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Issue 14, 2017
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Properties of polyplexes formed through interaction between hydrophobically-modified poly(ethylene imine)s and calf thymus DNA in aqueous solution

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Abstract

Polycationic polymers and DNA form soluble complexes in aqueous solution, which allows the transfer of genetic material into cells. Therefore, these chemically-modified polymers are of interest for use in studies aimed at better transfection efficiency and gene expression along with reduced cytotoxicity. In this study, branched poly(ethylene imine) (PEI) was modified by alkylation with n-alkyl groups (n = 4, 6, 8 and 12 carbons). The polyplexes formed through interaction of the modified PEIs and calf thymus DNA (ctDNA) were investigated using UV-Vis spectrophotometry, ethidium bromide fluorescence emission, circular dichroism spectroscopy, dynamic light scattering, and small-angle X-ray scattering techniques along with the determination of the zeta potential and viscosity. According to the results obtained, the formation of ctDNA–PEI polyplexes occurs in three steps. Firstly, when a small amount of polyelectrolyte is present the ctDNA chains are partially compacted. Subsequently, with the addition of more polyelectrolyte, the complexes have a null charge density and micrometric size. Lastly, with a higher concentration of PEI, the ctDNA is fully compacted by the PEI chains, leading to positively charged complexes with Rh values in the range of 52.0–86.0 nm. The viscosity and SAXS analysis suggested that the unmodified PEI exhibits the strongest interaction and promotes the best ctDNA condensation.

Graphical abstract: Properties of polyplexes formed through interaction between hydrophobically-modified poly(ethylene imine)s and calf thymus DNA in aqueous solution

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Publication details

The article was received on 20 Dec 2016, accepted on 15 Mar 2017 and first published on 15 Mar 2017


Article type: Paper
DOI: 10.1039/C6SM02835G
Citation: Soft Matter, 2017,13, 2609-2619
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    Properties of polyplexes formed through interaction between hydrophobically-modified poly(ethylene imine)s and calf thymus DNA in aqueous solution

    I. C. Bellettini, S. J. Fayad, V. G. Machado and E. Minatti, Soft Matter, 2017, 13, 2609
    DOI: 10.1039/C6SM02835G

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