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Influence of Polyethylene Glycol Chain Length on the Physicochemical and Biological Properties of Poly(ethylene imine)-graft-Poly(ethylene glycol) Block Copolymer/SiRNA Polyplexes
Abstract
Polyplexes between siRNA and poly(ethylene imine) (PEI) derivatives are promising nonviral carriers for siRNA. The polyplex stability is of critical importance for efficient siRNA delivery to the cytoplasm. Here, we investigate the effect of PEGylation at a constant ratio ( approximately 50%) on the biophysical properties of the polyplexes. Particle size, zeta potential, and stability against heparin as well as RNase digestion and reporter gene knockdown under in vitro conditions of different siRNA polyplexes were characterized. Stability and size of siRNA polyplexes were clearly influenced by PEI-PEG structure, and high degrees of substitution such as PEI(25k)-g-PEG(550)(30) resulted in large (300-400 nm), diffuse complexes (AFM) which showed condensation behavior only at high N/P ratios. All other polyplexes and the PEI control showed similar sizes (150 nm) and compact structures in AFM, with complete condensation reached at N/P ratio of 3. Stability of siRNA polyplexes against heparin displacement and RNase digestion could be modified by PEGylation. Protection against RNase digestion was highest for PEI(25k)-g-PEG(5k)(4) and PEI(25k)-g-PEG(20k)(1), while siRNA/PEI provided insufficient protection. In knockdown experiments using NIH/3T3 fibroblasts stably expressing beta-galactosidase, it was shown that PEG chain length had a significant influence on biological activity of siRNA. Polyplexes with siRNA containing PEI(25k)-g-PEG(5k)(4) and PEI(25k)-g-PEG(20k)(1) yielded similar efficiencies of ca. 70% knockdown as lipofectamine controls. Confocal microscopy demonstrated enhanced cellular uptake of siRNA into cytosol by polyplexes formation with PEI copolymers. In conclusion, both the chain length and graft density of PEG were found to strongly influence siRNA condensation and stability and hence affect the knockdown efficiency of PEI-PEG/siRNA polyplexes.
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Cited by
Knocking down barriers: advances in siRNA delivery
Whitehead, K. A., Langer, R., & Anderson, D. G. (2009) · Nature Reviews Drug Discovery · doi:10.1038/nrd2742 · Cited by 3,115
Nonviral vectors for gene delivery
Mintzer, M. A., & Simanek, E. E. (2009) · Chemical Reviews · doi:10.1021/cr800409e · Cited by 2,366
Lipid-Based DNA Therapeutics: Hallmarks of Non-Viral Gene Delivery
Buck, J., Grossen, P., Cullis, P. R., Huwyler, J., & Witzigmann, D. (2019) · ACS Nano · doi:10.1021/acsnano.8b07858 · Cited by 312
Polymeric nanoparticles for siRNA delivery and gene silencing
Patil, Y., & Panyam, J. (2009) · International Journal of Pharmaceutics · doi:10.1016/j.ijpharm.2008.09.039 · Cited by 270
Controlled pulmonary drug and gene delivery using polymeric nano-carriers
Beck-Broichsitter, M., Merkel, O. M., & Kissel, T. (2012) · Journal of Controlled Release · doi:10.1016/j.jconrel.2011.12.004 · Cited by 200
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Metadata
- Authors
- Mao, S., Neu, M., Germershaus, O., Merkel, O., Sitterberg, J., Bakowsky, U., & Kissel, T.
- Venue
- Bioconjugate Chemistry
- Publisher
- American Chemical Society (ACS)
- Published
- 2006-09-01
- Volume
- 17
- Issue
- 5
- Pages
- 1209-1218
- ISSN
- 1043-1802 (ISSN-L)
- 1520-4812
- OpenAlex
- W2078377919
- Cited by
- 319
- References
- 0
- FWCI
- 7.98
- Type
- journal article
- Language
- en
- Open access
- closed
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- Mao, S., Neu, M., Germershaus, O., Merkel, O., Sitterberg, J., Bakowsky, U., & Kissel, T. (2006). Influence of Polyethylene Glycol Chain Length on the Physicochemical and Biological Properties of Poly(ethylene imine)-graft-Poly(ethylene glycol) Block Copolymer/SiRNA Polyplexes. Bioconjugate Chemistry. https://doi.org/10.1021/bc060129j
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