Magnetic ferrite nanoparticles (MFNPs) have great application potential in biomedical fields such as magnetic resonance imaging, targeted drugs, magnetothermal therapy and gene delivery. MFNPs can migrate under the action of a magnetic field and target specific cells or tissues. However, to apply MFNPs to organisms, further modifications on the surface of MFNPs are required. In this paper, the common modification methods of MFNPs are reviewed, their applications in medical fields such as bioimaging, medical detection, and biotherapy are summarized, and the future application directions of MFNPs are further prospected.
Ferric Compounds ; Magnetic Resonance Imaging/methods* ; Magnetics ; Magnetite Nanoparticles/therapeutic use* ; Nanoparticles

Kidney Transplantation/adverse effects* ; Magnetics ; Anastomosis, Surgical ; Magnetic Phenomena

Magnetic anchoring technology provides a new development opportunity for current minimally invasive surgery. The magnetic anchoring abdominal video system based on this technology can effectively improve the operability and minimally invasiveness of single-port laparoscopic surgery. The development history of magnetically anchored abdominal video system was reviewed, and the design features and deficiencies of various types of magnetically anchored video devices were compared and analyzed. The evolution characteristics of the magnetic anchored video system are explained from minimally invasive and intelligent perspectives, and the challenges and opportunities of magnetic anchored video system are summarized and prospected.
Abdomen ; Laparoscopy ; Magnetics ; Minimally Invasive Surgical Procedures

The targeting of anti-tumor drugs is an important means of tumor treatment and reducing drug side effects. Oxygen-depleted hypoxic regions in the tumour, which oxygen consumption by rapidly proliferative tumour cells, are generally resistant to therapies. Magnetotactic bacteria (MTB) are disparate array of microorganism united by the ability to biomineralize membrane-encased, single-magnetic-domain magnetic crystals (magnetosomes) of minerals magnetite or greigite. MTB by means of flagella, migrate along geomagnetic field lines and towards low oxygen concentrations. MTB have advantage of non-cytotoxicity and excellent biocompatibility, moreover magnetosomes (BMs) is more powerful than artificial magnetic nanoparticles(MNPs). This review has generally described the biological and physical properties of MTB and magnetosomes, More work deals with MTB which can be used to transport drug into tumor based on aerotactic sensing system as well as the competition of iron which is a key factor to proliferation of tumor. In addition, we summarized the research of magnetosomes, which be used as natural nanocarriers for chemotherapeutics, antibodies, vaccine DNA. Finally, We analyzed the problems faced in the tumor treatment using of MTB and bacterial magnetosomes and prospect development trends of this kind of therapy.
Bacteria ; Ferrosoferric Oxide ; Gram-Negative Bacteria ; Magnetics ; Magnetosomes ; Neoplasms/therapy*

Based on the principle of magnetic anastomosis technique, the design of magnetic anastomosis system for endoscopic tissue clamping is proposed. The system includes a semi-ring magnet, a special structure transparent cap and a detachable push rod. With the help of the existing digestive endoscopy and endoscopic tissue gripper, the endoscopic close clamping and anastomosis of the bleeding or perforated tissue can be completed. After the anastomosis, the magnet falls off and is discharged through the digestive tract. Animal experiments showed that the system was easy to use, the fistula was clamped firmly, the magnet was discharged for 7~21 days, and there was no magnet retention and digestive tract obstruction. Further safety verification, optimization of endoscopic operation, the system can be used in clinical trial.
Anastomosis, Surgical ; Animals ; Constriction ; Endoscopy, Gastrointestinal ; Magnetics ; Magnets

Medical magnetic nanoparticles are nano-medical materials with superparamagnetism, which can be collected in the tumor tissue through blood circulation, and magnetic particle imaging technology can be used to visualize the concentration of magnetic nanoparticles in the living body to achieve the purpose of tumor imaging. Based on the nonlinear magnetization characteristics of magnetic particles and the frequency characteristics of their magnetization, a differential detection method for the third harmonic of magnetic particle detection signals is proposed. It was modeled and analyzed, to study the nonlinear magnetization response characteristics of magnetic particles under alternating field, and the spectral characteristics of magnetic particle signals. At the same time, the relationship between each harmonic and the amount of medical magnetic nanoparticle samples was studied. On this basis, a signal detection experimental system was built to analyze the spectral characteristics and power spectral density of the detected signal, and to study the relationship between the signal and the excitation frequency. The signal detection experiment was carried out by the above method. The experimental results showed that under the alternating excitation field, the medical magnetic nanoparticles would generate a spike signal higher than the background sensing signal, and the magnetic particle signal existed in the odd harmonics of the detected signal spectrum. And the spectral energy was concentrated at the third harmonic, that is, the third harmonic magnetic particle signal detection that meets the medical detection requirement could be realized. In addition, the relationship between each harmonic and the particle sample volume had a positive growth relationship, and the detected medical magnetic nanoparticle sample volume could be determined according to the relationship. At the same time, the selection of the excitation frequency was limited by the sensitivity of the system, and the detection peak of the third harmonic of the detection signal was reached at the excitation frequency of 1 kHz. It provides theoretical and technical support for the detection of medical magnetic nanoparticle imaging signals in magnetic particle imaging research.
Magnetics ; Magnetite Nanoparticles

Cholangiocarcinoma is a highly malignant tumor. It is not sensitive to radiotherapy and chemotherapy and has a poor prognosis. At present, there is no effective treatment. As a new method for treating cancer, magnetic fluid hyperthermia has been clinically applied to a variety of cancers in recent years. This article introduces it to the cholangiocarcinoma model and systematically studies the effect of magnetic fluid hyperthermia on cholangiocarcinoma. Starting from the theory of magnetic fluid heating, the electromagnetic and heat transfer models were constructed in the finite element simulation software COMSOL using the Pennes biological heat transfer equation. The Helmholtz coil was used as an alternating magnetic field generating device. The relationship between the magnetic fluid-related properties and the heating power was analyzed according to Rosensweig's theory. After the multiphysics coupling simulation was performed, the electromagnetic field and thermal field distribution in the hyperthermia region were obtained. The results showed that the magnetic field distribution in the treatment area was uniform, and the thermal field distribution met the requirements of hyperthermia. After the magnetic fluid injection, the cholangiocarcinoma tissue warmed up rapidly, and the temperature of tumor tissues could reach above 42 °C, but the surrounding healthy tissues did not heat up significantly. At the same time, it was verified that the large blood vessels around the bile duct, the overflow of the magnetic fluid, and the eddy current heat had little effect on thermotherapy. The results of this article can provide a reference for the clinical application of magnetic fluid hyperthermia for cholangiocarcinoma.
Cholangiocarcinoma ; Humans ; Hyperthermia ; Hyperthermia, Induced ; Magnetic Fields ; Magnetics

Coagulometer, known as blood coagulation analyzer, is a product that can provide accurate test results for medical diagnosis and treatment analysis by detecting a series of items closely related to thrombosis and hemostasis in coagulation reaction. On the basis of previous traditional methods, and with our deep understanding about the principles of hemagglutination detection, we propose a hemagglutination detection method by using the dual-magnetic circuit beads method. Then, the corresponding hemagglutination detection module is designed. The coagulation time of plasma can be measured by detecting the movement of the magnetic beads when the magnetic field intensity is appropriate. The activated partial thromboplastin time(APTT) of plasma is tested when the most suitable magnetic field intensity is found. The results preliminarily show that this blood coagulation test method is valid and the corresponding test module has a potential value in business.
Blood Coagulation ; Blood Coagulation Tests ; Magnetic Phenomena ; Magnetics ; Partial Thromboplastin Time

As drug carriers, magnetic nanoparticles can specifically bind to tumors and have the potential for targeted therapy. It is of great significance to explore non-invasive imaging methods that can detect the distribution of magnetic nanoparticles. Based on the mechanism that magnetic nanoparticles can generate ultrasonic waves through the pulsed magnetic field excitation, the sound pressure wave equation containing the concentration information of magnetic nanoparticles was derived. Using the finite element method and the analytical solution, the consistent transient pulsed magnetic field was obtained. A three-dimensional simulation model was constructed for the coupling calculation of electromagnetic field and sound field. The simulation results verified that the sound pressure waveform at the detection point reflected the position of magnetic nanoparticles in biological tissue. Using the sound pressure data detected by the ultrasonic transducer, the B-scan imaging of the magnetic nanoparticles was achieved. The maximum error of the target area position was 1.56%, and the magnetic nanoparticles regions with different concentrations were distinguished by comparing the amplitude of the boundary signals in the image. Studies in this paper indicate that B-scan imaging can quickly and accurately obtain the dimensional and positional information of the target region and is expected to be used for the detection of magnetic nanoparticles in targeted therapy.
Acoustics ; Computer Simulation ; Magnetics ; Magnetite Nanoparticles ; Tomography

In this study, we improved the culture method of mouse hippocampal primary microglia to obtain hippocampal ramified microglia with high activity and purity, which were resemble to the resting status of normal microglia in healthy brain in vivo. Hippocampal tissue was excised from 2-4-week-old SPF C57BL/6J mice and cut into pieces after PBS perfusion, and then manually dissociated into the single-cell suspension by using Miltenyi Biotec's Adult Brain Dissociation Kit. The tissue fragments such as myelin in the supernatant were removed by debris removal solution in the kit. The cell suspension was incubated with CD11b immunomagnetic beads for 15 min at 4 °C. To obtain high-purity microglia, we used two consecutive cell-sorting steps by magnetic activated cell sorting (MACS). After centrifugation, the cells were resuspended and seeded in a 24-well culture plate. The primary microglia were cultured with complete medium (CM) or TIC medium (a serum-free medium with TGF-β, IL-34 and cholesterol as the main nutritional components) for 4 days, and then were used for further experiments. The results showed that: (1) The cell viability was (56.03 ± 2.10)% by manual dissociation of hippocampus; (2) Compared with immunopanning, two-step MACS sorting allowed for efficient enrichment of microglia with higher purity of (86.20 ± 0.68)%; (3) After being incubated in TIC medium for 4 d, microglia exhibited branching, quiescent morphology; (4) The results from qRT-PCR assay showed that the levels of TNF-α, IL-1β and CCL2 mRNA in TIC cultured-microglia were similar to freshly isolated microglia, while those were much higher in CM cultured-microglia after incubation for 4 d and 7 d (P < 0.05). Taken together, compared to the conventional approaches, this modified protocol of mouse hippocampal primary microglia culture by using MACS and TIC medium enables the increased yield and purity of microglia in the quiescent state, which is similar to normal ramified microglia in healthy brain in vivo.
Animals ; Cell Culture Techniques ; methods ; Cell Separation ; methods ; Cells, Cultured ; Hippocampus ; Magnetics ; Mice ; Mice, Inbred C57BL ; Microglia ; cytology