addition to reduced graphene oxide (rGO) supports and their interplay with Cu sites in the catalyst surface. INORG CHEM COMMUN 2022. [DOI: 10.1016/j.inoche.2022.109591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Zambianco NA, da Silva VA, Orzari LO, Corat EJ, Zanin HG, Silva TA, Buller GA, Keefe EM, Banks CE, Janegitz BC. Determination of tadalafil in pharmaceutical samples by vertically oriented multi-walled carbon nanotube electrochemical sensing device. J Electroanal Chem (Lausanne) 2020. [DOI: 10.1016/j.jelechem.2020.114501] [Citation(s) in RCA: 3] [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: 12/17/2022]
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Marques AC, Lopes GR, Samico RP, Matos JD, Souza FA, Corat EJ, Nishioka RS. Evaluation of temperature and osteotomy speed with piezoelectric system. Minerva Dent Oral Sci 2020; 70:65-70. [PMID: 32698562 DOI: 10.23736/s2724-6329.20.04328-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Piezosurgery is an option to realize several clinical and surgical procedures, due to its advantages as precision in osteotomy. This study aims to evaluate the heating and osteotomy speed in bone blocks of ox's shins, to report the best way of its use in the clinical practice. METHODS A bone blocks had the dimensions as follow: 20 mm length, 10 mm width, and 5 mm wide. It was evaluated 5 different groups: group LM (low speed and medium pressure); group HM (high speed and medium pressure); group HH (high speed and high pressure); group LH (low speed and high pressure); group LL (low speed and low pressure). The heating increasement was measured with a thermal viewer and the osteotomy was timed when the cut depth reached 5 mm and the whole block detached itself. One-way ANOVA and Tukey tests were adopted to analyze the data and the level of significance was set at a P value of 0.05. RESULTS The pressure and speed of the tip, works directly in the generated temperature during osteotomy. The medium pressure level is the most favorable, because high pressure level caused a high increase in heating over the bone and low pressure presented a very long osteotomy time. CONCLUSIONS The high speed and medium pressure can be suggested as the most efficient in both standards of time/temperature to realize the osteotomy.
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Affiliation(s)
- Ana C Marques
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil
| | - Guilherme R Lopes
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil -
| | - Renata P Samico
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil
| | - Jefferson D Matos
- Department of Surgery, São Paulo State University (FOA-Unesp), Araçatuba, Brazil
| | | | - Evaldo J Corat
- National Institute for Space Research, São José dos Campos, Brazil
| | - Renato S Nishioka
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil
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Marques AC, Lopes GR, Samico RP, Matos JD, Souza FA, Corat EJ, Nishioka RS. Evaluation of temperature and osteotomy speed with piezoelectric system. Minerva Dent Oral Sci 2020. [PMID: 32698562 DOI: 10.23736/s0026-4970.20.04328-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Piezosurgery is an option to realize several clinical and surgical procedures, due to its advantages as precision in osteotomy. This study aims to evaluate the heating and osteotomy speed in bone blocks of ox's shins, to report the best way of its use in the clinical practice. METHODS A bone blocks had the dimensions as follow: 20 mm length, 10 mm width, and 5 mm wide. It was evaluated 5 different groups: group LM (low speed and medium pressure); group HM (high speed and medium pressure); group HH (high speed and high pressure); group LH (low speed and high pressure); group LL (low speed and low pressure). The heating increasement was measured with a thermal viewer and the osteotomy was timed when the cut depth reached 5 mm and the whole block detached itself. One-way ANOVA and Tukey tests were adopted to analyze the data and the level of significance was set at a P value of 0.05. RESULTS The pressure and speed of the tip, works directly in the generated temperature during osteotomy. The medium pressure level is the most favorable, because high pressure level caused a high increase in heating over the bone and low pressure presented a very long osteotomy time. CONCLUSIONS The high speed and medium pressure can be suggested as the most efficient in both standards of time/temperature to realize the osteotomy.
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Affiliation(s)
- Ana C Marques
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil
| | - Guilherme R Lopes
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil -
| | - Renata P Samico
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil
| | - Jefferson D Matos
- Department of Surgery, São Paulo State University (FOA-Unesp), Araçatuba, Brazil
| | | | - Evaldo J Corat
- National Institute for Space Research, São José dos Campos, Brazil
| | - Renato S Nishioka
- Department of Prosthodontics and Dental Materials, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, Brazil
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Rodrigues BVM, Leite NCS, Cavalcanti BDN, da Silva NS, Marciano FR, Corat EJ, Webster TJ, Lobo AO. Graphene oxide/multi-walled carbon nanotubes as nanofeatured scaffolds for the assisted deposition of nanohydroxyapatite: characterization and biological evaluation. Int J Nanomedicine 2016; 11:2569-85. [PMID: 27358560 PMCID: PMC4912317 DOI: 10.2147/ijn.s106339] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nanohydroxyapatite (nHAp) is an emergent bioceramic that shows similar chemical and crystallographic properties as the mineral phase present in bone. However, nHAp presents low fracture toughness and tensile strength, limiting its application in bone tissue engineering. Conversely, multi-walled carbon nanotubes (MWCNTs) have been widely used for composite applications due to their excellent mechanical and physicochemical properties, although their hydrophobicity usually impairs some applications. To improve MWCNT wettability, oxygen plasma etching has been applied to promote MWCNT exfoliation and oxidation and to produce graphene oxide (GO) at the end of the tips. Here, we prepared a series of nHAp/MWCNT-GO nanocomposites aimed at producing materials that combine similar bone characteristics (nHAp) with high mechanical strength (MWCNT-GO). After MWCNT production and functionalization to produce MWCNT-GO, ultrasonic irradiation was employed to precipitate nHAp onto the MWCNT-GO scaffolds (at 1-3 wt%). We employed various techniques to characterize the nanocomposites, including transmission electron microscopy (TEM), Raman spectroscopy, thermogravimetry, and gas adsorption (the Brunauer-Emmett-Teller method). We used simulated body fluid to evaluate their bioactivity and human osteoblasts (bone-forming cells) to evaluate cytocompatibility. We also investigated their bactericidal effect against Staphylococcus aureus and Escherichia coli. TEM analysis revealed homogeneous distributions of nHAp crystal grains along the MWCNT-GO surfaces. All nanocomposites were proved to be bioactive, since carbonated nHAp was found after 21 days in simulated body fluid. All nanocomposites showed potential for biomedical applications with no cytotoxicity toward osteoblasts and impressively demonstrated a bactericidal effect without the use of antibiotics. All of the aforementioned properties make these materials very attractive for bone tissue engineering applications, either as a matrix or as a reinforcement material for numerous polymeric nanocomposites.
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Affiliation(s)
- Bruno VM Rodrigues
- Laboratory of Biomedical Nanotechnology, Institute of Research and Development (IP&D), University of Vale do Paraiba (UNIVAP), Sao Jose dos Campos, Brazil
| | - Nelly CS Leite
- Laboratory of Biomedical Nanotechnology, Institute of Research and Development (IP&D), University of Vale do Paraiba (UNIVAP), Sao Jose dos Campos, Brazil
| | - Bruno das Neves Cavalcanti
- Department of Cardiology, Restorative Sciences and Endodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - Newton S da Silva
- Laboratory of Cell Biology and Tissue, Institute of Research and Development (IP&D), University of Vale Do Paraiba (UNIVAP)
| | - Fernanda R Marciano
- Laboratory of Biomedical Nanotechnology, Institute of Research and Development (IP&D), University of Vale do Paraiba (UNIVAP), Sao Jose dos Campos, Brazil
| | - Evaldo J Corat
- Associated Laboratory of Sensors and Materials, National Institute for Space Research, Sao Jose dos Campos, Brazil
| | - Thomas J Webster
- Department of Chemical Engineering, Northeastern University, Boston, MA, USA
- Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Anderson O Lobo
- Laboratory of Biomedical Nanotechnology, Institute of Research and Development (IP&D), University of Vale do Paraiba (UNIVAP), Sao Jose dos Campos, Brazil
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Cardoso LDR, Trava-Airoldi VJ, Silva FS, Zanin HG, Antunes EF, Corat EJ. Control of the Length and Density of Carbon Nanotubes Grown on Carbon Fiber for Composites Reinforcement. ACTA ACUST UNITED AC 2015. [DOI: 10.1557/opl.2015.211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTAligned multi-walled carbon nanotubes were grown on carbon fiber surface in order to provide a way to tailor the thermal, electrical and mechanical properties of the fiber-resin interface of a polymer composite. As the deposition temperature of the nanotubes is very high, an elevated exposure time can lead to degradation of the carbon fiber. To overcome this obstacle we have developed a deposition technique where the fiber is exposed to an atmosphere of growth for just one minute, and different concentrations of precursor solution were used.
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Silva TA, Zanin H, May PW, Corat EJ, Fatibello-Filho O. Electrochemical performance of porous diamond-like carbon electrodes for sensing hormones, neurotransmitters, and endocrine disruptors. ACS Appl Mater Interfaces 2014; 6:21086-21092. [PMID: 25402230 DOI: 10.1021/am505928j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Porous diamond-like carbon (DLC) electrodes have been prepared, and their electrochemical performance was explored. For electrode preparation, a thin DLC film was deposited onto a densely packed forest of highly porous, vertically aligned multiwalled carbon nanotubes (VACNT). DLC deposition caused the tips of the carbon nanotubes to clump together to form a microstructured surface with an enlarged surface area. DLC:VACNT electrodes show fast charge transfer, which is promising for several electrochemical applications, including electroanalysis. DLC:VACNT electrodes were applied to the determination of targeted molecules such as dopamine (DA) and epinephrine (EP), which are neurotransmitters/hormones, and acetaminophen (AC), an endocrine disruptor. Using simple and low-cost techniques, such as cyclic voltammetry, analytical curves in the concentration range from 10 to 100 μmol L(-1) were obtained and excellent analytical parameters achieved, including high analytical sensitivity, good response stability, and low limits of detection of 2.9, 4.5, and 2.3 μmol L(-1) for DA, EP, and AC, respectively.
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Affiliation(s)
- Tiago A Silva
- Department of Chemistry, Federal University of São Carlos , Rodovia Washington Luís km 235, 676, São Carlos, 13560-970, SP Brazil
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8
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Zanin H, May PW, Fermin DJ, Plana D, Vieira SMC, Milne WI, Corat EJ. Porous boron-doped diamond/carbon nanotube electrodes. ACS Appl Mater Interfaces 2014; 6:990-995. [PMID: 24392640 DOI: 10.1021/am4044344] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Nanostructuring boron-doped diamond (BDD) films increases their sensitivity and performance when used as electrodes in electrochemical environments. We have developed a method to produce such nanostructured, porous electrodes by depositing BDD thin film onto a densely packed "forest" of vertically aligned multiwalled carbon nanotubes (CNTs). The CNTs had previously been exposed to a suspension of nanodiamond in methanol causing them to clump together into "teepee" or "honeycomb" structures. These nanostructured CNT/BDD composite electrodes have been extensively characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Not only do these electrodes possess the excellent, well-known characteristics associated with BDD (large potential window, chemical inertness, low background levels), but also they have electroactive areas and double-layer capacitance values ∼450 times greater than those for the equivalent flat BDD electrodes.
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Affiliation(s)
- H Zanin
- School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom
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Zanin H, May PW, Hamanaka MHMO, Corat EJ. Field emission from hybrid diamond-like carbon and carbon nanotube composite structures. ACS Appl Mater Interfaces 2013; 5:12238-12243. [PMID: 24224845 DOI: 10.1021/am403386a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A thin diamond-like carbon (DLC) film was deposited onto a densely packed "forest" of vertically aligned multiwalled carbon nanotubes (VACNT). DLC deposition caused the tips of the CNTs to clump together to form a microstructured surface. Field-emission tests of this new composite material show the typical low threshold voltages for carbon nanotube structures (2 V μm(-1)) but with greatly increased emission current, better stability, and longer lifetime.
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Affiliation(s)
- H Zanin
- School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom
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10
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Lobo AO, Zanin H, Siqueira IAWB, Leite NCS, Marciano FR, Corat EJ. Effect of ultrasound irradiation on the production of nHAp/MWCNT nanocomposites. Mater Sci Eng C Mater Biol Appl 2013; 33:4305-12. [PMID: 23910347 DOI: 10.1016/j.msec.2013.06.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 05/23/2013] [Accepted: 06/19/2013] [Indexed: 10/26/2022]
Abstract
Large amounts of nanohydroxyapatite (nHAp)-multiwall carbon nanotube (MWCNT) nanocomposites are produced by two different aqueous precipitation methods. The ultrasonic irradiation (UI) and slow-drip addition under continuous magnetic stirring (DMS) methods were used to investigate the precipitation of nHAp acicular crystals. Calcium-nitrate, diammonium hydrogen phosphate, and ammonium hydroxide were used as precursor reagents. Superhydrophilic MWCNT were also employed. XPS analysis evidences that the functionalized MWCNTs are composed of 18 to 20 at.% of oxygen and that this property influences the nHAp formation. The high surface area of the MWCNT decreases the mean free path of ions, favoring the nHAp formation assisted by UI. The crystallinity was evaluated using the Scherrer equation. Semi-qualitative energy dispersive spectroscopy (EDS) analysis showed that the main components of HAp powders were calcium and phosphorus in the ratio Ca/P around of 1.67. Bioactivity properties of the nHAp/MWCNT-UI nanocomposites could be evaluated after 14 days soaking in simulated body fluid medium. Scanning electron microscopy, EDS, Fourier transform infrared attenuated total reflection spectroscopy, and X-ray diffraction techniques proved that the apatites formed on the surface and to points that the nHAp/MWCNT-UI have potential biological applications.
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Affiliation(s)
- Anderson O Lobo
- Laboratory of Biomedical Nanotechnology, Development Research Institute (IP&D), Universidade do Vale do Paraiba (Univap), Av. ShishimaHifumi, 2911, São José dos Campos, 12244-000 SP, Brazil.
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11
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Marsi TC, A.F. Corat M, M. Machado M, J. Corat E, R. Marciano F, O. Lobo A. Correlation and Comparison Between Thermodynamic Aspects and Cytocompatibility of Cells on Superhydrophobic and Superhydrophilic Vertically Aligned Carbon Nanotubes. ACTA ACUST UNITED AC 2013. [DOI: 10.2174/1877946811303020006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Antonioli E, Lobo AO, Ferretti M, Cohen M, Marciano FR, Corat EJ, Trava-Airoldi VJ. An evaluation of chondrocyte morphology and gene expression on superhydrophilic vertically-aligned multi-walled carbon nanotube films. Mater Sci Eng C Mater Biol Appl 2012; 33:641-7. [PMID: 25427468 DOI: 10.1016/j.msec.2012.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 10/03/2012] [Accepted: 10/26/2012] [Indexed: 12/18/2022]
Abstract
Cartilage serves as a low-friction and wear-resistant articulating surface in diarthrodial joints and is also important during early stages of bone remodeling. Recently, regenerative cartilage research has focused on combinations of cells paired with scaffolds. Superhydrophilic vertically aligned carbon nanotubes (VACNTs) are of particular interest in regenerative medicine. The aim of this study is to evaluate cell expansion of human articular chondrocytes on superhydrophilic VACNTs, as well as their morphology and gene expression. VACNT films were produced using a microwave plasma chamber on Ti substrates and submitted to an O2 plasma treatment to make them superhydrophilic. Human chondrocytes were cultivated on superhydrophilic VACNTs up to five days. Quantitative RT-PCR was performed to measure type I and type II Collagen, Sox9, and Aggrecan mRNA expression levels. The morphology was analyzed by scanning electron microscopy (SEM) and confocal microscopy. SEM images demonstrated that superhydrophilic VACNTs permit cell growth and adhesion of human chondrocytes. The chondrocytes had an elongated morphology with some prolongations. Chondrocytes cultivated on superhydrophilic VACNTs maintain the level expression of Aggrecan, Sox9, and Collagen II determined by qPCR. This study was the first to indicate that superhydrophilic VACNTs may be used as an efficient scaffold for cartilage or bone repair.
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Affiliation(s)
- Eliane Antonioli
- Research and Education Institute, Hospital Israelita Albert Einstein, Sao Paulo, SP, Brazil.
| | - Anderson O Lobo
- Laboratory of Biomedical Nanotechnology, Universidade do Vale do Paraíba, Sao Jose dos Campos, Sao Paulo, Brazil.
| | - Mario Ferretti
- Research and Education Institute, Hospital Israelita Albert Einstein, Sao Paulo, SP, Brazil; Ortophedic Division, Federal University of Sao Paulo, SP, Brazil.
| | - Moisés Cohen
- Research and Education Institute, Hospital Israelita Albert Einstein, Sao Paulo, SP, Brazil; Ortophedic Division, Federal University of Sao Paulo, SP, Brazil.
| | - Fernanda R Marciano
- Laboratory of Biomedical Nanotechnology, Universidade do Vale do Paraíba, Sao Jose dos Campos, Sao Paulo, Brazil.
| | - Evaldo J Corat
- Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, Sao Paulo, Brazil.
| | - Vladimir J Trava-Airoldi
- Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, Sao Paulo, Brazil.
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Marsi TCO, Santos TG, Pacheco-Soares C, Corat EJ, Marciano FR, Lobo AO. Biomineralization of superhydrophilic vertically aligned carbon nanotubes. Langmuir 2012; 28:4413-4424. [PMID: 22320358 DOI: 10.1021/la300111k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Vertically aligned carbon nanotubes (VACNT) promise a great role for the study of tissue regeneration. In this paper, we introduce a new biomimetic mineralization routine employing superhydrophilic VACNT films as highly stable template materials. The biomineralization was obtained after VACNT soaking in simulated body fluid solution. Detailed structural analysis reveals that the polycrystalline biological apatites formed due to the -COOH terminations attached to VACNT tips after oxygen plasma etching. Our approach not only provides a novel route for nanostructured materials, but also suggests that COOH termination sites can play a significant role in biomimetic mineralization. These new nanocomposites are very promising as nanobiomaterials due to the excellent human osteoblast adhesion.
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Affiliation(s)
- Teresa Cristina O Marsi
- Laboratory of Biomedical Nanotechnology, University of Vale do Paraiba (Univap), São José dos Campos, SP, Brazil
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Antunes EF, Edwards ER, Botelho EC, Costa ML, Corat EJ, Massi M. Epoxy composite with milimetric carbon nanotubes. J Nanosci Nanotechnol 2011; 11:9025-9031. [PMID: 22400296 DOI: 10.1166/jnn.2011.3478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Composite of multi-walled carbon nanotubes (MWCNT) and epoxy resin DGEBA were obtained with DDM hardener. The MWCNT were synthesized with length of millimeters by camphor/ferrocene pyrolysis. Different cure temperatures of DGEBA/DDM with addition of up to 1% MWCNT were studied to evaluate eventual changes in cure kinetics by differential scanning calorimetry (DSC). No change was detected in glass transition temperature with insertion of MWCNT although the cure enthalpy has been reduced.
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Affiliation(s)
- E F Antunes
- Instituto Nacional de Pesquisas Espaciais (INPE). Av. dos Astronautas, 1758-CEP: 12.245-970, São José dos Campos/SP, Brazil
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15
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Lobo AO, Corat MAF, Ramos SC, Matsushima JT, Granato AEC, Pacheco-Soares C, Corat EJ. Fast preparation of hydroxyapatite/superhydrophilic vertically aligned multiwalled carbon nanotube composites for bioactive application. Langmuir 2010; 26:18308-18314. [PMID: 20961085 DOI: 10.1021/la1034646] [Citation(s) in RCA: 24] [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: 05/30/2023]
Abstract
A method for the electrodeposition of hydroxyapatite films on superhydrophilic vertically aligned multiwalled carbon nanotubes is presented. The formation of a thin homogeneous film with high crystallinity was observed without any thermal treatment and with bioactivity properties that accelerate the in vitro biomineralization process and osteoblast adhesion.
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Affiliation(s)
- Anderson O Lobo
- Instituto Tecnologico de Aeronautica, Sao Jose dos Campos/SP, CEP: 12228-900, Brazil.
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16
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Antunes EF, Almeida EC, Rosa CBF, de Medeiros LI, Pardini LC, Massi M, Corat EJ. Thermal annealing and electrochemical purification of multi-walled carbon nanotubes produced by camphor/ferrocene mixtures. J Nanosci Nanotechnol 2010; 10:1296-1303. [PMID: 20352791 DOI: 10.1166/jnn.2010.1830] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Multi-walled carbon nanotubes (MWCNT) were obtained by pyrolysis of camphor/ferrocene mixtures, at different concentrations of ferrocene, on quartz, polished silicon and carbon felt substrates. A detailed study by electron microscopy, Raman spectroscopy, X-ray diffraction and thermogravimetric analysis was carried out to determine the purity degree of MWCNTs. Thermal annealing under vacuum and electrochemical purification were used for iron removal. The thermal annealing brings improvement on crystalline structure of MWCNTs, besides iron elimination from internal structure of the tubes, while the electrochemical treatments remove efficiently the iron from MWCNT surface.
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Affiliation(s)
- E F Antunes
- Instituto Nacional de Pesquisas Espaciais, São José dos Campos 12227-010, Brazil
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17
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Marciano FR, Lima-Oliveira DA, Da-Silva NS, Diniz AV, Corat EJ, Trava-Airoldi VJ. Antibacterial activity of DLC films containing TiO2 nanoparticles. J Colloid Interface Sci 2009; 340:87-92. [PMID: 19758597 DOI: 10.1016/j.jcis.2009.08.024] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 08/13/2009] [Accepted: 08/13/2009] [Indexed: 11/27/2022]
Abstract
Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO2) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli (E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO2 in DLC bulk was confirmed by Raman spectroscopy. As TiO2 content increased, I(D)/I(G) ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO2 concentration. As TiO2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO2 nanoparticles can be useful for producing coatings with antibacterial properties.
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Affiliation(s)
- F R Marciano
- Instituto Nacional de Pesquisas Espaciais (INPE), Laboratório Associado de Sensores e Materiais (LAS), Av. dos Astronautas 1758, São José dos Campos, 12227-010 SP, Brazil.
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18
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Barbosa DC, Melo LL, Trava-Airoldi VJ, Corat EJ. The activation energy for nanocrystalline diamond films deposited from an Ar/H2/CH4 hot-filament reactor. J Nanosci Nanotechnol 2009; 9:3944-3948. [PMID: 19504946 DOI: 10.1166/jnn.2009.ns94] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this work we have investigated the effect of substrate temperature on the growth rate and properties of nanocrystalline diamond thin films deposited by hot filament chemical vapor deposition (HFCVD). Mixtures of 0.5 vol% CH4 and 25 vol% H2 balanced with Ar at a pressure of 50 Torr and typical deposition time of 12 h. We present the measurement of the activation energy by accurately controlling the substrate temperature independently of other CVD parameters. Growth rates have been measured in the temperature range from 550 to 800 degrees C. Characterization techniques have involved Raman spectroscopy, high resolution X-ray difractometry and scanning electron microscopy. We also present a comparison with most activation energy for micro and nanocrystalline diamond determinations in the literature and propose that there is a common trend in most observations. The result obtained can be an evidence that the growth mechanism of NCD in HFCVD reactors is very similar to MCD growth.
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Affiliation(s)
- D C Barbosa
- Instituto Nacional de Pesquisas Espaciais, Laboratório Associado de Sensores e Materials, CP 515, 12227-010, São José dos Campos, SP, Brazil
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Lima LM, Motisuki C, Corat EJ, Santos-Pinto L. Comparative cutting effectiveness of an ultrasonic diamond tip and a high-speed diamond bur. Minerva Stomatol 2009; 58:93-98. [PMID: 19357615] [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: 05/27/2023]
Abstract
AIM The aim of this in vitro study was to compare an ultrasonic diamond tip to a high-speed conventional diamond bur regarding the cutting effectiveness in enamel and dentin of human teeth. METHODS Twenty permanent molars were longitudinally sectioned in the buccal-lingual plane giving 40 specimens, 20 for enamel and 20 for dentin groups. One cavity was performed in each specimen using a spherical diamond tip (83231, CVDentus(R), CVDVale, São José dos Campos, SP, Brazil) coupled with an ultrasound device or a conventional spherical diamond bur (1013, KG Sorensen, São Paulo, Brazil)) coupled with a high-speed turbine. A modified measurement analysis using the Radiocef 4.0 software (Radiocef Memory) was applied to determine the width and the depth of the cavities on scanning electron microscopy (SEM) at x50 magnification micrographs. The features of the cavities and the characteristics of the cutting instruments were also examined under different magnifications by SEM. RESULTS Statistical analysis by Kruskal-Wallis non-parametric and Dunn post hoc tests (P < or = 0.05) showed that cavities prepared in enamel and dentin with the ultrasonic diamond tip were shallower and narrower than those prepared with conventional diamond bur. The internal walls of cavities prepared in dentin by the ultrasonic diamond tip reproduced the superficial aspect of the diamond, however, scratches were observed in the internal walls of the dentin cut by high-speed conventional diamond bur. CONCLUSIONS Both instruments were effective in enamel and dentin cutting; however, cavities prepared with a high-speed conventional diamond bur showed more invasive characteristics.
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Affiliation(s)
- L M Lima
- Department of Pediatric Dentistry School of Dentistry of Araraquara, Sao Paolo State University, Araraquara, Sao Paolo, Brazil.
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Sucasaire W, Matsuoka M, Lopes KC, Mittani JCR, Avanci LH, Chubaci JFD, Added N, Trava V, Corat EJ. Raman and infrared spectroscopy studies of carbon nitride films prepared on Si (100) substrates by ion beam assisted deposition. J BRAZIL CHEM SOC 2006. [DOI: 10.1590/s0103-50532006000600014] [Citation(s) in RCA: 14] [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: 11/22/2022] Open
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Iha K, Faleiros AC, Corat EJ, Suárez-Iha MEV. Henry's Law as a Limit for an Isotherm Model Based on a Statistical Mechanics Approach. J Colloid Interface Sci 1998; 208:211-215. [PMID: 9820766 DOI: 10.1006/jcis.1998.5779] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The fundamental integral equation for isotherms derived from statistical mechanics was applied to the analysis of adsorption under low concentrations (or pressures). The model considers adsorption on an energetically heterogeneous surface characterized by an energy distribution function in the semiexponential form N(Q) = (m/RT)e-mQ/RT and by the individual adsorption of each site obeying the Langmuir isotherm. The expression derived guarantees a linear relationship of the covering degree, q, and the concentration, C, that is, q = HC (Henry's law), under the condition of low values of concentration. In this derivation H = mb0/(m - 1) is Henry's constant, while m > 1 and b0 are parameters to be adjusted to experimental data. Copyright 1998 Academic Press.
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Abstract
In this paper we obtain an asymptotic development compatible with Freundlich's isotherm, theta = KCm. That expression was derived underlying the theory of heterogeneous surface. We assume the distribution function of adsorption sites to be in the exponential form and the sites to follow the Langmuir energy homogeneous isotherm. The derived expression represents an analytical solution to the fundamental integral equation for the overall adsorption isotherm in its correct integration limit. From this expression we clearly identify the parameters K and m, the Freundlich parameters. We applied this expression to fit the experimental data for the adsorption of CO2 into BPL-activated carbon.
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Affiliation(s)
- MS Rocha
- Instituto de Quimica, USP, CP 26077, Sao Paulo, SP, 05599-970, Brazil
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Corat EJ, Airoldi VJ, Scolari SL, Ghizoni CC. Gain measurements in stimulated rotational Raman scattering in para hydrogen. Opt Lett 1986; 11:368-370. [PMID: 19730634 DOI: 10.1364/ol.11.000368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The dependence on CO(2)-laser pump energy of the output Stokes radiation obtained through stimulated rotational Raman scattering in para hydrogen is studied experimentally. The effective plane-wave gain for this process was determined as a function of the scattered wavelength by using a theoretical expression for the scattered pulse energy. Experimental values for the gain follow an inverse-wavelength law and are in close agreement with theory.
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Affiliation(s)
- E J Corat
- Laser Division, Institute for Advanced Studies, Centro T6cnico Aerospacial, 12231-Sao Jose dos Campos, Sao Paulo, Brazil
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