Cross-linking as a tool for enhancement of transfection efficiency of cationic vectors

A series of nanogel particles with the growing cross-linking degree was synthesized in reverse micelles by copolymerization of a cationic monomer N,N-dimethylaminoethylmethacrylate with increasing amounts of N,N′-methylenebisacrylamide (MBA). The growth of MBA content in the studied range of 0.2–15% (mol) resulted in a regular decrease of the particles’ size with a narrowing in their size distribution which occurred at the first of the cross-linker addition. In the second region, where the MBA content was more than 5% (mol), the size distribution was very narrow. The cross-linked polymers prepared at 2–5% of the cross-linker amount demonstrated a minimum size of the polyplexes and enhancement in the transfection with plasmid DNA and small interfering RNA targeted to the luciferase gene. The revealed changes in the properties of nanogels occurring upon the changes in the cross-linking degree appear to be a platform for a controlled manufacturing of efficient cross-linked cationic vectors.