PEG-Coated Nanospheres: Surface Optimization and Therapeutic Applications
Biodegradable polyethylene glycol (PEG)-coated nanospheres have important therapeutic applications as injectable blood persistent particulate carriers for the controlled release of drugs, site-specific drug delivery, or medical imaging. They are obtained by emulsion/solvent evaporation (Gref et al., 1994), solvent displacement (Bazile et al., 1995), or block copolymer adsorption on preformed particles (Stolnick et al., 1994). The hydrophilic PEG coating reduces the surface charge, avoids plasma protein adsorption, minimizes the interaction with phagocytic cells and therefore increases the blood circulation time. The blood half-life of such particles is increased to up to six hours in rats (Bazile et al., 1995), compared to uncoated ones, which are removed within minutes, essentially by macrophages located in the liver and spleen. These recent nanospheres have essential advantages over other long-circulating systems, such as increased stability, resistance against plasma protein insertion in the matrix, and the possibility of obtaining controlled release, on the basis of an appropriate choice of the core composition.
KeywordsHuman Serum Albumin Sodium Cholate Plasma Protein Adsorption Outer Aqueous Phase Entrapment Yield
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