Preparation of Ag nanoparticles in the presence of low generational poly(ester‐amine) dendrimers

Abstract

Stable Ag nanoparticles of 10-20 nm were prepared by reduction of AgNO 3 with NaBH 4 in water solution in the presence of low generational hydroxylterminated poly(ester-amine) dendrimer G1.0 (OH) 16 and amino-terminated poly(ester-amine) dendrimer G1.5 (NH 2 ) 8 by optimizing preparation conditions. UV-vis absorption spectra and transmission electron microscopy were adopted to characterize absorption properties of Ag þ /dendrimer complex, Ag/dendrimer nanocomposite aqueous solutions, and the morphology of the formed Ag nanoparticles, respectively. The results showed that the size of the Ag particles increased with Ag þ /dendrimer molar ratio, and the size of Ag nanoparticles in Ag/G1.0 (OH) 16 system was larger than that of Ag nanoparticles in Ag/G1.5 (NH 2 ) 8 system, while the polydispersities of two systems were similar. Moreover, the Ag/G1.5 (NH 2 ) 8 nanocomposite system was more stable than the Ag/G1.0 (OH) 16 one.

Dendrimers as Encapsulating, Stabilizing, or Directing Agents for Inorganic Nanoparticles

“…TEM is the most widely used method for characterization of the shape, size, and size distribution of NPs by observing and processing TEM images. ,,,− However, to allow meaningful quantitative data, hundreds of NPs have to be processed. One should also take into consideration if any aggregation is observed on a TEM grid.…”

Dendrimer-encapsulated silver nanoparticles as a novel electrochemical label for sensitive immunosensors

“…Therefore, we concentrated our efforts on the synthesis, characterizations and exploitation of Ag-DNCs in the electrochemical stripping analysis although similar results could certainly be obtained with other metals as well. As reported by others, stable Ag-NPs may be prepared inside of PAMAM dendrimers with surface carboxyl, hydroxyl groups as well as with amino groups (Ottaviani et al, 2002;Xu et al, 2007;Balogh and Tomalia, 1998). The first two cases predominantly consist of NPs embedded in the interior of the polymer scaffold due to the conjugation of Ag + and tertiary amines located inside of the PAMAM dendrimer prior to their reduction (type 'I' NPs) (Balogh and Tomalia, 1998), whereas dendrimers with surface amino groups aggregate easily, probably due to the silver conjugation with the terminal amines at neutral and basic pH and the subsequent formation of the peripheral NPs during their synthesis (type 'E' NPs).…”

“…The relatively free and accessible space inside and the flexible modulation of dendrimer properties is the reason for their potential use as nanoscaffolds for targeted drug delivery and diagnosis (Kobayashi et al, 2000;Kobayashi et al, 1999). The most common process of nanoparticle synthesis is usually based on a chemical complexation of a dendrimer with metal salt and its subsequent reduction by UV irradiation (Esumi et al, 1997;Zhao et al, 1998) or, more frequently, by addition of NaBH 4 (Endo et al, 2005;Xu et al, 2007). The resulting metal nanoparticles are formed either in the dendrimer interior or its periphery depending on the metal used, the type of reaction core and on the peripheral functional groups of the dendrimer.…”

The synthesis and characterization of biotin-silver-dendrimer nanocomposites as novel bioselective labels

“…A common condition which has to be respected during the preparation of a stable nanoparticle is the capping of the nanoparticles with protective surfactants or polymers. Among others, the poly(amidoamine) (PAMAM) dendrimers were extensively studied during the last decade as efficient host-or surface-stabilizing molecules for nanometersized metal nanoparticles (Balogh et al 1997, 1999, Endo et al 2005, Esumi et al 1997, Niu et al 2003, Ottaviani et al 2002, Zhao et al 1998, Xu et al 2007.…”

“…It has been shown that dendrimers act as an excellent template for the fabrication of metal nanoparticles due to their ability to form complexes with a variety of metal ions (Balogh et al 1997, Endo et al 2005, Esumi et al 1997, Ottaviani et al 2002, Zhao et al 1998. The process of nanoparticle synthesis is usually based on a chemical complexation of a dendrimer with a metal salt and its subsequent reduction by mixing with a reductant solution such as NaBH 4 (Endo et al 2005, Xu et al 2007 or by UV irradiation (Esumi et al 1997, Zhao et al 1998. The resulting dendrimer nanocomposites (DNC) show many excellent and unique physical and chemical properties due to atomic/molecular level dispersion of the inorganic guest and organic molecular host (Balogh et al 1997).…”