693 ISSN 1756-8919 10.4155/FMC.09.48 © 2009 Future Science Ltd Future Med. Chem. (2009) 1(4), 693–711 Review “There is a growing sense in the scientific and technical community that we are about to enter a golden new era. We are about to be able to build things that work on the smallest possible length scales, atom by atom, with the ultimate level of finesse. Over the past century, we have learned about the workings of these biological nanomachines to an incredible level of detail, and the benefits of this knowledge are begin- ning to be felt now in medicine. In the coming decades, we will certainly learn to modify and adapt this machinery to extend both the quality and the length of life. Biotechnology was the first nanotechnology and it has certainly a long, long way to go.” Richard E Smalley, Nobel Prize in Chemistry in 1996, testifying in front of the US congress in 1999 regarding the emergence of a new scientific domain that is nanotechnology [1] . Medicine and health constitute the major domains in which the introduction of nano- technology appears to be full of promise, par- ticularly in drug delivery [2,3] . Nanomedicine results from the integration of nanotechnology into medicine. It encompasses the development of nanometric systems for multipresentation and vectorization of therapeutic molecules. Indeed, drug resistance of some diseases compels doc- tors to administer an ever higher dose at higher frequency. The dosage evolution has generated an increase in toxicity and cost of treatment [4] . In addition, some therapeutic molecules require specific formulations to overcome problems asso- ciated with solubility, in vivo stability and bio- bio- availability, as well as side effects related to the accumulation of the drug at the target site [5] . Nanoscience opens the possibility of overcom- ing dosage and formulation issues. It offers new tools and technologies to work on a wide range of levels (atomic, molecular and supramolecular). This allows the building of drug vectors with different fundamental properties. The challenge of drug delivery consists of carrying the active molecules through different biological barriers to reach specific targets and treat the disease in an efficient and nontoxic way [3] . To be efficient, drug carriers must exhibit certain features: n Increase the drug stability and solubility: drug inclusion into the vector should enhance bio- bio- availability for a controlled release in time and reduction of the drug toxicity; n Tune the specific targeting of tissues by mod- ifying the size and surface coating (charge and grafted ligand, for example) of the particles used; n Ability to carry several therapeutic molecules in the same formulation. There are two types of vectorization that have been employed to carry therapeutic molecules to the target sites: passive and active targeting [6–8] . Passive targeting consists of using the car- rier properties and the individual characteris- tics of the target site environment to selectively accumulate the drug at the site of action, thus avoiding random distribution. This technique is based on the permeability of tumorous tis- sues that originates from the rapid vascular- ization of the cancerous cells. This generates defects and interstitial spaces (400–600 nm) Recent advances in the ield of nanometric drug carriers Over the past few years, health and medicine have been domains where nanotechnologies have shown great promise, in particular in the area of drug carriers and drug targeting. Many active substances suffer from poor solubility, instability in biological medium and low bioavailability. Inaccurate distribution and accumulation of the drug in the body could lead to some side effects possibly detrimental to drug development. With the advent of nanosciences applied to medicine, new tools are becoming available, giving rise to a whole range of drug carriers with different properties and functionalities. Nanocarriers should play a crucial role in the controlled and sustained delivery of drugs. Various types of functional nanosystems are currently being explored and the aim of this review is to give an overview of the most recent advances in the ield of nanometric drug carriers, including future strategies and perspectives. Julien Ogier 1 , Thomas Arnauld 2 & Eric Doris †3 † Author for correspondence 1 CEA, iBiTecS, Service de Chimie Bioorganique et de Marquage, 91191 Gif-sur-Yvette, France E-mail: ogierjulien@yahoo.fr 2 Technologie Servier, 25–27 rue Eugène Vignat, 45000 Orléans, France E-mail: thomas.arnauld@ fr.netgrs.com 3 CEA, iBiTecS, Service de Chimie Bioorganique et de Marquage, 91191 Gif-sur-Yvette, France E-mail: eric.doris@cea.fr DRug DeliveRy The process by which a formulated drug is administered NaNotechNology The science and technology of building structures, devices or systems at the atomic, molecular or macromolecular range For reprint orders, please contact reprints@future-science.com