Ultrasound-Assisted Magnetic Nanoparticle-Based Gene Delivery

Abstract

Low-intensity pulsed ultrasound (LIPUS), a special type of ultrasonic stimulation, is attracting a lot of attention for both clinical and scientific research. In this paper, we report a concept of a new method using magnetic nanoparticles (MNPs) for LIPUSassisted gene delivery. The MNPs are iron oxide superparamagnetic nanoparticles, coated with polyethyleneimine (PEI), which introduces a high positive surface charge, favorable for the binding of genetic material. Due to the paramagnetic properties of the MNPs, the application of an external magnetic field increases transfection efficiency; meanwhile, LIPUS stimulation enhances cell permeability. We found out that stimulation at the intensity of 30 mW/cm 2 for 10 minutes yields optimal results with a minimal adverse effect on the cells. Combining the effect of the external magnetic field and LIPUS, the genetic material (GFP or Cherry Red plasmid in our case) can enter the cells. The flow cytometry results showed that by using just a magnetic field to direct the genetic material, the transfection efficiency of HEK 293 cells that were treated with our MNPs was 56.1%. Coupled with LIPUS stimulation, it increased to 61.5% or 19% higher than the positive control (Lipofectamine 2000). In addition, compared with the positive control, our method showed less toxicity. Cell viability after transfection was 63.61%, 19% higher than with the standard transfection technique. In conclusion, we designed a new gene-delivery technique that is affordable, targeted, shows low-toxicity, yet high transfection efficiency, compared to other conventional approaches.