ABSTRACT
Nanotechnology has been applied in the eld of medicine-the so-called nanomedicine, bringing along increased expectations for the improvement of healthcare. Nanomedicine aims to treat, prevent, and diagnose several diseases (e.g., cancer) and traumatic injuries. The basic principle behind this technology is the application of nanoscale particles that vary from a few nanometers to hundreds of nanometers in size to deliver drugs to specic target sites. Their small size allows them to cross biological barriers, such as tissues, cells, and organelles, as nanoparticles are engineered to have similar size and structure to biological molecules (Husseini and Pitt, 2008). It is thought that the particle size is determinant for particle uptake. Thus, those particles smaller than 200 nm suffer uptake by unspecialized cells, whereas particles smaller than 35 nm may enter the nucleus, and particles smaller than 30 nm are able to reach the central nervous system (CNS) via olfactory neuronal transport (Salvati et al., 2011). Small molecules reach the organs and cellular compartments, according to equilibrium principles. Therefore, small molecules that are used routinely (e.g., chemotherapeutic agents for cancer therapy) have limited clinical use due to low water solubility, nonspecic biodistribution, and targeting, which results in low therapeutic indices. In addition, the risk of drug resistance shortly after the treatment, not only decreases the efcacy of the conventional drug but also decreases the therapeutic
CONTENTS
6.1 Introduction ................................................................................................ 131 6.2 Gene Delivery ............................................................................................. 133 6.3 Vaccine Delivery and Adjuvant ............................................................... 136 6.4 Conclusion .................................................................................................. 139 Acknowledgment ................................................................................................ 140 References ............................................................................................................. 140
efcacy of a newer targeted drug (Zhuo, 2010). However, nanoparticles are processed by cellular machinery and are trafcked by active processes, similar to drug biomolecules (Salvati et al., 2011). Nanoparticles for drug delivery should be physicochemically stable, have a high loading capacity, be able to incorporate both hydrophilic and hydrophobic drug molecules, and be feasible for several administration routes (e.g., oral, parenteral, nasal, and topical). Moreover, the advantages of nanoparticles go well beyond targeted delivery, since they also allow sustained drug release from the matrix, which results in the improvement of bioavailability, lower dosing frequency, and less side effects, ultimately resulting in better patient compliance (Fadeel and Garcia-Bennett, 2010).
