Microspheres loaded with polysaccharide nanoparticles for pulmonary delivery: Preparation, structure and surface analysis

In this work, we report the preparation of a nanoparticle-based dry powder for pulmonary administration. Hybrid chitosan/hyaluronic acid nanoparticles were produced by ionotropic gelation and characterized for their physicochemical properties, being further studied by solid nuclear magnetic resonance (NMR). Using mannitol as carrier, nanoparticles were microencapsulated by spray drying, resulting in a dry powder with appropriate aerodynamic properties for lung delivery. In order to investigate the nanoparticles distribution within the carrier matrix, several techniques were applied that permitted an in-depth analysis of the system structure and surface, such as confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS) in combination with time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Overall, the studies conducted revealed that nanoparticles are homogeneously distributed through mannitol microspheres, suggesting the success of the microencapsulation process. In the light of these findings, it was concluded that the developed delivery system holds great potential for lung delivery of macromolecules.