Oxidation as a Facile Strategy To Reduce the Surface Charge and Toxicity of Polyethyleneimine Gene Carriers

Abstract

Polyethyleneimine (PEI) is widely regarded as one of the most efficient non-viral transfection agents commercially available. However, a key concern is its pronounced cytotoxicity, ascribed mainly to its high amine content and cationic charge density. Significant past efforts to mitigate its toxicity usually involved lengthy synthetic procedures. We now propose a simple strategy using hydrogen peroxide (H2O2) to oxidize the amine groups. PEI/DNA complexes were first formed before some amine groups were removed with H2O2. This reduced surface charge while the remaining cationic charges still allowed for efficient transfection. The DNA was not damaged and remained bound after oxidation. Furthermore, H2O2 was quantitatively removed with sodium pyruvate prior to cell culture. Oxidized complexes caused no cytotoxicity even at high polymer concentrations. Compared to non-oxidized complexes used at subtoxic doses, oxidized complexes mediated significantly more GFP expression. A key strength of this approach is its simplicity as it involves only simple mixing of solutions. This strategy promises to further realize the potential of using PEI for the delivery of nucleic acids or other cargos.

Acute in Vivo Toxicity Mitigation of PEI-Coated Maghemite Nanoparticles Using Controlled Oxidation and Surface Modifications toward siRNA Delivery

“…A more recent publication describes a reduction in free PEI toxicity by using oxidation as a facile strategy, in order to reduce its surface charge. 66 Nevertheless and in the present study as detailed later, controlled PEI oxidation reactions do not reduce NPs' surface charge when using a significant molar amount of aqueous H 2 O 2 /K 2 S 2 O 8 , but rather increase it even when using very small molar amounts of aqueous H 2 O 2 /K 2 S 2 O 8 . This phenomenon of NPs toxicity mitigation likely arises from PEI-coordinating features of the Ce 3+/4+ metal cation shell as an active influential factor.…”

“…Such chemical modifications may strongly decrease the NPs' acute toxicity, probably because of the corresponding decrease of the number of PEI reactive primary amines. 66 An oxidation of both secondary and tertiary amines can also occur, but since the primary amines are more reactive, it is likely that these will react first. Primary amines can be oxidized into hydroxyl amines which should be less toxic than the primary amines.…”

Polyethylene imine-6-phosphogluconic acid nanoparticles – a novel zeta potential changing system

“…These findings are in good accordance with former studies 390 regarding toxicity of polyethylene imine. The influence on cell 391 viability by polyethylene imine is most likely due to its cationic 392 nature and amine content, which is believed to cause membrane 393 disruption (Seow et al, 2013). In addition, the introduction of 394 negative charges, such as ester bearing ligands, was reported to 395 reduce toxicity of this polymer, as the modification led to a reduction 396 of positive charges within the polymer (Dutta et al, 2008;Seow et al, …”

Mitochondrial-Targeted Polyethylenimine Functionalized Graphene Oxide Nanocarrier and its Anti-Tumor Effect on Human Lung Carcinoma Cells

“…7 In order to overcome the cytotoxicity of PEI-based nanocarriers, numerous modi¯cations have been proposed to reduce the charge-associated toxicity of the polymer. 8,9 Graphene oxide nanosheets (NGO), a type of sp 2 carbon nanomaterial derivative of graphene, have attracted signi¯cant interest in the area of nanomedicine since graphene's discovery in 2004. 10 Because of its physical and chemical attributes, NGO has already demonstrated its utility as a novel carrier in biomedical applications such as drug delivery, 11 photothermal therapy, 12 bioimaging 13,14 and catalysis.…”