Polymeric Nanoparticles for Targeted Drug and Gene Delivery Systems

Polymeric nanoparticles are engineered nanostructured materials of nm scale that can be tuned to load and then release therapeutic compounds entrapped within the polymeric core or retained in the polymeric matrix. The different polymeric matrix configurations define two main nanoparticle subcategories: polymeric nanospheres and nanocapsules. Polymeric nanospheres retain the therapeutic compounds adsorbed, dispersed, or cross-linked in the spherical polymeric structure for controlled delivery. Polymeric nanocapsules consist of an inner part (core) in which the therapeutic substance is contained and enveloped by a polymeric shell. The most important features of polymeric nanoparticles are high kinetic stability, structural versatility for controlled drug release, rigid morphology, capacity to incorporate hydrophilic or hydrophobic drugs, and multiple possibilities for surface functionalization. These attributes highlight the extraordinary potential of these nanomaterials as drug and gene delivery systems to target and treat diseased cells and tissues. Indeed, they have demonstrated excellent pharmaceutical utility to protect drugs and nucleic acids from degradation and for target-oriented and site-specific delivery minimizing adverse immune responses and side effects. In this chapter, we will describe the general and ideal forms of drug or nucleic acid-encapsulated polymeric nanoparticles, the different monomers, and polymers currently in use and their main preparation methods, and finally the biomedical applications for which they are best employed.