Nucleic acid complex

A nucleic acid complex comprising a first nucleic acid strand and a second nucleic acid strand,

• wherein the first nucleic acid strand comprises a base sequence capable of hybridizing with at least part of a target transcription product and has an antisense effect on the target transcription product;
• wherein half or less or none of the full length of the first nucleic acid strand is natural ribonucleosides,
• wherein the second nucleic acid strand comprises a base sequence complementary to the first nucleic acid strand and is bound to a phosphatidylethanolamine or an analog thereof;
• wherein the phosphatidylethanolamine or an analog thereof is represented by the general formula I:
• wherein R1 and R2 independently represent a substituted or unsubstituted C5-C32 alkyl group, or a substituted or unsubstituted C5-C32 alkenyl group, and
• wherein the first nucleic acid strand is annealed to the second nucleic acid strand.