Injectable supramolecular hydrogels as delivery system of siRNA loaded PLGA nanoparticles

The potential of gene technology to revolutionize disease management by targeting their underlying causes is undeniable. Nevertheless, the efficient administration of these treatments through physiological barriers is challenging. The aim of this research was to evaluate the potential of a supramolecular (SM), bioerodible and injectable hydrogel, composed of an ad-hoc custom synthesized poly(ether urethane) (PEU) and commercial α-cyclodextrins (CDs), as a conduit for localized gene therapy delivery. To this aim, poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) encapsulating small interfering RNA (siRNA) were designed and loaded within the SM hydrogels. PLGA NPs were prepared following a well-defined protocol, resuspended in a 14% w/v CD aqueous solution, and characterized through Dynamic light scattering (DLS) and Phase Analysis Light Scattering (PALS) techniques. The particle size was measured to be around 200 nm (PDI < 0.05), with a negative zeta potential (-20 mV). The encapsulation efficiency (ca. 55%) was quantified through RiboGreen assay. The NPs were incorporated into the SM hydrogels and a comparative analysis of unloaded and NPs loaded hydrogels showed no significant changes in the gelation kinetics, while rheological properties were slightly affected by the presence of NPs. Release kinetics found comprehensive elucidation through a fluorescence-based assay, revealing a uniform release curve, with complete release achieved after 48 hours of incubation. Both the hydrodynamic diameter and PDI of the released particles were significantly higher than the freshly prepared NPs, probably because the released NPs were entangled or mixed with gel erosion products. Cell culture experiments using the H1299 cell line evidenced NP uptake without translating the expected gene silencing outcomes. Collectively, this study underscored the promising utility of SM hydrogels as vehicles for gene delivery applications, premised upon their injectability, biodegradability, and favorable release profiles.