The present invention is directed to a biodegradable system for the
controlled release of bioactive substances. This system comprises novel
biodegradable and biocompatible polyphosphoesters that carry positive
charges. Process for making these polyphosphoesters, compositions
containing these polyphosphoesters and biologically active substances,
articles and methods for delivery of drugs and genes using this system
are described. A controlled gene delivery system based on these
polyphosphoesters is prepared by complex coacervation of nucleic acid
(DNA or RNA) with polymers. The release rates can be manipulated by
adjusting the charge ratios of polyphosphoesters to nucleic acids. This
gene delivery system yields a higher gene expression in muscle when
injected intramuscularly.
