The self-assembly of supramolecular complexes of nucleic acids and pol
ymers is of relevance to several biological processes including viral
and chromatin formation as well as gene therapy vector design. We now
show that template polymerization facilitates condensation of DNA into
particles that are <150 nm in diameter. Inclusion of a poly(ethylene
glycol)-containing monomer prevents aggregation of these particles. Th
e DNA within the particles remains biologically active and can express
foreign genes in cells. The formation or breakage of covalent bonds h
as until now not been employed to compact DNA into artificial particle
s.