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1.
Phys Rev Lett ; 129(5): 057201, 2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35960587

RESUMO

We report a magnetic transition region in La_{0.7}Sr_{0.3}MnO_{3} with gradually changing magnitude of magnetization, but no rotation, stable at all temperatures below T_{C}. Spatially resolved magnetization, composition and Mn valence data reveal that the magnetic transition region is induced by a subtle Mn composition change, leading to charge transfer at the interface due to carrier diffusion and drift. The electrostatic shaping of the magnetic transition region is mediated by the Mn valence, which affects both magnetization by Mn^{3+}-Mn^{4+} double exchange interaction and free carrier concentration.


Assuntos
Magnetismo , Eletricidade Estática , Temperatura
2.
Artigo em Inglês | MEDLINE | ID: mdl-35955097

RESUMO

(1) Background: The influence of serotonin on many regulatory mechanisms has not been sufficiently studied. The use of a physical method, assuming the possibility of its action on increasing the concentration of serotonin, may be the direction of therapy limiting the number of antidepressants used. The aim of the research was to study the effects of low-frequency magnetic fields of different characteristics on the circadian profile of serotonin in men with low back pain. (2) Methods: 16 men with back pain syndrome participated in the study. The patients were divided into two groups. In group 1, magnetotherapy (2.9 mT, 40 Hz, square wave, bipolar) was applied at 10.00 a.m. In group 2, the M2P2 magnetic stimulation program of the Viofor JPS device was used. Treatments in each group lasted 3 weeks, 5 days each, with breaks for Saturday and Sunday. The daily serotonin profile was determined the day before the exposure and the day after the last treatment. Blood samples (at night with red light) were collected at 8:00, 12:00, 16:00, 24:00, and 4:00. The patients did not suffer from any chronic or acute disease and were not taking any medications. (3) Results: In group 1, a significant increase in serotonin concentration was observed after 15 treatments at 4:00. In group 2, a significant increase in serotonin concentration was observed at 8:00 after the end of the treatments. In comparison between magnetotherapy and magnetic stimulation, the time points at which differences appeared after the application of serotonin occurred due to the increase in its concentrations after the application of magnetic stimulation. (4) Conclusions: Magnetotherapy and magnetic stimulation, acting in a similar way, increase the concentration of serotonin. Weak magnetic fields work similarly to the stronger ones used in TMS. It is possible to use them in the treatment of mental disorders or other diseases with low serotonin concentrations.


Assuntos
Dor Lombar , Magnetoterapia , Humanos , Dor Lombar/terapia , Campos Magnéticos , Magnetismo , Masculino , Serotonina
3.
Int J Mol Sci ; 23(15)2022 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-35955614

RESUMO

The structural, morphological and magnetic properties of MFe2O4 (M = Co, Ni, Zn, Cu, Mn) type ferrites produced by thermal decomposition at 700 and 1000 °C were studied. The thermal analysis revealed that the ferrites are formed at up to 350 °C. After heat treatment at 1000 °C, single-phase ferrite nanoparticles were attained, while after heat treatment at 700 °C, the CoFe2O4 was accompanied by Co3O4 and the MnFe2O4 by α-Fe2O3. The particle size of the spherical shape in the nanoscale region was confirmed by transmission electron microscopy. The specific surface area below 0.5 m2/g suggested a non-porous structure with particle agglomeration that limits nitrogen absorption. By heat treatment at 1000 °C, superparamagnetic CoFe2O4 nanoparticles and paramagnetic NiFe2O4, MnFe2O4, CuFe2O4 and ZnFe2O4 nanoparticles were obtained.


Assuntos
Cobalto , Magnetismo , Cobalto/química , Fenômenos Magnéticos , Óxidos , Zinco/química
4.
Biosensors (Basel) ; 12(7)2022 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-35884320

RESUMO

A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic conductor in various forms of wire, ribbon, and thin film. Also known as the giant magnetoimpedance (GMI) effect, this phenomenon forms the basis for the development of high-performance magnetic biosensors with magnetic field sensitivity down to the picoTesla regime at room temperature. Over the past decade, some state-of-the-art prototypes have become available for trial tests due to continuous efforts to improve the sensitivity of GMI biosensors for the ultrasensitive detection of biological entities and biomagnetic field detection of human activities through the use of magnetic nanoparticles as biomarkers. In this review, we highlight recent advances in the development of GMI biosensors and review medical devices for applications in biomedical diagnostics and healthcare monitoring, including real-time monitoring of respiratory motion in COVID-19 patients at various stages. We also discuss exciting research opportunities and existing challenges that will stimulate further study into ultrasensitive magnetic biosensors and healthcare monitors based on the GMI effect.


Assuntos
Técnicas Biossensoriais , COVID-19 , COVID-19/diagnóstico , Atenção à Saúde , Impedância Elétrica , Humanos , Magnetismo
5.
J Nanobiotechnology ; 20(1): 316, 2022 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-35794559

RESUMO

BACKGROUND: The magneto-mechanical force killing cancer cells is an interesting and important strategy for cancer therapy. RESULTS: Novel magnetic microspheres composed of a Fe3O4 nanocore, a bovine serum albumin (BSA) matrix, and a rod-like SiO2 nanoshell, which had flagellum-like surface for force-mediated cancer therapy were developed. One such magnetic microsphere (Fe3O4/BSA/rSiO2) at a cancer cell (not leave the cell surface) under a low frequency vibrating magnetic field (VMF) could generate 6.17 pN force. Interestingly, this force could induce cancer cell to generate reactive oxygen species (ROS). The force and force-induced ROS could kill cancer cells. The cell killing efficiency of Fe3O4/BSA/rSiO2 exposed to a VMF was enhanced with increasing silica nanorod length, and the microspheres with straight nanorods exhibited stronger cell killing ability than those with curled nanorods. Fe3O4/BSA/rSiO2 triggered by a VMF could efficiently inhibit mouse tumor growth, while these microspheres without a VMF had no significant effect on the cell cycle distribution, cell viability, tumor growth, and mouse health. CONCLUSIONS: These microspheres with unique morphological characteristics under VMF have great potential that can provide a new platform for treating solid tumors at superficial positions whether with hypoxia regions or multidrug resistance.


Assuntos
Neoplasias , Dióxido de Silício , Animais , Campos Magnéticos , Magnetismo , Camundongos , Microesferas , Espécies Reativas de Oxigênio , Soroalbumina Bovina/metabolismo
6.
ACS Appl Mater Interfaces ; 14(28): 31689-31701, 2022 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-35786842

RESUMO

Magnetic nanoparticles as drug carriers, despite showing immense promises in preclinical trials, have remained to be only of limited use in real therapeutic practice primarily due to unresolved anomalies concerning their grossly contrasting controllability and variability in performance in artificial test benches as compared to human tissues. To circumvent the deficits of reported in vitro drug testing platforms that deviate significantly from the physiological features of the living systems and result in this puzzling contrast, here, we fabricate a biomimetic microvasculature in a flexible tissue phantom and demonstrate distinctive mechanisms of magnetic-field-assisted controllable penetration of biocompatible iron oxide nanoparticles across the same, exclusively modulated by tissue deformability, which has by far remained unraveled. Our experiments deciphering the transport of magnetic nanoparticles in a blood analogue medium unveil a decisive interplay of the flexibility of the microvascular pathways, magnetic pull, and viscous friction toward orchestrating the optimal vascular penetration and targeting efficacy of the nanoparticles in colorectal tissue-mimicking bioengineered media. Subsequent studies with biological cells confirm the viability of using localized magnetic forces for aiding nanoparticle penetration within cancerous lesions. We establish nontrivially favorable conditions to induce a threshold force for vascular rupture and eventual target of the nanoparticles toward the desired extracellular site. These findings appear to be critical in converging the success of in vitro trials toward patient-specific targeted therapies depending on personalized vascular properties obtained from medical imaging data.


Assuntos
Nanopartículas de Magnetita , Nanopartículas , Neoplasias , Portadores de Fármacos/uso terapêutico , Humanos , Campos Magnéticos , Magnetismo , Nanopartículas de Magnetita/uso terapêutico , Nanopartículas/uso terapêutico , Neoplasias/terapia , Microambiente Tumoral
7.
Langmuir ; 38(31): 9708-9719, 2022 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-35880857

RESUMO

For the success of biomedical applications of magnetic iron oxide nanoparticles (MION), such as magnetic hyperthermia and magnetic particle imaging, it is essential to understand the orientational dynamics of MION in a complex fluid under an alternating field. Here, using the magnetic linear dichroism (MLD) measurement, we directly observed the orientational behavior of MION in a hydrogel under a damped oscillating magnetic field (DOMF) of 33 kHz in frequency. Hydrophobically modified ethoxylated urethane (HEUR) is examined as the network polymer because the mesh size of the network is controllable with its concentration. We used two MIONs: a bare MION (MION1) and a MION coated with an amphiphilic polymer (MION2). Where the mesh size of the gel network is larger than the particle's hydrodynamic diameter, MION1 in the hydrogel rotates in the same manner in a simple solution, although the macroscopic rheological property of the medium is quite different. Meanwhile, the orientational behavior of MION2 is dramatically changed by the addition of HEUR molecules even below the minimum gelation concentration, indicating that MION2 is associated with the flower micelles of HEUR. By analyzing the MLD waveform, the orientational behavior of MION1 in the HEUR gel under a DOMF can be explained with single-mode relaxation, whereas that of MION2 is complicated; a rapid partial rotation near the particle and a whole slow rotation of the particle-flower micelle associate are superimposed. It is hard to distinguish this difference in orientational behaviors from the dynamic magnetization curve because the dominant magnetization reversal process is Néel rotation, the rotation of the magnetic moment in the particle. The MLD measurement is a potential tool for optimizing biomedical techniques utilizing MIONs and for nanorheology or colloid science in a complex matrix such as a hydrogel or cytoplasmic matrix.


Assuntos
Hidrogéis , Magnetismo , Nanopartículas Magnéticas de Óxido de Ferro , Fenômenos Magnéticos , Micelas , Polímeros
8.
Sci Rep ; 12(1): 13080, 2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35906371

RESUMO

With the development and progress of nanotechnology, the prospect of using nanorobots to achieve targeted drug delivery is becoming possible. Although nanorobots can potentially improve nano-drug delivery systems, there remains a significant challenge to fabricating magnetically controllable nanorobots with a size suitable for drug delivery in complex in vivo environments. Most of the current research focused on the preparation and functionalization of microscale and milliscale robots due to the relative difficulties in fabricating nanoscale robots. To address this problem and move towards in vivo applications, this study uses electron beam lithography to fabricate achiral planar L-shaped nanorobots that are biocompatible with immune cells. Their minimal planar geometry enabled nanolithography to fabricate nanorobots with a minimum feature size down to 400 nm. Using an integrated imaging and control system, the locomotive behavior of the L-shaped nanorobots in a fluidic environment was studied by examining their velocity profiles and trajectories. Furthermore, the nanorobots exhibit excellent cell compatibility with various types of cells, including macrophage cells. Finally, the long-term cell culture medium immersion test demonstrated that the L-shaped nanorobots have robust stability. This work will demonstrate the potential to use these nanorobots to operate in vivo without triggering immune cell responses.


Assuntos
Elétrons , Nanotecnologia , Sistemas de Liberação de Medicamentos , Macrófagos , Magnetismo
9.
Elife ; 112022 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-35852850

RESUMO

Swimming microorganisms often experience complex environments in their natural habitat. The same is true for microswimmers in envisioned biomedical applications. The simple aqueous conditions typically studied in the lab differ strongly from those found in these environments and often exclude the effects of small volume confinement or the influence that external fields have on their motion. In this work, we investigate magnetically steerable microswimmers, specifically magnetotactic bacteria, in strong spatial confinement and under the influence of an external magnetic field. We trap single cells in micrometer-sized microfluidic chambers and track and analyze their motion, which shows a variety of different trajectories, depending on the chamber size and the strength of the magnetic field. Combining these experimental observations with simulations using a variant of an active Brownian particle model, we explain the variety of trajectories by the interplay between the wall interactions and the magnetic torque. We also analyze the pronounced cell-to-cell heterogeneity, which makes single-cell tracking essential for an understanding of the motility patterns. In this way, our work establishes a basis for the analysis and prediction of microswimmer motility in more complex environments.


Assuntos
Magnetospirillum , Bactérias Gram-Negativas , Campos Magnéticos , Magnetismo , Microfluídica , Torque
10.
Chem Commun (Camb) ; 58(65): 9088-9091, 2022 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-35876803

RESUMO

The complex [NiII14(HL2)12(HCOO)14Cl14(MeOH)(H2O)] describes an aesthetically pleasing wheel displaying ferromagnetic nearest neighbour exchange.


Assuntos
Magnetismo , Imãs
11.
Sci Rep ; 12(1): 12209, 2022 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-35842556

RESUMO

Magnetic compression technique (MCT) is a popular new anastomosis method. In this paper, we aimed to explore the feasibility of use of MCT for performing cystotomy in rabbits. The parent magnets and daughter magnets for rabbit cystostomy were designed and manufactured according to the anatomical characteristics of rabbit lower urinary tract. Twelve female New Zealand rabbits were used as animal models. After anesthesia, a daughter magnet was inserted into the bladder through the urethra, and the parent magnet was placed on the body surface projection of the bladder over the abdominal wall. The two magnets automatically attract each other. Postoperatively, the state of magnets was monitored daily, and the time when the magnets fell off was recorded. Cystostomy with MCT was successfully performed in all twelve rabbits. The mean operation time was 4.46 ± 0.75 min. The magnets fell off from the abdominal wall after a mean duration of 10.08 ± 1.62 days, resulting in the formation of bladder fistula. Macroscopic and microscopic examination showed that the fistula was well formed and unobstructed. The junction between bladder and abdominal wall was tight and smooth. We provide preliminary experimental evidence of the safety and feasibility of cystostomy based on MCT.


Assuntos
Cistostomia , Magnetismo , Animais , Cistostomia/métodos , Feminino , Fenômenos Magnéticos , Imãs , Pressão , Coelhos
12.
Sci Rep ; 12(1): 12445, 2022 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-35859162

RESUMO

Magnetic compression anastomosis, also known as magnamosis, is a safe and feasible method for digestive tract anastomosis. However, the pathological process involved in magnamosis of the digestive tract has not been investigated. This study aimed to establish the stages of digestive tract magnamosis in a rat model. Eighty-four Sprague-Dawley albino rats (200-250 g) were randomly divided into 14 groups (n = 6 per group). All rats underwent colonic magnamosis. Starting from postoperative day (POD) 1, one group of rats was sacrificed every other day to obtain the specimens. Burst pressure at the anastomotic site of each specimen was examined. Gross and histological examination of the anastomotic site was performed to establish the stages of the digestive tract magnamosis. Colonic magnamosis was successfully performed in all rats and the mean anastomosis time was 5.62 ± 0.91 min. The postoperative survival rate was 100%. The lowest anastomotic burst pressure was 78.33 ± 3.44 mmHg on POD3. The anastomotic burst pressure gradually increased and stabilized on POD21. Macroscopic and histological examination showed that the anastomotic mucosal and serosal layer did not heal on POD1. The serosal layer of the anastomosis healed by adhesion on POD3, and the mucosal layer began to heal on POD3-11 and was established by POD21. According to the anastomotic bursting pressure, digestive tract magnamosis can be staged into the magnetic maintenance, fragile, strengthening, and stable phases, which on histology correspond to the serosal adhesion formation, serosal healing, mucosal healing, and stereotyping, respectively.


Assuntos
Colo , Magnetismo , Anastomose Cirúrgica/métodos , Animais , Colo/patologia , Colo/cirurgia , Fenômenos Magnéticos , Ratos , Ratos Sprague-Dawley , Aderências Teciduais/patologia
13.
Sensors (Basel) ; 22(15)2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35898106

RESUMO

The magnetic navigation system (MNS) with gradient and uniform saddle coils is an effective system for manipulating various medical magnetic robots because of its compact structure and the uniformity of its magnetic field and field gradient. Since each coil of the MNS was geometrically optimized to generate strong uniform magnetic field or field gradient, it is considered that no special optimization is required for the MNS. However, its electrical characteristics can be still optimized to utilize the maximum power of a power supply unit with improved operating time and a stronger time-varying magnetic field. Furthermore, the conventional arrangement of the coils limits the maximum three-dimensional (3D) rotating magnetic field. In this paper, we propose an electrical optimization method based on a novel arrangement of the MNS. We introduce the objective functions, constraints, and design variables of the MNS considering electrical characteristics such as resistance, current density, and inductance. Then, we design an MNS using an optimization algorithm and compare it with the conventional MNS; the proposed MNS generates a magnetic field or field gradient 22% stronger on average than that of the conventional MNS with a sevenfold longer operating time limit, and the maximum three-dimensional rotating magnetic field is improved by 42%. We also demonstrate that the unclogging performance of the helical robot improves by 54% with the constructed MNS.


Assuntos
Imageamento por Ressonância Magnética , Magnetismo , Eletricidade , Desenho de Equipamento , Campos Magnéticos , Imageamento por Ressonância Magnética/métodos
14.
Nanoscale ; 14(31): 11129-11138, 2022 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-35904896

RESUMO

In this work, we describe the synthesis of magnetic nanoparticles composed of a maghemite core (MNP) and three different coatings (dextran, D-MNP; carboxymethyldextran, CMD-MNP; and dimercaptosuccinic acid, DMSA-MNP). Their interactions with red blood cells, plasma proteins, and macrophages were also assessed. CMD-MNP was selected for its good biosafety profile and for promoting a pro-inflammatory response in macrophages, which was associated with the nature of the coating. Thus, we proposed a smart miRNA delivery system using CMD-MNP as a carrier for cancer immunotherapy applications. Particularly, we prove that CMD-MNP-miRNA155 and CMD-MNP-miRNA125b nanoparticles can display a pro-inflammatory response in human macrophages by increasing the expression of CD80 and the levels of TNF-α and IL-6. Hence, our proposed miRNA-delivery nanosystem can be exploited as a new immunotherapeutic tool based on magnetic nanoparticles.


Assuntos
Nanopartículas de Magnetita , MicroRNAs , Nanopartículas , Humanos , Macrófagos , Magnetismo , Succímero
15.
Biosensors (Basel) ; 12(8)2022 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-35892451

RESUMO

The conventional signal amplification strategies for surface plasmon resonance (SPR) biosensors involve the immobilization of receptors, the capture of target analytes and their recognition by signal reporters. Such strategies work at the expense of simplicity, rapidity and real-time measurement of SPR biosensors. Herein, we proposed a one-step, real-time method for the design of SPR biosensors by integrating magnetic preconcentration and separation. The target analytes were captured by the receptor-modified magnetic nanoparticles (MNPs), and then the biotinylated recognition elements were attached to the analyte-bound MNPs to form a sandwich structure. The sandwich hybrids were directly delivered to the neutravidin-modified SPR fluidic channel. The MNPs hybrids were captured by the chip through the neutravidin-biotin interaction, resulting in an enhanced SPR signal. Two SPR biosensors have been constructed for the detection of target DNA and beta-amyloid peptides with high sensitivity and selectivity. This work, integrating the advantages of one-step, real-time detection, multiple signal amplification and magnetic preconcentration, should be valuable for the detection of small molecules and ultra-low concentrations of analytes.


Assuntos
Técnicas Biossensoriais , Ressonância de Plasmônio de Superfície , Técnicas Biossensoriais/métodos , Biotina/química , Fenômenos Magnéticos , Magnetismo , Ressonância de Plasmônio de Superfície/métodos
16.
Comput Methods Programs Biomed ; 223: 106975, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35792363

RESUMO

BACKGROUND AND OBJECTIVE: Magnetic hyperthermia is an oncological therapy that employs magnetic nanoparticles activated by alternating current (AC) magnetic fields with frequencies between 50 kHz and 1 MHz, to release heat in a diseased tissue and produce a local temperature increase of about 5 °C. To assess the treatment efficacy, in vivo tests on murine models (mice and rats) are typically performed. However, these are often carried out without satisfying the biophysical constraints on the electromagnetic (EM) field exposure, with consequent generation of hot spots and undesirable heating of healthy tissues. Here, we investigate possible adverse eddy current effects, to estimate AC magnetic field parameters (frequency and amplitude) that can potentially guarantee safe animal tests of magnetic hyperthermia. METHODS: The analysis is performed through in silico modelling by means of finite element simulation tools, specifically developed to study eddy current effects in computational animal models, during magnetic hyperthermia treatments. The numerical tools enable us to locally evaluate the specific absorption rate (SAR) and the produced temperature increase, under different field exposure conditions. RESULTS: The simulation outcomes demonstrate that in mice with weight lower than 30 g the thermal effects induced by AC magnetic fields are very weak, also when slightly overcoming the Hergt-Dutz limit, that is the product of the magnetic field amplitude and frequency should be lower than 5·109 A/(m·s). Conversely, we observe significant temperature increases in 500 g rats, amplified when the field is applied transversally to the body longitudinal axis. A strong mitigation of side-effects can be achieved by introducing water boluses or by applying focused fields. CONCLUSIONS: The developed physics-based modelling approach has proved to be a useful predictive tool for the optimization of preclinical tests of magnetic hyperthermia, allowing the identification of proper EM field conditions and the design of setups that guarantee safe levels of field exposure during animal treatments. In such contest, the obtained results can be considered as valid indicators to assess reference levels for animal testing of biomedical techniques that involve EM fields, like magnetic hyperthermia, thus complying with the Directive 2010/63/EU on the protection of animals used for scientific purposes.


Assuntos
Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Hipertermia Induzida , Animais , Campos Eletromagnéticos , Temperatura Alta , Hipertermia Induzida/métodos , Campos Magnéticos , Magnetismo , Camundongos , Ratos
17.
Anal Bioanal Chem ; 414(21): 6393-6402, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35792933

RESUMO

New approaches for the engineering of well-defined, pore modality, and multi-chemical functionality nanocomposites are crucial to generate the next generation of functional materials with recoverable and easy preparation properties. Here, a catalyst and heat free polymerization reaction is exploited and fabricated zwitterionic system around magnetic nanoparticles. N-aminoethyl piperazine propane sulfonate (AEPPS) and dopamine (DA) are introduced as the zwitterionic system, which provided abundant zwitterionic groups (NH2, SO3-, N+) and strong adhesion and various oxidation state properties. And that, the zwitterionic engineering will assemble between AEPPS and DA whereby Schiff base formation or Michael type addition. Whereafter, a series of sophisticated array of microscopic, spectroscopic, and structure techniques verify the formation of highly crosslinking internal zwitterionic architectures, well-defined core-shell structure, and better porosity. The zwitterionic structure-function relationships and striking porous structure are explored in a multi-interaction adsorption assay. The adsorption capacity of the magnetic nanocomposites was 1065.8 mg/g. And that, the system exhibited with hydrophilic-hydrophobic activity towards glycoprotein and better performance to bioactive protein (Ig-G) isolation form human whole blood sample. The synergistic enhancement interaction in hydrophilic target enrichment, easy preparation, and soft substrate properties of the AEPPS-DA zwitterionic materials make them intriguing candidates for sustainable biomedical loading and chromatographic separation.


Assuntos
Nanocompostos , Glicoproteínas , Humanos , Fenômenos Magnéticos , Magnetismo , Nanocompostos/química , Polimerização
18.
Nano Lett ; 22(13): 5538-5543, 2022 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-35766622

RESUMO

Ferrofluids (FFs) can adapt their shape to a magnetic field. However, they cannot maintain their shape when the magnetic field is removed. Here, with a magneto-responsive and reconfigurable interfacial self-assembly (MRRIS) process, we show that FFs can be structured by a magnetic field and maintain their shape, like solids, after removing the magnetic field. The competing self-assembly of magnetic and nonmagnetic nanoparticles at the liquid interface endow FFs with both reconfigurability and structural stability. By manipulating the external magnetic field, we show that it is possible to "write" and "erase" the shape of the FFs remotely and repeatedly. To gain an in-depth understanding of the effect of MRRIS on the structure of FFs, we systematically study the shape variation of these liquids under both the static and dynamic magnetic fields. Our study provides a simple yet novel way of manipulating FFs and opens opportunities for the fabrication of all-liquid devices.


Assuntos
Coloides , Nanopartículas , Coloides/química , Campos Magnéticos , Magnetismo , Nanopartículas/química
19.
Molecules ; 27(12)2022 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-35744799

RESUMO

Energy and water related problems have attracted strong attention from scientists across the world because of deficient energy and water pollution. Following this line, new strategy depended on preparing nanolayers of Al/Zn and magnetic nanoparticles of cobalt iron oxides nanocomposite in addition to long chains of hydrocarbons of stearic acid to be used as roofs, fillers and pillars; respectively, to design optical-active nanohybrids in sunlight for removing the colored pollutants from water in few minutes. By using long chains of hydrocarbons of stearic acid, X-ray diffraction (XRD) results and TEM images showed expansion of the interlayered spacing from 0.76 nm to 2.02 nm and insertion of magnetic nanoparticles among the nanolayers of Al/Zn. The optical properties and activities showed that the nanohybrid structure based on zinc oxide led to clear reduction of the band gap energy from 3.3 eV to 2.75 eV to be effective in sunlight. Photocatalytic degradation of the dye of acid green 1 confirmed the high activity of the prepared zinc oxide nanohybrids because of a complete removal of the dye after ten minutes in sunlight. Finally, this strategy was effective for producing photo-active nanohybrids for using renewable and non-polluting energy for purifying water.


Assuntos
Nanocompostos , Óxido de Zinco , Catálise , Magnetismo , Nanocompostos/química , Luz Solar , Água
20.
Molecules ; 27(12)2022 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-35744920

RESUMO

Magnetic composites and self-healing materials have been drawing much attention in their respective fields of application. Magnetic fillers enable changes in the material properties of objects, in the shapes and structures of objects, and ultimately in the motion and actuation of objects in response to the application of an external field. Self-healing materials possess the ability to repair incurred damage and consequently recover the functional properties during healing. The combination of these two unique features results in important advances in both fields. First, the self-healing ability enables the recovery of the magnetic properties of magnetic composites and structures to extend their service lifetimes in applications such as robotics and biomedicine. Second, magnetic (nano)particles offer many opportunities to improve the healing performance of the resulting self-healing magnetic composites. Magnetic fillers are used for the remote activation of thermal healing through inductive heating and for the closure of large damage by applying an alternating or constant external magnetic field, respectively. Furthermore, hard magnetic particles can be used to permanently magnetize self-healing composites to autonomously re-join severed parts. This paper reviews the synthesis, processing and manufacturing of magnetic self-healing composites for applications in health, robotic actuation, flexible electronics, and many more.


Assuntos
Magnetismo , Robótica , Campos Magnéticos
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