Credit: © 2007 Wiley

Large organic molecules that possess highly branched structures, such as dendrimers and so-called hyperbranched polymers, have generated a significant amount of interest in the scientific community because of their potential applications, ranging from drug delivery to chemical catalysis. By attaching reactive groups to the ends of the numerous branches in these compounds, each individual molecule can be zipped together through a series of crosslinking reactions to form more compact and rigid structures.

Now, a team of chemists led by Steven Zimmermann at the University of Illinois at Urbana in the US and Rainer Haag from the Freie Universität Berlin in Germany have made dendrimers and hyperbranched polymers from glycerol that can be zipped up to form organic nanoparticles1. Once made, these materials can be further modified through chemical reactions to increase their stability and make them water soluble. As the nanoparticles contain a large number of oxygen atoms in their molecular framework, they are ideal candidates to bind to positively charged ions and this is demonstrated for metals, such as caesium and potassium, as well as organic species such as ammonium and guanidinium ions.

The efficient synthesis developed by Zimmerman and Haag not only enables the formation of crosslinked organic nanoparticles in much larger amounts than previously possible, but the ability to tune their solubility and produce materials that can dissolve in water offers new avenues to explore in terms of their potential applications.