Perspective of Fe3O4 Nanoparticles Role in Biomedical Applications

Abstract

In recent years, although many review articles have been presented about bioapplications of magnetic nanoparticles by some research groups with different expertise such as chemistry, biology, medicine, pharmacology, and materials science and engineering, the majority of these reviews are insufficiently comprehensive in all related topics like magnetic aspects of process. In the current review, it is attempted to carry out the inclusive surveys on importance of magnetic nanoparticles and especially magnetite ones and their required conditions for appropriate performance in bioapplications. The main attentions of this paper are focused on magnetic features which are less considered. Accordingly, the review contains essential magnetic properties and their measurement methods, synthesis techniques, surface modification processes, and applications of magnetic nanoparticles.

Figure 1

The increasing number of articles related to biomedical applications of magnetic nanoparticles based on Elsevier database.

Figure 2

The polyhedral and ball models of magnetite crystal structure.

Figure 3

The statement of moment orientation in different magnetic structures such as paramagnetic, ferromagnetic, ferrimagnetic, and antiferromagnetic structures [60].

Figure 4

The schematic explanation of Fermi energy model of magnetic properties of materials. In (a) position, the up/down spins are located in balance states before applying external field. In (b) position, by applying external field, the energy state of aligned spins is higher than other ones; so, the magnetic properties are created [60].

Figure 5

The magnetic hysteresis loop of ferromagnetic and ferrimagnetic materials. In this figure, several critical parameters such as saturation magnetization (M _s), remnant magnetization (M _r), and coercive field (H _c) can be seen.

Figure 6

The schematic of variation of anisotropy energy as a function of moment vector directions. In easy axes (in this figure: 0 and π angles) the anisotropy energy is minimum and in hard axis (π/2) it is maximum amount [60].

Figure 7

The variation of thermal and anisotropy energies by particles resizing from large scale (ferromagnetic structure) to fine nanoscale (superparamagnetic structure) [92].

Figure 8

The variation of relaxation time as a function of thermal energy to anisotropy energy ratio values.

Figure 9

The details of superparamagnetic behavior as a function of blocking temperature and relaxation time. In state (a), temperature is below the blocking temperature and the anisotropy energy is dominated to the thermal energy; so, the moments are apparently fixed. In state (b), temperature is higher than blocking point and the thermal energy is larger than anisotropy one; thereby, the superparamagnetic structure is formed [95].

Figure 10

The principle of Mossbauer spectroscopy. The nuclear reactions in Mossbauer source cause the desired spectroscopy [123].

Figure 11

The disorder noises in M-H curves of nanoscale sample that are caused by utilization of diamagnetic substrate during measuring [126].

Figure 12

The effect of sample and coils positions on magnetic flux distribution. In case (a), the positions of sample and coil are determined by arrow and circle, respectively. Moreover, the sample distance from center point is defined by “d” symbol. In (b) case, it is clear that the imbalance position of sample and coil led to creating considerable errors in flux amounts [126].

Figure 13

Theoretical ternary phase diagram of microemulsion systems [158].

Figure 14

The schematics of organic coating models such as core-shell, mosaic, and shell-core structures [184].

Figure 15

The schematic of some copolymer modes like alternating, random, block, and graft modes.

Figure 16

The schematic of some possible structures of inorganic coatings such as core-shell, matrix (mosaic), shell-core, and shell-core-shell structures [184].

Figure 17

The schematic of T ₁ and T ₂ relaxations mechanisms. (a) The schematic of T ₁ recovery mechanism and (b) the schematic of T ₂ decay mechanism [190].

Figure 18

The schematic of magnetic targeted drug delivery mechanism [191].

Figure 19

The schematic of magnetic relaxation mechanisms such as Neel and Brownian relaxation mechanisms [90].

Figure 20

The difference of temperature increasing between target tissue, which is containing Fe₃O₄ particles (marked with solid circles), and another one, without these particles (marked with hollow circles). Based on this figure, the presence of magnetic particles causes targeted hyperthermia [192].

Figure 21

The effect of applying magnetic hyperthermia with magnetite particles in hamster samples after 30 days (120 kHz AC magnetic field, 90 min per day). In case (a), without hyperthermia treatment, the tumors volume is increased while in case (b) the volume of treated tumors by hyperthermia is obviously decreased [193].