Polymeric nanocapsules as nanocarriers

Abstract

Recently many kinds of nanocarriers have been developed for delivery of therapeutic agents to improve medical treatments due to their unique physic-chemical properties. These include their small size, which allows them to reach the cellular level, their high surface to volume ratio, which increases interactions with target cells and their ability to be structurally and functionally modified to control their biodistribution. In addition, nanocarriers allow the improvement of aqueous solubility of poorly soluble drugs, the drug protection in order to avoid its degradation before reaching its target, its selective transport to the sites of infection and the controlled release of the medication to decrease the frequency of administration, which in turn reduces adverse effects. In particular, the nanocarriers synthesized for this work are nanocapsules formed by a lipid core surrounded by a polymer coating. The amphiphilic core allows the encapsulation of both hydrophobic and hydrophilic molecules. The coating using chitosan polymer increases stability and protects the encapsulated molecule from degradation. Chitosan is a biocompatible polysaccharide rich in amino groups, which makes it very easy to functionalize nanocapsules with other molecules to modify their properties according to the needs. The material obtained has been characterized in terms of size (100-200 nm average diameter) and Z potential (positive). To date, a wide range of different molecules have been successfully encapsulated, which proves the high versatility of this nanocarrier. Active molecules, such as antibiotics, nucleic acids and proteins have been encapsulated in order to improve their efficacy. Besides, gold nanoparticles of a smaller size (14 nm) have been encapsulated to protect them from degradation in the gastrointestinal tract, making it a suitable system for oral delivery. Nanocapsules have also been labeled with fluorophores, allowing their tracking during in vitro cell internalization studies and in vivo biodistribution assays. Grafting nanocapsules surface with PEG has improved their stability in physiological media and biocompatibility. From the obtained results, chitosan nanocapsules are a promising nanocarrier for the delivery of therapeutic agents.