Development, Characterization, and Performance Evaluation of Nanoliposomes with Tunable Rigidity for Delivery Applications

Nanoparticle-based delivery systems have emerged as a promising platform for delivery of therapeutics and diagnostics to specific sites in the body. To date, some of the nanocarrier’s physicochemical properties including size, shape, and surface chemistry, are well established as key factors for their delivery performance. Recent studies have suggested that the mechanical properties of nanoparticles can also influence their performance as delivery carriers. This rather new aspect of nanoparticles that may provide new avenues for improving drug delivery, remains unexplored in nanoliposomes -one of the most successful delivery carriers developed to date. The goal of this doctoral project is to develop nanoliposomes with tunable rigidity, characterize their physical and mechanical properties, and investigate the role of nanoliposomes’ rigidity in their cellular interactions to provide an improved understanding of the significance of nanoparticles’ mechanics for their delivery applications. One focus of this study is development and characterization of nanoliposomes with various rigidity levels. To enable tuning the liposomal mechanical properties without changing their other physicochemical properties, we prepared nanoliposomes with cores of hydrogels of various compositions and thus, mechanics. Two biocompatible and biodegradable hydrogels, poly(ethylene glycol) diacrylate (PEGDA) and alginate, were used as the liposome core at various compositions, and the resultant gel-core nanoliposomes (GNLs) were characterized for size distribution, morphology, and surface potential. Next, the mechanical properties of the resultant GNLs was assessed. To this end, we initially evaluated the mechanical properties of bulk hydrogels at different compositions using rheological measurements and compression testing to determine hydrogels’ elastic modulus as a function of their composition. Subsequently, we precisely assessed the mechanical properties of the GNLs in nanoscale using atomic force microscopy (AFM). Upon careful optimization of these experiments, we successfully imaged the GNLs via AFM and determined their Young’s modulus by single particle indentation. Ultimately, we focus on the effect of particles’ rigidity on their cellular interactions including cellular uptake using different cell types (glioblastoma tumor cells, brain endothelial cells, astrocytes, and spleen immune cells) as well as their transport across an in vitro blood-brain-barrier (BBB) model. Briefly, nanoliposomes with more rigidity demonstrated higher cellular uptake compared to their softer counterparts. However, the ability of GNLs to cross the BBB was not affected by their rigidity. Similarly, exocytosis assay of GNLs on endothelial cells indicated this rigidity independency. Further, the effect of particles’ elasticity on their cellular interaction on immune cells was investigated. Particularly, particles with medium rigidity showed the highest cellular uptake on macrophages. The findings of this research can lead to improved nanotherapeutics’ design for enhanced delivery to diseased tissues.