Self-Assembly and Drug Encapsulation of DMOAD-Loaded Elastin Collagen Nanovesicles

• Kelly Czapor, Biomedical Engineering, University of Delaware

• Christopher Price, Biomedical Engineering, University of Delaware
• Kristi Kiick, Biomedical Engineering, University of Delaware

Nanoparticle-systems have been widely studied for the controlled delivery of various therapeutics. We’re developing elastin-collagen nanovesicles (ECnVs) for the delivery of disease modifying anti-osteoarthritis drugs, like dexamethasone (Dex), in the context of joint injury/disease. This work focused on the synthesis of varied elastin-like peptides (ELP) and collagen-like peptides (CLP) precursors, and their subsequent conjugation to create drug encapsulating ECnVs. Elastin’s lower critical solution temperature behavior allows for ECnVs that exhibit thermoresponsive, on-demand cargo release while CLPs form triple helices that stabilize the ELPs and permit binding to denatured collagen, permitting enhanced particle retention and drug-delivery in vivo.

ELPs and CLPs were synthesized using solid-phase peptide synthesis, purified using high performance liquid chromatography, and their identity confirmed using mass spectroscopy. ELP sequences consisting of (VPGFG)6G’, (VPGYG)6G’, (VPGWG)6G’, F6, Y6, W6, respectively, were generated. The CLP sequence consisted of (GPO)8GG. ELPs were conjugated to CLPs via a copper-catalyzed click chemistry to generate F6G8, Y6G8, and W6G8 conjugates. Successful conjugation and purity were confirmed via mass spectroscopy. ELP-CLP peptides were then dissolved in PBS and incubated at 80℃ to allow melting of the CLP helices and ELP-CLP dissolution. Dexamethasone fluorescein (Dex-CF) was added to the heated sample, which was then cooled to 37℃ to promote ECnV self-assembly and DEX-CF encapsulation. ECnV particle size (~100nm for all) and particle morphology (spherical) was confirmed using dynamic light scattering and transmission electron microscopy, respectively. Dex-CF encapsulation efficiencies were 38.40.9% for F6G8,19.13.2% for Y6G8, and 35.612% W6G8 indicating that the F6G8 sequence was the most consistently effective of the three and all sequences were able to successfully encapsulate the Dex-CF. This work demonstrated the successful synthesis, self-assembly, and cargo encapsulation of F6G8, Y6G8, and W6G8 ECnVs, and serves as the basis for generating of Dex-loaded ECnVs to study Dex release, thermoresponsivness, and retention in future in vitro and in vivo models.