Available online at www.sciencedirect.com Journal of Virological Methods 147 (2008) 213–218 Laboratory formulated magnetic nanoparticles for enhancement of viral gene expression in suspension cell line Shanta Raj Bhattarai a , Sun Young Kim b , Kyu Yun Jang c , Ki Chang Lee d , Ho Keun Yi e , Dae Yeol Lee b , Hak Yong Kim f , Pyoung Han Hwang b,∗ a Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, South Korea b Department of Pediatrics and Research Institute of Clinical Medicine, School of Medicine, Chonbuk National University, 634-18 Geumam-dong, Deokjin-gu, Jeonju, Jeonbuk 561-712, South Korea c Department of Pathology, School of Medicine, Chonbuk National University, Jeonju, South Korea d Department of Veterinary Radiology, School of Veterinary Medicine, Chonbuk National University, Jeonju, South Korea e Department of Biochemistry, School of Dentistry, Chonbuk National University, Jeonju, South Korea f Department of Textile Engineering, Chonbuk National University, Jeonju, South Korea Received 2 July 2007; received in revised form 26 August 2007; accepted 30 August 2007 Available online 1 November 2007 Abstract One factor critical to successful gene therapy is the development of efficient delivery systems. Although advances in gene transfer technology including viral and non-viral vectors have been made, an ideal vector system has not yet been constructed. Due to the growing concerns over the toxicity and immunogenicity of viral DNA delivery systems, DNA delivery via improve viral routes has become more desirable and advantageous. The ideal improve viral DNA delivery system should be a synthetic materials plus viral vectors. The materials should also be biocompatible, efficient, and modular so that it is tunable to various applications in both research and clinical settings. The successful steps towards this improve viral DNA delivery system is demonstrated: a magnetofection system mediated by modified cationic chitosan-coated iron oxide nanoparticles. Dense colloidal cationic iron oxide nanoparticles serve as an uptake-enhancing component by physical concentration at the cell surface in presence of external magnetic fields; enhanced viral gene expression (3–100-fold) due to the particles is seen as compared to virus vector alone with little virus dose. © 2007 Elsevier B.V. All rights reserved. Keywords: Magnetofection; Gene; Viral vectors; Magnetic nanoparticles; Chitosan; Iron oxide 1. Introduction Gene therapy is a potential theraputic modality that requires effective gene delivery into lining cells (Giannoukakis and Thomson, 1999; Pfeifer and Verma, 2000; Hunt and Vorburger, 2002). To the date the most common methods for delivering genes into cell in vitro include cells treated with viruses such as retrovirous and adenovirus, calcium phosphate, liposome, particle bombardment, fine needle naked DNA injection, elec- troporation, or any combination of these methods (Giannoukakis and Thomson, 1999; Pfeifer and Verma, 2000; Hunt and ∗ Corresponding author. Tel.: +82 63 250 1472; fax: +82 63 250 1464. E-mail address: hwaph@chonbuk.ac.kr (P.H. Hwang). Vorburger, 2002; Bergelson et al., 1997). Although viral meth- ods are powerful methods to deliver the engineered gene into cells with high efficiency in different cell line but not success- fully deliver in suspension cell line especially leukemia cells (Fields, 1996). And also high doses of viral gene delivery sys- tem causes greatest two potential dangers like oncogenesis and inflammation. So there is urgent need of alternative method of viral gene delivery system or improvement of this system by reducing the viral doses, time of infection and eventually reduce the viral side effect and applied it in variety of cell line for gene delivery vector. Focusing above burning issue, a combined chemical and physical method was applied to improve the viral gene deliv- ery system. Among different chemical or physical method, gene delivery by the use of magnetic forces, so-called magnetofec- 0166-0934/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jviromet.2007.08.028