Patent ID: 8404224

Claim:
A therapeutic agent delivery system, comprising: a polymer having the formula: PB-(L 1 -N + (R a )(R b )-L 2 -A(═O)—OR c ) n (X − ) n wherein PB is the polymer backbone having n pendant groups L 1 -N + (R a )(R b )-L 2 -A(═O)—OR c ); N + is a cationic center; R a and R b are independently selected from hydrogen, alkyl, and aryl; A(═O)—OR c is the hydrolyzable group, wherein A is selected from the group consisting of C, S, SO, P, or PO, and R c is an alkyl, aryl, acyl, or silyl group that may be further substituted with one or more substituents; L 1 is a linker that covalently couples the cationic center to the polymer backbone; L 2 is a linker that covalently couples the cationic center to the hydrolyzable group; X − is the counter ion associated with the cationic center, wherein the counter ion comprises a therapeutic agent selected from the group consisting of a nucleic acid, an amino acid, a peptide, and a protein; and n is an integer from about 10 to about 10,000.