Dendrimer, from the Greek word (dendron) for tree, refers to a synthetic, three-dimensional molecule with branching parts. Dendrimers are formed using a nano-scale, multistep fabrication process. Each step results in a new “generation” that has twice the complexity of the previous generation - a first generation dendrimer is the simplest; a tenth generation dendrimer is the most complex and can take months to engineer. Donald Tomalia, a researcher working for chemical giant Dow, first synthesized and named dendrimers in 1979.
Why Are Dendrimers Important and How Can They be Used in Medical Applications?
Dendrimers are “stealth molecules” that have many potential applications, including diagnostic and therapeutic applications. By customizing and controlling dendrimer “architecture,” nanotechnologists are developing dendrimers for drug delivery, diagnostic imaging and as carriers of genetic material. Dendrimers can easily move across biological membranes and they can store a wide range of metals, organic or inorganic molecules among their branches. Companies developing these synthetic molecules claim that most dendrimers don’t trigger the immune system when injected or used topically, and have low cytotoxicity (that is, toxicity to cells). However, some forms of dendrimers can induce clotting in the bloodstream - a potential concern for in vivo applications.
Other Industry Applications for Dendrimers
Dendrimers could also be used in coatings and materials, electronics and photonics. A look at the patent assignees for dendrimer technology reveals the wide range of potential applications - patents are assigned to chemical, petroleum, tire, cosmetics and pharmaceutical companies, among others.
Commercialization of Dendrimers - an Overview
Commercial development of dendrimers has been slow because of the difficulty of scaling-up production and because their cost is prohibitively high. Diagnostic-grade, tenth generation dendrimers go for US$1,650/100mg. A new, copper-catalyzed process for dendrimer synthesis announced in 2004 has reportedly increased yields. Dendritic Nanotechnologies has reportedly filed for patents on a new, one-step process to synthesize dendrimers, which could potentially drive down the cost of production.
Examples of Products that Use Dendrimers
Dendrimer-based products (and those in the pipeline) include, for example:
• A dendrimer-based tool for detecting cardiac damage is being developed by Dade Behring, one of the world’s largest medical diagnostic firms.
• The world’s first drug based on dendrimers, developed by Australian-based Starpharma, is a topical gel for use as a “liquid condom” to reduce the risk of HIV infection in women. StarPharma’s “VivaGel” microbicide has gone through initial animal testing and phase-one safety trials in humans.
• The US Army Research Laboratory is developing a dendrimer-based anthrax detection agent, dubbed “Alert Ticket”;
• ExxonMobil owns patent 5,906,970 on a “flow improver” based on dendrimer technology - an additive that will increase the flow of oil in cold temperatures.