Nanoparticles surfaces characteristics

In addition, our FTIR and XPS analyses of the nanoparticle samples showed that the removal of the capping shells from the surface of the bimetallic nanocrystalline core was very effective by the calcination treatment. The vibrational bands characteristic of the capping molecules in the C-H stretching region (VaCCHs) 2955 cm VjlCHs) 2872 cm Va(CH2) 2917 cm Vj(CH2) 2848 cm ) were not detected by FTIR for samples after calcination. XPS analysis of the calcined samples also showed no bands that can be associated with the presence of sulfur species (S(2pl/2) 163.8 eV, and S(2p3/2) 162.5 eV) on the nanoparticles surface. 

The chemical reactivity of nanoparticle surfaces, presents interesting additional opportunities for evaluating nanoparticle surface composition. Some noble metal particles (Pd and Au in particular) can be extracted from the PAMAM dendrimer interiors into organic solution with long-chain thiols [37]. The resulting nanoparticles, referred to as Monolayer Protected Clusters (MPCs), retain the size distributions and spectroscopic characteristics of the original DENs and allow for recycling the expensive dendrimer [16]. 

Luck, M., Paulke, B.-R., Schroder, W., Blunk,T.,and Muller, R. H., Analysis of plasma protein adsorption on polymeric nanoparticles with different surface characteristics. J. Biomed. Mat. Res. 39,478 - 485 (1998). 

As mentioned earlier, surface characteristics of the nanoparticles are of primary importance for the interaction of the nanoparticles with the surrounding... 

The hydrophilicity of the nanoparticle surface can be evaluated by hydrophobic interaction chromatog-raphy. This technique, based on affinity chromatography, allows a very rapid discrimination between hydrophilic and hydrophobic nanoparticles. The nanoparticles are passed through a column containing a hydrophobic interaction chromatography gel. The nanoparticles that are retained by the gel and only eluted after the addition of a surfactant are considered as hydrophobic, whereas the nanoparticles that do not interact with the gel and that are directly eluted from the column are considered as hydrophilic. Apart from the hydrophobic interaction chromatography, the field flow fractionation techniques recently appeared to present interesting potential for the characterization of nanoparticles with different surface characteristics. ... 

Nanoparticles are discrete nanometer (10 m)-scale assemblies of atoms. Thus, they have dimensions between those characteristic of ions (lO m) and those of macroscopic materials. They are interesting because the number of atoms in the particles is small enough, and a large enough fraction of them are at, or near surfaces, to significantly modify the particle s atomic, electronic, and magnetic structures, physical and chemical properties, and reactivity relative to the bulk material. Nanoparticle surfaces themselves may be distinctive. Particles may be terminated by atomic planes or clusters that are not common, or not found, at surfaces of the bulk mineral. These, and other size-related effects will lead to modified phase stability and changes in reaction kinetics. 

The catalytic nanoparticles possess unique catalytic properties due to their large surface area and considerable number of surface atoms leading to an increased amount of active sites [1-3]. The catalytic properties of nanoparticles depend on the nanoparticle size, nanoparticle size distribution, and nanoparticle environment [4]. Moreover, the surface of nanoparticles plays an important role in catalysis, being responsible for their selectivity and activity. As was demonstrated in the last decade, the formation of nanoparticles in a nanostructured polymeric environment allows enhanced control over nanoparticle characteristics, yet the stabilizing polymer (its functionality) is of great importance, determining the state of the nanoparticle surface [5-8]. 

Chemical properties. Increased surface area increases the chemical activity of a material. For example, a metal in bulk form may not be a catalyst the same metal in nanoscale particles may be an excellent catalyst. Important research measures pH, oxidation and reduction characteristics, and surface properties. An important concern is how nanostructures can change the chemical mechanisms of such key processes as hydrolysis and catalytic responses as well as differing hydrophobic, hydrophilic, or amphipathic surface properties. The atomic structures of high-energy surface sites and various types of defect sites on nanocrystals are needed, as well as their effect on reactivity. An initial priority is to gain exploitable knowledge of the physical chemistry of various nanoparticle surfaces. 

Nanoparticles, due to their unique properties and surface characteristics, can protect the drug from P-gp, cytochrome P-450, and the destructive factors in the GI tract and can increase the permeability of drugs through the gastrointestinal barrier [62]. These reports confirm that nanoparticulate systems with unique properties can increase the transport of many compounds across the GI barrier. Numerous examples of nanoparticles being used to deliver antibodies, cytokines, other proteins, and drug substances into specific cells or tissues with good safety and trustworthiness are reported in the literature [49, 71,85]. 

The fate of injected nanoparticles can be controlled by adjusting their size and surface characteristics to effectively deliver drug to the targeted tumor tissue nanoparticles must have the ability to remain in the bloodstream for a considerable time without being eliminated (Cho et al. 2008). 

Plasma treatment of nanoparticles for nanofluids can be obtained by plasma treatment using low-temperature plasmas. The diamond nanoparticle surfaces, for example, can be modified by the low-temperature plasmas of methane and oxygen mixtures, which can improve their dispersion characteristics including dispersibility and suspension stability in water for nanofluid. Plasma treatment of diamond nanoparticles with selected plasma chemistry imparted various functional groups on the particle surfaces and tailored... 

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