Bioactive Hybrid Particles from Poly(D,L-lactide-co-glycolide) Nanoparticle Stabilized Lipid Droplets

Biodegradable and bioactive hybrid particles composed of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles and medium-chain triglycerides were prepared by spray drying lipid-in-water emulsions stabilized by PLGA nanoparticles, to form PLGA-lipid hybrid (PLH) microparticles approximately 5 μm in mean diameter. The nanoparticle stabilizer was varied and mannitol was also incorporated during the preparation to investigate the effect of stabilizer charge and cryoprotectant content on the particle microstructure. An in vitro lipolysis model was used to demonstrate the particles' bioactivity by manipulating the digestion kinetics of encapsulated lipid by pancreatic lipase in simulated gastrointestinal fluid. Lipid digestion kinetics were enhanced in PLH and PLGA-lipid-mannitol hybrid (PLMH) microparticles for both stabilizers, compared to a coarse emulsion, in biorelevant media. An optimal digestion rate was observed for the negatively charged PLMH system, evidenced by a 2-fold increase in the pseudo-first-order rate constant compared to a coarse emulsion. Improved microparticle redispersion, probed by dual dye confocal fluorescence microscopy, increased the available surface area of lipid for lipase adsorption, enhancing digestion kinetics. Thereby, lipase action was controlled in hybrid microparticles by altering the surface charge and carbohydrate content. Our results demonstrate that bioactive microparticles composed of versatile and biodegradable polymeric particles and oil droplets have great potential for use in smart food and nutrient delivery, as well as safer and more efficacious oral delivery of drugs and drug combinations.