(M1230-01-03) Pegylation Enhanced Mucin Penetration of Biotinylated PLGA Nanoparticles

Purpose: The purpose of this work was to develop a mucosal vaccine delivery platform by which the surface of PLGA nanoparticles is modified with polyethylene glycol (PEG). The design hinges on the biotinylated nanoparticles (bNPs) we have previously described which localize both antigens and adjuvants in the same draining lymph node.[1] This co-localization is thought to be decisive in generating protective immunity. For respiratory viral infections, including respiratory syncytial virus, mucosal immunization confers the advantage of priming resident lymphocytes at the site of viral entry and replication.[2] However, the effectiveness of delivering particle-based vaccines via intranasal administration is impeded by mucus turnover. The gel-like mucus acts as a physical and diffusion barrier, trapping nanoparticles and hindering their ability to penetrate the lung epithelium under which dendritic cells reside.[3] Due to PEG's hydrophilicity and its ability to form a ‘brush’ conformation, nanoparticles coated with PEG can penetrate mucosal barriers more efficiently by minimizing interactions with mucins in mucus and reducing adhesion to the mucus, which facilitates easier diffusion through the mucus layer.[4, 5] This study investigated the impact of pegylation on bNPs on the nanoparticles’ penetration through a mucin matrix.

Methods: bNPs were prepared using the method we have previously described.[1] bNPs labeled with IRDye 680RD-Streptavidin (SA) were designated as ‘bNP^SA’. Pegylation was achieved by incubating bNP^SA with 1% (w/v) mPEG solution, forming ‘bNP^SA/PEG’. Ibidi chemotaxis µ-slide was arranged to simulate the penetration of nanoparticles through the mucus layer. Fill the middle vertical channels with 1% (w/v) mucin solution and the receiving chambers (the right channel of each section) with PBS. Then fill the input chambers (the left channel of each section) with SA solution, bNP^SA, and bNP^SA/PEG, respectively. The fluorescence intensity of the slide was observed using Li-Cor Odyssey. Quantify the fluorescence area and integrated density of the receiving chambers with ImageJ. Data analysis was conducted using GraphPad Prism.

Results: Pegylated or non-pegylated bNPs labeled with the near-infrared dye SA were perfused into the input chambers. The extent of penetration through the mucin matrix was determined based on the area and intensity of the fluorescence in the receiving chambers. Both measurements indicated that the pegylated nanoparticles (bNP^SA/PEG) penetrated through the mucin matrix more efficiently than the non-pegylated nanoparticles (bNP^SA).

Conclusion: The results supported the role of PEG in promoting the nanoparticles’ penetration through a mucin matrix. Future studies will investigate the effects of different concentrations of PEG on the mucin penetration of bNPs.

References: [1] Hartmeier, P. R.; Kosanovich, J. L.; Velankar, K. Y.; et al. Immune Cells Activating Biotin-Decorated PLGA Protein Carrier. Mol Pharm 2022, 19 (7), 2638-2650.
[2] Lavelle, E. C.; Ward, R. W. Mucosal vaccines - fortifying the frontiers. Nat Rev Immunol 2022, 22 (4), 236-250.
[3] Bandi, S. P.; Bhatnagar, S.; Venuganti, V. V. K. Advanced materials for drug delivery across mucosal barriers. Acta Biomater 2021, 119, 13-29.
[4] Guo, Y.; Ma, Y.; Chen, X.; et al. Mucus Penetration of Surface-Engineered Nanoparticles in Various pH Microenvironments. ACS Nano 2023, 17 (3), 2813-2828.
[5] Prasher, P.; Sharma, M.; Singh, S. K.; et al. Targeting mucus barrier in respiratory diseases by chemically modified advanced delivery systems. Chem Biol Interact 2022, 365, 110048.


Fig. 1. Fluorescence Results of the Slide. (A) Near-infrared imaging of the slide. After filling the input chambers for 1 hour at room temperature (~10℃), observed fluorescence in the 700 nm detection channel and a resolution of 5 µm. (B) Fluorescence intensity of the receiving chambers.