2.8. Particle Size and Zeta Potential Measurements

Particle size measurements were carried out using dynamic light scattering (DLS) with the Malvern Zetasizer Nano ZS (Malvern Instruments GmbH, Herrenberg, Germany), and a nanoparticle tracking analysis (NTA) was performed with the NanoSight^® LM10 (Malvern Instruments GmbH). The polyplexes were tested using N/P ratios between 2 and 40. Both measurements were performed at 25 °C. For the DLS measurements, the polyplexes were prepared in 100 µL saline buffer. For the NTA measurements, the same samples were diluted with bidistilled water at a ratio of 1:3 to a total volume of 300 µL. A red laser light at 638 nm and a tracking time of 30 s and 5 repetitions per sample were chosen as the experimental settings for the NTA.

The Zetasizer Nano ZS (Malvern Instruments GmbH) was used to measure the zeta potential in bidistilled water. The undiluted sample was measured at RT using a high-concentration capillary cell (ZEN1010, Malvern Instruments GmbH). The results of the Zetasizer Nano ZS were evaluated as triplicates using the Malvern software 6.20. All experiments were performed thrice (mean ± SEM).