CdSe/ZnS core-shell nanoparticles

Figure 8.7 Top Effect of density on the optical bandgap for aerogels prepared from naked CdSe nanopaiticles and CdSe-ZnS core-shell nanoparticles. Bottom CdSe-ZnS core-shell aerogel and xerogel monohths under normal (left) and UV (right) illumination. The native aerogel and xerogel are orange under normal hght and fluorescent green under UV stimulation.

CdSe-Based Nanoparticles. 1-Hexadecylamine capped CdSe nanoparticles or CdSe/ZnS core-shell nanoparticles in a polymer composite comprising PVK and l-(2-ethylhexyloxy)-2,5-dimethyl-4-(4-nitrophenylazo)-benzene as chromophore serve as sensitizers. " ... 

Figure 17.11. A. Photos of CdSe aerogels (large monolith) and xerogels (small monolith) under ambient (left) and UV (right) illumination B. Optical absorption data [black, converted from diffuse reflectance) and photo-luminescence [green) for CdSe/ZnS core/shell nanoparticles and corresponding aerogels and xerogels. Reproduced with permission from J. Am. Chem. Soc., 129 1840-1841 (2007). Copyright 2007 American Chemical Society.

Fig. 6 CdSe/ZnS core/shell nanoparticles functionalised with tri-antennaty. galactoside-capped dendron.

Figure 1.24 Schematic silica encapsulation of Au nanoparticles (left) and CdSe/ZnS core shell AMP quantum dots. Reprinted with permission from Ref (69) 2004, American Chemical Society.

The preparation of both, the particles themselves and the protective surface layer, has direct influence on their cytotoxicity. It is common belief that in the case of core/shell nanoparticles, properly prepared, close shell or multiple shells such as ZnS/Si02-shells prevents the leakage of toxic elements and thus makes cytotoxicity unlikely. Naturally, a better solution is to avoid cytotoxic materials in the first place. QDs, for example, can be synthesized without utilization of any class A or B elements InP/ZnS QDs have photophysical properties comparable to those of CdSe-based systems [43, 93]. Principally, whenever a new approach for QD synthesis or coating is used or if the QDs are applied in an extreme environment that could compromise their integrity, it is recommended to assess their cytotoxicity. 

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