Chitosan micro- and nanospheres: fabrication and applications for drug and DNA delivery.

Polysaccharides and other cationic polymers have been recently used in pharmaceutical research and industry for their properties to control the release of antibiotics, DNA, proteins, peptide drugs or vaccines. They have been also extensively studied as non viral DNA carriers for gene delivery and therapy. Chitosan is one of the most used since it can promote long-term release of incorporated drugs. Here, we reviewed the recent literature on the preparation of chitosan micro- and nanospheres using different manufacturing processes (nanofabrication). Moreover, the preparation of chitosan and chitosan/DNA nanospheres using a novel and simple osmosis-based method has been recently reported. This novel nanofabrication method may be a useful alternative to obtain small DNA-containing nanospheres (38+/-4 nm) for biomedical applications. The reported method has general applicability to various synthetic or natural biopolymers. Solvent, temperature and membrane cut-off are the physicochemical parameters able to control the overall osmotic process leading to obtain several nanostructured systems with different size and shape that may be used in several biotechnological applications.