Fabrication of protein-loaded PLGA nanoparticles: effect of selected formulation variables on particle size and release profile

In this study, the processing conditions for fabricating bovine serum albumin (BSA)-loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles via a water/oil/water double emulsion technique were adjusted and release profiles were studied. Particle size and surface morphology of the BSA-loaded PLGA nanoparticles were comprehensively controlled as a function of processing determinants. The nanoparticles were intended as a carrier for controlled delivery of therapeutic proteins; however, BSA was chosen as a hydrophilic model protein encapsulated within PLGA nanoparticles to investigate the effective formulation parameters. Several key processing parameters were changed including surfactant(s) concentration in the internal and external aqueous phases, BSA concentration, poly(vinyl alcohol) (PVA) characteristics, and power of ultrasonicator probe to investigate their effects on the morphological characteristics and size distribution of the nanoparticles (NPs). The prepared NPs showed spherical shape with smooth and pore-free surfaces along with a relatively narrow particle size distribution. The mean particle size of the optimized formulation was 251.3 ± 8.5 nm, which is ideal for drug delivery applications. Our results demonstrate that using PVA with Mw 13–23 kDa and degree of hydrolysis approximately 87–89 % yields better results than PVA of higher molecular weight and higher degree of hydrolysis. Surfactants concentrations in internal (Span 60) and external phase (Tween 80) of the emulsions, which play a key role in determining NP characteristics and cumulative percentage BSA released, were optimized at 14 % (w/w) and 4 % (w/v), respectively. Optimal level of ultrasonication power (50 W) was also determined. According to the results, the optimized protein-loaded NPs with proper shape, size, and surface properties were prepared and these may act as a good candidate for protein delivery.