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Encapsulation of DNA by cationic diblock copolymer vesicles
A V Korobko1, W Jesse, J R C van der Maarel
1Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 29, 2004
Summary
Researchers developed a novel single emulsion technique to encapsulate DNA fragments within polymer capsules using a cationic diblock copolymer. This method offers controlled DNA release from vesicles, demonstrating broad applicability for nano-encapsulation.
Area of Science:
- Polymer Chemistry
- Nanotechnology
- Biophysics
Background:
- Encapsulation of nucleic acids is crucial for gene delivery and diagnostics.
- Cationic polymers are effective in complexing with negatively charged DNA.
- Developing stable, controllable nano-capsules for biomolecules remains a challenge.
Purpose of the Study:
- To investigate the encapsulation of double-stranded DNA (dsDNA) fragments using a specific cationic diblock copolymer.
- To characterize the formation and properties of the resulting DNA-loaded capsules and vesicles.
- To explore the conditions for DNA release from the encapsulated structures.
Main Methods:
- Utilized a single emulsion technique involving an aqueous DNA solution and toluene, stabilized by poly(butadiene-b-N-methyl-4-vinyl pyridinium) [PBd-b-P4VPQ].
- Employed phase contrast, polarized light, and fluorescence microscopy, alongside scanning electron microscopy for characterization.
- Investigated DNA release triggered by osmotic pressure and ionic strength variations.
Main Results:
- Successfully encapsulated dsDNA fragments within polymer capsules, observing DNA compaction via birefringence and fluorescence.
- Demonstrated the formation of stable vesicles upon dispersion in aqueous media, stabilized by poly(ethylene glycol).
- Determined DNA release thresholds at osmotic pressures below 10^5 N/m^2 or ionic strength above 0.1 M.
- Showcased the method's versatility by encapsulating pUC18 plasmid and demonstrating a charge-inverse system.
Conclusions:
- The single emulsion technique with PBd-b-P4VPQ is an effective method for encapsulating DNA into submicrometer capsules and vesicles.
- The developed vesicles provide controlled release of DNA based on environmental stimuli.
- The encapsulation strategy is adaptable for various nucleic acids and polymer systems.