(480b) Fabrication of Highly Uniform Nanoparticles From Recombinant Silk-Elastinlike Protein Polymers for Gene Delivery Applications

Control of the size and dimensions of silk-elastinlike protein (SELP) polymeric nanoparticles has been demonstrated using an electrospray differential mobility analyzer (ES-DMA) system. The nanoparticles formed as droplets encapsulating the polymer dry. The resulting nanoparticle size distribution depended on the buffer concentration, polymer concentration, and molecular weight of the polymer. The three different polymers used differed in molecular weight based on the number of their silk and elastin units per monomer repeat. The three polymers were SELP-815K, SELP-47K, SELP-415K, with SELP-815K having eight silk motifs, fifteen elastin motifs, and one lysine-substituted elastin motif, etc. The DMA narrowed the size distribution by electrostatically classifying the aerosolized nanoparticles. Transmission electron microscopy images demonstrated that the spherical polymeric nanoparticles are faceted. The faceting appeared to be consistent with a buckling instability, which occurs when the solvent evaporates at the vapor-liquid interface generating a thin hydrogel film that subsequently buckles as additional solvent evaporates. Cylindrical or rod-like particles were also observed presumably caused by formation of polymer stabilized filaments accompanied by a jet instability. The spherical nanoparticles display high uniformity in composition and size, encouraging further development of these nanoparticles as drug and gene delivery carriers.