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The influence of chitosan valence on the complexation and transfection of DNA The weaker the DNA-chitosan binding the higher the transfection efficiency

Grupo de Nanomateriales y Materia Blanda, Departamento de Física de Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
Colloids and surfaces B: Biointerfaces (Impact Factor: 4.15). 01/2011; 82(1):54-62. DOI: 10.1016/j.colsurfb.2010.08.013
Source: PubMed

ABSTRACT The DNA-chitosan polyplexes have attracted for some years now the attention of physical-chemists and biologists for their potential use in gene therapy, however, the correlation between the physicochemical properties of these polyplexes with their transfection efficiency remains still unclear. In a recent paper we demonstrated by means of DLS that the DNA-chitosan complexation is favored at acidic conditions considering that fewer amounts of chitosan were required to compact the DNA. As a second study, in the present work we analyze the influence of chitosan valence on the complexation and transfection of DNA. Three chitosans of different molecular weights (three different valences) are characterized as gene carriers at 25°C and pH 5 over a wide range of chitosan-Nitrogen to DNA-Phosphate molar ratios, N/P, by means of conductometry, electrophoretic mobility, isothermal titration calorimetry (ITC), transmission electron microscopy (TEM), atomic force microscopy (AFM), and β-galactosidase and luciferase expression assays.

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    • "Moreover, its properties can be tuned to a considerable extent by simply controlling the degree of deacetylation and polymerization, or the pH-dependent degree of ionization [34]. Chitosan properties controlled by these parameters, affect its interaction with DNA [35] [36] [5] and, as a consequence, the properties and performance of the resulting polyplexes [6] as vectors for gene delivery. However, the effects of the different parameters are interconnected in a non trivial way. "
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    • "Therefore, novel composites of HA and organic polymers that can compensate for the weak mechanical properties of HA have become of great interest [4] [5]. Chitosan, (C 6 H 11 O 4 N) n is an N-deacetylation product of chitin and is a unique polysaccharide based biopolymer that shares a number of chemical and structural similarities with collagen and has been used as a skin grafting template, hemostatic agent, DNA and drug delivery vehicle, and as a wound healing material [6] [7] [8] [9] [10] [11]. Also, chitosan (CTS) films support the growth, function, and cellular activity of osteoblasts and chondrocytes [12]. "
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    • "For instance the binding affinities for pDNA/cationic polymer systems measured by ITC were also heavily exothermic [18], however they were reported two to three logarithmic units lower for liposomal or cationic peptide/nucleic acid interactions [26] [27]. This increased complex stability may explain the inferior transfection effectiveness of these siRNA/chitosan polyplexes compared to liposomal systems reflecting an impact on the siRNA release from the carrier system [28]. ITC also allowed for direct quantification of N:P ratios between chitosan and siRNA at which full saturation of the polymer with siRNA, or vice versa, is obtained. "
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