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Re-dissolution and de-compaction of DNA-cationic surfactant complexes using non-ionic surfactants
Conrad P Corbyn1, Paul D I Fletcher, Rabia Gemici
1Surfactant & Colloid Group, Department of Chemistry, University of Hull, Hull, UK HU6 7RX.
Physical Chemistry Chemical Physics : PCCP
|December 22, 2009
Summary
Non-ionic surfactants can de-compact and re-dissolve DNA-cationic surfactant complexes by stripping the cationic surfactant. This occurs when the free cationic surfactant concentration falls below a critical level due to mixed micelle formation.
Area of Science:
- Biochemistry
- Colloid and Surface Chemistry
Background:
- Cationic surfactants condense DNA into complexes that precipitate from aqueous solutions.
- Anionic surfactants are known to de-compact and re-dissolve these DNA-cationic surfactant complexes.
Purpose of the Study:
- To investigate the efficacy of non-ionic surfactants in de-compacting and re-dissolving DNA-cationic surfactant complexes.
- To elucidate the mechanism of de-compaction and re-dissolution induced by non-ionic surfactants.
Main Methods:
- Solubility phase-boundary measurements.
- Fluorescence microscopy to observe de-compaction.
- Light scattering analysis.
- Critical micelle concentration measurements.
- Regular solution mixed micelle theory calculations.
Main Results:
- Non-ionic surfactants of the alkylpolyoxyethylene type effectively de-compact and re-dissolve DNA-cationic surfactant complexes.
- Evidence indicates a 'stripping mechanism' where cationic surfactant is removed from DNA into non-ionic micelles.
- This mechanism operates even without favorable electrostatic interactions between surfactants.
- De-compaction and re-dissolution are linked to the reduction of free monomeric cationic surfactant concentration below a critical value.
Conclusions:
- Non-ionic surfactants provide a viable method for de-compacting and re-dissolving DNA-cationic surfactant complexes.
- The primary mechanism involves the stripping of cationic surfactant into mixed micelles, driven by reducing free surfactant concentration.
- This finding has implications for understanding and manipulating DNA-surfactant interactions in various applications.
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