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   From: TortureTechnologyNResearch@yahoo.com   
      
   Small is fantastic - Exciting times for nanomedicine   
      
   Nov 21st 2012  | From The World In 2013 print edition   
      
   Nanotechnology Microrockets Propelled Through Blood Stream   
      
      
   In the film “Fantastic Voyage”, a microscopic submarine travels   
   through a human body. That sort of adventure is not on the horizon in   
   2013, but nanomedicine—medicine on an atomic and molecular scale—is   
   growing up fast. In the coming year not only will a steady pace of   
   innovation and discoveries be maintained, but the world will also   
   begin to see the emergence of more effective therapeutic, diagnostic   
   and imaging methods. These innovations will include the ability to   
   detect disease from the presence of a few molecules; medical imaging   
   at a level approaching molecular resolution; and targeted therapeutics   
   capable of finding diseased tissue and delivering treatment to it and   
   it alone.   
      
   One example of the latter, developed by BIND Biosciences, which we   
   co-founded, is known as BIND-014. It consists of spheres about 100   
   nanometres (billionths of a metre) in diameter. These encapsulate an   
   anti-cancer drug in a coating invisible to the immune system and this   
   coating is, itself, covered with homing molecules that have a strong   
   affinity with a type of protein produced by many cancers but not much   
   by healthy tissue. BIND-014 particles circulate until they come across   
   a tumour. The particles then stick to the tumour cells and the   
   particle releases its pharmacological payload. BIND-014, which has now   
   undergone a human clinical trial, thus enables more of the   
   administered dose of a drug to reach tumours, making treatment both   
   safer and more effective.   
      
   Other sorts of “smart” nanoparticles can respond to biological changes   
   or physiological challenges by altering their properties. Some act as   
   scouts, looking for diseased tissue. When they find it, they induce it   
   to give off chemicals that summon other nano-particles to the site,   
   bringing reinforcements to the battle. There are also stealth   
   nanoparticles that have been designed to shed their camouflage layer   
   only once they reach their destination. Still others can encapsulate   
   drugs indefinitely, releasing their payload only when and where   
   conditions suggest the drug is needed—for example, when there are high   
   glucose concentrations in the blood that result in the release of   
   insulin.   
      
   A mission for microrockets   
      
   On the diagnostic front, a variety of nanotechnologies have been   
   developed for the detection of cancers, including circulating tumour   
   cells (CTCs), which are responsible for a cancer’s spread. The   
   challenge is that CTCs are few and far between. Normally, a few mingle   
   with the 10m or so white blood cells and 5 billion red blood cells in   
   each milli-litre of blood, making their detection and isolation a   
   formidable challenge. Recently, though, a group at the University of   
   California, San Diego, has developed self-propelled “microrockets”   
   about 10,000 nano-metres long. These carry a small amount of zinc as   
   fuel and, in a reaction that may be familiar from school chemistry   
   lessons, this fuel can be made to react with natural acids in the body   
   to generate hydrogen, which is then used to propel the rocket. Thus,   
   at least in tissues which are acidic, microrockets should be able to   
   move actively about. Experiments suggest they can navigate through a   
   sample of blood at a speed of about 0.3 metres an hour.   
      
   Moreover, such microrockets might be guided from outside the body   
   using magnets, if suitable magnetically sensitive materials were built   
   into them. That guidance, plus their rapid propulsion, would make them   
   more likely than otherwise to encounter CTCs, which they could then   
   selectively pick up and transport to a desired location for analysis.   
      
   Proteus, the submarine in “Fantastic Voyage”, was nuclear-powered—a   
   system of propulsion that remains beyond nanotechnology. But zinc   
   propulsion is still an impressive feat. As it suggests, the field is   
   advancing by leaps and bounds. With luck nanomedicine will, indeed,   
   make its own fantastic voyage into the future.   
      
   Omid Farokhzad: associate professor of anaesthesiology, Harvard   
   Medical School   
      
   Robert Langer: institute professor, the David H. Koch Institute for   
   Integrative Cancer Research   
      
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