Core-shell NPs

For example, Mandal et al. have reported the synthesis of Au core-shell NPs containing a gold core and poly(methyl methacrylate) (PMMA) shells by surface-confined living radical polymerization on gold nanoparticles. The synthesis of Au NPs has been carried out in the presence of 11-mercaptoundecanol (MUD) and subsequent esterification with 2-bromoisobutyryl bromide (BIB). Atom transfer... 

Bifunctional biolabels with magnetic and luminescent properties are highly desirable for in vitro and in vivo bioimaging. There are several strategies to use NPs to comprise such biolabels, such as core/shell NPs, for example, the magnetic cores of iron oxide doped with cobalt and neodymium and luminescent shells of Gd203 Eu (Dosev et al., 2005,2007). 

Au coated Cu core-shell NP label on DNA probe ASVofCu +atGCE CoUtoxin gene 24 bp 5.0 pM [34]... 

Core-shell NPs exhibit unique properties with several possible applications. In the case of fluorescent saniconductor NPs, core-shell NPs help to increase the robustness and enhance the photoluminescence quantum yield as well as the probability of radioactive recombination. NPs with magnetic, plasmonic and semi-conducting properties can be used as cores or shells for manipulating the properties of these hybrid structures. Properties of either component within the hybrids (core-shell NPs) can be modulated through a conjugating component or interface. 

Core-shell NPs based on metallic ReOj NPs have been prepared with metallic shells as in ReOj-Au and ReOj-Ag by the reduction of metal salts over ReOj NP seeds. ReOj-SiO and ReOj-TiO are prepared by the hydrolysis of the organometal-lic precursors over ReOj NPs [83]. Figure 13.8 shows TEM images and ultraviolet... 

UV)-visible spectra of ReOj-Au and ReOj-TiO nanocrystals. Cu-CUjO core-shell NPs of different shapes are obtained on a H-terminated Si(lOO) substrate using CuSO 5HjO and NaClO as electrolytes [84]. 

Peng et al. [85] report the synthesis of CdSe/CdS NPs with core diameters ranging from 2.3 to 3.9nm with a shell thickness up to three monolayers. Their results indicate that in the excited state the hole is confined to the core and the electron is delocalized throughout the entire structure. ZnSe-CdS core-shell NPs are prepared via the traditional pyrolysis of organometallic precursors. The two-step synthesis involves the fabrication of 4.5-6nm ZnSe seeds followed by a subsequent deposition... 

Eosin-doped core-shell NPs (Ag Si02 Si02+EiTC)... 

Iron oxide NPs can be enclosed in a shell (core-shell NPs), such as dextran, lipids, or silica. The porosity of silica allows noncovalent entrapment of many other kinds of probes, such as rhodamine dyes and inorganic complexes, or covalently conjugating probes and/or targeting functions. They can also be doped with other ions, such as luminescent Tb " or Co " in ferrite NPs. 

Magnetic NPs composed of more than one type of atoms found only in strictly defined areas of the material (e.g., gold and silver atoms in Au [core]/Ag [shell] NPs). The core/shell NP system contains one type of atom located within the inner sphere (core), while others form the outer layer (shell) of the particle (Zhang et al. 2010). 

Among metal oxide compositions, the chemistry of silica is the most widely studied and weU established, from the classical Stober synthesis of a silica sphere [23] to the recently developed surfactant-mediated synthesis of mesoporous silica [24, 25]. These developments were mainly enabled by the availability of stable silica precursors, their controllable hydrolysis and condensation, and the stable oxidation state of silica. Based on previously established chemistries, sol-gel or microemulsion methods were used to synthesize silica-shell-based core-shell NPs. 

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