-
ACS Nano Feb 2016Extracellular vesicles, including exosomes, are nanoscale membrane particles that carry molecular information on parental cells. They are being pursued as biomarkers of...
Extracellular vesicles, including exosomes, are nanoscale membrane particles that carry molecular information on parental cells. They are being pursued as biomarkers of cancers that are difficult to detect or serially follow. Here we present a compact sensor technology for rapid, on-site exosome screening. The sensor is based on an integrated magneto-electrochemical assay: exosomes are immunomagnetically captured from patient samples and profiled through electrochemical reaction. By combining magnetic enrichment and enzymatic amplification, the approach enables (i) highly sensitive, cell-specific exosome detection and (ii) sensor miniaturization and scale-up for high-throughput measurements. As a proof-of-concept, we implemented a portable, eight-channel device and applied it to screen extracellular vesicles in plasma samples from ovarian cancer patients. The sensor allowed for the simultaneous profiling of multiple protein markers within an hour, outperforming conventional methods in assay sensitivity and speed.
Topics: Cell Line, Tumor; Electrochemical Techniques; Equipment Design; Exosomes; Humans; Magnets; Neoplasms; Point-of-Care Testing
PubMed: 26808216
DOI: 10.1021/acsnano.5b07584 -
Scientific Reports Apr 2022Recent technical advancements allow cardiac MRI (CMR) examinations in the presence of so-called MRI conditional active cardiac implants at 3.0 T. However, the artifact...
Recent technical advancements allow cardiac MRI (CMR) examinations in the presence of so-called MRI conditional active cardiac implants at 3.0 T. However, the artifact burden caused by susceptibility effects remain an obstacle. All measurements were obtained at a clinical 3.0 T scanner using an in-house designed cubic phantom and optimized sequences for artifact evaluation (3D gradient echo sequence, multi-slice 2D turbo spin echo sequence). Reference sequences according to the American Society for Testing and Materials (ASTM) were additionally applied. Four representative active cardiac devices and a generic setup were analyzed regarding volume and shape of the signal void. For analysis, a threshold operation was applied to the grey value profile of each data set. The presented approach allows the evaluation of the signal void and shape even for larger implants such as ICDs. The void shape is influenced by the orientation of the B0-field and by the chosen sequence type. The distribution of ferromagnetic material within the implants also matters. The void volume depends both on the device itself, and on the sequence type. Disturbances in the B0 and B1 fields exceed the visual signal void. This work presents a reproducible and highly defined approach to characterize both signal void artifacts at 3.0 T and their influencing factors.
Topics: Artifacts; Magnetic Resonance Imaging; Magnets; Phantoms, Imaging; Prostheses and Implants
PubMed: 35428775
DOI: 10.1038/s41598-022-09690-z -
International Journal of Nanomedicine 2022Arterial thrombosis is a serious threat to human health. Recently, many thrombus-targeted nanoparticles (NPs) have been constructed for detecting thrombi or monitoring...
BACKGROUND
Arterial thrombosis is a serious threat to human health. Recently, many thrombus-targeted nanoparticles (NPs) have been constructed for detecting thrombi or monitoring thrombolysis, but their thrombus-targeting performance is limited. Considering this drawback, we designed a specific bionic system with enhanced thrombus-targeting ability.
MATERIALS AND METHODS
In the bionic system, gelatin was chosen as a carrier, and FeO served as a magnetic navigation medium and a magnetic resonance (MR) imaging agent. The CREKA peptide, which targets fibrin, was conjugated to the surface of gelatin to prepare targeted NPs (TNPs), which were then engulfed by macrophages to construct the bionic system. At the targeted site, the bionic system released its interior TNPs under low-intensity focused ultrasound (LIFU) irradiation. Moreover, the targeting performance was further improved by the conjugated CREKA peptide.
RESULTS
In this study, we successfully constructed a bionic system and demonstrated its targeting ability in vitro and in vivo. The results indicated that most TNPs were released from macrophages under LIFU irradiation at 2 W/cm for 10 min in vitro. Additionally, the enhanced thrombus-targeting ability, based on the natural tropism of macrophages toward inflammatory thrombi, magnetic navigation and the CREKA peptide, was verified ex vivo and in vivo. Moreover, compared with the bionic system group, the group treated with TNPs had significantly decreased liver and spleen signals in MR images and significantly enhanced liver and spleen signals in fluorescence images, indicating that the bionic system is less likely to be cleared by the reticuloendothelial system (RES) than TNPs, which may promote the accumulation of the bionic system at the site of the thrombus.
CONCLUSION
These results suggest that the magnet-guided bionic system with LIFU responsiveness is an excellent candidate for targeting thrombi and holds promise as an innovative drug delivery system for thrombolytic therapy.
Topics: Bionics; Gelatin; Humans; Magnets; Nanoparticles; Thrombosis; Tropism
PubMed: 35558339
DOI: 10.2147/IJN.S357050 -
Molecules (Basel, Switzerland) Aug 2022We developed a method of sorption determination via the atomic emission of Cu, Zr and Hf metals in the waste of samarium-cobalt magnets. This method was based on the...
We developed a method of sorption determination via the atomic emission of Cu, Zr and Hf metals in the waste of samarium-cobalt magnets. This method was based on the preconcentration of impurities using S- and N-containing heterochain sorbents, with further determination of the analytes via inductively coupled plasma atomic emission spectrometry (ICP-OES). Different sorbents such as PED (polyethelendiamine), TDA (polythiodimethanamine), PhED (-phenylpolyethediamine) and PTE (polythioether) were tested for Ti, Cu, Zr, Nb and Hf extraction. The PTE sorbent ensured the maximum extraction of the analytes (recovery 60% for Ti, 80% for Nb, 95-100% for Cu, Zr and Hf) and thus was selected for further research. Additionally, various acidities of chloride solution (0.01-1 M HCl) were investigated for metal sorption. Under the optimised sorption conditions, trace impurities of Cu, Zr and Hf were determined using ICP-OES with a relative standard deviation of less than 5%. The obtained results were confirmed by the added-found method and cross-method experiments. The detection limits (DLs) were 1.5, 2, 0.15, 2 and 0.75 µg/L for Ti, Cu, Zr, Nb and Hf, respectively. The proposed method can be successfully used for the determination of various microelements in other waste REE-magnetic materials.
Topics: Cobalt; Magnets; Metals; Samarium; Spectrum Analysis
PubMed: 36014512
DOI: 10.3390/molecules27165275 -
Computer Methods and Programs in... Nov 2021Magnetic tracking involves the use of magnetic sensors to localize one or more magnetic objectives, in those applications in which a free line-of-sight between them and...
BACKGROUND AND OBJECTIVES
Magnetic tracking involves the use of magnetic sensors to localize one or more magnetic objectives, in those applications in which a free line-of-sight between them and the operator is hampered. We applied this concept to prosthetic hands, which could be controlled by tracking permanent magnets implanted in the forearm muscles of amputees (the myokinetic control interface). Concerning the system design, the definition of a sensor distribution which maximizes the information, while minimizing the computational cost of localization, is still an open problem. We present a simple yet effective strategy to define an optimal sensor set for tracking multiple magnets, which we called the Peaks method.
METHODS
We simulated a proximal amputation using a 3D CAD model of a human forearm, and the implantation of 11 magnets in the residual muscles. The Peaks method was applied to select a subset of sensors from an initial grid of 480 elements. The approach involves setting an appropriate threshold to select those sensors associated with the peaks in the magnetic flux density and its gradient distributions. Selected sensors were used to track the magnets during muscle contraction. For validating our strategy, an alternative method based on state-of-the-art solutions was implemented. We finally proposed a calibration phase to customize the sensor distribution on the specific patient's anatomy.
RESULTS
80 sensors were selected with the Peaks method, and 101 with the alternative one. A localization accuracy below 0.22 mm and 1.86° for position and orientation, respectively, was always achieved. Unlike alternative methods from the literature, neither iterative or analytical solution, nor a-priori knowledge on the magnet positions or trajectories were required, and yet the outcomes achieved with the two strategies proved statistically comparable. The calibration phase proved useful to adapt the sensors to the patient's stump and to increase the signal-to-noise ratio against intrinsic noise.
CONCLUSIONS
We demonstrated an efficient and general solution for solving the design optimization problem (i.e. identifying an optimal sensor set) and reducing the computational cost of localization. The optimal sensor distribution mirrors the field shape traced by the magnets on the sensing surface, being an intuitive and fast way of achieving the same results of more complex and application-specific methods. Several applications in the (bio)medical field involving magnetic tracking will benefit from the outcomes of this work.
Topics: Amputees; Hand; Humans; Magnetic Phenomena; Magnetics; Magnets
PubMed: 34537492
DOI: 10.1016/j.cmpb.2021.106407 -
Science Advances Jun 2016Solving intractable mathematical problems in simulators composed of atoms, ions, photons, or electrons has recently emerged as a subject of intense interest. We extend...
Solving intractable mathematical problems in simulators composed of atoms, ions, photons, or electrons has recently emerged as a subject of intense interest. We extend this concept to phonons that are localized in spectrally pure resonances in an electromechanical system that enables their interactions to be exquisitely fashioned via electrical means. We harness this platform to emulate the Ising Hamiltonian whose spin 1/2 particles are replicated by the phase bistable vibrations from the parametric resonances of multiple modes. The coupling between the mechanical spins is created by generating two-mode squeezed states, which impart correlations between modes that can imitate a random, ferromagnetic state or an antiferromagnetic state on demand. These results suggest that an electromechanical simulator could be built for the Ising Hamiltonian in a nontrivial configuration, namely, for a large number of spins with multiple degrees of coupling.
Topics: Computer Simulation; Electron Spin Resonance Spectroscopy; Ions; Magnets; Models, Statistical; Monte Carlo Method; Phase Transition; Phonons; Quantum Theory; Spin Labels
PubMed: 28861469
DOI: 10.1126/sciadv.1600236 -
Annals of the Royal College of Surgeons... Mar 2022
Topics: Equipment Failure; Foreign Bodies; Humans; Magnets; Needles
PubMed: 34415204
DOI: 10.1308/rcsann.2021.0135 -
Sensors (Basel, Switzerland) Jun 2023Magnetic field sensors using magnetoelectric (ME) effects in planar ferromagnetic-piezoelectric heterostructures convert a magnetic field into an output voltage. The...
Magnetic field sensors using magnetoelectric (ME) effects in planar ferromagnetic-piezoelectric heterostructures convert a magnetic field into an output voltage. The parameters of ME sensors are determined by characteristics of the magnetic constituent. In this work, the low-frequency ME effects in heterostructures comprising a layer of antiferromagnetic hematite α-FeO crystal with easy-plane anisotropy and a piezoelectric layer are studied. The effects arise due to a combination of magnetostriction and piezoelectricity because of mechanical coupling of the layers. The field dependences of magnetization and magnetostriction of the hematite crystal are measured. The resonant ME effects in the hematite-piezopolymer and hematite-piezoceramic structures are studied. The strong coupling between magnetic and acoustic subsystems of hematite results in a tuning of the acoustic resonance frequency by the magnetic field. For the hematite layer, the frequency tuning was found to be ~37% with an increase in the bias field up to 600 Oe. For the hematite-PVDF heterostructure, the frequency tuning reached ~24% and the ME coefficient was 58 mV/(Oe∙cm). For the hematite-piezoceramic heterostructure, the frequency tuning was ~4.4% and the ME coefficient 4.8 V/(Oe∙cm). Efficient generation of the second voltage harmonic in the hematite-piezoceramic heterostructure was observed.
Topics: Acoustics; Anisotropy; Magnetic Fields; Magnets
PubMed: 37447750
DOI: 10.3390/s23135901 -
Magma (New York, N.Y.) Jul 2023Low-cost low-field point-of-care MRI systems are used in many different applications. System design has correspondingly different requirements in terms of imaging...
OBJECTIVE
Low-cost low-field point-of-care MRI systems are used in many different applications. System design has correspondingly different requirements in terms of imaging field-of-view, spatial resolution and magnetic field strength. In this work an iterative framework has been created to design a cylindrical Halbach-based magnet along with integrated gradient and RF coils that most efficiently fulfil a set of user-specified imaging requirements.
METHODS
For efficient integration, target field methods are used for each of the main hardware components. These have not been used previously in magnet design, and a new mathematical model was derived accordingly. These methods result in a framework which can design an entire low-field MRI system within minutes using standard computing hardware.
RESULTS
Two distinct point-of-care systems are designed using the described framework, one for neuroimaging and the other for extremity imaging. Input parameters are taken from literature and the resulting systems are discussed in detail.
DISCUSSION
The framework allows the designer to optimize the different hardware components with respect to the desired imaging parameters taking into account the interdependencies between these components and thus give insight into the influence of the design choices.
Topics: Point-of-Care Systems; Equipment Design; Magnetic Resonance Imaging; Neuroimaging; Magnets; Phantoms, Imaging
PubMed: 37208554
DOI: 10.1007/s10334-023-01093-z -
International Journal of Molecular... Jun 2023Functionalized perfluoroalkyl lithium β-diketonates (LiL) react with lanthanide(III) salts (Ln = Eu, Gd, Tb, Dy) in methanol to give heterobimetallic Ln-Li complexes of...
Functionalized perfluoroalkyl lithium β-diketonates (LiL) react with lanthanide(III) salts (Ln = Eu, Gd, Tb, Dy) in methanol to give heterobimetallic Ln-Li complexes of general formula [(LnL)(LiL)(MeOH)]. The length of fluoroalkyl substituent in ligand was found to affect the crystal packing of complexes. Photoluminescent and magnetic properties of heterobimetallic β-diketonates in the solid state are reported. The effect of the geometry of the [LnO] coordination environment of heterometallic β-diketonates on the luminescent properties (quantum yields, phosphorescence lifetimes for Eu, Tb, Dy complexes) and single-ion magnet behavior ( for Dy complexes) is revealed.
Topics: Lanthanoid Series Elements; Lithium; Magnets; Luminescence; Fluorocarbons
PubMed: 37298728
DOI: 10.3390/ijms24119778