US Patent 7914588 - Synthesis of fluorescent metal nanoclusters

http://www.freepatentsonline.com/7914588.html

This patent is from Los Alamos National Security teaches a method of preparing biomolecule taggants based on metal nanoparticles. Claim 1 reads:

1. A method for preparing fluorescent nanoclusters, comprising:

mixing an aqueous solution of a dendrimer template and a metal precursor in a dark environment at a temperature of 4 degrees Celsius that is cold enough to prevent the substantial formation of non-fluorescent metal nanoclusters and nanoparticles but allow the formation of a complex between the dendrimer template and metal from the metal precursor, whereby a complex forms between the template and metal from the metal precursor; and

increasing the temperature, whereby the complex is reduced and fluorescent metal nanoclusters are produced.