Backgorund/Objectives: Respiratory diseases represent a substantial global health burden and require effective localised pulmonary delivery strategies, particularly for poorly water-soluble therapeutic molecules. Nanoparticle-based drug delivery systems, especially those manufactured using microfluidics, have emerged as promising approaches to overcome pulmonary barriers, enhance local drug retention, and reduce systemic side effects. Among these nanocarriers, solid lipid nanoparticles (SLNs) and solid hybrid nanoparticles (SHNs) combine biocompatibility with controlled release and improved formulation stability. Methods: In this study, SLNs and lipid-chitosan SHNs were developed using microfluidic technology as candidate platforms for pulmonary drug delivery, with Cyclosporine A (CyA) used as a model hydrophobic cyclic peptide. Nanocarriers were produced using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol as lipids, with low-molecular-weight chitosan incorporated to obtain hybrid systems. Physicochemical properties were evaluated using dynamic light scattering (DLS) and ζ potential measurements, while morphology and structural organisation were investigated using transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Results: The microfluidic approach enabled the production of nanoparticles with controlled sizes below 200 nm, narrow size distributions, and good reproducibility. In addition, the SHNs exhibited a positive surface charge, high encapsulation efficiency (~80%), and good colloidal and thermal stability. In vitro release studies showed an initial burst release followed by sustained CyA release, reaching approximately 94% cumulative release within 6 h. The Korsmeyer-Peppas model was used as the standard kinetic model. No blank nanoparticles were used as controls in the EE and release assay. Conclusions: Overall, these findings support further investigation of microfluidic-produced lipid and hybrid nanoparticles as candidate platforms for pulmonary drug delivery.
