Cationic Polylactic Acid-Based Nanoparticles Improve BSA-FITC Transport Across M Cells and Engulfment by Porcine Alveolar Macrophages.

This work described the development of a cationic polylactic acid (PLA)-based nanoparticles (NPs) as an antigen delivery system using dimethyldioctadecylammonium bromide (DDA) to facilitate the engulfment of BSA-FITC by porcine alveolar macrophages (3D4/2 cells) and heat-labile enterotoxin subunit B (LTB) to enhance the transport of BSA-FITC across M cells. The experimental design methodology was employed to study the influence of PLA, polyvinyl alcohol (PVA), DDA, and LTB on the physical properties of the PLA-based NPs. The size of selected cationic PLA NPs comprising 5% PLA, 5% PVA, and 0.6% DDA with or without LTB absorption was range from 367 to 390 nm with a polydispersity index of 0.26, a zeta potential of + 26.00 to + 30.55 mV, and entrapment efficiency of 41.43%. Electron micrographs revealed NPs with spherical shape. The release kinetic of BSA from the NPs followed the Korsmeyer-Peppas kinetics. The cationic PLA NPs with LTB surface absorption showed 3-fold increase in BSA-FITC transported across M cells compared with the NPs without LTB absorption. The uptake studies demonstrated 2-fold increase in BSA-FITC intensity in 3D4/2 cells with cationic NPs as compared with anionic NPs. Overall, the results suggested that LTB decreased the retention time of BSA-FITC loaded in the cationic PLA NPs within the M cells, thus promoting the transport of BSA-FITC across the M cells, and cationic NPs composed of DDA help facilitate the uptake of BSA-FITC in the 3D4/2 cells. Further studies in pigs with respiratory antigens will provide information on the efficacy of cationic PLA NPs as a nasal antigen carrier system.