Effect of molecular weight of amine end-modified poly(β-amino ester)s on gene delivery efficiency and toxicity
Author(s)Eltoukhy, Ahmed A.; Siegwart, Daniel J.; Alabi, Christopher A.; Rajan, Jay S.; Langer, Robert; Anderson, Daniel Griffith; ... Show more Show less
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Amine end-modified poly(β-amino ester)s (PBAEs) have generated interest as efficient, biodegradable polymeric carriers for plasmid DNA (pDNA). For cationic, non-degradable polymers, such as polyethylenimine (PEI), the polymer molecular weight (MW) and molecular weight distribution (MWD) significantly affect transfection activity and cytotoxicity. The effect of MW on DNA transfection activity for PBAEs has been less well studied. We applied two strategies to obtain amine end-modified PBAEs varying in MW. In one approach, we synthesized four amine end-modified PBAEs with each at 15 different monomer molar ratios, and observed that polymers of intermediate length mediated optimal DNA transfection in HeLa cells. Biophysical characterization of these feed ratio variants suggested that optimal performance was related to higher DNA complexation efficiency and smaller nanoparticle size, but not to nanoparticle charge. In a second approach, we used preparative size exclusion chromatography (SEC) to obtain well-defined, monodisperse polymer fractions. We observed that the transfection activities of size-fractionated PBAEs generally increased with MW, a trend that was weakly associated with an increase in DNA binding efficiency. Furthermore, this approach allowed for the isolation of polymer fractions with greater transfection potency than the starting material. For researchers working with gene delivery polymers synthesized by step-growth polymerization, our data highlight the potentially broad utility of preparative SEC to isolate monodisperse polymers with improved properties. Overall, these results help to elucidate the influence of polymer MWD on nucleic acid delivery and provide insight toward the rational design of next-generation materials for gene therapy.
DepartmentDavid H. Koch Institute for Integrative Cancer Research at MIT; Harvard University--MIT Division of Health Sciences and Technology; Massachusetts Institute of Technology. Department of Biological Engineering; Massachusetts Institute of Technology. Department of Biology; Massachusetts Institute of Technology. Department of Chemical Engineering
Eltoukhy, Ahmed A., Daniel J. Siegwart, Christopher A. Alabi, Jay S. Rajan, Robert Langer, and Daniel G. Anderson. “Effect of Molecular Weight of Amine End-Modified Poly(β-Amino Ester)s on Gene Delivery Efficiency and Toxicity.” Biomaterials 33, no. 13 (May 2012): 3594–3603.
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