Polyethylenimines (PEIs) are widely used in gene delivery to increase delivery efficiencies. However, recent research demonstrated that PEI has cytotoxicity even at low concentrations (<100 ppm). Free PEI in solution was considered to be responsible for such cytotoxicity. Free PEI used in gene delivery can be adsorbed to different surfaces and has further biological impacts, which has led to some recent concerns. It is therefore of general interest to understand how PEI would be adsorbed to different surfaces as contaminants. In this study, we combined a surface sensitive technique, sum frequency generation (SFG) vibrational spectroscopy, and a quartz crystal microbalance (QCM) to study PEI adsorption on various surfaces including surfaces of SiO2, CaF2, and polystyrene. Both branched and linear PEIs were examined. The PEI solution concentration effect was also investigated. It was found that PEI tended to adopt some degree of ordering at various solution/polymer interfaces even when the PEI concentration was low. The higher the concentration, the faster PEI tended to reach its maximum order. It was also found that the adsorbed PEI molecules gradually lost order after reaching the maximum order. The PEI adsorption behavior on different materials after removing the surfaces from the PEI solution has also been studied. This research provides a general understanding on adsorption behavior of PEI contaminants on different surfaces.

Polyethylenimine adsorption at various surfaces and interfaces

246th National Meeting (2013)

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