Histone-Mimetic Gold Nanoparticles as Self-Activating and Tailorable Gene Delivery Scaffolds

Meghan J. Reilly and Millicent O. Sullivan. Chemical Engineering, University of Delaware, 150 Academy St, Newark, DE 19716

The field of gene therapy has garnered significant interest over the past two decades as a method for revolutionizing the treatment of various diseases such as Alzheimer's, Parkinson's, and many types of cancer. In recent years, non-viral methods of delivery have received particular attention due to safety concerns and production limitations associated with viral vectors. However, inefficient DNA release is a common cause of ineffective non-viral DNA delivery. A novel solution to this constraint is the development of biomimetic scaffolds capable of regulating DNA accessibility. The presented study involves the design of histone-mimetic gold nanoparticles (HMGNs) as gene therapy packaging materials. Colloidal gold serves as a scaffold for the incorporation of histone H3 tail peptides trimethylated at lysine 4 (H3K4Me3). H3K4Me3 has a high density of positively charged residues that provide a DNA condensation template and impart protection from nuclease degradation. H3K4Me3 is known to be highly enhanced at the transcription start site for essentially all active genes. In addition, recognition of this trimethylated K4-containing peptide sequence by nucleosome remodeling factors has been implicated in mechanisms for chromatin activation. The purpose of the presented work is to assemble and characterize these HMGNs as well as to investigate the influence of HMGN functionalization on DNA binding, protection, and release. To this end, peptide-functionalized gold particles have been prepared. Their size and morphology have been characterized by methods such as UV-Vis spectroscopy and TEM. In addition, the self-assembly of H3K4Me3 with plasmid DNA has also been investigated by dynamic light scattering, zeta-potential, and gel mobility shift assays. These selected studies are aimed at validating the HMGN approach to gene delivery and will provide the framework for further development of our system.