ABSTRACT
Medical scientists have long dreamt of drugs that would accumulate specifically in target tissues; either disease targets, or particular tissues in order to increase the specificity of their medicines. In the last 20 to 25 years, a number of groups have pursued this objective using a variety of materials formulated into “drug delivery systems” (1,2). Drug delivery systems is a catch-all term used to describe any formulation in which drugs are encapsulated or attached to various materials, which may modify the properties of the drug in terms of its localization in the body, its pharmacokinetics, or its uptake into particular cells or tissues. Drug delivery systems relevant to nanotoxicology may comprise macromolecules such as proteins, DNA, natural or synthetic polymers or constructs of nanoparticulate size such as micelles, polymeric micelles, polyelectrolyte complexes, liposomes, or nanoparticles prepared from polymers or lipids. These delivery systems have now been brought together under the heading nanomedicines (3). A significant amount of in vivo work has been done to determine how such systems behave and to understand why these constructs behave in a particular way to exploit delivery systems more effectively. This understanding is clearly the inverse of nanotoxicology where we wish to know where nanoparticles go to so we can assess their toxicity at that site.
