ABSTRACT
Nanotechnology is the science that deals with structures in the size range of nanometers. It has the potential to greatly impact our lives. The employment of nanotechnology has opened new vistas in the areas of personalized health care, drug delivery, gene therapy, diagnostics, imaging, and novel drug discovery techniques. Enormous research is going on in the eld of nanotechnology to resolve various issues such as bioavailability, spatial and temporal delivery of drugs, and precise delivery of new molecules like genes and deoxyribonucleic acid (DNA). The delivery of therapeutic and diagnostic agents through the colloidal carriers is at the forefront of nanotechnology as it provides numerous opportunities for efcient exploitation of different formulations and routes of administration. In this perspective, rst, solid-core nanoparticles (NPs) were reported as an alternative drug carrier. NPs are dened as particulate dispersions or solid particles with a size in the range of 10-200 nm, built from macromolecular and/or molecular assemblies, in which the active principle is dissolved, dispersed, encapsulated, or even adsorbed or attached to the external interface. NPs are divided into two main classes based on their structures: nanospheres and nanocapsules that can be obtained by varying the methods of preparation. Nanospheres are matrix systems in which the drug is physically and uniformly dispersed and have a homogeneous structure, whereas nanocapsules are the systems in which the drug is conned in a cavity surrounded by a unique polymer membrane exhibit a typical core-shell structure (Figure 10.1). Their higher kinetic stability and rigid morphology are the major advantages over other colloidal drug delivery systems (such as liposome, niosome, microemulsions, nanoemulsions, etc.). Pharmaceutical NPs are one of the colloidal vehicles that possess the ability to carry drugs, accumulate preferentially at the target site, or release drugs in a controlled way within the body, which leads to improved pharmacokinetics and biodistribution of therapeutic
agents with consequent reduction in systemic side effects and more efcient use of the therapeutic agents (Kreuter 1994; Alexis et al., 2008; Qi et al., 2012). They do not only allow the delivery of small drug molecules but are also expected to deliver peptides, proteins, and nucleic acids, hence opening the gate for gene therapy (Kim et al., 2005; Kommareddy et al., 2005; Jeon et al., 2012). NPs are usually administered through the parenteral route; however, because of their excellent barrier-crossing property, they are also being investigated for oral (Yin et al., 2007; Agueros et al., 2009; Kalaria et al., 2009; Jain et al., 2011), ocular (Motwani et al., 2008; Gupta et al., 2010; Basaran et al., 2011), nasal (Michael et al., 2009; Shahnaz et al., 2012), pulmonary (Ungaro et al., 2012), periodontal (Pinon-Segundo et al., 2005; Saboktakin et al., 2011), and transdermal (Elnaggar et al., 2011; Gupta and Vyas, 2012) routes. In spite of being a young technology, thousands of nanopharmaceuticals have been patented worldwide (Caruthers et al., 2007) and many have been approved by the Food and Drug Administration (FDA) for clinical purposes (Table 10.1).
