I was reading about a drug designed by a company called: GlycoSyn. The drug is a topical antiviral compound called VivaGel, which is active against multiple infectious viruses such as HIV, chlamydia, herpes simplex virus, hepatitis B. This product is a water based dendrimer microbicide. Dendrimers are like microscopic balls with hooks that are build piece by piece, tiny balls with a dense network of branches that present a polyvalent arrays to receptors. It would be fantastic to build a drug that could be ingested and that could target a combination of infectious viruses. Any ideas about companies developing these drugs?

DENDRIMERS BRANCH OUT
Once considered little more than curiosities, these treelike molecules bear fruit with pharmaceutical, biotech, and polymer science applications


BRANCHING OUT Snapshots in the growth of a fifth-generation PAMAM dendrimer


VIRAL WARFARE The dendrimers (ball-and-stick structures) in VivaGel prevent HIV infection by binding to receptors on the virus's surface (orange). This interaction keeps HIV from infecting T cells.



BETHANY HALFORD, C&EN WASHINGTON


Dendrimers--treelike macromolecules with branching tendrils that reach out from a central core--have a way of grabbing scientists' imaginations. With dendrimers and dendritic polymers now playing key roles in new technologies and the first dendrimer-based pharmaceutical poised to enter the market as early as 2008, dendrimer scientists are hoping to snare profits as well.

Dendrimer research has been slowly but steadily gaining ground since the late 1970s, when scientists like Fritz Vgtle, at the University of Bonn, in Germany, and Donald A. Tomalia, then working for Dow Chemical in Midland, Mich., started to build the first of these branching molecules. A keyword search for "dendrimers" and "dendritic polymers" shows that the number of dendrimer-related papers published has grown from a handful in the early 1990s to nearly 1,000 papers in 2004 alone.

Researchers have made all manner of dendrimers: graphitelike dendrimers, light-harvesting dendrimers, dendrimers with cross-linked surfaces, dendrimers that self-destruct. Scientists have used the hollow cavities deep within the branching structures to hold metal nanoparticles, drugs, and imaging agents. Dendrimer researchers seem limited only by their creativity and, of course, the relatively high cost of making the dendrimers.

The macromolecules are constructed around a simple core unit. Each successive reaction introduces a new "generation" of branching. But as the molecules grow, the cramped conditions at the dendrimer's periphery lead to longer reaction times and more complicated mixtures of products from which the desired dendrimer has to be fished out. This means that dendrimers don't necessarily come cheap. Three hundred milligrams of a seventh-generation polyamidoamine, or PAMAM, dendrimer costs about $600.

NOT EVERYONE agrees that the cost of dendrimers is too high, however. "There are two myths about dendrimers," according to Sonke Svenson, a senior scientist at Dendritic NanoTechnologies in Mount Pleasant, Mich. "The first myth is that dendrimers in general are too expensive for commercialization, and the second is that the technology has been around for 20 years with no applications."
Svenson had these myths in mind when hammering out the scientific program of last month's Fourth International Dendrimer Symposium (IDS-4), held at Central Michigan University in Mt. Pleasant, with the meeting's other organizers--Tomalia, currently the president and chief technical officer at Dendritic NanoTechnologies; and professors Jean M. J. Fréchet of the University of California, Berkeley, and J. Fraser Stoddart of the University of California, Los Angeles.

"I decided that it is important to show that you can make money with dendrimers," Svenson told C&EN. As a result, the symposium's lineup featured a session on the commercial applications of dendrimers.

One myth-busting commercial application that the entire dendrimer community has been keeping an eye on comes from Starpharma, a firm based in Melbourne, Australia. Dendrimers' ability to ferry active compounds has gotten some attention from pharmaceutical companies for possible drug delivery applications, but it's the dendrimer itself that's the active ingredient in Starphama's new pharmaceutical.

I learned that dendrimers are built from starting atom, such as nitrogen, to which carbon and other substances are added by repeating series of chemical reactions that produce a spherical branching structure as it is shown in the previous post. As th eprocess repeats, more layers are added until the sphere is expanded to the size required by the investigator. I would like to know if these reagents can be used for applications in MR imaging

Roshan said:

I learned that dendrimers are built from starting atom, such as nitrogen, to which carbon and other substances are added by repeating series of chemical reactions that produce a spherical branching structure as it is shown in the previous post. As th eprocess repeats, more layers are added until the sphere is expanded to the size required by the investigator. I would like to know if these reagents can be used for applications in MR imaging

Dendrimer technologies don't stop at making some kinds of gel for topical use as it is described by DD. Denrimers are a major architectural groups of nanoscale chemical polymers. The term was used by Dr. Tomalia-president of Dendritic Nanotechnologies- in 1984. Dendrimers are used in nanomedicine and cancer diagnostics. They can be used in gene therapy as a gene vector (Qiagen) and linked ti antibodies, developed by DadeBehring to detect heart damage.