This study designs a novel nanoparticle system with core–shell structure based on pullulan and poly(β-amino) ester (PBAE) for the hepatoma-targeted codelivery of gene and chemotherapy agent. Plasmid DNA expressing green fluorescent protein (pEGFP), as a model gene, was fully condensed with cationic PBAE to form the inner core of PBAE/pEGFP polycomplex. Methotrexate (MTX), as a model chemotherapy agent, was conjugated to pullulan by ester bond to synthesize polymeric prodrug of MTX-PL. MTX-PL was then adsorbed on the surface of PBAE/pEGFP polycomplex to form MTX-PL/PBAE/pEGFP nanoparticles with a classic core–shell structure. MTX-PL was also used as a hepatoma targeting moiety, because of its specific binding affinity for asialoglycoprotein receptor (ASGPR) overexpressed by human hepatoma HepG2 cells. MTX-PL/PBAE/pEGFP nanoparticles realized the efficient transfection of pEGFP in HepG2 cells and exhibited significant inhibitory effect on the cell proliferation. In HepG2 tumor-bearing nude mice, MTX-PL/PBAE/pEGFP nanoparticles were mainly distributed in the tumor after 24 h postintravenous injection. Altogether, this novel codelivery system with a strong hepatoma-targeting property achieved simultaneous delivery of gene and chemotherapy agent into tumor at both cellular and animal levels.Keywords: chemotherapy agent; gene; hepatoma; poly(β-amino) ester; pullulan

This study reports the design of a novel pH-sensitive nanoparticle carrier based on pullulan for realizing intracellular drug delivery. A series of pullulan derivatives (UCPA) were synthesized by conjugation of both urocanic acid (a pH-sensitive grafted moiety) and cholesterol succinate (a hydrophobically modified moiety) to pullulan. UCPAs exhibited amphiphilic and pH-sensitive properties, and their responding pH value was around 6.5. UCPA nanoparticles prepared by the precipitation method had roughly spherical shapes, and sizes ranging from 150 to 300 nm. Doxorubicin (DOX), as a model antitumor drug, was physically loaded into the UCPA nanoparticles and its in vitro release at different pH values was studied using a dialysis method. UCPA-1 nanoparticles, with the degree of substitution (DS) of urocanyl and cholesterol moieties of 6.8% and 3.5%, respectively, exhibited relatively high drug-loading capability and strong in vitro pH-induced drug release. The results of MTT assays, flow cytometric analyses and confocal microscopy observations confirmed that the UCPA-1 nanoparticles can realize the intracellular delivery of DOX after internalization and enhanced cytotoxicity of DOX against MCF-7 cells.