Structure and stability of the complex formed by oligonucleotides
Cui Zheng1, Lin Niu, Jingjing Yan
1Beijing National Laboratory for Molecular Sciences and the Key Laboratory of Polymer Chemistry & Physics of Ministry of Education, College of Chemistry & Molecular Engineering, Peking University, Beijing, P R China.
Physical Chemistry Chemical Physics : PCCP
|April 21, 2012
Summary
Poly(L-lysine) (PLL) forms complexes with DNA, but oligonucleotide complexes are unstable and quickly dissociate. These findings challenge traditional polyelectrolyte theories for gene delivery vectors.
Area of Science:
- Biotechnology
- Materials Science
- Molecular Biology
Background:
- Polycations and cationic lipids are common non-viral vectors for nucleic acid delivery.
- Understanding polycation complexation with various DNA forms is crucial for optimizing gene delivery systems.
Purpose of the Study:
- To comparatively study the complexation of poly(L-lysine) (PLL) with double-stranded DNA (dsDNA), double-stranded oligonucleotides (ds-oligo), and single-stranded oligonucleotides (ss-oligo).
- To investigate the stability and behavior of these complexes under physiological conditions.
Main Methods:
- Complexation was studied using a titration method in PBS buffer.
- Laser light scattering was employed to monitor complex formation and molecular weight.
- Atomic force microscopy (AFM) was used to visualize complex structures and stability.
Main Results:
- Oligonucleotide complexes (ss-oligo and ds-oligo) exhibited higher molecular weights than dsDNA complexes immediately after mixing at equivalent charge ratios.
- Complexes formed with oligonucleotides demonstrated significant instability, with scattered intensity decreasing to solvent levels over weeks.
- AFM revealed that freshly prepared oligonucleotide complexes are sensitive to environmental changes and prone to rapid dissociation.
Conclusions:
- Poly(L-lysine) can complex with various nucleic acid types, but oligonucleotide complexes show poor stability.
- The behavior of oligonucleotide-polycation complexes deviates from predictions of classical polyelectrolyte theories.
- Further research is needed to understand and improve the stability of oligonucleotide complexes for gene delivery applications.
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