Poly-L-Lysine Doped FmocFF Nanogels as Delivery Platforms for siRNA

Cationic nanogels (NGs), obtained by combining the low molecular weight peptide hydrogelator, Fmoc-FF, with poly-L-Lysine (PLL, MW ~ 24000 Da) have been evaluated as potential tools for effective delivery of Short Interfering RNA (siRNA) into cells. Mixed hydrogels composed by FmocFF in combination with PLL in increasing amount (from 1.0 to 7.0 mg/mL) were formulated through solvent-switch method and characterized in terms of their mechanical properties, loading capabilities and stability. Injectable NG loaded with Cyanine 3-labeled siRNA (siRNA-Cy3) was obtained by a top-down approach through submicronization of the macroscopic hydrogel in the presence of polysorbate 80 (TWEEN®80) and sorbitane monooleate 80 (SPAN®80) as colloidal stabilizing surfactants. siRNA-Cy3 loading and release were evaluated by fluorescence spectroscopy, with and without Ribogreen marker, and electrophoresis. NGs, with a mean diameter of 284.1 nm and a zeta potential of +31.4 mV, were found able to efficiently encapsulate siRNA-Cy3 (98%) and release it (70% after 72 h) in simulated biological fluids. Preliminary in vitro studies on Human Embryonic HEK293 Kidney cells indicated a safety profile under the experimental conditions and validated the capacity of NG formulation to be internalized by active endocytic processes. Cationic peptide based NGs are promising nanoplatforms for the active delivery of siRNA.