Polyethylenimine (PEI) is one of the most popular polymers used for condensing DNA in cell-transfection and gene-therapy applications. The PEI polymer backbone is intrinsically hydrophobic, semiflexible, and contains closely-spaced amine groups which are charged when protonated. As a result, the polymer exhibits unusual polymer dynamics. Mannobiose-grafted PEI (PEI-m) is used as carriers for DNA vaccines that provide long-term immunity against chronic pathologies like AIDs and cancer, and has lower carrier-induced toxicity. Our studies indicate that the backbone protonation of PEI-m occurs intermittently with pH in a salt-independent manner. Clustered phases which exist in PEI solutions are attenuated when mannobiose is grafted to the backbone. The pKa of the PEI backbone is shifted to lower pH following mannobiosylation. Oligosaccharide-grafting also increase the hydrodynamicdiameter of the PEI polymer, and dynamic modeling is being performed to determine the relative contribution from backbone stiffening and the side-chain bulk. The grafting of a hydrophilic moiety modifies the semiflexibility, protonation, and clustering dynamics of the PEI backbone; which would in turn affect the packing of DNA into delivery nanoparticles.

Effect on oligosaccaride grafting on the polyelectrolyte and protonation dynamics of polyethyleneimine

254th National Meeting (2017)

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