Sterically stabilized self-assembling reversibly cross-linked polyelectrolyte complexes with nucleic acids for environmental and medical applications

One of the principal problems facing nucleic acid delivery systems using polyplexes is the instability of the complexes in the presence of proteins and high salt concns. The authors have used a crosslinking polymer to overcome this problem. Pendant thiol moieties have been incorporated into a PAA (polyamidoamine) homopolymer and a PEG [poly(ethylene glycol)]-PAA-PEG copolymer reported previously as a self-assembling system. When mixed with DNA, small monodisperse sterically stabilized particles are formed in quant. yields. Optimization of the formulation resulted in nanoparticles which are stable in seawater. This crosslinked formulation has been successfully tested in both freshwater and estuarine field trials as a water tracer. Future work will develop these particles as a groundwater tracer and also for therapeutic applications of nucleic acid delivery.