Magnetic Nanoparticles

Magnetic Nanoparticles List

Magnetic nanoparticles (MNPs) have quantum size effect, surface effect, small size effect and macroscopic quantum tunneling effect. It has good magnetic guidance, biocompatibility and biodegradability, and can bind a variety of biological functional molecules (enzymes, DNA, proteins, etc.). Magnetic nanoparticles have a series of unique and superior physical and chemical properties. With the development of synthesis technology, a series of magnetic nanoparticles with controllable shape, good stability, and monodisperse have been successfully produced. Magnetic nanoparticle materials have become a hot research topic in many disciplines, especially in the fields of magnetic fluid, catalysis, biomedicine and environmental protection.

Applications:

• Magnetic resonance imaging: In the field of disease diagnosis, a well-known application is the use of MNPs as a contrast agent for magnetic resonance imaging. This method can better distinguish between healthy and diseased tissues, and can see a variety of different in the body biological variation. Because of their low toxicity, iron oxide magnetic nanoparticles are used to enhance magnetic resonance imaging signals.
• Magnetic labeling: In diagnosis, magnetic nanoparticles can magnetically label cells, DNA and proteins and other organisms. An interesting application is to label stem cells to monitor the distribution and changes of transplanted stem cells in the human body without trauma. In addition, compared with traditional labeling methods, such as enzymes, fluorescent dyes, chemiluminescent molecules, radioisotopes, etc., this kind of magnetic labeling with great development potential shows many advantages in MNP. For example, the magnetically labeled cancer cells can be purified, transported, and detected on the surface of a single biochip, which facilitates the creation of a simple, cost-effective cancer cell screening and display function when implementing lab-on-a-chip laboratory on a chip.
• Controllable drug release: In addition to its small size and low toxicity to the human body, magnetic nanoparticles have another advantage that they can move under the action of an external magnetic field gradient, so that they can penetrate deep into human tissues. In this way, the medicine can be delivered to the target area of the body in a controlled manner. The method to achieve this application is to put the drug in a non-biorepellent MNPs carrier, inject this ferrofluid into the human blood, and then apply an external magnetic field to make the drug/carrier combination converge to the target point on.
• Hyperthermia therapy: Based on the property that magnetic nanoparticles can be heated in a time-varying magnetic field, they can be used to "burn off" cancer cells (hyperthermia therapy). It is usually used in conjunction with chemotherapy. When the temperature of cancer cells exceeds 41°C, they are more sensitive to temperature than normal. These applications all show the bright prospects of the target treatment method, which allows us to destroy only the target that needs to be destroyed, without causing damage to the surrounding healthy tissue.
• Cell isolation: The attraction between an external magnetic field and magnetic nanoparticles can be used to separate many kinds of organisms. For example, separating cancer cells in blood samples or stem cells in bone marrow to improve diagnosis and remove toxins from the body. In addition, after activation of biological properties, MNPs can produce cellular uptake through the endocytotic pathway, so that specific cell compartments can be determined. Once the uptake occurs, the set cell body compartment can be isolated with a magnetic field, so that the proteosome analysis method can be used for accurate research.
• Catalyst: As an ideal carrier for homogeneous catalysts, magnetic nanoparticles have attracted much attention for their application in catalyst loading. This is mainly due to the fact that MNPs with sufficiently small particle size are superparamagnetic, that is, they have strong magnetism in an external magnetic field, and the magnetism disappears quickly when there is no external magnetic field, so that the supported catalyst can be easily dispersed in the reaction system by controlling the external magnetic field. Aggregation and separation have the advantages of simple operation and high separation efficiency. In addition, MNPs have a large specific surface area, can support high-density catalysts, and the active sites of the catalyst can be evenly distributed in the reaction medium, thereby improving the activity and selectivity of the supported catalyst.
• Water treatment: With the rapid development of nanotechnology, nanomaterials have been widely used in the removal of pollutants in water. Nanomaterials are prone to agglomeration when removing pollutants in the water, which affects their degradation effect on pollutants. At the same time, it is difficult to recover and separate and cause secondary pollution of water bodies. Magnetic nanoparticles have received widespread attention due to their magnetic properties that can be quickly separated from water. At the same time, the magnetic nanoparticles can also be surface modified so that different functional groups or biologically active substances can be added as needed. These characteristics make magnetic nanoparticles have good application prospects in water treatment.

Figure 1. Magnetic nanoparticles are used in water treatment.

References

1. Srikanth Singamaneni, Valery N. Bliznyuk, Christian Binek and Evgeny Y. Tsymbal. Magnetic nanoparticles: recent advances in synthesis, self-assembly and applications [J]. J. Mater. Chem., 2011, 21, 16819–16845.
2. Liane M. Rossi, Natalia J. S. Costa, Fernanda P. Silva and Robert Wojcieszak. Magnetic nanomaterials in catalysis: advanced catalysts for magnetic separation and beyond [J]. Green Chem., 2014, 16, 2906–2933.