Export file:


  • RIS(for EndNote,Reference Manager,ProCite)
  • BibTex
  • Text


  • Citation Only
  • Citation and Abstract

Increased poly(ethylene glycol) density decreases transfection efficacy of siRNA/poly(ethylene imine) complexes

Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone, Lexington, KY 40536, USA

Topical Section: Drug delivery

Small interfering RNA (siRNA) inhibits specific gene expression in cells to treat genetic diseases including cancer, but siRNA-based cancer therapy is often hindered by inefficient siRNA delivery to tumor. Poly(ethylene glycol)-conjugated poly(ethylene imine) (PEG-PEI) is widely studied as a promising siRNA carrier. PEG-PEI can form ion complexes with siRNA and enhance siRNA gene silencing (transfection) due to its high buffering capacity. However, the transfection efficacy of PEG-PEI formulations changes due to variable polymer compositions. This study investigates the effects of PEG-related factors [molecular weight (PEG MW), substitution rate (PEG%), and short PEI contaminants] on siRNA transfection efficiency of PEG-PEI in a model human colon cancer cell line (HT29). High PEG density increased PEG-PEI mass to form complexes yet decreased in vitro transfection efficiency. Low PEG MW (550 Da, 2 kDa, and 5 kDa) induced complexation between PEG-PEI and siRNA at a reduced charge ratio (N/P ratio). Dialysis removed short PEI contaminants, and the dialyzed PEI with PEG (PEG-PEI-d) formed siRNA complexes with minimal particle size distribution than PEG-PEI. siRNA/PEG-PEI-d complexes showed transfection efficiency similar to siRNA/PEG-PEI complexes at a lower N/P ratio. These results conclude that PEG MW, density, and small PEI contaminants are three major factors influencing transfection of siRNA/PEI complexes.
  Article Metrics

Keywords nanoparticles; gene delivery; gene therapy; vectors; polyion complexes

Citation: Steven Rheiner, Younsoo Bae. Increased poly(ethylene glycol) density decreases transfection efficacy of siRNA/poly(ethylene imine) complexes. AIMS Bioengineering, 2016, 3(4): 454-467. doi: 10.3934/bioeng.2016.4.454


  • 1. Resnier P, Montier T, Mathieu V, et al. (2013) A review of the current status of siRNA nanomedicines in the treatment of cancer. Biomaterials 34: 6429-6443.    
  • 2. Lachelt U, Wagner E (2015) Nucleic Acid Therapeutics Using Polyplexes: A Journey of 50 Years (and Beyond). Chem Rev 115: 11043-11078.    
  • 3. Choudhury SR, Hudry E, Maguire CA, et al. (2016) Viral vectors for therapy of neurologic diseases. Neuropharmacology: (In Press).
  • 4. Liu Y, Liu Z, Wang Y, et al. (2013) Investigation of the performance of PEG-PEI/ROCK-II-siRNA complexes for Alzheimer’s disease in vitro. Brain Res 1490: 43-51.    
  • 5. Aliabadi HM, Maranchuk R, Kucharski C, et al. (2013) Effective response of doxorubicin-sensitive and -resistant breast cancer cells to combinational siRNA therapy. J Control Release 172: 219-228.    
  • 6. Aliabadi HM, Landry B, Sun C, et al. (2012) Supramolecular assemblies in functional siRNA delivery: where do we stand? Biomaterials 33: 2546-2569.    
  • 7. Guo P, Coban O, Snead NM, et al. (2010) Engineering RNA for targeted siRNA delivery and medical application. Adv Drug Deliver Rev 62: 650-666.    
  • 8. Dominska M, Dykxhoorn DM (2010) Breaking down the barriers: siRNA delivery and endosome escape. J Cell Sci 123: 1183-1189.    
  • 9. Zhang S, Zhao B, Jiang H, et al. (2007) Cationic lipids and polymers mediated vectors for delivery of siRNA. J Control Release 123: 1-10.    
  • 10. Wightman L, Kircheis R, Rössler V, et al. (2001) Different behavior of branched and linear polyethylenimine for gene delivery in vitro and in vivo. J Gene Med 3: 362-372.    
  • 11. Lee SY, Huh MS, Lee S, et al. (2010) Stability and cellular uptake of polymerized siRNA (poly-siRNA)/polyethylenimine (PEI) complexes for efficient gene silencing. J Control Release 141: 339-346.    
  • 12. Varkouhi AK, Scholte M, Storm G, et al. (2011) Endosomal escape pathways for delivery of biologicals. J Control Release 151: 220-228.    
  • 13. Fire A (1999) RNA-triggered gene silencing. Trends Genet 15: 358-363.    
  • 14. Fire A, Xu SQ, Montgomery MK, et al. (1998) Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 391: 806-811.    
  • 15. Lv H, Zhang S, Wang B, et al. (2006) Toxicity of cationic lipids and cationic polymers in gene delivery. J Control Release 114: 100-109.    
  • 16. Zintchenko A, Philipp A, Dehshahri A, et al. (2008) Simple modifications of branched PEI lead to highly efficient siRNA carriers with low toxicity. Bioconjugate Chem 19: 1448-1455.    
  • 17. Wen S, Zheng F, Shen M, et al. (2013) Surface modification and PEGylation of branched polyethyleneimine for improved biocompatibility. J Appl Polym Sci 128: 3807-3813.    
  • 18. Ogris M, Steinlein P, Carotta S, et al. (2001) DNA/polyethylenimine transfection particles: influence of ligands, polymer size, and PEGylation on internalization and gene expression. AAPS PharmSci 3: 43-53.    
  • 19. Alexis F, Pridgen E, Molnar LK, et al. (2008) Factors affecting the clearance and biodistribution of polymeric nanoparticles. Mol Pharm 5: 505-515.    
  • 20. Rheiner S, Rychahou P, Bae Y (2015) Effects of the lipophilic core of polymer nanoassemblies on intracellular delivery and transfection of siRNA. Biophysics 2: 284-302.    
  • 21. Pandey AP, Sawant KK (2016) Polyethylenimine: A versatile, multifunctional non-viral vector for nucleic acid delivery. Mater Sci Eng C Mater Biol Appl 68: 904-918.    
  • 22. Forsbach A, Müller C, Montino C, et al. (2011) Impact of delivery systems on siRNA immune activation and RNA interference. Immunol Lett 141: 169-180.
  • 23. Huang FW, Wang HY, Li C, et al. (2010) PEGylated PEI-based biodegradable polymers as non-viral gene vectors. Acta Biomater 6: 4285-4295.    
  • 24. Fitzsimmons RE, Uludag H (2012) Specific effects of PEGylation on gene delivery efficacy of polyethylenimine: interplay between PEG substitution and N/P ratio. Acta Biomater 8: 3941-3955.    
  • 25. Miteva M, Kirkbride KC, Kilchrist KV, et al. (2015) Tuning PEGylation of mixed micelles to overcome intracellular and systemic siRNA delivery barriers. Biomaterials 38: 97-107.    
  • 26. Milla P, Dosio F, Cattel L (2012) PEGylation of proteins and liposomes: a powerful and flexible strategy to improve the drug delivery. Curr Drug Metab 13: 105-119.    
  • 27. Tang GP, Zeng JM, Gao SJ, et al. (2003) Polyethylene glycol modified polyethylenimine for improved CNS gene transfer: effects of PEGylation extent. Biomaterials 24: 2351-2362.    
  • 28. Mao S, Neu M, Germershaus O, et al. (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 Chem 17: 1209-1218.    
  • 29. Petersen H, Fechner PM, Martin AL, et al. (2002) Polyethylenimine-graft-poly (ethylene glycol) copolymers: influence of copolymer block structure on DNA complexation and biological activities as gene delivery system. Bioconjug Chem 13: 845-854.    
  • 30. Holland JW, Hui C, Cullis PR, et al. (1996) Poly (ethylene glycol)—lipid conjugates regulate the calcium-induced fusion of liposomes composed of phosphatidylethanolamine and phosphatidylserine. Biochemistry 35: 2618-2624.    
  • 31. Mishra S, Webster P, Davis ME (2004) PEGylation significantly affects cellular uptake and intracellular trafficking of non-viral gene delivery particles. Eur J Cell Biol 83: 97-111.    


This article has been cited by

  • 1. Steven Rheiner, Derek Reichel, Piotr Rychahou, Tadahide Izumi, Hsin-Sheng Yang, Younsoo Bae, Polymer nanoassemblies with hydrophobic pendant groups in the core induce false positive siRNA transfection in luciferase reporter assays, International Journal of Pharmaceutics, 2017, 528, 1-2, 536, 10.1016/j.ijpharm.2017.06.056
  • 2. Ngoc Do Quyen Chau, Giacomo Reina, Jésus Raya, Isabella Anna Vacchi, Cécilia Ménard-Moyon, Yuta Nishina, Alberto Bianco, Elucidation of siRNA complexation efficiency by graphene oxide and reduced graphene oxide, Carbon, 2017, 10.1016/j.carbon.2017.07.016
  • 3. Derek Reichel, Louis T. Curtis, Elizabeth Ehlman, B. Mark Evers, Piotr Rychahou, Hermann B. Frieboes, Younsoo Bae, Development of Halofluorochromic Polymer Nanoassemblies for the Potential Detection of Liver Metastatic Colorectal Cancer Tumors Using Experimental and Computational Approaches, Pharmaceutical Research, 2017, 10.1007/s11095-017-2245-9

Reader Comments

your name: *   your email: *  

Copyright Info: 2016, Younsoo Bae, et al., licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

Download full text in PDF

Export Citation

Copyright © AIMS Press All Rights Reserved