NANOPARTICLES *
CHAPTER 5 CHAPTER 5
5.3 APPLICATIONS
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With this kind of theory, it can be seen that it can be used in many parts of biomedical applications.
It can separate rare tumor cells from blood and can be used to target the low-number cells. So it can lead to enhanced detection of materials in blood and processed technology for polymerase chain reactions.
Also, for the separation applications, it can be used in optical sensing, due to the high sensitivity of the magnetic nanoparticles. If the target material is the solid matrix, it can act as the surface to locate the target material and to increase the concentration.
5.3.1.1.1 Drug delivery
Compared to traditional chemotherapies, magnetic nanoparticles have the advantages of treating the target area more specifically. Due to the guide of the magnet, it can be delivered to the specific site and then release the drug. Since the drug is used only for the specific site, so it can reduce the dose amount, so that it will reduce the effect of the systematic side effect on the body.
Many researches have been done on this subject. As early as late 1970s, experiments have been done on rat tails since rat tails have simplest structure and cam be analyzed more convenient. And then more experiments spread to swine, rabbits, and rats. But due to the limitation of technologies, not much of experiment has been done on human being, the only progress on human are the trail I phase experi- ment. With more and more successful experiments on animals, it is believed that technologies will be more mature to affect human beings.
Fig. 5.14 shows the mechanism of drug delivery application of magnetic nanoparticles.
From Fig. 5.14, it can be seen that the drug is first coated with magnetic material and then injected into the body. The external magnet guides the nanoparticles into one specific site along the blood ves- sel. When it arrives at the target site, it can be attracted into the tumor tissue. It then releases the drug due to the change of the internal environment (such as the pH). In previous studies, much research has been done on rabbits (Pankhurst, Connolly, Jones, & Dobson, 2003). It shows no toxicity of the drug delivery group since the drug was delivered into the tumor directly for treatment. The whole process lasted 30 days and the result is encouraging and shows that magnetic nanoparticles can be used in this kind of drug delivery.
FIGURE 5.14
hypothetical magnetic drug delivery system in cross section.
From Pankhurst, Q., Connolly, J., Jones, S., & Dobson, J. (2003). Application of magnetic nanoparticles in biomedicine. Journal of Physics D: Applied Physics.
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5.3.2 APPLICATION OF METALLIC NANOPARTICLES
Metallic nanoparticles have different applications in different types of fields. These particles have struc- ture with optical and electronic properties. These particles can be used in electronic applications, as an example the positioning of individual molecules of lambda-DNA in an electrode gap (Sarma, 2003).
Metal nanoparticles have recently found to be applicable in catalysis. Haruta (2004) have discov- ered that supported gold nanoparticles are extremely catalytically active for carbon monoxide (CO) at the temperature much lower than room temperature, when the particle size of the gold is less than 5 nm. This finding is very efficient for nanocatalysts for many chemical reactions. The interfaces cre- ated between the gold nanoparticles with transition metal oxide supports, such as zirconia, iron oxide, titania, cerium oxide, and others, are attributed to account for the ultra-high catalytic activity and selec- tivity. However, the activity of these metal clusters (in particular, gold nanoparticles) in a reaction is very much dependent on the method of preparation, particle size, shape, dispersion, and the type of supported metal oxide (Yu et al., 2008).
One of the most applicable metal nanoparticles is gold nanoparticles which have been used in dif- ferent fields. These applications are enzymatic biosensor, genosensors, immunosensors, and electro- catalytic chemosensors (Fredy, 2008).
5.3.3 APPLICATION OF POLYMER NANOPARTICLES
Unique properties for polymers that include their thermal behavior, processability, and ability to assemble into ordered structures would offer potential for compatibilizing nanocrystals, directing their assembly, and providing a mechanism for charge transports. The confirmation of theoretical predictions for spatial distribution for nanoparticles inside polymer hosts would depend on interactions between ligand periphery and polymer environment (Skaff et al., 2008).
A nonexhaustive review of some recent advances for semiconductors; where four major approaches have designed to integrate semiconductor nanoparticles into polymer matrices (Skaff et al., 2008):
● Simple mixing of nanoparticles with functional or nonfunctional polymers
● Growth of nanoparticles from organometallic precursors
● Chain-end attachment of polymers to nanoparticle surfaces, either by mixing end functional polymers with the nanoparticles or by growing polymers radially outward from nanoparticle surface
● Assembling nanoparticles in polymer templates, where the structure of template dictates the assembly of nanoparticles.
The integration of nanoparticles into polymers is one of the most significant theoretical and experi- mental interests in the polymer and engineering communities.
Inorganic fillers have been used for some time in conjunction with organic polymer materials, largely in an effort to enhance the physical and mechanical properties over those of the polymers alone.
Polymer-Nanoparticle Composites Part 1 (Nanotechnology), 2010.
In the 19th century, huge research efforts were done by Charles and Nelson Goodyear, the pioneers in the chemistry of rubber, who had showed that vulcanized rubber can be toughened significantly by the addition of Zinc Oxide (ZnO) and Magnesium Sulfate (MgSO4). Also, Leo Baekeland investigated
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