(514d) DNA-Loaded Particles for Nonviral Gene Delivery Prepared From Corn Protein (Zein)

There is a significant and immediate demand for nonviral gene delivery techniques in gene therapy and tissue engineering applications, yet current approaches do not deliver genetic material efficiently. Natural polymers have been applied to drug/gene delivery and tissue engineering, and have an advantage over synthetic biomaterials in that these natural biomaterials provide innate degradability, biocompatibility, and bioactivity. However, many natural polymers suffer from poor mechanical stability, and have a rapid solubilization in aqueous environments because of their hydrophilicity, leading to fast release profiles if drugs or DNA are incorporated. Zein, the storage protein of corn, has potential to be used for polymeric DNA delivery, as well as to be fabricated into DNA-incorporating films and scaffolds for tissue engineering applications, because of its hydrophobicity and bioactive properties. Zein's hydrophobic nature makes it a good natural polymer to be used to form nano/microspheres that can encapsulate DNA, while also providing for sustained release. Additionally, zein also has the capability to protect DNA in the acidic environment of the stomach and to delay release until the intestines, as would be necessary for polymeric delivery for oral route applications. This protein has been used extensively in drug tablet coatings and has generally regarded as safe (GRAS) status. In this study, zein particle formation with DNA encapsulation was achieved through the coacervation method with encapsulation efficiencies ranging from ~3% to ~100% for zein to DNA ratios ranging from 10:1 to 100:1, respectively. These spheres range in diameter from ~220 nm to ~570 nm with an average zeta potential of -30.66 mV. A maximum loading of ~12.5 ìg DNA per mg zein and a minimum diameter of ~220 nm are achieved in particles with a 40:1 zein to DNA ratio. Release studies provide evidence of sustained release, with only ~20% of DNA released after 8 days in vitro. The above results demonstrate the ability of this method to be tuned to produce nano/microspheres with varying amounts of encapsulated DNA as well as varying sizes. These DNA-loaded zein particles have the potential to be used for controlled release of DNA for systemic and oral delivery of therapeutic genes and vaccines and can also be used as building blocks to fabricate films and tissue engineering scaffolds to create matrices loaded with DNA for localized delivery, which can guide tissue regeneration.