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Stability and binding affinity of DNA/chitosan complexes by polyanion competition
Pei Lian Ma1, Marc Lavertu1, Françoise M Winnik2
1Department of Chemical Engineering and Institute of Biomedical Engineering, Polytechnique Montréal, PO 6079 Succ. Centre-Ville, Montreal, PQ, H3C 3A7, Canada.
Carbohydrate Polymers
|September 21, 2017
Summary
Chitosan complexes release DNA only when exposed to highly charged heparin. Increased chitosan properties and N/P ratio enhance DNA complex stability against premature release, crucial for gene delivery.
Area of Science:
- Biomaterials Science
- Gene Delivery Systems
- Polymer Chemistry
Background:
- DNA/chitosan complexes are investigated for gene delivery.
- Understanding complex stability in biological environments is crucial for efficient gene transfer.
- Interaction with anionic biomolecules can affect complex integrity.
Purpose of the Study:
- To assess the stability of DNA/chitosan complexes when exposed to anionic biomolecules.
- To determine factors influencing DNA release from these complexes.
- To understand the implications for gene delivery efficiency.
Main Methods:
- Fluorescence spectroscopy was used to quantify DNA release.
- Isothermal titration microcalorimetry (ITC) was employed to study binding affinities.
- Systematic variation of chitosan properties (deacetylation, molecular weight) and complex N/P ratio.
Main Results:
- Heparin, a highly charged polyanion, was the only tested substance to release DNA from complexes.
- DNA release by heparin decreased with increased chitosan deacetylation, molecular weight, and N/P ratio.
- ITC confirmed heparin's strong binding affinity to chitosan, comparable to DNA.
Conclusions:
- Sufficiently high charge density of anionic components can trigger DNA release, impacting gene delivery.
- Extracellular DNA release reduces delivery efficiency, while intracellular release is necessary for gene transfer.
- Optimizing the N/P ratio of DNA/polycation complexes is vital to prevent premature DNA dissociation in the extracellular environment.
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