| abstract |
The present invention provides a block copolymer which can be suitably used for a drug carrier capable of forming a stable complex with a nucleic acid and of releasing the nucleic acid intracellularly. The block copolymer is represented by formula (1) or (2). In the formulas, R 1 and R 2 are, independent of one another, a hydrogen atom or an optionally substituted C 1-12 linear-chain or branched alkyl group, A is a hydrophilic polymer chain, L 1 and L 3 are linking groups, B is a cation-containing group, R 3 is an arbitrary amino acid side chain, z is an integer between 5 and 500, x is an integer that is at least 40% of z, y is an integer and can be 0, z-x-y is an integer and can be 0, p is an integer between 1 and 10, and q is an integer between 1 and 10. |