Comment on "Nanorobotics control design: a collective behavior approach for medicine"

Following the paper by Calcavani and Freitas (see ibid., vol.4, no.2, p.133-40, 2005), the limitations on nanorobot design and activity imposed by Brownian motion events, communication problems, and the nature of the intercellular space are discussed. It is shown that severe problems exist for a nanorobot designed to enter tissues for therapeutic purposes when it is smaller than about 1 /spl mu/m in any one of its dimensions.