Biodegradable PLGA-b-PEG polymeric nanoparticles: synthesis, properties and nanomedical applications as drug delivery system.

During the past decades many synthetic polymers have been studied for nanomedicine applications and in particular as drug delivery systems. For this purpose polymers must be non toxic, biodegradable and biocompatible. PLGA (poly(lactic-co-glycolic acid)) is one of the most studied polymers due to its complete biodegradability and ability to self-assemble into nanometric micelles that are able to entrap small molecules like drugs and to release them into body in a time-depend manner. Despite these fine qualities, the use of PLGA polymeric nanoparticles for in vivo applications still remains an open challenge due to many factors such as poor stability in water, big diameter (150-200 nm) and the removal of these nanocarriers from the bloodstream by the liver and spleen thus reducing drastically the concentration of drugs in tumor tissue. PEG (poly(ethylene glycol)) is the most used polymers for drug delivery applications and the first PEGylated product is already on the market for over 20 years. This is due to its stealth behavior that inhibits the fast recognition by the immune system (opsonization) and generally leads to a reduced blood clearence of nanocarriers increasing blood circulation time. Furthermore PEG is hydrophilic and able to stabilize nanoparticles by steric and not ionic effects especially in water. PLGA-PEG block copolymer is an emergent system because it can be easily synthesized and it possesses all good qualities of PLGA and also PEG capability so in the last decade it arose as one of the most promising system for nanoparticles formation, drug loading and in vivo drug delivery applications. This review will discuss briefly on PLGA-b-PEG synthesis and physicochemical properties, together with its improved qualities with respect to the single PLGA and PEG polymers. Moreover, we will focus on but in particular will treat nanoparticles formation and uses as new drug delivery system for nanomedical applications.