Double-stranded RNA homopolymer poly(rC).poly(rG) for a new pH-sensitive drug carrier.

Double-stranded RNA homopolymer poly(rC).poly(rG) has been used as a new pH-sensitive drug carrier. The poly(rC).poly(rG) had proton buffering capacity around pH 6, owing to protonation of cytosine, as determined by acid-base titration. By circular dichroism measurement, the protonation caused conformational change of the RNA. The poly(rC).poly(rG) and doxorubicin (Dox), as an anticancer drug, formed the complexes which released the drugs at endosomal pH. The resulting complex exhibited higher anticancer activity than the Dox alone. These results result suggest that the poly(rC).poly(rG) is a promising biopolymer for a new class of pH-sensitive drug carriers.