ISBN : 978-93-85073-24-3 sized robots that could be introduced into the human body and perform cellular repairs at the molecular level. However, the first scientist to voice the possibility of nanomedicine was the Noble physicist Richard P. Feymman, who in his historical 1959 lecture at Caltech said “There’s plenty of room at the bottom” and even proposed the first known nanomedical procedure to cure heart disease through “swallowing the surgeon” [40]. Based on Feymman’s insight into nanomedicine, manipulation of the materials/devices at the molecular level, nanomedicine today has evolved and branched into hundreds of different directions, e.g. nanoparticles, biosensors and nanotherapeutics [41]. Many approaches are being actively pursued towards nanomedicine. One of the nanomedical approache is to develop nanoparticles as carriers for drug molecules to achieve enhanced bioavailability, therefore, controlled drug delivery [42-44]. Bioavailability refers to the availability of the drug molecules at the specific site over a period of time. Tuning for enhanced bioavailability, which could not be achieved by the small-molecule drug alone, relies on manipulations of the nanocarriers. Nanoparticles (diameter < 1000 nm) are one attractive system as nanocarriers for controlled drug delivery, because they have the abilities to protect the therapeutics from degradation and help them to achieve improved solubility, increased loading capacity, and prolonged circulation time. In addition, they can also incorporate multiple types of therapeutics and various detection elements into one single formulation for imaging and more effective treatment. Furthermore, they can be functionalized with targeting ligands at the surface to obtain targeted delivery of therapeutics [45-54]. Therefore, lots of researchers are pursuing the nanoparticle approach for therapeutic delivery. The arsenal of nanoparticles at the forefront of the controlled drug delivery research includes dendrimers [55-57], polymer micelles [5860], chitosan nanoparticles [61-65], liposomes [66-70], polymersomes [71-76], carbon assemblies [77-79], gold nanoparticles including nanoshells and nanocages [80-84]. Need of Nanocarriers Nanotechnology is a novel area of science that provides, with a new hope, the tools and technology to work at atomic, molecular and supramolecular levels leading to creation of devices and delivery systems with fundamentally new properties and 3
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