Modification of Nanoparticles

To improve or change the dispersion of nanoparticies, enhance the surface activity of nanoparticies, generate new physical, chemical, and mechanical properties and new features on the surface of the particles, and improve the compatibility between the nanoparticies and other materials, physical or chemical methods are needed to alter the structure and the surface state of nanoparticies. 

In order to control the surface of nanoparticies and to apply those nanoparticies in industry and biomedicine, an in-depth understanding of the basic properties of the nanoparticies is indispensable. 

In order to prepare a stable magnetic fluid, the surface of Fe304 nanoparticies was modified with different surfactants in our research [13], as that did for silica nanoparticies [14]. 

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The conjugation of vitamin B12 has been shown to increase oral bioavailability of peptides, proteins, and particles.44 46 62,63 Russsell-Jones and coworkers have attempted to exploit RME of vitamin B12 for the enhanced intestinal uptake of macromolecules such as luteinizing hormone—releasing factor (LHRH), granulocyte colony-stimulating factor, erythropoietin, and a-interferon.44,46,63 Also, they demonstrated that surface modification of nanoparticles with vitamin B12 can increase their intestinal uptake.44,62 The extended applications of this unique transport system, however, appear partially hampered by its limited uptake capacity. In human being, the uptake of vitamin B12 is only 1 nmol per intestinal passage. 

In numerous works dealing with the combination of nanoparticles and FR compounds, surface modifications of nanoparticles were only aimed to promote good dispersion of the nanoparticles into the polymer matrix (with intercalated or exfoliated morphologies for layered silicates as nanoparticles), even in the presence of the usual FRs, for example ammonium polyphosphate (APP) or magnesium hydroxide (MH). The initial aim was to combine the individual effects of each component to achieve strong synergistic effects. 

Moreover, the development of new strategies for surface modifications of nanoparticles with compounds having FR activity could provide a new field of research on FR systems. The use of novel phosphorus-, nitrogen-, or halogen-containing modifiers, instead of alkylammonium ions, for layered silicates seems promising. FR action conferred by the surface modifier can be combined with action due to composite morphology, particularly when the host polymer is a polymer blend instead of a pure polymer. 

Figure 13.15 Schematic representation of synthesis and surface modification of nanoparticles [54]. (Reproduced with permission from W.J. Rieter et al., Surface modification and functionalization of nanoscale metal-organic frameworks for controlled release and luminescence sensing, Journal of the American Chemical Society, 129, 9852-9853, 2007. 2007 American Chemical Society.)...

Tan, J.S. Butterfield, D.E. Voycheck, C.L. Caldwell, K.D. Li, J.T. Surface modification of nanoparticles by PEO/PPO block copolymers to minimize interactions with blood components and prolong blood circulation in rats. Biomaterials 1993,14, 823-833. 

Other materials have also been used to produce modified nanoparticle films to detect organic vapors. Murray and coworkers [26] showed that the modification of nanoparticles with a carboxylate ligand, which can complex with a metal ion, Cu2 +,... 

Storm, G. Belliot, S.O. Daemen, T. Lasic, D.D. Surface modification of nanoparticles to oppose uptake by the mononuclear phagocyte system. Adv. Drug Deliv. Rev. 1995, 17, 31-48. 

Surface modification of nanoparticles in some cases allow the formation of stable dispersions in liquid hydrocarbons [57], If molybdenum sulphide nanoparticles are considered as friction-modifying additives for liquid lubricants, then a whole range of new possibilities appears. The action of tribologically active additives as nanoparticles has been proposed as in Fig. 8.6. 

Fig. 11.5 Possible methods for the modification of nanoparticles for improved handling and processing [11.2]...

For instance, maleic copolymers with different contents of galactose moieties and dodecyl chains were synthesized and used as both a stabilizer and a surface coating for the preparation of poly(s-caprolactone) nanoparticles by the emulsification-diffusion technique. The smface modification of nanoparticles was confirmed by -potential measurements. Nanoparticles were also shown to be recognized by a galactose-specific lectin, demonstrating the presence of galactose rmits on the particle surface [69],... 

In this work, we introduce nanoparticle/polymer matrix composites to the readers, in combination with our research experience. In order to fully describe the nanoparticle/polymer matrix composites, we will discuss the synthesis and modification of nanoparticles and the preparation, characterization, and applications of nanoparticle/polymer matrix composites. 

Because the commercially available nanoparticles stick to each other and form large agglomerates, simple addition of these agglomerated nanoparticles into polymers would result in composites with properties even worse than the unfilled version. Therefore, surface modification of nanoparticles has to be made in advance to decrease par tides/par tides interaction and increase particles/polymer matrix interaction. 

The surface modification of nanoparticles to improve their targeting ability ... 

CrystallographicaUy speaking, particle surfaces consist of physical defects that can act as luminescence-quenching sites. Owing to the high specific surface area, nanoparticles tend to have much lower luminescence intensity than micron-sized particles. However, surface modification of nanoparticles can be used to enhance or tailor the luminescence properties of nanoparticles. ... 

The modification of nanoparticles has been achieved by spontaneous grafting on a number of surfaces of metallic and metallic oxides (in this case, the bond is therefore an O-aryl bond). Modification of the surface of carbon nanotubes by diazonium salts permits the unbundling of CNTs produced by chemical vapor deposition [236],... 

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