Carbohydrate Polymers 84 (2011) 216–222 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol Gold/cationic polymer nano-scaffolds mediated transfection for non-viral gene delivery system Tewin Tencomnao a , Apirak Apijaraskul b , Varaporn Rakkhithawatthana c , Saowaluk Chaleawlert-umpon d , Nuttaporn Pimpa d , Warayuth Sajomsang d , Nattika Saengkrit d,∗ a Center for Excellence in Omics-Nano Medical Technology Development Project, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand b Undergraduate Program in Medical Technology, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand c Graduate Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand d National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand article info Article history: Received 7 September 2010 Received in revised form 29 November 2010 Accepted 21 December 2010 Available online 25 December 2010 Keywords: Gene delivery Gold nanoparticle Modified chitosan Polyethyleneimine Layer-by-layer deposit abstract Gene delivery scaffolds based on DNA plasmid condensation with colloidal gold/cationic polymer were developed. The synthesized gold nanoparticles displayed spherical shape with an average size of 12 nm under observation with a transmission electron microscope. Gold/cationic polymer nano-scaffolds were formed though electrostatic interaction yielding gold/polyethyleneimine (PEI), gold/chitosan and gold/chitosan/PEI complexes. Luciferase-encoding plasmid DNA was subsequently added and adsorbed on the prepared scaffolds to be used as a non-viral gene carrier. Physicochemical properties of DNA- binding scaffolds were examined including size and zeta potential. The results indicated that the sizes of gold/polymer based scaffolds were generally less than 400 nm, and they carried positive charge on their surfaces. Gel retardation assay and atomic force microscopy confirmed the condensation of plasmid DNA on gold/polymer based scaffolds. Confocal fluorescent microscopy verified the presence of DNA in the cell using gold nano-scaffold as a carrier. Transfection efficiency assay using A549 and HeLa human cell lines revealed that gold/polymer based nano-scaffolds provided transfection efficiency approximately 10 times higher than polymeric-based gene carriers. This study proposed simple and practical approach, having the potential for use as an alternative gene carrier in non-viral gene delivery system. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction Gene therapy is one of the most promising strategies for treating genetic defective diseases. Since the use of viral gene deliv- ery system causes an increased risk of cytotoxicity and immune response, there is a need for a safer gene carrier. Recently, non- viral gene delivery has gained much attention as an alternative choice in gene delivery (Wong, Pelet, & Putnam, 2007). A vari- ety of synthetic non-viral gene carriers including cationic polymer, cationic lipid and lipid–polymer hybrid system have been devel- oped (Boas & Heegaard, 2004; Ewert, Evans, Bouxsein, & Safinya, 2006; Pack, Hoffman, Pun, & Stayton, 2005). The technical aspects of each approach are being investigated to achieve optimal gene transfection efficiency. With the progressive advances in nanotech- nology, gold nanoparticles have been intensively used for different biomedical applications including sensing, photothermal therapy, tracking and drug delivery (Huang, El-Sayed, Oian, & El-Sayed, ∗ Corresponding author. Tel.: +66 2564 7100x6558; fax: +66 2564 6981. E-mail address: nattika@nanotec.or.th (N. Saengkrit). 2006; Murphy et al., 2008; Tsai, Chen, & Liaw, 2008; Xia et al., 2010; Xiulan, Xiaolian, Jian, Zhou, & Chu, 2005). However, there were very few studies conducted regarding to the use of gold, for a non-viral gene delivery purpose (Noh et al., 2007; Ow Sullivan, Green, & Przybycien, 2003; Zhang et al., 2007). Here, we demonstrated the use of two different non-viral gene carriers in combination. The study investigated the roles of gold- bound cationic polymers for gene delivery into human cell lines. Gold nanoparticles have the advantages of easy preparation, and the possibility of chemical modification of surfaces for further tar- geting purposes (Gang, Martin, & Rotellao, 2006; Ow Sullivan et al., 2003). Furthermore, colloidal gold is considerably as a biocompat- ible material (Shukla et al., 2005). Meanwhile, cationic polymers such as polyethyleneimine (PEI) and chitosan derivatives have been developed so far as gene carrier molecules (Boussif et al., 1995; Lv, Zhang, Wang, Cui, & Yan, 2006). PEI is considered as the effective cationic polymer for gene delivery due to its buffer- ing capacity via proton sponge effect leading to osmotic swelling, membrane disruption and eventually DNA escape. Chitosan is rec- ognized as a biodegradable polymer with biocompatibility, low cytotoxicity and low immunogenicity. Therefore, chitosan deriva- 0144-8617/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2010.12.063