M Ferrari (2005)
Curr Opin Chem Biol 9(4):343-6.
An ideal injected therapeutic drug would travel through the vasculature, reach the intended target at full concentration, and there act selectively on diseased cells and tissues only, without creating undesired side effects. Unfortunately, even the best current therapies fail to attain this ideal behavior, by a wide margin. A primary reason is the fact that the target recognition abilities of the current therapeutics molecules are quite limited. Furthermore, the natural defenses of the body present a sequence of formidable obstacles on the drug's pathway to the intended lesion. Requiring any molecule to have sufficient therapeutic efficacy, target recognition specificity, as well as all of the tools required to bypass multiple biological barriers is probably unrealistic. A different approach is to decouple the problem (i.e. employ the drug molecules for their therapeutic action only, and deliver them to the intended site by vectors that can be preferentially concentrated at desired body locations through the concurrent action of multiple targeting mechanisms). These vectors must also be large enough to comprise all the requirements for the evasion of the body defenses, while still sufficiently small so as not to create undesired blockages of even the smallest of blood vessels - and thus, by definition, nanotechnological.