Influence of surfactant on glass transition temperature of poly(lactic-co-glycolic acid) nanoparticles

Poly(d,l-lactic-co-glycolic acid) (PLGA) is one of the most commonly used drug carriers in nanomedicines because of its biodegradability, biocompatibility and low toxicity. However, the physico-chemical characterization and study of drug release are often lacking the investigation of the glass transition temperature (T-g), which is an excellent indicator of drug release behavior. In addition, the residual surfactant used during the synthesis of nanoparticles will change the glass transition temperature. We thus prepared PLGA nanoparticles with polymeric (poly(vinyl alcohol) (PVA)) and ionic (didodecyldimethylammonium bromide (DMAB)) surfactant to investigate their influence on the glass transition temperature. Determination of T-g in dry and wet conditions were carried out. The use of concentrated surfactant during synthesis resulted in a larger amount of residual surfactant in the resulting particles. Increasing residual PVA content resulted in an increase in particle T-g for all but the most concentrated PVA concentrations, while increasing residual DMAB content resulted in no significant change in particle T-g. With the presence of residual surfactant, the T-g of particle and bulk samples measured in wet conditions is much lower than that in dry conditions, except for bulk PLGA containing the ionic surfactant, which may be related to the plasticizing effect of the DMAB molecules. Notably, the T-g of both particles in wet conditions is approaching physiological temperatures where subtle changes in T-g could have dramatic effects on drug release properties. In conclusion, the selection of surfactant and the remaining amount of surfactant are crucial parameters to utilize in designing the physico-chemical properties of PLGA particles.

Automated summary

PLGA is a commonly used drug carrier in nanomedicines due to its biodegradability, biocompatibility, and low toxicity. The glass transition temperature (T-g), which is an indicator of drug release behavior, is often overlooked in the physico-chemical characterization and study of drug release. This study investigated the influence of polymeric (PVA) and ionic (DMAB) surfactants on the T-g of PLGA nanoparticles and found that the choice and residual amount of surfactant are crucial parameters in designing the physico-chemical properties of PLGA particles.