ABSTRACT
There is significant interest in recent years in developing biodegradable nanoparticles as a drug/gene delivery system (1-5). Nanoparticles are colloidal particles that range in size from 10 to 1000 nm in diameter, and are formulated using biodegradable polymers in which a therapeutic agent can be entrapped, adsorbed, or chemically coupled (2,4). The
advantages of using nanoparticles for drug delivery applications result from their three main basic properties. First, nanoparticles, because of their small size, can penetrate through smaller capillaries, which could allow efficient drug accumulation at the target sites (6,7). Second, the use of biodegradable materials for nanoparticle preparation can allow sustained drug release within the target site over a period of days or even weeks (8-10). Third, the nanoparticle surface can be modified to alter biodistribution of drugs or can be conjugated to a ligand to achieve target-specific drug delivery (11,12). Although a number of different polymers have been investigated for formulating biodegradable nanoparticles, poly(D,L-lactide-co-glycolide) (PLGA) and poly lactic acid (PLA) are the most extensively studied polymers for controlled drug delivery applications (13,14). The lactide/glycolide polymers chains are cleaved by hydrolysis into natural metabolites (lactic and glycolic acids), which are eliminated from the body by the citric acid cycle (14). Further, these polymers are approved by the U.S. Food and Drug Administration for human use.
