Abstract
The growing interest in gene therapy is coupled with the strong need for the development of safe and efficient gene transfection vectors. A composite based on chitosan and fumed silica has been found to be a prospective gene delivery carrier. This study presents an investigation of the nature of the bonds between a series of nucleotides with a chitosan layer deposited on a fumed silica surface. Experimentally measured surface complex formation constants (logK) of the nucleotides were found to be in the range of 2.69–4.02, which is higher than that for the orthophosphate (2.39). Theoretically calculated nucleotide complexation energies for chitosan deposited on the surface range from 11.5 to 23.0 kcal·mol–1, in agreement with experimental data. The adsorption of nucleotides was interpreted using their calculated speciation in an aqueous solution. Based on the structures of all optimized complexes determined from quantum-chemical PM6 calculations, electrostatic interactions between the surface-located NH3+ groups and −PO3H––/–PO32– fragments of the nucleotides were identified to play the decisive role in the adsorption mechanism. The saccharide fragment of monophosphates also plays an important role in the binding of the nucleotides to chitosan through the creation of hydrogen bonds.
Highlights
IntroductionThe increased interest in gene therapy has called for proper materials to serve as safe and efficient gene transfection vectors.[1] Among biopolymers, chitosan and its derivatives represent perspective materials for a large number of applications, especially in the pharmaceutical, environmental, and industrial fields.[2−6] These biopolymers, originating from marine waste, have attracted much attention as nonviral vectors due to their valuable properties as well as a high positive charge density in low-pH solution localized on the primary amino groups
Gene therapy has proved to be an effective solution for most known diseases
We have found that positive charge in the chitosan fragment is predominantly localized on the protonated amino group, while the negative charge in the nucleotides is localized on the phosphate fragments
Summary
The increased interest in gene therapy has called for proper materials to serve as safe and efficient gene transfection vectors.[1] Among biopolymers, chitosan and its derivatives represent perspective materials for a large number of applications, especially in the pharmaceutical, environmental, and industrial fields.[2−6] These biopolymers, originating from marine waste, have attracted much attention as nonviral vectors due to their valuable properties as well as a high positive charge density in low-pH solution localized on the primary amino groups. These beneficial features give chitosan the capability as gene carriers.[9,10] Some studies have reported the modification of chitosan to improve the transfection efficiency of chitosan formulations.[11,12] the interaction mechanism between chitosan and DNA is still unclear at the molecular level
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