Object: Although siRNA/microRNA-based gene therapy has enormous potential,it is severely limited by a lack of specific cell-targeting delivery systems.Anti-osteoporosis gene-based drug development strategies are presently focused on targeting osteoblasts to either suppress bone loss or increase bone mass.Recently,we investigated an osteoblast-targeting peptide(SDSSD),which could selectively bindto osteoblasts via periostin.Here,wedeveloped a small nucleic acid delivery system with SDSSD-modified polyurethane(PU)that delivers siRNA/microRNA drugs to osteoblasts.