MAGNETIC NANOPARTICLES AND THEIR BIOLOGICAL APPLICATIONS
Creators: name: Hussain, Zahid
Publisher: name: Zenodo
Year: 2024
Subjects: MAGNETIC
NANOPARTICLES
AND THEIR
BIOLOGICAL APPLICATIONS

description: MAGNETIC NANOPARTICLES AND THEIR BIOLOGICAL APPLICATIONS

 

AbstractMagnetic nanoparticles (MNPs) have garnered significant attention in recent years due to their unique magnetic properties, biocompatibility, and versatility in a wide range of biological applications. These nanoscale materials can be precisely manipulated using external magnetic fields, enabling their use in targeted drug delivery, hyperthermia-based cancer therapy, magnetic resonance imaging (MRI), and biosensing. Functionalization of MNPs with biomolecules further enhances their specificity and efficacy in biomedical contexts. Additionally, their potential for use in separating biomolecules and cells has revolutionized diagnostic and therapeutic techniques. This review explores the synthesis, functionalization, and diverse biological applications of magnetic nanoparticles, emphasizing their role in advancing modern medicine and biotechnology.

 

1. INTRODUCTION TO NANOPARTICLES

 

Nanoparticles have unique characteristics, not common amongst bulk materials and they are attractive targets because of this. Organic molecules are used for the surface modification of nanoparticles. This phenomenon is also important for their proper fictionalization not only for nanocomposite fabrication as well as for biological applications. Magnetic nanoparticles are not only important because of their peculiar characteristics but also for their various applications in different fields such as:

·         Ultra high density magnetic recording

·          Magnetic fluids

·         Biomedical materials. 

 

Nanoclusters are ultrafine particles having nanometer dimensions and these are located in the transition region between molecules and microscopic structures. Remarkable new phenomena are exhibited by magnetic nanoparticles like super paramagnetism, high field irreversibility, extra anisotropy contributions, high saturation field or shifted loops after field cooling. These mechanisms come up from finite size and surface effects of individual nanoparticles. [1]

 

2.0 MAGNETIC NANOPARTICLES

 

A lot of research is being done on the unique physical properties of nanoparticles. A unique case is the magnetic properties in which the difference between a massive (bulk) material and a nanomaterial is especially marked. It was discovered that magnetization (per atom) and the magnetic anisotropy of nanoparticles can be much greater than that of a bulk specimen. The magnetic properties of nanoparticles can be analyzed by many factors like the chemical makeup, the kind and the degree of defectiveness of the crystal lattice, the particle shape and size, the structure, the contact of the particle with the surrounding matrix and the neighboring particles. But all these factors cannot always be controlled during the manufacture of nanoparticlesthat are nearly equal in size and chemical composition; therefore, the properties of nano-materials of the same type can be markedly different. [8]

Magnetic nanoparticles are abundantly found in nature and can be present in many biological objects. Magnetic nanomaterials are utilized in recording information and storage systems, in permanent magnets, in magnetic cooling systems and as magnetic sensors, etc. [2]

The magnetization actions of these particles above a citical temperature, i.e. the blocking temperature, are very much similar to that of atomic paramagnets (superparamagnetism) except that an extremely large susceptibilities and moments are involved.There are also a wide range of Industrial applications of magnetic nanoparticles i.e., magnetic seals for motors, magnetic inks used in bank cheques, recording media and biomedical applications such as magnetic resonance contrast media and cancer treatment through certain agents. But in each prospective application magnetic nanoparticles ought to have completely different properties. For example, in data storage applications, these have to be stable, switchable magnetic state to represent bits of information, a condition which has no effect of temperature fluctuations. [1]

 

3.0 THEORY OF MAGNETIC NANOPARTICLES      

 

Frenkel and Dorfman visualized that particles of a suitably small size should be single-domain in 1930. In the mid-20th century, the theory of single-domain particles started develop actively 288 ± 299 and the related phenomena were considered experimentally.300 ± 309 These studies recognized a substantial rise in the coercive force of a ferromagnet on passing from a multidomain to the single-domain structure, which is significant for the creation of permanent magnets.[3]

The magnetic properties are basically innate in the 2 ± 30 nm core sized particles.

 

4. PREPARATION OF MAGNETIC NANOPARTICLES

 

4.1 Classification of Nanoparticles and Nanomaterials preparation

 

The preparation of nanoparticles classified on the basis of the type of the precursor and the features of its processing are:

·          Preparation by dispersion from the macroscopic materials.

·          Chemically synthesized, i.e., targeted change in the substance composition with termination of the nascent phases growth at the nano-size stage.

·          Transformations of nanoparticles with an alteration in the composition.[5]

 

The preparation of particles of specified size and shape (at least, the scatter of sizes should be small, 5%± 10%, and controllable) is an important feature of their synthesis. The control of shape and the possibility of creation of anisotropic magnetic structures are essentially important. In order to eradicate the interparticle interactions, nanoparticles are often needed to be isolated from one another by the immobilization on a substrate surface or on an inert matrix. The controllable distance between the particles in the matrix is an important factor. In conclusion, the synthetic mechanism must be relatively simple, inexpensive and reproducible. [1]

               

Nanoparticles of a complex composition must be prepared sometimes while the production of magnetic materials, for example ferrites, complex NdFeB or SmCo5 alloys, etc., the range of synthetic approaches substantially narrows down in such cases. For example, when the thermal evaporation of compounds is done with a complex elemental composition, it is often accompanied by a violation of the stoichiometry in the vapor phase that results in the formation of other substances. The atomic beam synthesis does not result in a homogeneous distribution of elements on the substrate. The physical methods of generation of magnetic nanoparticles in the gas or solid phase using high-energy treatment of the material, while the nanoparticle synthesis carried out in solutions at moderate temperatures are the chemical methods. The chemical methods have been developed most intensively in recent years for the magnetic nanoparticles preparation; however, physical methods cannot be considered yet as outworn.[3]

 

 

 

 

4.2 General synthesis of Magnetic Nanoparticles

 

In a common route, nucleation and growth steps are separated during the synthesis of monodisperse NPs in the solution phase. According to Lamer, a burst nucleation occurs when the monomers quickly amplify over critical super saturation without further creation of nuclei afterwards. Then the produced nuclei grow at the same rate, forming monodisperse particles. However, small NPs agglomerate easily and have an extremely high surface area to volume ratio to minimize their surface energy. To prevent this agglomeration, surfactant molecules should be used to coat the particle surface. The repulsive forces given by the surfactant molecules around any two NPs provide the much-needed long-term NP stabilization.

 

Lamer model: separate nucleation and growth for the synthesis of monodisperse nanoparticles; (b) a typical “hot-injection” set-up to achieve the burst nucleation in.The so-called “heating-up” strategy is also greatly used in which the initiation of the particle clustering and growth starts by heating up to a certain temperature of a pre-mixed solution of precursors, surfactants, and solvent. It is indicated from the recent synthetic advance that by fine control of the reaction parameters, both hot-injection and heating-up procedures are able of producing highly monodisperse NPs (standard deviation in diameter σ < 10%) [4]

4.3 Design and synthesis of magnetic nanoparticles

 

The nano-scale dimensions, their magnetic properties and their capability of carrying active biomolecules are the crucial features of nanoparticles, for specific tasks in biotechnology. The nano-scale dimensions of particles, when necessary, allow passing through the narrowest blood vessels and also facilitates their penetration through cell membranes when they are needed to be targeted in the human body. For gene or drug delivery nanoparticles can be manipulated by an external magnetic field, which forces them to the target organs when these particles are ferromagnetic/super paramagnetic. The active biomolecules bound to the surface of these nanoparticles can then be released. As a result, a functional magnetic nanoparticle comprises of a number of components;

·         the magnetic core,

·         the protective coating, and

·         The surface functionality. [5]

 

 

 

 

5.0 METHODS FOR THE SYNTHESIS OF MAGNETIC NANOPARTCILES

 

Different routes for the synthesis of magnetic nanoparticle synthesis have been reported. Some of them are one-step, while others are multi-step procedures. All have both the advantages and disadvantages but none of them gives a universal solution for all types of magnetic nanoparticles. It is to be considering that which route is to be chosen that is suitable for preparing specific magnetic nanoparticles. Simple, basic inorganic chemistry, particularly iron chemistry is involved in most of them. The following are several commonly used methods. [7]

 

5.1 Wet precipitation and co-precipitation:

From the oldest methods for preparation of magnetic nanoparticles is wet precipitation. By carefully maintaining the pH of an iron salt solution, iron oxide forms as a fine suspension with particle sizes as small as 5 nm. The simple technique for making magnetic nanoparticles does not need any specialized facilities

Co-precipitation can also b used to prepare mixed oxide particles (eg, magnetite Fe3O4, ferrites including CoFe2O4 NiFe2O4) with a stoichiometry solution of the two metal ions

Some drawbacks of this procedure are:

·         Controlling the pH is essential in order to control the particle size, which is governed by kinetic factors.

·         Nanoparticles with bigger particle size distributions and irregular shapes are usually synthesized by wet precipitation.

·         Oxidation of the iron(II) precursor should also be avoided for successful synthesis of magnetite.

Scaling up the process can be done but it is not easy as a large quantity of water is involved. Finally, as controlling the pH is subtle, it is nearly impossible to precipitate a protective coating at the same time. Coating these nanoparticles individually after preparation can be difficult. [6]

5.2 Reverse micelle mechanism:

 

The formation of micelles is a common phenomenon of surfactant chemistry. Molecules with a hydrophilic head and a long, hydrophobic tail are surfactants. The micelles formation occurs only if the surfactant molecules’ concentration reaches a certain level, this particular concentration is called critical micelle concentration 1 (CMC1, when CMC2 is the concentration mediating the self-assembly of liquid crystals). Normal micelles form in an aqueous medium (e.g., use of detergents in cleaning processes) but reverse micelles are formed in an oily medium (hexane). These reverse micelles have a hydrophilic centre which stores the inorganic components of the reaction mixture. Inorganic precursors such as iron (III) chloride are dissolved in an aqueous medium and then mixed with the oily reaction mixture with the surfactants for the synthesis of iron oxide-based magnetic nanoparticles. This step is followed by the adding up of pH regulators (e.g., ammonia or sodium hydroxide) and inorganic coating materials (for example silica or gold). [24]

 

The size of these particles can be easily controlled with the help of micelles and as a result the nanoparticles prepared using reverse micelle routes tend to have a homogeneous size. The inorganic coating materials can also be added to the micelles during their synthesis, so nanoparticles produced by this methodology can be coated with an inorganic protective layer during the procedure. This method is also effective in synthesizing magnetite nanoparticles with inorganic coatings such as silica. Size of these nanoparticles ranges from a few nanometers to tens or hundreds nm with a narrow distribution.

However one disadvantage of this technique is that the synthetic organic coatings are not possible because the monomers will remain in the organic phase of the micelle solution. The size of the nanoparticles completely depends on the size of micelle, which ranges from 20–500 nm. Outside this limit synthesis of particles is not possible by using the reverse micelle method, and in addition to this, with such a large amount of organic solvent involved in making the micelles, the reverse micelle method is hard to scale-up. [7]

5.3 Chemical vapor condensation (CVC)

 

Metal nanoparticles are synthesized when some volatile metal compounds are heated and decomposed in an inert gas atmosphere. This is called the chemical vapor condensation (CVC). Metallic iron nanoparticles formed using the CVC mechanism has been discussed in literature. Iron carbonyl, Fe (CO) 5, was used as iron precursor with an average particle size of 5–13 nm in that study. It is possible to oxidize these metallic iron nanoparticles further. Maghemite nanoparticles of 4 to 16 nm and magnetite nanoparticles of 3 to 20 nm were manufactured by the oxidation of metallic iron nanoparticles.

Although this mechanism forms high-quality nanoparticles special facilities are required. More importantly, some by products like in the case of Fe(CO)5 with CO as by-product are very toxic and hard to handle. [8]

 

5.4 Physical methods for the preparation of Magnetic Nanoparticles

 

a. Condensation methods

The technique of the production of nanoparticle from supersaturated metal vapors is based on the classical nucleation theory in which the nascent phase clusters are defined by the spherical liquid drop model. Nanoparticles are manufactured using different ways of metal evaporation such as:

·         Laser vaporization thermal vaporization.

·          Arc discharge.

·          Plasma vaporization.

·         Solar energy induced evaporation.

 In each technique, particular installations are used differing in engineering solutions of particular units.In Thermal vaporization, a metal or alloy sample is heated in a tungsten boat using an argon or helium stream. The kinetic energy is lost by the atoms of the vaporized metal upon collisions with the inert gas atoms. They afterwards gather in clusters and condense on a cooled substrate as a nanodispersed powder. By differing the evaporation rate, temperature of the substrate and gas pressure and composition, particle size can be controlled in the range of 3 ± 100 nm. Mostly before opening the installation and taking the sample out, nanoparticles are passivated by passing an inert gas/ oxygen mixture for a few minutes. Particularly, this methodology was utilized to prepare heterometallic nanoparticles (*30 nm) with the following chemical makeup:

 Fe ±M (M=Ni, Mn, Pt, Cr).

In the low-energy cluster beam deposition (LECBD) non-charged particles with a very low kinetic energy are deposited on a substrate. The particles are not wasted by getting onto the substrate and thus can be inserted into different types of matrices formed simultaneously by vaporization of their components from another source. [9]

In the electrochemical generation method substantial amounts of rather small (1 ± 2 nm) nano particles are prepared with a narrow dispersion. An electrochemical cell that was containing an alcohol solution of tetra alkyl ammonium halide was utilized to get cobalt particles. By passing the current, the cobalt anode was dissolved to give Co nanoparticles near the cathode (glass carbon). The effect of electrolysis conditions on the magnetic characteristics of the nanoparticles formed as a result was studied using a few examples. The average particle size that is formed upon electrochemical dispersion is inversely proportional to the current density. This colloid solution of nanoparticles that is produced upon electrolysis can be stored under argon for a period of few months by the evaporation of the solvent yields crystallites that can be readily converted again into a colloid suspension.The electrochemical process is used for obtaining Fe2O3 nanoparticles that is stable in organic solvents because of the adsorption of cationic surfactants. [3]

 

6. BIOLOGICAL APPLICATIONS OF THE MAGNETIC NANOPARTICLES

 

Magnetic nanoparticles offer a no of applications. However, their biological applications are most important. In these biological applications, the Magnetic nanoparticles work at the cellular and the molecular level for the detection of pathogenic organisms, Magnetic Resonance Imaging (MRI), Agents for the Drug Delivery, Purification of the Proteins (specially the His-Tag protein), and the detection and the treatment of the Tumours by the Hyperthermia. [10]

 

6.1. DETECTION OF THE PATHOGENIC ORGANISMS

 

The Magnetic nanoparticles have been employed for the detection of the Pathogens in the biological samples. It includes two examples:

 

6.1.1 Detection of the Pathogens in the Blood samples 

It includes the principle of the Fluorescence imaging. The FePt Nanoparticles are used here along with the Vancomycin Fluorescent probe. This combination is introduced in the blood sample and it readily detects the presents of the pathogen. One of the advantages if this method is that it’s not time taking. The detection can be done within 2 hours. [11]

 

                       

                                Fig the detection of pathogens in the blood sample

 

6.1.2 Detection of the Bacteria in the Milk sample

In an experiment, The Antibody Conjugated Magnetic nanoparicles have been used for the detection of the Salmonella in the milk sample. The Magnetic Nanoparticles are combined with the sample matrix having the Bacteria. This joined complex is then exposed to the Antibody Immobilized Titanium Dioxide Nanocrystals TNs (having the capability to absorb UV light). Secondly, the UV-Visible Absorption spectrum of the unbound TNs is obtained. The light absorption intensity is reversely proportional to the Salmonella concentration, so the result showed high sensitivity toward low concentrations of Salmonella bacteria. The detection limit of Salmonella is near to be more than 100 CFU mL−1. [12] 

                         

                   fig. scheme for the detection of bacteria in the biological sample

6.1.3 Magnetic Glyco nanoaprticles

Magnetic Glyco Nanoparticles (MGNPs) have been developed to detect the harmful bacteria in the biological samples. The mechanism behind this is that many bacteria use the sugars (glycol compounds) on their surfacesfor the infection. These sugars are coated on the Magnetic nanoparticles and then exposed to the bacteria. Later on, the bacteria are easily identified and removed by the magnetic device. [13]

6.2. DRUG DELIVERY BY MAGNETIC NANOPARTICLES

                                  

the magnetic nanoparticles are employed for the drug delivery. This is an important biological application since it can be used to deliver anti-cancer drugs to the targeted areas of the body.

 

6.2.1 History of the Drug Delivery via MNPs.

The concept that MNPs can be used for the drug delivery was given in 1970,s by Wider, Senyi and their colleagues. The main idea behind this is that the Therapeutic agents are coated or injected in the magnetic Nanoparticles. These are then introduced at the targeted site of the body to treat the biological problem. [14]

Before the introduction of this idea, the drugs that were used to treat the cancerous tissues, used to damage the healthy cells along with the non healthy cells. so, The motivation of this idea comes from the 2 objectives of the Drug Delivery via MNPs. First one is to reduce the associated Side effects of the cytotoxic drugs and the second is to enhance the localized targeting of the drug. [15]

 

6.2.2 The Coating materials for the Magnetic nanoparticles

The MNPs are coated with the different materials in order to prevent corrosion. The coating materials can be the natural polymers or the synthetic polymers. The Natural Polymers include the Carbohydrates and proteins. These are of importance because they the biocompatible. The carbohydrates include Starch and Dextran mostly. The Dextran has been used widely in the drug delivery for the cancer treatment.

The Synthetic Polymers include  Poly L Lactic Acid (PLA), Poly ethylene Glycol (PEG), Poly vinyl Alcohol (PVA). The PVA is mainly used. This is important because its Hydroxyl Group OH- makes the Hydrophobic coating sure. Their use in the biomedical applications was demonstrated by the Schulze et al in 2006. [14]

Several Metal coatings have also been introduced. The most important is the Gold coatings. They were first introduced in the 2001. The other coating materials include Iron, Cobalt and Nickel. Another coating material Silica has gained much importance. It has been used in the eye surgery to for the repairing of the detached retina. [15]

 

6.2.3 Example of the Drug Delivery in the treatment of Brain Tumor

The drug delivery to the brain is very important because it is difficult for the drug to pass the blood-brain barrier first and then affect. In an experiment, it has been reported that the use of the 10-20nm Magnetic nanoparticles are effective in the drug delivery. The analysis reveals the presence of these MNPs in the interstitial space in the tumors that showed that they delivered the drug to the targeted area without damaging the healthy cells. [15]

 

 

                     Fig: Drug Delivery by MNPs

 

6.2.4 Limitations of the Drug Delivery via MNPs

the limitations associated with the magnetically drug delivery include that magnetic carriers can face toxic responses, the blood vessels may get embolized by the accumulation of these MNPs, and the fact that if the drug is released, it cant be attracted to magnetic field again.

 

6.3. PURIFICATION OF THE RECOMBINANT PROTEINS

 

Magnetic nanoparticles have been used for the purification of the His-tag proteins. The Hexahistidine tag proteins are common in proteins and they are purified by Magnetic nanoparticles under immobilized metal ions affinity chromatography (IMAC). The MNPs can be used to purify the His-tag fusion proteins from the cell lysates. [16]

The mechanism of action behind this biomedical application is that firstly the MNPs are prepared by the co precipitation of Fe3+/Fe2+ in h2O medium and coated with silica. These MNPs are then charged with Ni2+. These MNPs are efficient binder to the His-Tag in the cell lysate. The size of MNPs used for this is usually 12nm. The advantages of using MNPs are the cost efficiency, versatility, and their biocompatibility. [17]

 

                        Fig. Action of MNPs

 

 

                Fig. Purification of Recombinant Proteins by MNPs

 

6.4. HYPERTHERMIA

 

This is one of the most significant biological applications of the MNPs. It includes the treatment of the cancer by the thermotherapy.

 

6.4.1 History 

The use of MNPs to treat cancer by using high temperatures comes from 1953 when the scientist Gilchrist et all used the heating techniques on the tissue sample by the application of 20-100nm Fe2O3 nanoparticles. [5] In present times, a group of scientist in Berlin showed the feasibility of this process to be used for the human patients as well. The first experimented on the brain tumours. The iron oxide nanoparticles were coated with the aminosilane and then injected at the sites of the tumour. [18]

 

6.4.2 Mechanism of Hyperthermia

The basic principle behind this is to disperse the magnetic nanoparticles in the desired tissue and then apply the AC magnetic field that makes the particles to get heated. [19] it is actually a direct cell killing effect at the temperatures above 42-43 degree Celsius. Fine iron oxide nanoparticles are particularly important in it as they increase the temperature. [20]

 

 

6.4.3 Important technical points in the Hyperthermia

Following are some of the important technical points that should be taken under consideration:

1. The frequency and the strength of AC Magnetic field to be applied is important as it causes deleterious physiological problems in the tissues upon high level. For example, they the high frequency or strength may stimulate the skeletal muscle, or cardiac cell for non specific inductive heating of the tissue. So the optimum range is recommended as frequency= 0.05-1.2 MHz and amplitude H=1-15kA/m.

2. The amount of magnetic nanoparticle to be applied is important as well. However, it depends upon the method of injection of MNPs. This includes the example that if direct injection of MNPs causes the large amounts to be localized at the tumour site whereas intravascular injection methods doesn’t have this much amount. So it is recommended that about 5-10 mg of MNPs concentrated in each cm3 of tumour tissue is sufficient enough for the hyperthermia in human.

3. The best used MNPs are iron oxides magnetite (Fe3O4) and magnetite (γ -Fe2O3) because they are biocompatible magnetic nanoparticles. [15]

 

 

 

               Fig. Hyperthermia (thermal Delivery) by MNPs

 

6.4.4 Advantages of Hyperthermia

The hyperthermia is an advantageous technique in the following respects:

 

1. The heat is only applied at the targeted areas so it is not damaging for the other healthy tissues.

2. The nanoparticles are much more capable of absorbing the high power at high Magnetic field than the Micro sized particles

3. The size and shape of the MNPs are very important in the heating mechanism. So once the appropriate route of their synthesis is achieved, the hyperthermia can be brought to high levels to treat cancer. [20]

 

 

 

6.5. IMAGING USING THE MAGNETIC NANOPARTICLES

 

Another great biological application of the magnetic nanoparticle is the MRI.

 

6.5.1 Magnetic resonance imaging (MRI)

The principle of the MRI by MNPs includes the counterbalance between the small magnetic moment on a proton and large no of protons present in the biological tissues. [15]

 

6.5.2. MRI contrasts agents

 

5.2.2.1 Iron oxides Nanopartciles

The Iron oxides nanoparticles are the most commonly used MNPs used for MRI. They are used because they are less toxic, biodegradable, and chemically stable. It has been approved that they can be used in human applications as well. [10]

Especially the Iron oxides that are coated with Dextran are so biocompatible that they are excreted via liver after the treatment. These MNPs are taken up by the reticuloendothelial cells that include lymph nodes and bone morrow as well. So MRI then can be used to visualize any defect in these tissues. So, they have been employed to identify the lymph tumour and brain tumour etc. [15]

 

                           Fig. Iron Oxide Nanoparticles 

 

 

5.2.2.2 Cobalt Nanoparticles

The Co NPs offer a clear advantage over the Iron oxide nanoparticle that they have high room temperature saturation magnetization. This means that they can be used for the improved MRI as they have large impact on the relaxation of protons. However, the Co NPs are prone to oxidation so it becomes difficult to fabricate the water soluble Co NPs. [20]

 

6.5.3 Magnetic Particle Imaging (MPI)

 

In 2005 Gleich and Weizenecker from Philips Research in Hamburg introduced a new technique known as MPI (magnetic particle imaging). This includes the mechanism that in the presence of a large dc magnetic field, the magnetization curve becomes flat, and the harmonic signals disappear. So only the harmonic signals are received from that field-free point of the sample whereas all other signals are damped out. [16]

 

6.5.3.1 Biological applications of MPI

 

MPI technique offer no of biological applications such as:

1. MPI can be used to image those tissues that are quite underneath the skin such as the small intestine or vascular tissues.

2. MPI has single sided scanner unlike the MRI scanner that has the problem of specimen needing to be placed on the scanner. In addition, the single sided have shown the resonance of 1mm that is quite promising. [20]

 

6. 6 DIAGNOSTIC APPLICATION

(ISOLATION OF THE DESIRED COMPOUND USING MNPs  )

 

It includes the Magnetic solid phase extraction (MSPE). The basic mechanism behind this application is that the target is present in the suspension. The Magnetic adsorbent is added in the suspension and is mixed. The target gets adsorb on the Magnetic adsorbent. Later on, the Magnetic adsorbent is purified from the suspension by using the Magnetic separator and the target compound is purified and collected as well. The major example of MNPs involved in this is of Iron oxide nanoparticles. The advantage of using this technique is that the suspension is relatively stable, even in the absence of magnetic field, against the sedimentation. [20]

 

6.7. MONITERING OF GENE EXPRESSION BY MNPs

 

MNPs have been employed to monitor the gene expression. This is of importance because in the gene expression, certain receptors of cell walls are produced at high rate, as these receptors are later on, targeted by the Magnetic nanoparticles. It ultimately can help in differentiating the expressing and non expressing cells. [15]

 

                                 Fig. Gene Expression by MNPs

 

7 FUTURE OF MNPs FOR BIOLOGICAL APPLICATIONS

 

The future of MNPs is as very promising that shows that potential of MNPs to be used in various biological fields. Following are some of the techniques that are being tested for their proper implication in future.

 

7.1. Magnetic twisting Cytometry

This is being experimented that the binding of the ferromagnetic nanoparticles to the receptors of cell wall is a promising biological application as it can be used for various purposes. [21]

 

7.2. Magnetic Biosensing

Researches are being done to bind the magnetic nanoparticles with the specific molecules of the analyte for the detection of the target molecules. The changes in the proton relaxation times are determined.

[22]

 

7.3. Magnetic Nanoparticles and the Tissue culturing techniques

This is being experimented that MNPs can be used in the tissue culturing. For example, when the MNPs are attached on the cell wall, then upon the magnetic field application, they start specific growth biochemical reactions in the cell, by increasing the growth rate. [23]

 

 

 

 

8. CONCLUSION

 

Despite their all advantageous biological applications, the use of all the applications is not that much Market based. The reason is that it is quite a new technology. Several researches are made on the animals first and then tested on the humans. So, the scope of MNPs is very much broad when its limitations are overcome.