Dendrimers encapsulated gold nanoparticles

Y.G. Kim, S.K. Oh, R.M. Crooks, Preparation and Characterization of 1-2 nm Dendrimer-Encapsulated Gold Nanoparticles Having Very Narrow Size Distributions, Chemistry of Materials 16, 167, 2004. 

Y. Haba, C. Kojima, A. Harada, T. Ura, H. Horinaka and K. Kono, Preparation of poly(ethylene glycol)-modified poly(amido amine) dendrimers encapsulating gold nanoparticles and their heat-generating ability. Langmuir, 23,5243-5246 (2007). 

Kim, Y.-G., Oh, S.-K. and Crooks, R.M. (2004) Preparation and characterization of l-2nm dendrimer-encapsulated gold nanoparticles having very narrow size distributions. Chemistry (f Materials, 16, 167 72. 

The emission of the metal particles may thus originate from a band-to-band transition in the metal particle, which occurs at about 516 nm for gold [60, 119]. As stated above, the nature of the interaction of the dendrimer (PAMAM) host is still uncertain, there could be very strong electrostatic interactions that may play a part in the enhancement of the metal particles quantum efficiency for emission. However, one would expect that this enhancement would result in slightly distorted emission spectra, different from what was observed for the gold dendrimer nanocomposite. Further work is necessary to completely characterize the manner in which the dendrimer encapsulation enhances the emission of the metal nanoparticles. With further synthetic work in preparation of different size nanoparticles (in other words elongated and nonspherical shape particles, including nanorods) it may be possible to develop the accurate description of a... 

The possibility of using electrostatic charge attraction has been exploited in the preparation of gold dendrimer encapsulated nanoparticles (DENs), which under appropriate conditions can be fully distributed along the surface of monodispersed MWCNTs (Fig. 3.21) [103]. 

Photothermal ablation therapy with metal nanoparticles is further enhanced with these particles being encapsulated inside dendrimers that improve biocompatibility and retention and facihtate surface modifications. For example, gold nanoparticles have been entrapped in G5 PAMAM dendrimers with fohc acid on the surface for targeting malignant tumors (Shi et al. 2007). 

While they are not strictly redox-containing dendrimers. Crooks and Zhao have encapsulated platinum and other metallic nanoparticles inside PAMAM dendrimers. The catalytic properties of these materials have been examined using cyclic voltammetry, and it was found that a gold electrode, modified with large hydroxyl-terminated PAMAM dendrimers containing clusters of 60 platinum atoms, was readily able to catalyze O2 reduction [98]. Similar results have been reported for palladium clusters encapsulated in the same hydroxyl-terminated PAMAM dendrimers [99]. 

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