Polyelectrolyte layer assembly of bacterial nanocellulose whiskers with plasmid DNA as biocompatible non-viral gene delivery system

The nanocrystalline fraction of the natural biopolymer bacterial nanocellulose (BNC) was isolated by controlled degradation resulting in anionic surface modifications. The potential of those nanowhiskers for safe and efficient gene delivery was tested using electrostatic layer assemblies with different poly(ethylene imine)s (2.5 and 25 kDa) and plasmid DNA. For different isolation techniques (sulfuric acid hydrolysis and oxidation) the influence of varying preparation conditions such as concentration of the degrading agent, reaction time and temperature on the physicochemical characteristics of the nanowhiskers like morphology, size, and surface charge could be demonstrated. All nanowhiskers were found to be highly cyto- and hemo-compatible in vitro in short-term (2–8 h) or long-term (24–72 h) studies as well as ex ovo in a shell-less hen’s egg model over 8 h. The use of a polyelectrolyte layer technique based on electrostatic interactions with different poly(ethylene imine)s and plasmid DNA enabled the formation of small sized (ca. 200 nm), DNA stabilizing nanowhiskers and facilitated the transfection of CHO-K1 cells with high biocompatibility. In conclusion, by the use of BNC as sustainable raw material, in combination with optimized and controllable preparation conditions and surface modifications, BNC nanowhiskers modified by a polyelectrolyte layer approach could be used as renewable, “green” drug delivery system for bioactive substances such as nucleic acids.