(16f) Micelleplexes: Terpolymer Micelle-Based Gene Delivery Vectors with Superior DNA Protection against Enzymatic Degradation

Protecting polynucleotides from nuclease degradation under physiological environment is an unresolved challenge associated with in vivo non-viral gene delivery. To address this problem, our research explores a new approach for improving DNA protection using a novel hydrophobically modified PEGylated polycation. Our approach utilizes an ABC triblock copolymer (?terpolymer?) composed of (A) hydrophilic poly(ethylene glycol) (PEG), (B) hydrophobic poly(n-butyl acrylate) (PnBA) and (C) cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). Using this ABC sequence of blocks, spherical micelle-like aggregates coated with mixed PEG and PDMAEMA chains can be fabricated in water which can then be used as basic building blocks for constructing virus-mimetic DNA particles; when these micelles are mixed with DNA, the PDMAEMA chains in the corona primarily interact with the negatively charged phosphates on DNA, and the viral capsid-like morphology of the nanometers-thick micelle coating can be created at the outer surface of collapsed DNA. In this presentation, we will discuss our recent experiments (including polymer synthesis, nanostructure/surface charge characterization, and enzyme degradation/gene transfection assays) that support the feasibility of the proposed approach for in vivo gene delivery. Our results suggest that: (i) the cationic terpolymer micelles are very effective in condensing DNA molecules into the desired (virus-mimetic) morphology having sizes and molecular-level properties suitable for use as (in vivo) gene carriers; (ii) the resultant DNA/micelle complexes (?micelleplexes?) exhibit a great stability against serum nuclease-induced degradation, which far exceeds what can be achieved using conventional PEGylation-based approaches under similar conditions.