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Posted: June 29, 2007
Carbon nanotubes as 'longboat delivery system' for anti-cancer drugs
(Nanowerk News) Scientists are reporting development of carbon nanotubes as a "longboat delivery system" that shows potential for addressing shortcomings that have hindered development of more generally applicable platinum-based anticancer drugs. These include analogues of the widely used and extremely potent drugs cisplatin, carboplatin, and oxaliplatin. The report is scheduled for the July 11 issue of the Journal of the American Chemical Society, a weekly publication ("Soluble Single-Walled Carbon Nanotubes as Longboat Delivery Systems for Platinum(IV) Anticancer Drug Design").
The Massachusetts Institute of Technology's Stephen J. Lippard and Stanford University's Hongjie Dai and colleagues note that efforts to produce such molecules have been hindered because the required form of platinum loses activity in the body and becomes ineffective before reaching the tumor. Their solution was to develop a carbon nanotube delivery system, ultimately for shuttling platinum compounds safely through the body's biochemical obstacle course and into the tumor. Once inside the tumor cell, the compounds convert from an inactive form into an active anti-cancer drug.
The chemistry involves attaching platinum compounds to single wall carbon nanotubes (SWNTs), one-atom thick sheets of graphite rolled up into a cylinder with a diameter about 50,000 times smaller than the width of a human hair. The SWNTs act as efficient transporters for the platinum warhead, carrying it to the tumor cell and then releasing the platinum as an active drug. In one experiment with cultured cells, the SWNTs produced platinum levels inside the cells 6-8 times higher than those for the platinum unit administered in the traditional way. The longboat SWNTs have the potential to carry other passengers to and into the cancer cell, as demonstrated by the co- delivery of platinum and a fluorescent dye to the cancer cell, which in the future will include tumor-targeting components.