(M1330-10-56) Impact of Nebulization on the Physicochemical Properties of Polymeric Nanoparticles for Pulmonary Drug Delivery Applications

Purpose: Lung cancer is one of the leading causes of cancer-related mortalities worldwide as it is usually diagnosed at an advanced stage, necessitating rigorous and effective treatment upon diagnosis. Inhalable nanoparticle formulations can facilitate the delivery of therapeutics to the lungs in a site-specific and sustained manner. Polymeric nanoparticles (NPs) are being currently investigated owing to their biodegradability, biocompatibility, and sustained drug release characteristics at a rate corresponding to the rate of polymer degradation. Currently, there is great emphasis on developing multiple polymers or lipid layers incorporated within a single system to improve the distribution and half-life of the formulations, and for combination therapy. However, there are limited studies evaluating the physicochemical properties of these single polymer and multi-polymer/lipid formulations post-nebulization. Previously, we demonstrated that polymeric NPs coated with the commercial lung surfactant Infasurf® can evade phagocytosis by alveolar macrophages in vitro. The present work focuses on evaluating physicochemical properties and in vitro therapeutic efficacy of the formulation, after passing through a commercial nebulizer Aeroneb®.

Methods: Paclitaxel (PTX) was encapsulated within the poly lactic-co-glycolic acid (PLGA) nanoparticles (PLGA-PTX NPs) by double-emulsion solvent evaporation method. The NPs were then coated with the lung surfactant (LS) by thin-film hydration technique to form LS_PLGA-PTX NPs. The NPs were characterized pre and post nebulization using dynamic light scattering (DLS), and surface morphology by scanning electron microscopy (SEM). Retention of the lipid layer on the NPs post nebulization was confirmed by Fourier-transform infrared spectroscopy (FTIR) and quantified using Stewart’s lipid assays. The PTX entrapment efficiency (EE %) and in vitro release performance of the NPs after nebulization was determined. The Aeroneb® was also evaluated for its NP nebulization efficiency, nebulization time, and fluid output rate. In vitro studies were performed to confirm the cytocompatible nature of nebulized NPs using A549 lung adenocarcinoma cells.

Results: Particle size, ζ potential and polydispersity index (PDI) of the NPs was found to be 140.6 ± 3.9 nm, -33.0 ± 1.6 mV and 0.298 ± 0.04 respectively pre-nebulization and 142.1 ± 10.81 nm, -31.4 ± 2.9 mV and 0.261 ± 0.01 respectively post-nebulization. SEM images demonstrated the spherical morphology of NPs pre- and post-nebulization and their size coincided with the DLS measurements. FTIR analysis and Stewart’s assay confirmed the retention of the lipid layer on the nebulized NPs. The nebulization efficiency, nebulization time and fluid output rate of the commercial nebulizer Aeroneb® were determined to be 89.03 ± 3.0 %, 420 ± 57 secs, and 261.99 ± 45.1 respectively. The encapsulation efficiency % of PTX was found to be 84.3 ± 4.27 % and the drug release study displayed an initial burst release followed by a sustained release in PBS at 37 °C.

Conclusion: The LS_PLGA-PTX NPs were stable and cytocompatible, and the lung surfactant coating stayed intact post-nebulization. Ongoing studies are investigating the therapeutic efficacy of the nebulized NPs in vitro on A549 lung adenocarcinoma cells.

Acknowledgements: We would like to acknowledge funding support from the Rhode Island Foundation Medical Research Grant (##20174376) and Rhode Island IDeA Network of Biomedical Research Excellence (RI-INBRE) grant (P20GM103430). We would also like to thank Dr. Edmund Egan and Ony Biotech for gifting us the Infasurf used in our experiments.


FTIR spectra confirming the retention of the lung surfactant coating on the NPs’ surface post nebulization.


Experimental setup using the Aeroneb® nebulizer for performing in vitro studies.