Core nanoparticles

In a different way, metallic-core nanoparticles [346-349] (prepared cf. Section 3.10) equipped with biocompatible coats such as L-cysteine or dextrane may be exploited for highly efficient and cell-specific cancer cell targeting, i.e., for improving diagnosis and therapy of human cancer. In a recent proof-of-principle experiment an unexpectedly low toxicity of the L-cysteine-covered cobalt nanoparticles was demonstrated [433] For diagnostic purposes, it is expected to use the advantageous magnetic properties of the metallic-core nanoparticles to obtain a contrast medium for MRI with considerably increased sensitivity, capable to detect micro-metastases in the environment of healthy tissues [434 37]. 

Fig. 29 shows the spectra of the LaP04 Eu3+ (5%) core nanoparticles before a LaPCU shell was grown onto them. Site-selective emission spectra for the excitation at 17 294, 17 286, and 17 279 cm-1 correspond to the L-, M-, and H-sites in the bulk counterparts respectively. For comparison, no other site than L-, M-, and H-sites were identified in the site-selective emission spectra of Eu3+ LaPCU/LaPCU core-shell nanoparticles over the whole excitation range (17 249-17294 cm-1), indicating that these three sites are located in the interior of... 

The Exploration of Biomedical Multimodality in Small Solid Core Nanoparticles... 

Fig. 6.21 Stracture of the silica-core nanoparticles with grafted sulfonated oligomers (a) and physical crosslinking with Nation (b) (From Ref. [50] with permission)...

Monomers that can be polymerized onto the core nanoparticles include those that upon polymerization can exhibit an inherent conductivity. A variety of copolymers or derivatives of poly(aniline) (PANI), poly(pyrrole), poly(thiophene), PEDOT, and poly(p-phen-ylene vinylene) can be used. 

To prevent the flocculation of the core nanoparticles, the dispersion contains a steric stabilizer, such as PVP, poly(ethylene oxide), poly(vinyl alcohol), poly(styrene sulfonate), hydrox ropyl cellulose, or methyl cellulose. 

In addition to the preparation of microgram samples on the RDE tip, this approach has been modified to scale up to gram-size quantities using an electrochemical cell where core nanoparticles are dispersed as powder in the electrolyte and a Ru02-coated Ti cylinder acts as the working electrode (WE) [9],... 

Core-shell catalyst materials may also be prepared by non-electrochemical routes. Core-shell nanoparticles may be produced in solutimi using colloidal methods, by sequential deposition of the core and shell components [33], or Pt layers may be deposited chemically or via displacement reactions onto preprepared core nanoparticles, but in cmitrast to approaches described in Sect. 19.3.1, no applied potential is required typically core particles or colloidal core-shell particles are deposited onto carbon supports. 

Choi I, Ahn SH, Kim JJ, Kwon OX (2011) Preparation of PtjiieirPd core nanoparticle with electroless deposition of copper for polymer electrolyte membrane fuel cell. Appl Catal B Environ 102 608-613... 

Pimpha N, Sunintaboon P, Inphonlek S et al (2010) Gene delivery efficacy of polyethyleneimine-introduced chitosan shell/poly(methyl methacrylate) core nanoparticles for rat mesenchymal stem cells. J Biomater Sci Polym Ed 21 205-223... 

Gref R, Luck M, Quellec P, Marchand M, Dellacherie E, Hamisch S, et al. Stealth corona-core nanoparticles surface modified by polyethylene glycol (PEG) influences of the corona (PEG chain length and surface density) and of the core composition on phagocytic uptake and plasma protein adsorption. Colloids Surf B Biointerfaces October 1, 2000 18(3 ) 301-13. 

In another example, highly monodispersed (M,/M <1.01) core-shell nanoparticles with monodispersed silica core nanoparticle, and a metal oxide (Ti02 or Zr02) (Si02/Ti02, Si02/Zr02) with a diameter of... 

Table 1 Comparison of specific Pt mass and PGM mass activities of PtML electrocatalysts on different core nanoparticles for the ORR measured by the kinetic currents at 0.9 V. The values for conventional Pt/C electrocatalyst are given for comparison...

Alginate-coated chitosan core nanoparticles loaded with rabeprazole, an antiulcer agent which is chemically instable in the stomach, were developed using water-in-oil (W/O) nanoemulsion technique. The drug permeation from the prepared NP was significantly higher and controlled RP release compared to the pure drug [106],... 

In addition, high-resolution TEM images showed layers of the peptide surrounding the core nanoparticle. 

Sarmento and co-workers used alginate-cored nanoparticles that had been complexed with chitosan to produce a delivery system for insulin. These particles are negatively charged, and can complex insulin with 70% efficiency. Release of the protein is triggered by a change in pH. These particles have been orally administered to diabetic rats, and the serum glucose level has responded well [58]. 

A number of authors have investigated the use of Pt/Au alloy and Pt-decorated Au (shell-core) nanoparticles as catalysts for formic acid oxidation in acid solution. Park et al. [94] described chemical reduction techniques for preparing Pt/Au alloy, pure Au, and Pt-modified Au nanoparticles on carbon supports. The Pt/Au alloy and Pt-modified Au nanoparticles showed higher activities for formic acid oxidation than pure Pt, especially at low potentials in the region of 0.2 V. These results of Park et al. [94] are supported by the data of Kristian et al. [95]. Although the detailed mechanism of operation of these new electrocatalysts remains to be fully clarified, the combination of improved performance, combined with a substantial reduction in the use of Pt, are attractive features of Pt-decorated Au nanoparticle electrocatalysts from a fuel cell viewpoint. 

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