Self-Assembled Functional Nanostructure of Plasmid DNA with Ionic Liquid [Bmim][PF₆]: Enhanced Efficiency in Bacterial Gene Transformation

Abstract

The electrostatic interaction between the negatively charged phosphate groups of plasmid DNA and the cationic part of hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]), initiates spontaneous self-assembly to form the functional nanostructures made up of DNA and ionic liquid (IL). These functional nanostructures were demonstrated as promising synthetic nonviral vectors for the efficient bacterial pGFP gene transformation in cells. In particular, the functional nanostructures that were made up of 1 μL of IL ([Bmim][PF6]) and 1 μg of plasmid DNA can increase the transformation efficiency by 300-400% in microbial systems, without showing any toxicity for E. coli DH5α cells. (31)P nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron (XPS) spectroscopic analysis revealed that the electrostatic interaction between negatively charged phosphate oxygen and cationic Bmim(+) tends to initiate the self-assembly process. Thermogravimetric analysis of the DNA-IL functional nanostructures showed that these nanostructures consist of ∼16 wt % ionic liquid, which is considered to provide the stability to the plasmid DNA that eventually enhanced the transformation efficiency.

Progress toward Understanding the Interactions between DNA Nanostructures and the Cell

“…Soni et al electrostatically complexed plasmids with the cationic part of the hydrophobic ionic liquid 1‐butyl‐3‐methylimidazodium hexafluorophosphate (Bmim PF 6 ) to generate morphologically irregular DNA structures of ≈70 nm in diameter. With the assistance of heat shock, the resultant structures show fourfold higher transformation into Escherichia coli cells than unmodified plasmids . In 2017, Zhao et al prepared a structural cousin of SNAs by electrostatically immobilizing plasmid DNA on the surface of iron oxide nanoparticles that are precoated with branched polyethyleneimine .…”

Ionic liquids for the preparation of biopolymer materials for drug/gene delivery: a review

“…32 Moreover, the radius of DNA gels usually increased due to the incorporation of IL molecules onto the surface of DNA. 32,229 Yet, gene delivery is a complicated process, for which there are several systematic and cellular barriers to overcome, such as the slow diffusion of hydrophilic DNA across the hydrophobic lipid bilayer membrane, and the slight electrostatic repulsion due to anionic DNA and the anionic head groups of the bilayer membrane. 230 Thus, to improve the gene transformation efficiency, comparatively hydrophobic ILs was preferred to be crafted with DNA to efficiently transfer DNA across the bilayer membrane and prevent enzymatic damages.…”

Recent Advances of Using Ionic Liquids for Biopolymer Extraction and Processing

“…IL [BMIM][PF 6 ] was incorporated into DNA based functional nanostructures and successfully utilized as synthetic nonviral vectors for the efficient bacterial pGFP gene transformation in cells ( Figure ). A 300−400% enhancement in the transformation efficiency in microbial systems was achieved …”

“…A: Enhanced efficiency in bacterial gene transformation of ionic gels composed of plasmid DNA (pGFP) with [BMIM][PF 6 ]; B: Hierarchical assembly of purified pGFP plasmid DNA with IL and the electrostatic interaction of the [BMIM] + ion and PO 4 − of the DNA strand. Reproduced with permission . Copyright 2015, American Chemical Society.…”