Nanoscale Res Lett (2009) 4:982–992 DOI 10.1007/s11671-009-9345-3 N A N O E X P R E S S Preparation and Characterization of Cationic PLA-PEG Nanoparticles for Delivery of Plasmid DNA Weiwei Zou Æ Chunxi Liu Æ Zhijin Chen Æ Na Zhang Received: 4 March 2009 / Accepted: 6 May 2009 / Published online: 21 May 2009 to the authors 2009 Abstract The purpose of the present work was to for- mulate and evaluate cationic poly(lactic acid)-poly(ethyl- ene glycol) (PLA-PEG) nanoparticles as novel non-viral gene delivery nano-device. Cationic PLA-PEG nanoparti- cles were prepared by nanoprecipitation method. The gene loaded nanoparticles were obtained by incubating the report gene pEGFP with cationic PLA-PEG nanoparticles. The physicochemical properties (e.g., morphology, particle size, surface charge, DNA binding efﬁciency) and biolog- ical properties (e.g., integrity of the released DNA, pro- tection from nuclease degradation, plasma stability, in vitro cytotoxicity, and in vitro transfection ability in Hela cells) of the gene loaded PLA-PEG nanoparticles were evaluated, respectively. The obtained cationic PLA-PEG nanoparti- cles and gene loaded nanoparticles were both spherical in shape with average particle size of 89.7 and 128.9 nm, polydispersity index of 0.185 and 0.161, zeta potentials of ?28.9 and ?16.8 mV, respectively. The obtained cationic PLA-PEG nanoparticles with high binding efﬁciency ([95%) could protect the loaded DNA from the degrada- tion by nuclease and plasma. The nanoparticles displayed sustained-release properties in vitro and the released DNA maintained its structural and functional integrity. It also showed lower cytotoxicity than Lipofectamine 2000 and could successfully transfect gene into Hela cells even in presence of serum. It could be concluded that the estab- lished gene loaded cationic PLA-PEG nanoparticles with excellent properties were promising non-viral nano-device, which had potential to make cancer gene therapy achievable. W. Zou C. Liu Z. Chen N. Zhang (&) School of Pharmaceutical Science, Shandong University, 44 Wenhua Xi Road, 250012 Ji-nan, China e-mail: zhangnancy9@sdu.edu.cn 123 Keywords Cationic PLA-PEG nanoparticles (DNA-PLA-PEG-NPs) Gene therapy Nanoprecipitation method Non-viral gene vector Introduction Gene therapy is a rapidly advancing ﬁeld with enormous potential to treat vital human diseases such as cancer and inherited genetic disorders fundamentally. The development of potent gene transfer systems that can deliver foreign genes efﬁciently and safely into target cells is of crucial importance for successful gene therapy. The non-viral vector, possessing signiﬁcantly low safety risks and convenient preparation in large quantities easily and inexpensively, has been suggested as an alternative to viral vector [1]. Therefore, to develop a safe and effective nonviral vector system is an urgent matter. Among non-viral vectors, cationic gene delivery polymers include poly(ethylenimine) (pEI), poly(2-dimethylamino- ethyl methacrylate) (pDMAEMA), and poly-L-lysine (pLL) have been frequently studied. Their gene binding and con- densation capacities as well as their in vitro and in vivo transfection properties have been reported in recently ample literatures. These polymers are, however, non-degradable and there is consequently a risk that accumulation in the body occurs, in particular after repeated administration. Further, most of these cationic polymers show some cytotoxicity likely due to adverse interactions with membranes resulting in loss of cytoplasmic proteins, in permeabilization of cel- lular membranes and collapse of the membrane potential [2]. Consequently, there is a need for biodegradable gene delivery polymers. It’s clear that the potential advantages of biodegradable carriers are their reduced toxicity (provided that degradation leads to non-toxic products) and avoidance of accumulation of the polymer in the cells. Moreover, the