A comprehensive approach to characterize navigation instruments for magnetic guidance in biological systems.

Achieving non-invasive spatiotemporal control over cellular functions, tissue organization, and behavior is a desirable aim for advanced therapies. Magnetic fields, due to their negligible interaction with biological matter, are promising for in vitro and in vivo applications, even in deep tissues. Particularly, the remote manipulation of paramagnetic (including superparamagnetic and ferromagnetic, all with a positive magnetic susceptibility) entities through magnetic instruments has emerged as a promising approach across various biological contexts. However, variations in the properties and descriptions of these instruments have led to a lack of reproducibility and comparability among studies. This article addresses the need for standardizing the characterization of magnetic instruments, with a specific focus on their ability to control the movement of paramagnetic objects within organisms. While it is well known that the force exerted on magnetic particles depends on the spatial variation (gradient) of the magnetic field, the magnitude of the field is often overlooked in the literature. Therefore, we comprehensively analyze and discuss both actors and propose a novel descriptor, termed 'effective gradient', which combines both dependencies. To illustrate the importance of both factors, we characterize different magnet systems and relate them to experiments involving superparamagnetic nanoparticles. This standardization effort aims to enhance the reproducibility and comparability of studies utilizing magnetic instruments for biological applications.

Feasibility of a low-cost magnet tracking device in confirming nasogastric tube placement at point of care, a clinical trial.

An affordable and reliable way of confirming the placement of nasogastric tube (NGT) at point-of-care is an unmet need. Using a novel algorithm and few sensors, we developed a low-cost magnet tracking device and showed its potential to localize the NGT preclinically. Here, we embark on a first-in-human trial. Six male and 4 female patients with NGT from the general ward of an urban hospital were recruited. We used the device to localize the NGT and compared that against chest X-ray (CXR). In 5 patients, with the sensors placed on the sternal angle, the trajectory of the NGT was reproduced by the tracking device. The tracked location of the NGT deviated from CXR by 0.55 to 1.63 cm, and a downward tracking range of 17 to 22 cm from the sternal angle was achieved. Placing the sensors on the xiphisternum, however, resulted in overt discordance between the device's localization and that on CXR. Short distance between the sternal angle and the xiphisternum, and lower body weight were observed in patients in whom tracking was feasible. Tracking was quick and well tolerated. No adverse event occurred. This device feasibly localized the NGT in 50% of patients when appropriately placed. Further refinement is anticipated.ClinicalTrials.gov identifier: NCT05204901.

Magnetic tweezers principles and promises.

Magnetic tweezers have become popular with the outbreak of single molecule micromanipulation: catching a single molecule of DNA, RNA or a single protein and applying mechanical constrains using micron-size magnetic beads and magnets turn out to be easy. Various factors have made this possible: the fact that manufacturers have been preparing these beads to catch various biological entities-the ease of use provided by magnets which apply a force or a torque at a distance thus inside a flow cell-some chance: since the forces so generated are in the right range to stretch a single molecule. This is a little less true for torque. Finally, one feature which also appears very important is the simplicity of their calibration using Brownian motion. Here we start by describing magnetic tweezers used routinely in our laboratory where we have tried to develop a device as simple as possible so that the experimentalist can really focus on the biological aspect of the biomolecules that he/she is interested in. We discuss the implications of the various components and their important features. Next, we summarize what is easy to achieve and what is less easy. Then we refer to contributions by other groups who have brought valuable insights to improve magnetic tweezers.

Observation of magnet-induced star-like radiation of a plasma created from cancer cells in a laser trap.

We present a new phenomenon resulting from the interaction of magnetic beads with cancer cells in a laser trap formed on a slide containing a depression 16.5 mm in diameter and 0.78 mm of maximum depth. This phenomenon includes the apparent formation and expansion of a dark bubble that attracts and incinerates surrounding matter when it explodes, which leads to a plasma emitting intense radiation that has the appearance of a star on a microscopic scale. We have observed the star-like phenomenon for more than 4 years, and the intensity depends on the laser's power. Measuring the laser power of the dark bubble shows the entrapment of electromagnetic energy as it expands.

Multifunctional flexible magnetic drive gripper for target manipulation in complex constrained environments.

Soft actuators capable of remote-controlled guidance and manipulation within complex constrained spaces hold great promise in various fields, especially in medical fields such as minimally invasive surgery. However, most current magnetic drive soft actuators only have the functions of position control and guidance, and it is still challenging to achieve more flexible operations on different targets within constrained spaces. Herein, we propose a multifunctional flexible magnetic drive gripper that can be steered within complex constrained spaces and operate on targets of various shapes. On the one hand, changing the internal pressure of the magnetic gripper can achieve functions such as suction or injection of liquid and transportation of targets with smooth surfaces. On the other hand, with the help of slit structures in the constrained environment, by simply changing the position and orientation of the permanent magnet in the external environment, the magnetic gripper can be controlled to clamp and release targets of linear, flaked, and polyhedral shapes. The full flexibility and multifunctionality of the magnetic gripper suggest new possibilities for precise remote control and object transportation in constrained spaces, so it could serve as a direct contact operation tool for hazardous drugs in enclosed spaces or a surgical tool in human body cavities.

A chemical magnet: Approaches to guide precise protein localization.

Small molecules that chemically induce proximity between two proteins have been widely used to precisely modulate protein levels, stability, and activity. Recently, several studies developed novel strategies that employ heterobifunctional molecules that co-opt shuttling proteins to control the spatial localization of a target protein, unlocking new potential within this domain. Together, these studies lay the groundwork for novel targeted protein relocalization modalities that can rewire the protein circuitry and interactome to influence biological outcomes.

Magnetic Control of Nonmagnetic Living Organisms.

Living organisms inspire the design of microrobots, but their functionality is unmatched. Next-generation microrobots aim to leverage the sensing and communication abilities of organisms through magnetic hybridization, attaching magnetic particles to them for external control. However, the protocols used for magnetic hybridization are morphology specific and are not generalizable. We propose an alternative approach that leverages the principles of negative magnetostatics and magnetophoresis to control nonmagnetic organisms with external magnetic fields. To do this, we disperse model organisms in dispersions of Fe3O4 nanoparticles and expose them to either uniform or gradient magnetic fields. In uniform magnetic fields, living organisms align with the field due to external torque, while gradient magnetic fields generate a negative magnetophoretic force, pushing objects away from external magnets. The magnetic fields enable controlling the position and orientation of Caenorhabditis elegans larvae and flagellated bacteria through directional interactions and magnitude. This control is diminished in live spermatozoa and adult C. elegans due to stronger internal biological activity, i.e., force/torque. Our study presents a method for spatiotemporal organization of living organisms without requiring magnetic hybridization, opening the way for the development of controllable living microbiorobots.

A Gadolinium(III) Complex Based on Pyridoxine Molecule with Single-Ion Magnet and Magnetic Resonance Imaging Properties.

Pyridoxine (pyr) is a versatile molecule that forms part of the family of B vitamins. It is used to treat and prevent vitamin B6 deficiency and certain types of metabolic disorders. Moreover, the pyridoxine molecule has been investigated as a suitable ligand toward metal ions. Nevertheless, the study of the magnetic properties of metal complexes containing lanthanide(III) ions and this biomolecule is unexplored. We have synthesized and characterized a novel pyridoxine-based GdIII complex of formula [GdIII(pyr)2(H2O)4]Cl3 · 2 H2O (1) [pyr = pyridoxine]. 1 crystallizes in the triclinic system and space group Pi. In its crystal packing, cationic [Gd(pyr)2(H2O)4]3+ entities are connected through H-bonding interactions involving non-coordinating water molecules and chloride anions. In addition, Hirshfeld surfaces of 1 were calculated to further investigate their intermolecular interactions in the crystal lattice. Our investigation of the magnetic properties of 1, through ac magnetic susceptibility measurements, reveals the occurrence of a slow relaxation in magnetization in this mononuclear GdIII complex, indicating an unusual single-ion magnet (SIM) behavior for this pseudo-isotropic metal ion at very low temperatures. We also studied the relaxometric properties of 1, as a potential contrast agent for high-field magnetic resonance imaging (MRI), from solutions of 1 prepared in physiological serum (0.0-3.2 mM range) and measured at 3 T on a clinical MRI scanner. The values of relaxivity obtained for 1 are larger than those of some commercial MRI contrast agents based on mononuclear GdIII systems.

Magnetic capture device for large volume sample analysis.

Immunomagnetic separation (IMS) techniques employing superparamagnetic particles can successfully isolate various components from mixtures. However, their utility can be limited for large-volume samples, viscous samples, or those containing a high density of particulate matter because of the need to generate high field gradients for particle recovery. Therefore, a new class of immunomagnetic particles was devised utilizing a single, macroscopic Pyrex spinbar conjugated with biorecognition elements to address these limitations. Advantages include an inherent capacity for effective mixing, an almost instantaneous recovery of the spinbar that can be performed without expensive equipment and with no loss of magnetic particles during processing, and reduced transfer of sample matrix. As a result, spinbars can provide an effective means for IMS with large-volume assays composed of complex matrices.

Magnet ingestion in growing children: a multi-center observational study on single and multiple magnet incidents.

Over the past 15 years, there has been a noticeable uptick in incidents involving children ingesting multiple magnetic foreign bodies which can cause injuries and gastrointestinal complications including death. The current study aimed to identify the prevalence, clinical presentation, and management of single or multiple magnet ingestions. A retrospective multi-central cross-sectional study was conducted to include all pediatric patients < 18 years presented to the emergency department with ingestion of single or multiple magnets and admitted across hospitals in Qatar, UAE, KSA, Tunisia, and Turkey between January 2011 and December 2021. Demographics, symptoms, management, and outcomes were analyzed. There were 189 magnet ingestions, of which 88 (46.6%) were multiple magnet ingestions. Most patients (55.6%) were male, and the median age was 3.9 (IQR 2-7) years. An abdominal X-ray was obtained in all cases. 119 (62%) patients were conservatively treated, 53 (28%) required surgical intervention and 17 (8.9%) underwent gastroscopy. None of the patients with single magnet ingestions experienced morbidity or severe outcomes. Multiple magnet ingestions led to significant morbidity including hospitalizations, perforations (44.3%), severe intestinal necrosis (19.3%), peritonitis (13.6%), severe abdominal infection (10.2%), and septic shock (4.5%). The rate of surgical intervention (59.1% vs. 1.0%) and gastroscopy (15.9% vs. 3.0%) was significantly higher in the multiple ingestion group compared to the single magnet ingestion group. No deaths were identified. A high risk of serious complications, including the need for surgery to remove the magnets and substantial morbidity may result from swallowing more than one magnet. Magnet safety requirements, public education, and improved legislation are urgently required.

Comparing forceps and self-assembled intraocular rare earth magnet in removing metallic intraocular foreign bodies in 25-guage vitrectomy.

PURPOSE: To compare the efficacy and efficiency of self-assembled intraocular rare earth magnet and forceps in removing intraocular foreign bodies(IOFBs) undergoing 25-gauge(G) pars plana vitrectomy. METHODS: A total of 30 patients with metallic IOFB underwent 25-G PPV were enrolled into this study. Self-assembled intraocular rare earth magnet were used in 15 patients(bar group), and forceps were used in 15 patients(forceps group). Success rate of removing IOFB, time taken to remove IOFB, incidence of IOFB slippage and fall, iatrogenic retinal damages were compared between the two groups. RESULTS: There was no significant difference in success rate of removing IOFBs between the groups(93.3% and 100%, P > 0.99). The median time taken of removing FB was significantly shorter in bar group than in forceps group(112 and 295 s, P = 0.001). None of the patients in bar group had IOFB slippage and fall, or related iatrogenic retinal damage in the process of removal. In forceps group, IOFB slippage and fall during removal were observed in 7 of 15(47.6%) patients, related iatrogenic retinal injuries were recorded in 6 of 15(40.0%) patients, both were significantly higher than bar group(P = 0.003 and P = 0.017, respectively). CONCLUSIONS: Compared with forceps, the assembled intraocular magnet can greatly reduce the possibility of IOFB slippage and fall, prevent related iatrogenic retinal damage, and shorten the time taken to remove IOFB. The assembled intraocular magnet can be an useful tool in removing metallic IOFBs in PPV.

Management patterns of multiple magnet ingestion reported to New Jersey Poison Information and Education System.

BACKGROUND: Ingestion of multiple high-powered neodymium rare-earth magnets poses a significant risk for gastrointestinal (GI) injury such as bowel perforation or ischemia. Given the rising incidence of rare earth magnetic ingestions and the corresponding increase in serious injuries in children, published guidelines recommend urgent endoscopic removal of all magnets within endoscopic reach in cases involving ingestions of two or more magnets. RESEARCH QUESTION: Do management patterns for multiple magnet ingestion align with current practice guidelines, and does hospital length of stay (LOS) differ based on the initial emergency department (ED) approach? METHODS: This is a retrospective chart review of consecutive patient encounters reported to the New Jersey Poison Information and Education System (NJPIES) between January 2021 and April 2022 involving multiple magnet ingestion. Potential cases were retrieved from the NJPIES TOXICALL® database, using substance codes relating to magnet or foreign body ingestion. Two-sample T tests were used to determine the statistical difference in the hospital LOS between the group of patients receiving early emergent esophagogastroduodenoscopy (EGD) versus those receiving expectant management on initial presentation. RESULTS: There was a difference in the average LOS of 2.7 days (p = 0.023) longer in the expectant management group with no medical complications in either group. Twenty-five percent or 2 out of 8 cases deviated from guidelines. CONCLUSION: The initial ED decision to pursue expectant management instead of attempting emergent EGD removal of magnets may result in prolonged hospitalization, increased risk for readmission, and delayed definitive removal of magnets due to nonprogression along the GI tract.

Design and hierarchical analysis of magnetic actuated robot: A governing equation based approach.

As the alternative solution to the conventional guidewire, the magnetic robot can help interventionists perform percutaneous coronary intervention (PCI) because magnetic fields are transparent and safe for biological tissues. Despite extensive research on magnetic robots, the exploration of their deflection control for practical applications still requires further research. In this paper, a hierarchical analysis framework (HAF) is proposed to control the magnetic robot's deflection. Six deflection subpatterns are analyzed through HAF, incorporating statistical and regression analyses to establish governing equations of magnetic robots. The performance of the control equations is validated through precise control of the magnetic continuum robot (MCR) and magnet-tipped robot (MTR) in both uniform and gradient magnetic fields. Experimental results show that under the uniform magnetic field, the average root mean square error (RMSE) of governing equation of MCR is 0.08±0.05°, 0.41±0.34°, 1.47±0.49° and 1.07±0.66° for four-types horizontal deflection, 0.19±0.07mm and 0.16±0.10mm for two-types vertical deflection, respectively. Based on the governing equations, the MTR is able to precisely navigate to coronary arteries with various degrees of stenosis (30%, 52%, and 60%), and successfully pass through a series of rings, with an average error of 1.05 mm. The research successfully demonstrates the potential of HAF in creating robust and reliable governing equations for magnetic actuation in medical robotics, with significant implications for enhancing the precision and safety of PCI procedures.

The possible influence of third-order shim coils on gradient-magnet interactions: an inter-field and inter-site study.

OBJECTIVE: To assess the possible influence of third-order shim coils on the behavior of the gradient field and in gradient-magnet interactions at 7 T and above. MATERIALS AND METHODS: Gradient impulse response function measurements were performed at 5 sites spanning field strengths from 7 to 11.7 T, all of them sharing the same exact whole-body gradient coil design. Mechanical fixation and boundary conditions of the gradient coil were altered in several ways at one site to study the impact of mechanical coupling with the magnet on the field perturbations. Vibrations, power deposition in the He bath, and field dynamics were characterized at 11.7 T with the third-order shim coils connected and disconnected inside the Faraday cage. RESULTS: For the same whole-body gradient coil design, all measurements differed greatly based on the third-order shim coil configuration (connected or not). Vibrations and gradient transfer function peaks could be affected by a factor of 2 or more, depending on the resonances. Disconnecting the third-order shim coils at 11.7 T also suppressed almost completely power deposition peaks at some frequencies. DISCUSSION: Third-order shim coil configurations can have major impact in gradient-magnet interactions with consequences on potential hardware damage, magnet heating, and image quality going beyond EPI acquisitions.

Use of magnets in pediatric surgery.

Since the 1970s, magnets have been progressively harnessed for use in minimally invasive treatment of pediatric surgical disease. In particular, multiple magnetic devices have been developed for treating esophageal atresia, pectus excavatum and scoliosis. These devices, which can be placed via small incisions or under endoscopic or fluoroscopic guidance, provide the added benefit of sparing patients multiple large, invasive procedures, and allowing for gradual correction of congenital anomalies over days to months, depending on the disease. In the following text, we detail the current landscape of magnetic devices used by pediatric surgeons, illustrate their use through clinical cases, and review the available body of literature with respect their outcomes and complications.

High gain differentiator based neuro-adaptive arbitrary order sliding mode control design for MPE of standalone wind power system.

In this paper, we introduce a novel Maximum Power Point Tracking (MPPT) controller for standalone Wind Energy Conversion Systems (WECS) with Permanent Magnet Synchronous Generators (PMSG). The primary novelty of our controller lies in its implementation of an Arbitrary Order Sliding Mode Control (AOSMC) to effectively overcome the challenges caused by the measurement noise in the system. The considered model is transformed into a control-convenient input-output form. Additionally, we enhance the control methodology by simultaneously incorporating Feedforward Neural Networks (FFNN) and a high-gain differentiator (HGO), further improving the system performance. The FFNN estimates critical nonlinear functions, such as the drift term and input channel, whereas the HGO estimates higher derivatives of the system outputs, which are subsequently fed back to the control inputs. HGO reduces sensor noise sensitivity, rendering the control law more practical. To validate the proposed novel control technique, we conduct comprehensive simulation experiments compared against established literature results in a MATLAB environment, confirming its exceptional effectiveness in maximizing power extraction in standalone wind energy applications.

Magnet Recognition® and Pathway to Excellence®, Complementary Programs.

The American Nurses Credentialing Center® (ANCC) provides healthcare organizations with 2 complementary programs: Magnet Recognition Program® and Pathway to Excellence®. Both programs support nurses in providing the best care. Understanding each program's framework and focus allows organizations to choose which program is the best fit. Nursing is searching for solutions, the ANCC's Magnet Recognition®, and the Pathway to Excellence® programs offer evidence-based frameworks to support professional nursing practice. The frameworks result in improved nurse engagement, retention, interprofessional collaboration, nurse and patient safety, and patient outcomes.

Complications related to unwitnessed magnet ingestion in paediatrics: Case series.

Foreign body inges tion is one of the mo s t common problems a mo ng chi ldren. There is a great te ndency among children between the age of six months to six years to p lace objects, such as coins, fish bone, pins, button batteri es, magnets and o th er hous ehold ite ms, in their m outh and often swa llow them. Magnet ingestion is not uncommon. Hazardous effects can occur owing to the fact that these are usually unwitnessed leading to disparity in histor y an d delayed presentation. Nowadays these m agnets are made of Neodymium which is a s trong element and can be moulded into various shapes and sizes, making them more attractive to children . Single magnet ingestion may pass with out complication, bu t multip le ingested magnets pose risk of severe complications such as obstruction, inter bowel fistulae, and perforation often requiring urgent intervention. Here, we present three cases who presented to the emergency d epartment with unusu al prese nt ation s an d ultimately under went exp loratory La parotomy with surprising intra- operative findings along with magnetic objects.

Magneto-Mechanical Coupling Study of Magnetorheological Elastomer Thin Films for Sensitivity Enhancement.

Magnetorheological elastomer thin films (MREFs) exhibit remarkable deformability and an adjustable modulus under magnetic fields, rendering them promising in fields such as robotics, flexible sensors, and biomedical engineering. Here, we fabricated MREF by introducing magnetostrictive particles (MSPs) and evaluated the magneto-mechanical coupling effect on the enhancement of sensitivity. The saturation magnetization (Ms) in a parallel anisotropic TbDyFe-PDMS MREF was 5.8 emu/g, and the initial tensile modulus was 55% greater than that of an Iso MREF. We propose a nonlinear magnetorheological formula on the magnetostriction effect, incorporating magnetic dipole interactions and the nonlinear prestress of magnetic particles. This formula highlights the complex nonlinear relationship between the external magnetic field (H) and the key parameters that affect the enhanced MR effect of MSPs-MREF, such as saturation magnetization, remanence (Mr), magnetostriction constant (λs) and stress deviator in ferromagnetic particles (Sed) in the magnetic chain structure. Furthermore, we validate the influence of the key parameters of the rectified magnetorheological formula on a nonlinear magneto-mechanical behavior of MSPs-MREF in PDMS-based MSPs-MREF models by using finite-element simulations. Finally, we developed a biosensor based on MSPs-MREF to detect human serum albumin at low concentrations in human urine samples. There is a 4-fold increase in sensitivity, a lower detection of limit (0.442 µg/mL), and a faster response time (15 min) than traditional biosensors, which in the future might provide an effective way of detecting biomolecules of low concentrations.