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de Araujo CIL, Teixeira HA, Toro OO, Liao C, Benetti LC, Borme J, Schafer D, Brandt I, Ferreira R, Alpuim P, Freitas PP, Pasa AA. Room temperature two terminal tunnel magnetoresistance in a lateral graphene transistor. Nanoscale 2021; 13:20028-20033. [PMID: 34842882 DOI: 10.1039/d1nr05495c] [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: 06/13/2023]
Abstract
We investigate the behavior of both pure spin and spin-polarized currents measured with four-probe non-local and two probe local configurations up to room temperature and under an external gate voltage in a lateral graphene transistor, produced using a standard large-scale microfabrication process. The high spin diffusion length of pristine graphene in the channel, measured both directly and by the Hanle effect, and the tuning of the relationship between the electrode resistance areas present in the device architecture allowed us to observe local tunnel magnetoresistance at room temperature, a new finding for this type of device. The results also indicate that while pure spin currents are less sensitive to temperature variations, spin-polarized current switching by an external voltage is more efficient, due to a combination of the Rashba effect and a change in carrier mobility by a Fermi level shift.
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Affiliation(s)
- C I L de Araujo
- Departamento de Fìsica, Laboratório de Spintrônica e Nanomagnetismo, Universidade Federal de Viçosa, Viçosa, 36570-900, Minas Gerais, Brazil.
| | - H A Teixeira
- Departamento de Fìsica, Laboratório de Spintrônica e Nanomagnetismo, Universidade Federal de Viçosa, Viçosa, 36570-900, Minas Gerais, Brazil.
| | - O O Toro
- Departamento de Fìsica, Laboratório de Spintrônica e Nanomagnetismo, Universidade Federal de Viçosa, Viçosa, 36570-900, Minas Gerais, Brazil.
| | - C Liao
- INL-International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
| | - L C Benetti
- INL-International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
- Laboratório de Filmes Finos e Superfícies (LFFS), Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil
| | - J Borme
- INL-International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
| | - D Schafer
- Laboratório de Filmes Finos e Superfícies (LFFS), Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil
| | - I Brandt
- Laboratório de Filmes Finos e Superfícies (LFFS), Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil
| | - R Ferreira
- INL-International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
| | - P Alpuim
- INL-International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
| | - Paulo P Freitas
- INL-International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
| | - A A Pasa
- Laboratório de Filmes Finos e Superfícies (LFFS), Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil
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Mojica Pisciotti ML, Lima E, Vasquez Mansilla M, Tognoli VE, Troiani HE, Pasa AA, Creczynski-Pasa TB, Silva AH, Gurman P, Colombo L, Goya GF, Lamagna A, Zysler RD. In vitro and in vivo experiments with iron oxide nanoparticles functionalized with DEXTRAN or polyethylene glycol for medical applications: magnetic targeting. J Biomed Mater Res B Appl Biomater 2014; 102:860-8. [PMID: 24458920 DOI: 10.1002/jbm.b.33068] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [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: 05/16/2013] [Revised: 09/13/2013] [Accepted: 10/20/2013] [Indexed: 01/30/2023]
Abstract
In this research work, DEXTRAN- and polyethylene glycol (PEG)-coated iron-oxide superparamagnetic nanoparticles were synthetized and their cytotoxicity and biodistribution assessed. Well-crystalline hydrophobic Fe3 O4 SPIONs were formed by a thermal decomposition process with d = 18 nm and σ = 2 nm; finally, the character of SPIONs was changed to hydrophilic by a post-synthesis procedure with the functionalization of the SPIONs with PEG or DEXTRAN. The nanoparticles present high saturation magnetization and superparamagnetic behavior at room temperature, and the hydrodynamic diameters of DEXTRAN- and PEG-coated SPIONs were measured as 170 and 120 nm, respectively. PEG- and DEXTRAN-coated SPIONs have a Specific Power Absorption SPA of 320 and 400 W/g, respectively, in an ac magnetic field with amplitude of 13 kA/m and frequency of 256 kHz. In vitro studies using VERO and MDCK cell lineages were performed to study the cytotoxicity and cell uptake of the SPIONs. For both cell lineages, PEG- and DEXTRAN-coated nanoparticles presented high cell viability for concentrations as high as 200 μg/mL. In vivo studies were conducted using BALB/c mice inoculating the SPIONs intravenously and exposing them to the presence of an external magnet located over the tumour. It was observed that the amount of PEG-coated SPIONs in the tumor increased by up to 160% when using the external permanent magnetic as opposed to those animals that were not exposed to the external magnetic field.
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Affiliation(s)
- M L Mojica Pisciotti
- Div. Resonancias Magnéticas, Centro Atómico Bariloche/CONICET, S. C. Bariloche, 8400, Argentina
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Borges AMG, Benetoli LO, Licínio MA, Zoldan VC, Santos-Silva MC, Assreuy J, Pasa AA, Debacher NA, Soldi V. Polymer films with surfaces unmodified and modified by non-thermal plasma as new substrates for cell adhesion. Mater Sci Eng C Mater Biol Appl 2012; 33:1315-24. [PMID: 23827577 DOI: 10.1016/j.msec.2012.12.031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 09/29/2012] [Accepted: 12/04/2012] [Indexed: 01/04/2023]
Abstract
The surface properties of biomaterials, such as wettability, polar group distribution, and topography, play important roles in the behavior of cell adhesion and proliferation. Gaseous plasma discharges are among the most common means to modify the surface of a polymer without affecting its properties. Herein, we describe the surface modification of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) films using atmospheric pressure plasma processing through exposure to a dielectric barrier discharge (DBD). After treatment the film surface showed significant changes from hydrophobic to hydrophilic as the water contact angle decreasing from 95° to 37°. All plasma-treated films developed more hydrophilic surfaces compared to untreated films, although the reasons for the change in the surface properties of PS and PMMA differed, that is, the PS showed chemical changes and in the case of PMMA they were topographical. Excellent adhesion and cell proliferation were observed in all films. In vitro studies employing flow cytometry showed that the proliferation of L929 cells was higher in the film formed by a 1:1 mixture of PS/PMMA, which is consistent with the results of a previous study. These findings suggest better adhesion of L929 onto the 1:1 PS/PMMA modified film, indicating that this system is a new candidate biomaterial for tissue engineering.
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Affiliation(s)
- A M G Borges
- Department of Chemistry, Federal University of Santa Catarina, 88040-900 Florianopolis, Brazil
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Delatorre RG, da Silva RC, Cruz JS, Garcia N, Pasa AA. Electrodeposited magnetite with large magnetoresistive response at room temperature and low magnetic fields. J Solid State Electrochem 2008. [DOI: 10.1007/s10008-008-0621-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Spangenberg T, de Mello NF, Creczynski-Pasa TB, Pasa AA, Niehus H. AFM in-situ characterization of supported phospholipid layers formed by solution spreading. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/pssa.200304368] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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