A system for delivering a therapeutic dose of a drug is disclosed. The system includes a delivery medium with therapeutic units attached thereto. The delivery medium is preferably a polymeric hydrogel matrix that has therapeutic units incorporated therein or metal nanoparticles with therapeutic units complexed thereto. The therapeutic units include nucleic acid moieties. The nucleic acid moieties preferably include strands of nucleic acid and drug moieties complexed with the strands of nucleic acid. Where the system includes a polymeric hydrogel matrix, an active drug is controllably released from the polymer hydrogel matrix to provide a therapeutic dose to a biological system or biological tissue. The active drug is controllably released from the hydrogel matrix by altering the environment the hydrogel matrix, or by enzymatic cleavage of the nucleic acid moieties or by a combination thereof.