Читать книгу Magnetic Nanoparticles in Human Health and Medicine - Группа авторов - Страница 29

According to the underlying interaction mechanism of MNPs with various forms of external applied magnetic fields, we have identified three types of application that could have a major impact in nanomedicine, in the near future:

1 Applications based on the existence of a magnetic force. The magnetic force can be defined as the force developed when MNPs, as tiny nanoscale magnets possessing a dipolar magnetic moment, interact with an external static magnetic field gradient. The acquired magnetic mobility of MNPs, due to this interaction, leads to their movement toward the higher magnetic field zones, a phenomenon known as magnetophoresis. Magnetophoresis can be used in some specific applications such as magnetic drug targeting, magnetic cell targeting, magnetofection, magnetic purification/separation of the cell or its constituents (molecules, exosomes, and organelles), controllable in vivo genome editing, or induction into apoptosis.

2 Applications based on magnetic relaxation of protons. In this case, the non‐uniform local dipolar magnetic fields generated by MNPs, in their vicinity, significantly modify the longitudinal (T1) and transversal (T2) relaxation times of protons. This is the main mechanism involved in the use of MNPs as contrast agents for MRI applications. So far, MRI has been successfully used in diagnostic imaging, cell tracking, molecular imaging, and image‐guided drug delivery.

3 Applications based on magnetic heating. The conversion of electromagnetic energy, resulted from the interaction of MNPs with an external alternating (AC) radiofrequency (RF) magnetic field, into thermal energy, is exploited in MH for different purposes as: apoptosis induction in cancer cells, thermal ablation of tumors, nanowarming, magnetogenetics, or controlled drug release.

In the following section, we will address the use of MNPs as contrast agents in MRI, which represented their first biomedical application introduced in clinical practice. Afterward, we will introduce the Magnetic Particles Imaging (MPI) technique, which is a transverse to the static magnetic field and irradiating recent imaging technique possessing a much higher resolution as compared to MRI. Lastly, we will present a short overview of recent advancements reported in the field of MH.