Dendrimer-Metal Nanocomposites

Abstract

Dendrimer metal nanocomposites are novel hybride materials that display unique physical and chemical properties as a consequence of the atomic/molecular level dispersion of inorganic and organic molecules. In their synthesis, dendrimers are used as templates to pre-organize metal ions followed by an in-situ reduction, which will immobilize and stabilize atomic domains of the reaction product(s). Size, shape, size distribution and surface functionality of these nanocomposites are determined and controlled by the dendritic macromolecules and may also be influenced by the encapsulated compounds. Solubility of these molecular nanocomposites is controlled by the polymer. Thus, it is possible to solubilize conventionally insoluble inorganic compounds in water or other solvents using dendritic hosts. Conceptually, these materials have enormous potential for applications such as catalysts or molecular devices.In this work, surface-modified poly(amido-amine) dendrimers were used to prepare {Cu(0)-PAMAM}, {Ag(0)-PAMAM} and {Au(0)-PAMAM} dendrimer-metal nanocomposites containing stable and solvent soluble zero valence metals. Characterization of the resulting nanocomposites has been carried out by TEM, UV-visible spectroscopy, and scattering techniques. Depending on the chemistry of ion preorganization in the dendrimer, internal (“I”), external (“E”) and mixed (“M”) type nanocomposite structures could be identified according to the varying location of the actual metal content.The effect of structural differences was found to be reflected in the optical properties of the nanocomposites.

Fabrication of {198Au0} radioactive composite nanodevices and their use for nanobrachytherapy

“…Hydrolysis of [AuCl 4 ] − is a complex process [35] that readily occurs in aqueous solutions of PAMAMs as the nitrogen ligands neutralize HCl, the hydrolysis byproduct. Reduction is usually performed either by adding external reducing agents such as N 2 H 4 [4] or NaBH 4 [6], or by utilizing the reductive nature of terminal groups of PAMAMs [36,37]. Reduction of Au 3+ ions by the PAMAM itself may be accelerated by applying UV-irradiation [38].…”

“…These organicinorganic hybrid nanoparticles are composed of very small and uniformly dispersed inorganic guest domains that are physically trapped within nanoscopic sized organic hosts [4][5][6][7][8][9]. Using PAMAM dendrimers as templates, composite nanoparticles can be fabricated with precise size, nearly monodisperse distribution, and with well-defined surface charge.…”

Advances of Cancer Therapy by Nanotechnology

“…There are more than 50 different types of dendrimers (13). Among them, polyamidoamine and poly (propylenemine) have been commercialized and used extensively as biomaterials in gene and drug delivery (14,15) and for nanoparticle encapsulation (16,17) in imaging (18,19).…”

Self Assembly and Optical Properties of Dendrimer Nanocomposite Multilayers

“…[43,[47][48][49][50] These silver-dendrimer complexes and nanocomposites are stable and soluble in polar solvents, such as water, methanol, etc. In preliminary experiments the solutions of silver-PAMAM complexes proved to be quite insensitive to light: one day exposure to daylight resulted in only approximately 50% conversion based on increase of intensity of the 420 nm surface plasmon (SP) peak in the visible spectra.…”

“…For example, non-linear optical behavior [47] and large optical limiting [51] (by factors up to 115 at 532 nm) was found for a solution of {Ag 0 } E external type DNCs. Laser-induced optical breakdown was also observed, which was later studied by acoustic methods.…”