Effects of Ultrasonic Agitation on the Structural and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanocrystals

Silva, Anielle Christine Almeida; Gratens, X.; Chitta, V. A.; Franco, Sinésio Domingues; Silva, Ricardo Souza da; Condeles, José Fernando; Dantas, Noélio O.

doi:10.1002/ejic.201402563

Cited by 10 publications

(8 citation statements)

References 48 publications

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“…The latter is relative to the graphite (JCPDS Card No. 75-1621) and may be associated with the packaging of GO sheets. , …”

Section: Resultsmentioning

confidence: 79%

“…The typical morphology of graphene oxide sheets was confirmed by the transmission electron microscopy (TEM) image displayed in Figure a. One can note the presence of characteristic creases and darker regions related to the packaging of the GO sheets. − High-resolution TEM (HR-TEM) images (Figure b,c) show the atomic planes of GO oriented in the same direction with an interplanar distance of 7.7 Å. The selected area diffraction (SAD) technique (Figure d) exhibited two concentric rings, where the innermost concentric ring (001) is attributed to the interplanar distance of the carbon atoms, while the other ring corresponds to the plane (002).…”

Section: Resultsmentioning

confidence: 85%

“…CoFe 2 O 4 nanocrystals consisting of spinel and cubic structures and an average size of ca. 18 nm were prepared following a synthesis route previously reported by Almeida Silva et al A stable dispersion of nanocrystals (20 mg) was prepared in a 20 mL PAH solution (1.0 mg/mL at pH 4) under ultrasonication for 2 h. The nanostructured morphologies of CoFe 2 O 4 nanocrystals and GO were confirmed by transmission electron microscopy (TEM) analysis (Philips CM-200) equipped with selection area diffraction (SAD).…”

Section: Methodsmentioning

confidence: 99%

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Layer-by-Layer Films with CoFe₂O₄Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Morais

Orlandi

Schoening

et al. 2022

ACS Appl. Nano Mater.

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Sensor devices have proved to be a promising technology for portable microelectronic systems for biomedical and environmental applications. Depending on the target analyte and/or the sensor platform chosen, the study of (nano)materials and their ideal incorporation in the device as a receptor layer have great importance for developing sensing units with enhanced properties and performance. Here, we employed the layer-by-layer (LbL) technique to fabricate nanostructured films as sensing units for detecting H2O2 and heavy metal ions (Cd2+ and Cu2+). The LbL film was deposited on electrolyte–insulator–semiconductor (EIS) field-effect devices, combining CoFe2O4 nanocrystals embedded into polyallylamine hydrochloride (PAH) and graphene oxide (GO) as a PAH-CoFe2O4/GO structure. Scanning electron microscopy revealed a LbL film morphology with high surface area presenting heterogeneous clusters of nanocrystals covered by a homogeneous coating of GO. The electrochemical characterization to monitor the film growth and the sensing properties for detecting H2O2 and Cd2+ and Cu2+ ions was carried out by capacitance–voltage (C/V) and constant-capacitance (ConCap) measurements. The results demonstrated catalytic features in detection experiments for an optimized EIS-LbL sensor containing a 6-bilayer PAH-CoFe2O4/GO LbL film. This sensor system was sensitive for all analytes and exhibited a low limit of detection of ca. 314.3 μM for H2O2 and 0.54 and 0.47 μM for Cd2+ and Cu2+ ions, respectively. These findings prove the relevance of incorporating nanostructured films as a receptor layer to enhance sensing properties and may envisage a proof-of-concept field-effect sensor system for environmental applications.

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“…The latter is relative to the graphite (JCPDS Card No. 75-1621) and may be associated with the packaging of GO sheets. , …”

Section: Resultsmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 85%

Section: Methodsmentioning

confidence: 99%

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Layer-by-Layer Films with CoFe₂O₄Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Morais

Orlandi

Schoening

et al. 2022

ACS Appl. Nano Mater.

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Section: Discussionmentioning

confidence: 99%

“…The increase in Se concentration favors larger QDs and discontinuous growth, which are characteristics of MSQDs 53 . The CdSe‐MSQDs showed diameters of 1.13, 1.16, 1.18, and 1.20 nm for 0.4, 0.5, 0.8, and 0.9 CdSe‐MSQDs, respectively, conferring to them the ability to easily cross all cell membrane types 53 . It is possible to confirm through the FL microscopy analysis the presence of CdSe‐MSQDs in the brain of the embryos exposed to the nanoparticles, indicated by the red dots inside the cells (Figure 5).…”

Section: Discussionmentioning

confidence: 99%

Increased selenium concentration in the synthesis of CdSe magic‐sized quantum dots affects how the brain responds to oxidative stress

et al. 2021

Self Cite

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CdSe magic‐sized quantum dots (MSQDs) have been widely used as fluorescent probes in biological systems due to their excellent optical properties with a broader fluorescence spectrum and stable luminescence in biological media. However, they can be cytotoxic and alter the redox balance depending on the amounts of Cd2+ adsorbed on their surface. Thus, the present study aimed to evaluate whether increases in selenium concentration in the synthesis of CdSe‐MSQDs decrease the oxidative stress caused by Cd2+‐based quantum dots. CdSe‐MSQDs synthesized with different concentrations of selenium were investigated against oxidative stress in the brain of chicken embryos by examining total antioxidant capacity, lipid peroxidation, thiol, and glutathione contents, as well as the activities of glutathione peroxidase, superoxide dismutase (SOD), catalase (CAT), and glutathione reductase. In addition, the vascularization of the chorioallantoic membrane (CAM) analysis was performed. Higher selenium concentrations alter the surface defect levels (decrease free Cd2+) and controlled the oxidative effects of CdSe‐MSQDs by reducing the lipid peroxidation, restoring the glutathione defense system and the antioxidant enzymes SOD and CAT, and maintaining the vascular density of the CAM. The current findings reinforce the study of the effects of the presence of Cd2+ ions on the surface of quantum dots, changing toxicity, and aiming interesting strategies of nanomaterials in biological systems.

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Engineering the magnetic properties of acrylonitrile butadiene styrene‐based composites with magnetic nanoparticles

Merazzo,

García Díez,

Tubio

et al. 2023

Polymer Composites

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This work reports the engineering of the magnetic properties of composites based on acrylonitrile butadiene styrene (ABS) by the inclusion of different magnetic nanoparticles (MNP). ABS‐based composites with different MNP, including permalloy, Fe3O4, CoFe2O4, Ni, and Co‐carbon coated, with a 10 wt% content have been prepared and their morphological, electric, thermal, magnetic, and mechanical properties evaluated. Films were processed by solvent casting under two different processing conditions, no magnetic field applied during solvent evaporations, and an out‐of‐plane magnetic field application. It is shown that ABS‐based composites preserve the magnetic properties of the filler, providing a simple way to tune the magnetic behavior in the polymer. The inclusion of permalloy, Fe3O4, CoFe2O4, Ni, and Co‐carbon coated fillers, allow to obtain saturation magnetizations of 6.2, 4.1, 7.3, 3.7, 4.4, and 4.9 emu/g, respectively, and coercive fields of 88.5, 30.9, 128, 2529.8, 123.6, and 197.4 Oe, respectively. It was found that the mechanical properties of the composites depend on filler type and dimensions, maintaining the thermoplastic behavior of the matrix when the fillers are small (up to 40 nm) and losing it when the fillers are bigger (from 60 to 135 nm). Further, the breaking stress, elongation at break, and the Young's modulus are material dependent, showing higher values when the fillers are Fe3O4 and CoFe2O4 and lower values when the fillers are permalloy, Ni, and Co‐carbon; for example, these values are the highest in the case of the ABS‐Fe3O4 composite with values of 28.7 MPa, 4.1%, and 1266.9 MPa, respectively, while ABS‐Co composite shows the lowest breaking stress and elongation at break with 9.2 MPa and 1.5%, respectively. The ABS‐permalloy composite presents the lowest Young's modulus with 781.5 MPa. Also, the magnetic fillers do not change significantly the thermal, dielectric, and the electrical properties of the composites at this concentration (10 wt%). Overall, the present work demonstrates the feasibility of the modulation of the mechanical and the tuning of the magnetic properties of ABS‐based magnetic nanocomposites by changing the magnetic material and by applying a magnetic field during the processing of the composites, allowing their application in areas including sensors, actuators, and magnetic devices.Highlights Magnetic nanoparticles can engineer the magnetic properties in a composite. Nanoparticles (NP) can engineer mechanical properties depending on their material. NP can engineer mechanical properties depending on their dimensions. With this process, the thermal, electric, and dielectric properties are preserved. Applied magnetic fields during solvent evaporations affects the Young's modulus.

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Effects of Ultrasonic Agitation on the Structural and Magnetic Properties of CoFe₂O₄ Nanocrystals

Cited by 10 publications

References 48 publications

Layer-by-Layer Films with CoFe₂O₄Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Layer-by-Layer Films with CoFe₂O₄Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Increased selenium concentration in the synthesis of CdSe magic‐sized quantum dots affects how the brain responds to oxidative stress

Engineering the magnetic properties of acrylonitrile butadiene styrene‐based composites with magnetic nanoparticles

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Effects of Ultrasonic Agitation on the Structural and Magnetic Properties of CoFe2O4 Nanocrystals

Cited by 10 publications

References 48 publications

Layer-by-Layer Films with CoFe2O4Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Layer-by-Layer Films with CoFe2O4Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Increased selenium concentration in the synthesis of CdSe magic‐sized quantum dots affects how the brain responds to oxidative stress

Engineering the magnetic properties of acrylonitrile butadiene styrene‐based composites with magnetic nanoparticles

Contact Info

Product

Resources

About

Effects of Ultrasonic Agitation on the Structural and Magnetic Properties of CoFe₂O₄ Nanocrystals

Layer-by-Layer Films with CoFe₂O₄Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

Layer-by-Layer Films with CoFe₂O₄Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices