the following chemical is used in vector gene transfer a idiom Bromide depo 39 glycosyl c nitrocellulose d tag polymerase
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INTRODUCTION
Research in recent years has witnessed major concern about gene therapy providing novel approaches to the treatment of many diseases caused by genetic disorders (Guo et al., 2008). The delivery of nucleic acids to target cells and tissues, despite all achieved advances, still remains challenging (Li, Huang, 2000; Chesnoy, Huang, 2000). Specifically, gene therapy pursues the development of non-toxic effective gene carrier encapsulating and carrying foreign genetic materials into specific cell types including cancerous cells (El-Aneed, 2004).
Gene delivery carriers are generally divided into two major groups named viral and non-viral vectors (Liu, Huang, 2002). Each of these vectors demonstrates its own advantages and drawbacks (Cusack, Tanabe, 2002). Many deficiencies in several areas including the induction of host inflammatory and immune response are reported for viral vectors, though they provide high gene delivery efficiency (Tros-de-Ilarduya, Sun, Duzgunes, 2010). Non-viral vectors, especially polymers, show remarkably lower safety risks that can be applied for specific therapeutic purposes. Their most specific feature is being capable of carrying large DNA molecules and being produced most cost-effectively and in large quantity (Dehshahri et al., 2014). However, low transfection efficiency remains the major drawback of non-viral systems (Merdan, Kopecek, Kissel, 2002).
Polyallylamine (PAA) possessing a high density of primary amino groups (as free amino or as cationic ammonium salts) has recently attracted much attention as a non-viral gene delivery system (Nimesh, Kumar, Chandra, 2006; Boussif et al., 1999). Negatively charged DNA can be bound and packaged by PAA carrying a strong positive charge. However, PAA application as a gene delivery system has severely been restricted by cytotoxicity of PAA that is due to its strong polycationic character (Pathak et al., 2007). The lack of provision of endosomal escape resulting from the low buffering capacity of PAA is another disadvantage of this polymer (Pathak, Patnaik, Gupta, 2009). Numerous modifications have been carried out on this polymer to make it an effective and non-toxic carrier, including the preparation of nanocomplexes composed of PAA-dextran-DNA with an average size of about 150 nm, by Nimesh, Kumar, and Chandra (2006). Compared to the PAA-DNA nanoparticles, the evaluation of transfection efficiency of the prepared nanoparticles in HEK 293 cells showed an increase in the transfection efficiency and decrease in cytotoxicity. Moreover, in order to improve the endosomal release and enhance the gene transfer efficiency of the polymer, Pathak, Patnaik, and Gupta (2009) replaced primary amino groups of PAA (17 kDa) with imidazolyl moieties. Recently, we modified PAA with bromoalkane derivatives (Oskuee et al., 2015a) and acrylate derivatives (Oskuee et al., 2015b). Better transfection activity and less cytotoxicity were observed in some of the prepared vectors.
The present study aims at enhancing PAA transfection efficiency through replacing primary amino groups with cholesterol, reducing the polymer cytotoxicity, developing polymer hydrophobic interaction with the cell membrane, and maintaining the polymer buffering capacity. It is expected that as nanoparticles cross the cell membrane, vector release from the endosome becomes easier (through endosome membrane instability) and polymer toxicity decreases.
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