Biodistribution properties of nanoparticles based on mixtures of PLGA with PLGA–PEG diblock copolymers

Abstract

The basic characteristics and the biodistribution properties of nanoparticles prepared from mixtures of poly(lactide-co-glycolide) (PLGA) with poly(lactide-co-glycolide)–poly(ethylene glycol) (PLGA–PEG) copolymers were investigated. A PLGA(45)–PEG(5) copolymer of relatively low PEG content and a PLGA(5)–PEG(5) copolymer of relatively high PEG content were included in the study. Increasing the PLGA–PEG content of the PLGA/PLGA–PEG mixture, or when PLGA(45)–PEG(5) was replaced by PLGA(5)–PEG(5), a decrease in the size of the nanoparticles and an increase in the rate of PEG loss from the nanoparticles were observed. The blood residence of the PLGA/PLGA(45)–PEG(5) nanoparticles increased as their PLGA–PEG content was increased, reaching maximum blood longevity at 100% PLGA(45)–PEG(5). On the contrary, the blood residence of PLGA/PLGA(5)–PEG(5) nanoparticles exhibited a plateau maximum in the range of 80–100% PLGA(5)–PEG(5). At PLGA–PEG proportions lower than 80%, the PLGA/PLGA(45)–PEG(5) nanoparticles exhibited lower blood residence than the PLGA/PLGA(5)–PEG(5) nanoparticles, whereas at PLGA–PEG proportions higher than 80%, the PLGA/PLGA(45)–PEG(5) nanoparticles exhibited higher blood residence than the PLGA/PLGA(5)–PEG(5) nanoparticles. These findings indicate that apart from the surface PEG content, the biodistribution properties of the PLGA/PLGA–PEG nanoparticles are also influenced by the size of the nanoparticles and the rate of PEG loss from the nanoparticles.