Self-assembly and applications of nucleic acid solid-state films

While most nucleic acid (NA)-lipid or NA-polymer complexes are studied in solution, there is growing interest in understanding their properties as naturally derived, biodegradable, biocompatible, solid-state materials with tailorable properties influenced by environmental parameters. Therapeutic and cell programming applications comprise an important new research field, particularly in gene transfection and silencing using plasmid DNA and siRNA with targeted local delivery for use in cell culture. Dried solid films have lower nuclease degradation, fewer barriers to long term storage, and allow localized delivery by direct implantation in combination with controlled release and dosage adjustment. In contrast to particulate complexes or other methods of drug delivery which are prepared and must remain in solution, films can regain their biological activity once wetted. However our understanding of the types of cationic agents that predictably form self-standing films with NA is still limited. The self-assembly and structural, physical, and chemical properties of these materials are of key importance to maintaining their activity. We therefore discuss the material properties of NA-lipid and NA-polymer films as the focus of this article. Recent studies have indicated that there is also growing interest in NA films beyond bioengineering and medical applications in the fields of nano- and optoelectronics. We survey the self-assembly of solid-state materials composed of NA complexed with lipids, surfactants, or polymers, and summarize investigations of nanoscopic assembly, structure, optical, and macroscopic material properties. We further evaluate the current and future applications of NA-lipid and NA-polymer films and the benefits and drawbacks of each type.