Abstract: A unit structure-type pharmaceutical composition includes a single nucleic acid, such as an antisense nucleic acid, electrostatically bound to a single block copolymer having a cationic polyamino acid segment and a hydrophilic polymer chain segment. The negative charges of the nucleic acid are counterbalanced, at least substantially, by the positive charges of the cationic polyamino acid segment such that the pharmaceutical composition is electrically neutral or nearly electrically neutral. Further, the nucleic acid is covered with the hydrophilic polymer chain segment. The block copolymer thereby improves the blood retention capability of the nucleic acids.

Abstract: A nucleic acid-encapsulating polymer micelle complex is formed of a block copolymer containing an uncharged hydrophilic polymer chain block and a cationic polymer chain block; and two single-stranded DNA molecules having mutually complementary base sequences of 1000 or more bases in length, double-stranded DNA of 1000 or more base pairs in length in which at least a part of a double helix structure is dissociated and forms a single-stranded structure, or one single-stranded DNA molecule of 1000 or more bases in length.

Abstract: A unit structure consists of a single nucleic acid having a length of 10 to 30 bases, and a single block copolymer having a cationic polyamino acid segment and a hydrophilic polymer chain segment. In this unit structure: (i) a difference between a total of positive charges derived from cationic groups of the cationic polyamino acid segment and a total of negative charges derived from the nucleic acid in the unit structure falls within a range of ±10% of the total of the negative charges derived from the nucleic acid, (ii) the hydrophilic polymer chain segment comprises polyethylene glycol, (iii) the polyethylene glycol has a radius of inertia (Rg) equal to or longer than the length of the nucleic acid, and (iv) the cationic polyamino acid segment is bound to the nucleic acid via electrostatic bonds.

Abstract: A unit structure-type pharmaceutical composition includes a single nucleic acid, such as an antisense nucleic acid, electrostatically bound to a single block copolymer having a cationic polyamino acid segment and a hydrophilic polymer chain segment. The negative charges of the nucleic acid are counterbalanced, at least substantially, by the positive charges of the cationic polyamino acid segment such that the pharmaceutical composition is electrically neutral or nearly electrically neutral. Further, the nucleic acid is covered with the hydrophilic polymer chain segment. The block copolymer thereby improves the blood retention capability of the nucleic acids.

Abstract: A unit structure-type pharmaceutical composition includes at least one nucleic acid, such as siRNA, electrostatically bound to at least one block copolymer having a cationic polyamino acid segment and a hydrophilic polymer chain segment. The negative charge(s) of the nucleic acid are counterbalanced, at least substantially, by the positive charge(s) of the cationic polyamino acid segment such that the pharmaceutical composition is electrically neutral or nearly electrically neutral. Further, the nucleic acid is covered with the hydrophilic polymer chain segment(s). The at least one block copolymer thereby improves the blood retention capability of the nucleic acid(s).

Abstract: A nucleic acid-encapsulating polymer micelle complex is formed of a block copolymer containing an uncharged hydrophilic polymer chain block and a cationic polymer chain block; and two single-stranded DNA molecules having mutually complementary base sequences of 1000 or more bases in length, double-stranded DNA of 1000 or more base pairs in length in which at least a part of a double helix structure is dissociated and forms a single-stranded structure, or one single-stranded DNA molecule of 1000 or more bases in length.

Abstract: An excellent nucleic acid delivery composition is provided which has reduced cytotoxicity and improved nucleic acid introduction efficiency and gene expression efficiency. The composition comprises: a block copolymer having an uncharged hydrophilic polymer segment and a cationic polymer segment; a cationic polymer; and a nucleic acid, wherein the mol percentage (B/H ratio) of the cationic groups of the block copolymer to the total cationic groups of the block copolymer and the cationic polymer is between 25% and 90%.

Abstract: A unit structure-type pharmaceutical composition includes at least one nucleic acid, such as siRNA, electrostatically bound to at least one block copolymer having a cationic polyamino acid segment and a hydrophilic polymer chain segment. The negative charge(s) of the nucleic acid are counterbalanced, at least substantially, by the positive charge(s) of the cationic polyamino acid segment such that the pharmaceutical composition is electrically neutral or nearly electrically neutral. Further, the nucleic acid is covered with the hydrophilic polymer chain segment(s). The at least one block copolymer thereby improves the blood retention capability of the nucleic acid(s).

Abstract: An excellent nucleic acid delivery composition is provided which has reduced cytotoxicity and improved nucleic acid introduction efficiency and gene expression efficiency. The composition comprises: a block copolymer having an uncharged hydrophilic polymer segment and a cationic polymer segment; a cationic polymer; and a nucleic acid, wherein the mol percentage (B/H ratio) of the cationic groups of the block copolymer to the total cationic groups of the block copolymer and the cationic polymer is between 25% and 90%.

Abstract: The present invention discloses a vesicle which is excellent in structure stability and environmental responsiveness and also can be produced by a simple operation. More particularly, the present invention discloses a vesicle comprising a membrane formed of a first block copolymer containing a non-chargeable hydrophilic segment and a chargeable segment, and a second block copolymer containing a non-chargeable hydrophilic segment and a chargeable segment having an electric charge which is opposite to that of the chargeable segment of the first block copolymer.

Abstract: The present invention discloses a vesicle which is excellent in structure stability and environmental responsiveness and also can be produced by a simple operation. More particularly, the present invention discloses a vesicle comprising a membrane formed of a first block copolymer containing a non-chargeable hydrophilic segment and a chargeable segment, and a second block copolymer containing a non-chargeable hydrophilic segment and a chargeable segment having an electric charge which is opposite to that of the chargeable segment of the first block copolymer.