Hyaluronic acid (HA), a natural anionic mucopolysaccharide, was used to coat polyethylenimine-poly(gamma-benzyl L-glutamate)/DNA (PEI-PBLG/DNA) complexes. HA was further modified by introducing RGD peptide with grafting density of one RGD in every 1.9 HA repeating units. HA can coat the cationic surface of PEI-PBLG/DNA complexes without destroying them even at high weight ratio of HA/PEI-PBLG/DNA = 40/10/1. Coating the complexes by HA and HA-RGD caused lower surface charges and little bigger size than the naked PEI-PBLG/DNA HA/PEI-PBLG/DNA has little lower transfection efficiency compared with naked PEI-PBLG/DNA, while the transfection efficiency of HA-RGD/PEI-PBLG/DNA is 9.7 times of HA/PEI-PBLG/DNA for the RGD target bonding affinity to the receptors on the cell surface. HA coating on PEI-PBLG/DNA reduced the electrostatic binding affinity to the cells while the RGD binding affinity for integrin on HeLa cells can not only compensate the reduced binding affinity but also enhance the affinity for HA-RGD/PEI-PBLG/DNA. RGD and RDG competition assay and lactate dehydrogenase (LDH) release studies further confirmed the specific target functions of RGD on HA. Cell viability measurements confirmed the high viability (above 70% viability) of the cells treated with HA-RGD and HA coated complex particles. These results would show that HA-RGD coated PEI-PBLG/DNA complexes have an attractive feature to a targeting in vivo non-viral gene delivery system. (C) 2011 Elsevier B.V. All rights reserved.