Magnetic solid phase extraction of aminoglycosides residue in chicken egg samples using Fe3O4-GO-Agarose-Chitosan composite.

Difficulties in identification of drug residues in food products arise due to their trace amounts in complex matrices. An eco-friendly and low-cost agarose-chitosan-magnetic graphene oxide based adsorbent was synthesized and employed for determination of aminoglycosides from chicken egg samples through HPLC. Synthesized adsorbent was characterized by SEM, FTIR, XRD, and VSM. Among two investigated aminoglycosides, streptomycin was derivatized with ninhydrin while gentamicin was detected without its derivatization. Impact of experimental variables such as adsorbent dose, extraction time, temperature, pH, and analyte concentration on extraction efficiency was investigated. Statistical analysis for determination of streptomycin and gentamicin demonstrated excellent linearity in the range of 0.2-1.6 µg kg-1, LOQ of 0.3 and 0.6 µg kg-1 for streptomycin and gentamicin, respectively and LOD of 0.1 and 0.19 µg kg-1 for streptomycin and gentamicin, respectively with RSD of 2.5% and recoveries up to 94%. Regeneration studies revealed that composite film can be used four times without considerable reduction in its extraction efficiency.

Regenerative bioelectronics: A strategic roadmap for precision medicine.

In the past few decades, stem cell-based regenerative engineering has demonstrated its significant potential to repair damaged tissues and to restore their functionalities. Despite such advancement in regenerative engineering, the clinical translation remains a major challenge. In the stance of personalized treatment, the recent progress in bioelectronic medicine likewise evolved as another important research domain of larger significance for human healthcare. Over the last several years, our research group has adopted biomaterials-based regenerative engineering strategies using innovative bioelectronic stimulation protocols based on either electric or magnetic stimuli to direct cellular differentiation on engineered biomaterials with a range of elastic stiffness or functional properties (electroactivity/magnetoactivity). In this article, the role of bioelectronics in stem cell-based regenerative engineering has been critically analyzed to stimulate futuristic research in the treatment of degenerative diseases as well as to address some fundamental questions in stem cell biology. Built on the concepts from two independent biomedical research domains (regenerative engineering and bioelectronic medicine), we propose a converging research theme, 'Regenerative Bioelectronics'. Further, a series of recommendations have been put forward to address the current challenges in bridging the gap in stem cell therapy and bioelectronic medicine. Enacting the strategic blueprint of bioelectronic-based regenerative engineering can potentially deliver the unmet clinical needs for treating incurable degenerative diseases.

Biohybrid magnetic microrobots: An intriguing and promising platform in biomedicine.

Biohybrid magnetic microrobots (BMMs) have emerged as an exciting class of microrobots and have been considered as a promising platform in biomedicine. Many microorganisms and body's own cells show intriguing properties, such as morphological characteristics, biosafety, and taxis abilities (e.g., chemotaxis, aerotaxis), which have made them attractive for the fabrication of microrobots. For remote controllability and sustainable actuation, magnetic components are usually incorporated onto these biological entities, and other functionalized non-biological components (e.g., therapeutic agents) are also included for specific applications. This review highlights the latest developments in BMMs with a focus on their biomedical applications. It starts by introducing the fundamental understanding of the propulsion system at the microscale in a magnetically driven manner, followed by a summary of diverse BMMs based on different microorganisms and body's own cells along with their relevant applications. Finally, the review discusses how BMMs contribute to the advancements of microrobots, the current challenges of using BMMs in practical clinical settings, and the future perspectives of this exciting field. STATEMENT OF SIGNIFICANCE: Biohybrid magnetic microrobots (BMMs), composed of biological entities and functional parts, hold great potential and serve as a novel and promising platform for biomedical applications such as targeted drug delivery. This review comprehensively summarizes the recent advancements in BMMs for biomedical applications, mainly focused on the representative propulsion modalities in a magnetically propelled manner and diverse designs of BMMs based on different biological entities, including microorganisms and body's own cells. We hope this review can provide ideas for the future design, development, and innovation of micro/nanorobots in the field of biomedicine.

Tadpole-Like Flexible Microswimmers with the Head and Tail Both Magnetic.

In analogy to eukaryotic cells that move by beating the flagella, magnetically powered micro/nanorobots with flexible filaments are capable of eluding the limitation of the scallop theorem to generate net displacement in a three-dimensional space, but they are limited by complicated fabrication and low speed. Here, we demonstrate a tadpole-like flexible microswimmer with a head and tail that are both magnetic by developing a magnetically assisted in situ polymerization method. The flexible microswimmer consists of a magnetic-bead head fixed to a nanochain bundle of magnetic nanoparticles (tail), and the tail length and stiffness can be adjusted simply by changing the duration and strength of the applied magnetic field during fabrication, respectively. For the microswimmer under an oscillating magnetic field, the magnetic head generates an undulatory motion, which can be further increased by the flexible magnetic tail. The magnetically induced undulation of the head and tail generates a traveling wave propagating through its flexible tail, resulting in efficient tadpole-like propulsion of the microswimmer. The flexible microswimmer runs at a maximum motion speed when the tail length is ∼5 times the diameter of the magnetic head, corresponding to ∼half the wavelength of the undulatory motion. The flexible microswimmers reported here are promising for active sensing and drug delivery, as the tails can be designed with various responsive hydrogels, and the results are expected to advance flexible micro/nanorobots.

Programmable magnetic robot (ProMagBot) for automated nucleic acid extraction at the point of need.

Upstream sample preparation remains the bottleneck for point-of-need nucleic acid testing due to its complexity and time-consuming nature. Sample preparation involves extracting, purifying, and concentrating nucleic acids from various matrices. These processes are critical for ensuring the accuracy and sensitivity of downstream nucleic acid amplification and detection. However, current sample preparation methods are often laboratory-based, requiring specialized equipment, trained personnel, and several hours of processing time. As a result, sample preparation often limits the speed, portability, and cost-effectiveness of point-of-need nucleic acid testing. A universal, field-deployable sample preparation device is highly desirable for this critical need and unmet challenge. Here we reported a handheld, battery-powered, reconfigurable, and field-deployable nucleic acid sample preparation device. A programmable electromagnetic actuator was developed to drive a magnetic robot (ProMagBot) in X/Y 2D space, such that various magnetic bead-based sample preparations can be readily translated from the laboratory to point-of-need settings. The control of the electromagnetic actuator requires only a 3-phase unipolar voltage in X and Y directions, and therefore, the motion space is highly scalable. We validated the ProMagBot device with a model application by extracting HIV viral RNAs from plasma samples using two widely used magnetic bead kits: ChargeSwitch and MagMAX beads. In both cases, the ProMagBot could successfully extract viral RNAs from 50 µL plasma samples containing as low as 102 copies of viral RNAs in 20 minutes. Our results demonstrated the ability of ProMagBot to prepare samples from complex mediums at the point of need. We believe such a device would enable rapid and robust sample preparation in various settings, including resource-limited or remote environments, and accelerate the development of next-generation point-of-need nucleic acid testing.

Response of the competitive balance model to the external field.

The competitive balance model was proposed as an extension of the structural balance theory, aiming to account for heterogeneities observed in real-world networks. In this model, different paradigms lead to form different friendship and enmity. As an example, friendship or enmity between countries can have a political or religious basis. The suggested Hamiltonian is symmetrical between paradigms. Our analyses show that a balanced state can be achieved if just one paradigm prevails in the network and the paradigm shift is possible only by imposing an external field. In this paper, we investigate the influence of the external field on the evolution of the network. We drive the mean-field solutions of the model and verify the accuracy of our analytical solutions by performing Monte-Carlo simulations. We observe that the external field breaks the symmetry of the system. The response of the system to this external field, contingent upon temperature, can be either paramagnetic or ferromagnetic. We observed a hysteresis behavior in the ferromagnetic regime. Once communities are formed based on a certain paradigm, then they resist change. We found that to avoid wasting energy we need to know the level of stochastic behavior in the network. Analogous to magnetic systems, we observe that susceptibility adheres to Curie's law.

Fabrication of three-lobed magnetic microrobots for cell transportation.

Mobile microrobots have the potential to transform medical treatments based on therapeutic delivery. Specifically, microrobots are promising candidates for cell transportation in cell-based therapies. Despite recent progress in cellular manipulation by microrobots, there is a significant need to design and fabricate microrobots to advance the field further. In this work, we present a facile approach to manufacturing three-lobed microrobots by a bench-top procedure. The microrobots are actuated by a harmless magnetic field which makes them biofriendly. Chemically, these microrobots are made of organosilica. The microrobots showed equally good control in both the open-loop and closed-loop settings. The three-lobed microrobots have two modes of motion during the open-loop control experiments. We employed these two modes for single-cell transportation. Our results show that the three-lobed microbots are very promising for cell transportation in a fluid.

Green hydrophobic maltodextrin nanosponges for magnetic solid-phase extraction of hypothalamic peptides from plasma samples.

In this work, for the first time, magnetic-phthalated maltodextrin nanosponges (M-PAMDNSs) were synthetized and introduced as efficient and green sorbents. The integration of phthaloyl groups as hydrophobic moieties into networks of maltodextrin nanosponges provided good enrichment for hypothalamic-related peptides (HRPs). The synthesized materials were characterized by 1H nuclear magnetic resonance spectroscopy, water contact angle, attenuated total reflection-Fourier transform infrared spectroscopy, dynamic light scattering, zeta potential, pH point of zero charge, acid-base titration, field-emission scanning electron microscopy, Brunauer-Emmett-Teller, and vibrating sample magnetometer. Under the optimized conditions (sorbent amount: 5.0 mg, desorption solvent volume and type: 300 µL of methanol: H2O: trifluoroacetic acid, extraction time: 15 min, and desorption time: 10 min), the developed magnetic solid-phase extraction (MSPE) method in combination with HPLC-UV was used as a novel and sensitive analytical method for the determination of HRPs in plasma samples. The proposed MSPE-HPLC-UV method provided good linearity (1.5-500 ng mL-1 R2 ≥ 0.9988), low limits of detection (0.1-0.2 ng mL-1) and quantification (0.4-0.8 ng mL-1), desirable precision (RSD ≤ 8.8%, n ₌ 5), satisfactory enrichment factor (EFs ≥ 66.0), and well relative recoveries (92.8-108.8%). Overall, the established method effectively expanded the analytical potential of MSPE approach for the quantification of HRPs in biological samples.

Temperature dependent magnetorelaxometry of magnetic nanoparticle ensembles.

Magnetorelaxometry imaging (MRXI) is a non-invasive, quantitative imaging technique for magnetic nanoparticles (MNPs). The image resolution of this technique significantly depends on the relaxation amplitude (ΔB). For this work, we measured the room temperature (299 K) relaxation signals of eight commercial MNP sample systems with different magnetic properties, in both fluid and immobilized states, in order to select the most suitable sample for a particular MRXI setting. Additionally, the effect of elevated temperatures (up to hyperthermia temperature, 335 K) on the relaxation signals of four different MNP systems (Synomag, Perimag, BNF and Nanomag) in both states were investigated. The ΔBvalues of fluid samples significantly decreased with increasing temperature, and the behaviour for immobilized samples depended on their blocking temperature (TB). For samples withTB< 299 K, ΔBalso decreased with increasing temperature. Whereas for samples withTB> 299 K, the opposite behaviour was observed. These results are beneficial for improving the image resolution in MRXI and show, among the investigated systems, and for our setup, Synomag is the best candidate for futurein vitroandin vivostudies. This is due to its consistently high ΔBbetween 299 and 335 K in both states. Our findings demonstrate the feasibility of temperature imaging by MRXI.

Magneto-Responsive Textiles for Non-Invasive Heating.

Magneto-responsive textiles have emerged lately as an important carrier in various fields, including biomedical engineering. To date, most research has been performed on single magnetic fibers and focused mainly on the physical characterization of magnetic textiles. Herein, from simple woven and non-woven textiles we engineered materials with magnetic properties that can become potential candidates for a smart magnetic platform for heating treatments. Experiments were performed on tissue-mimicking materials to test the textiles' heating efficiency in the site of interest. When the heat was induced with magneto-responsive textiles, the temperature increase in tissue-mimicking phantoms depended on several factors, such as the type of basic textile material, the concentration of magnetic nanoparticles deposited on the textile's surface, and the number of layers covering the phantom. The values of temperature elevation, achieved with the use of magnetic textiles, are sufficient for potential application in magnetic hyperthermia therapies and as heating patches or bandages.

Inducing Magnetic Properties with Ferrite Nanoparticles in Resins for Additive Manufacturing.

Additive manufacturing and nanotechnology have been used as fundamental tools for the production of nanostructured parts with magnetic properties, expanding the range of applications in additive processes through tank photopolymerization. Magnetic cobalt ferrite (CoFe2O4) and barium ferrite (BaFe12O19) nanoparticles (NPs) with an average size distribution value (DTEM) of 12 ± 2.95 nm and 37 ± 12.78 nm, respectively, were generated by the hydroxide precipitation method. The dispersion of the NPs in commercial resins (Anycubic Green and IRIX White resin) was achieved through mechanochemical reactions carried out in an agate mortar for 20 min at room temperature, with limited exposure to light. The resulting product of each reaction was placed in amber vials and stored in a box to avoid light exposure. The photopolymerization process was carried out only at low concentrations (% w/w NPs/resin) since high concentrations did not result in the formation of pieces, due to the high refractive index of ferrites. The Raman spectroscopy of the final pieces showed the presence of magnetic NPs without any apparent chemical changes. The electron paramagnetic resonance (EPR) results of the pieces demonstrated that their magnetic properties were maintained and not altered during the photopolymerization. Although significant differences were observed in the dispersion process of the NPs in each piece, we determined that the photopolymerization did not affect the structure and superparamagnetic behavior of ferrite NPs during processing, successfully transferring the magnetic properties to the final 3D-printed piece.

Evaluation of the Size of a Defect in Reinforcing Steel Using Magnetic Flux Leakage (MFL) Measurements.

This study aimed to evaluate 2D magnetic flux leakage (MFL) signals (Bx, By) in D19-size reinforcing steel with several defect conditions. The magnetic flux leakage data were collected from the defected and new specimens using an economically designed test setup incorporating permanent magnets. A two-dimensional finite element model was numerically simulated using COMSOL Multiphysics to validate the experimental tests. Based on the MFL signals (Bx, By), this study also intended to improve the ability to analyze defect features such as width, depth, and area. Both the numerical and experimental results indicated a high cross-correlation with a median coefficient of 0.920 and a mean coefficient of 0.860. Using signal information to evaluate defect width, the x-component (Bx) bandwidth was found to increase with increasing defect width and the y-component (By) amplitude rise with increasing depth. In this two-dimensional MFL signal study, both parameters of the two-dimensional defects (width and depth) affected each other and could not be evaluated individually. The defect area was estimated from the overall variation in the signal amplitude of the magnetic flux leakage signals with the x-component (Bx). The defect areas showed a higher regression coefficient (R2 = 0.9079) for the x-component (Bx) amplitude from the 3-axis sensor signal. It was determined that defect features are positively correlated with sensor signals.

How Magnetic Composites are Effective Anticancer Therapeutics? A Comprehensive Review of the Literature.

Chemotherapy is the most prominent route in cancer therapy for prolonging the lifespan of cancer patients. However, its non-target specificity and the resulting off-target cytotoxicities have been reported. Recent in vitro and in vivo studies using magnetic nanocomposites (MNCs) for magnetothermal chemotherapy may potentially improve the therapeutic outcome by increasing the target selectivity. In this review, magnetic hyperthermia therapy and magnetic targeting using drug-loaded MNCs are revisited, focusing on magnetism, the fabrication and structures of magnetic nanoparticles, surface modifications, biocompatible coating, shape, size, and other important physicochemical properties of MNCs, along with the parameters of the hyperthermia therapy and external magnetic field. Due to the limited drug-loading capacity and low biocompatibility, the use of magnetic nanoparticles (MNPs) as drug delivery system has lost traction. In contrast, MNCs show higher biocompatibility, multifunctional physicochemical properties, high drug encapsulation, and multi-stages of controlled release for localized synergistic chemo-thermotherapy. Further, combining various forms of magnetic cores and pH-sensitive coating agents can generate a more robust pH, magneto, and thermo-responsive drug delivery system. Thus, MNCs are ideal candidate as smart and remotely guided drug delivery system due to a) their magneto effects and guide-ability by the external magnetic fields, b) on-demand drug release performance, and c) thermo-chemosensitization under an applied alternating magnetic field where the tumor is selectively incinerated without harming surrounding non-tumor tissues. Given the important effects of synthesis methods, surface modifications, and coating of MNCs on their anticancer properties, we reviewed the most recent studies on magnetic hyperthermia, targeted drug delivery systems in cancer therapy, and magnetothermal chemotherapy to provide insights on the current development of MNC-based anticancer nanocarrier.

Molecular Biological Effects of Weak Low-Frequency Magnetic Fields: Frequency-Amplitude Efficiency Windows and Possible Mechanisms.

This review covers the phenomenon of resonance-like responses of biological systems to low-frequency magnetic fields (LFMF). The historical development of this branch of magnetobiology, including the most notable biophysical models that explain the resonance-like responses of biological systems to LFMF with a specific frequency and amplitude, is given. Two groups can be distinguished among these models: one considers ion-cofactors of proteins as the primary targets for the LFMF influence, and the other regards the magnetic moments of particles in biomolecules. Attention is paid to the dependence of resonance-like LFMF effects on the cell type. A radical-pair mechanism of the magnetic field's influence on biochemical processes is described with the example of cryptochrome. Conditions for this mechanism's applicability to explain the biological effects of LFMF are given. A model of the influence of LFMF on radical pairs in biochemical oscillators, which can explain the frequency-amplitude efficiency windows of LFMF, is proposed.

Magnetic Biochar Derived from Fenton Sludge/CMC for High-Efficiency Removal of Pb(II): Synthesis, Application, and Mechanism.

Magnetic biochar composites (MBC) were developed by a simple one-step pyrolysis method using Fenton sludge waste solid and carboxymethyl cellulose sodium. Detailed morphological, chemical, and magnetic characterizations corroborate the successful fabrication of MBC. Batch adsorption experiments show that the synthesized MBC owns high-efficiency removal of Pb(II), accompanied by ease-of-separation from aqueous solution using magnetic field. The experiment shows that the equilibrium adsorption capacity of MBC for Pb(II) can reach 199.9 mg g-1, corresponding to a removal rate of 99.9%, and the maximum adsorption capacity (qm) reaches 570.7 mg g-1, which is significantly better than that of the recently reported magnetic similar materials. The adsorption of Pb(II) by MBC complies with the pseudo second-order equation and Langmuir isotherm model, and the adsorption is a spontaneous, endothermic chemical process. Investigations on the adsorption mechanism show that the combination of Pb(II) with the oxygen-containing functional groups (carboxyl, hydroxyl, etc.) on biochar with a higher specific surface area are the decisive factors. The merits of reusing solid waste resource, namely excellent selectivity, easy separation, and simple preparation make the MBC a promising candidate of Pb(II) purifier.

A Vectorial Current Density Imaging Method Based on Magnetic Gradient Tensor.

Magnetic current imaging is deemed an emerging powerful technique for visualizing electrical currents in electronic devices. However, the existing magnetic-field-based Fourier Transform back-evolution method is limited by its mono-function of imaging the magnitude of current density in devices under test, and subject to background noise distortion. Here, we developed a novel vectorial current density imaging method based on the detection of the magnetic field gradient generated by current carrying conductors. A closed form solution of current density inversion was analytically derived and numerically verified. Experiments were conducted by scanning tri-axial fluxgate sensor over different shapes of electrical wires. The results show that a current density resolution of 24.15 mA/mm2, probe-to-sample separation of 2 mm, and spatial resolution of 0.69 mm were achieved over a maximum scanning area of 300 mm × 300 mm. Such a method is verified to be capable of simultaneously imaging both magnitude and directions of current density, which is a promising technique for in situ noninvasive inspection for the power electronic and semiconductor industry.

Triggering Magnets for Wiegand Sensors: Electrodeposited and Origami-Magnetized CoNiP Micro-Magnets.

Miniature sensors are key components for applications in the Internet of Things (IoT), wireless sensor networks, autonomous vehicles, smart cities, and smart manufacturing. As a miniature and self-powered magnetic sensor, the Wiegand sensor possesses advantageous traits including changing-rate-independent output, low cost, and remarkable repeatability and reliability. A typical Wiegand sensor requires hard magnetic pole pieces that provide external fields for triggering voltage outputs that are called Wiegand pulses. However, the wire-shaped sensing element of Wiegand sensors is the critical issue that limits the design, selection, and adoption of the external triggering magnets. Currently, the widely used pole piece materials are rare-earth magnets. However, adopting rare-earth magnets brings strong stray fields, causing an electromagnetic interference (EMI) problem. In this study, patterned CoNiP hard magnets were electrodeposited on flexible substrates through microfabrication. Origami magnetization was utilized to control the resultant stray fields and thus the pole piece of CoNiP magnets can successfully trigger the output of the Wiegand pulse. In comparison, the output voltage of the triggered pulse acquired through the patterned CoNiP magnets is comparable to that acquired by using the rare-earth magnets. Furthermore, both the volume (and hence the weight) of the Wiegand sensor and the EMI issue can be significantly reduced and mitigated, respectively, by the CoNiP magnets.

Field Dynamic Balancing for Magnetically Suspended Turbomolecular Pump.

A field dynamic balancer is crucial to the applications of magnetically suspended turbomolecular pumps. Therefore, this paper presents a novel field dynamic balancing method based on autocentering control mode without any additional instrumentation. Firstly, the dynamics of the active magnetic bearing rotor system with unbalance are modeled. Through model analysis, it was found that making the rotor rotate around the geometric axis can improve the accuracy of dynamic balancing. Secondly, the relationship between the correcting masses and the synchronous currents based on the influence coefficient method is established. Then, an autocentering controller is designed to make the rotor rotate around the geometric axis. The synchronous currents can be detected and extracted by the current transducers to calculate the unbalance correction mass. Finally, the experimental results show that this novel field dynamic balancing method can effectively eliminate the majority of rotor unbalance. Compared with the original unbalance of a rotor, the synchronous current in the A-end has been reduced by 71.4% and the synchronous current in the B-end, by 90.8% with the proposed method.

Magnetic Properties of FeNi/Cu-Based Lithographic Rectangular Multilayered Elements for Magnetoimpedance Applications.

The rectangular elements in magnetoimpedance (MI) configuration with a specific nanocomposite laminated structure based on FeNi and Cu layers were prepared by lift-off lithographic process. The properties of such elements are controlled by their shape, the anisotropy induced during the deposition, and by effects associated with the composite structure. The characterizations of static and dynamic properties, including MI measurements, show that these elements are promising for sensor applications. We have shown that competition between the shape anisotropy and the in-plane induced anisotropy of the element material is worth taking into account in order to understand the magnetic behavior of multilayered rectangular stripes. A possibility of the dynamic methods (ferromagnetic and spin-wave resonance) to describe laminated planar elements having a non-periodic modulation of both structure and magnetic parameters of a system is demonstrated. We show that the multilayered structure, which was originally designed to prevent the development of a "transcritical" state in magnetic layers and to reach the required thickness, also induces the effects that hinder the achievement of the goal, namely an increase in the perpendicular magnetic anisotropy energy.

Magnetic cork composites as biosorbents in dispersive solid-phase extraction of pesticides in water samples.

This study assessed the use of magnetic biosorbents in dispersive solid-phase extraction with a gas chromatograph-electron capture detector for the determination of trifluralin, chlorothalonil, transfluthrin, bromopropylate, and bifenthrin in water samples. To our knowledge, this is the first time that magnetic cork composites are used as an adsorbent in dispersive solid-phase extraction. The advantages of magnetic cork composites include their density regulation and high surface areas. The magnetic composites can be recovered using a magnetic field for desorption purposes, which can improve the operation process and reduce the extraction time. Moreover, the parameters affecting the extraction performances were optimized. The method has a limit of detection between 0.30 and 2.02 µg L-1. Good linearities (R2 > 0.99) were obtained in the linear range of 1.00 to 2000 µg L-1. The relative recoveries of the analytes in tap water, river, and lake water samples spiked at different concentrations ranged between 90% and 104%, and the relative standard deviations were less than 7.1%. Therefore, this study showed that Fe3O4/cork magnetic composites can be used as efficient and eco-friendly biosorbents in dispersive solid-phase extraction for the determination of pesticides in water samples. The use of these composites contributes to the current trend of green chemistry.