Packaging of DNA by shell crosslinked nanoparticles

We demonstrate compaction of DNA with nanoscale biomimetic constructs which are robust synthetic analogs of globular proteins, These constructs are si milar to 15 nm in diameter, shell crosslinked knedel-like (SCKs) nanopartic les, which are prepared by covalent stabilization of amphiphilic di-block c o-polymer micelles, self-assembled in an aqueous solution. This synthetic a pproach yields size-controlled nanoparticles of persistent shape and contai ning positively charged functional groups at and near the particle surface. Such properties allow SCKs to bind with DNA through electrostatic interact ions and facilitate reduction of the DNA hydrodynamic diameter through reve rsible compaction, Compaction of DNA by SCKs was evident in dynamic light s cattering experiments and was directly observed by in situ atomic force mic roscopy. Moreover, enzymatic digestion of the DNA plasmid (pBR322, 4361 bp) by EcoRI was inhibited at low SCK:DNA ratios and prevented when less than or equal to 60 DNA bp were bound per SCK, Digestion by MspI in the presence of SCKs resulted in longer DNA fragments, indicating that not all enzyme c leavage sites were accessible within the DNA/SCK aggregates, These results have implications for the development of vehicles for successful gene thera py applications.