Nanotech News

October 31, 2005

New Silver-Dendrimer Nanoparticles Enable Intracellular Detection

Nanoscale dendrimers, a type of spherical polymer, have shown promise as multifunctional delivery agents for anticancer drugs and imaging agents (see earlier story). Now, investigators at the University of Michigan and the Roswell Park Cancer Institute have developed silver-containing dendrimers that can function as non-toxic intracellular molecular beacons that should be capable of labeling individual biomolecules within a cell.

Reporting its work in the journal Nano Letters, a team led by Lajos Balogh, Ph.D., of the Roswell Park Cancer Center, and James Baker Jr., M.D., of the University of Michigan, describe how they construct dendrimer nanoparticles with diameters ranging from 3 to 7 nanometers, each loaded with 25 atoms of silver. The silver atoms, trapped within the branches of the dendrimer, fluoresce with sufficient brightness that a single silver-loaded dendrimer nanoparticle can be positioned accurately within a cell using a standard confocal fluorescence microscope.

In vitro assays showed that the surface properties of the new materials played a significant role in determining if the dendrimer-silver nanocomposites were toxic to cells. The results were identical to those obtained using the analogous dendrimers that did not contain silver, and the investigators noted that this was the first demonstration that the biological properties of a dendrimer nanocomposite were determined by the dendrimer. In their paper, the researchers also present data on the physical characterization of four different dendrimer-silver nanocomposites.

This work is detailed in a paper titled, “Silver/dendrimer nanocomposites as biomarkers: fabrication, characterization, in vitro toxicity, and intracellular detection.” This paper was published online in advance of print publication. An abstract is available through the journal’s website.
View abstract.