Ultra low range dna ladder

The thickness and surface profile of the DNA films coated on the MSS were measured by using a 3D surface profiler (VK-X3000, KEYENCE Corporation, Osaka, Japan) under the laser confocal mode and a surface stylus profiler (DekTak, Bruker). To confirm the structure of DNA, the circular dichroism (CD) spectra of an aqueous solution and a drop-casted film of DNA were measured using a spectropolarimeter (J-820, JASCO). An aqueous solution of DNA (5 mg mL⁻¹) was drop-casted on a quartz substrate. The base-pair lengths of the DNA molecules were confirmed by electrophoresis. Electrophoresis was performed using a polyacrylamide gel (e-PAGEL 10–20%, ATTO) in TG buffer at 21 mA for 65 min (WSE-1150 PageRunAce, ATTO). Ultra-Low-Range DNA Ladder (Thermo Fisher Scientific) was used for the quantification based on base size. The DNA samples were stained for 30 min in TBE buffer with SYBR™ Gold (Thermo Fischer Scientific, Waltham, MA, USA).

For gel electrophoresis,
400 μL SYBR Safe DNA Gel Stain, DNA loading dye, SDS solution
(6×), TAE buffer (Tris–acetate–EDTA) (50×),
TrackIt 100 bp DNA Ladder, and Ultra Low Range DNA Ladder were purchased
from Thermo Fisher Scientific. Agarose was purchased from Bio-Rad
Laboratories. NuPAGE 4–12%, Bis–Tris, 1.0 mm, and Mini
Protein Gel (12-well) were purchased from Invitrogen.

The stability of G4-CpG ODN in the complexes was confirmed by PAGE. Naked 12.5 μM G4-CpG ODN or ε-PLL/G4-CpG ODN complexes (both at 3 μL) at different N/P ratios were mixed with 27 μL of 1× D-PBS containing 55.6% (v/v) FBS to obtain a final concentration of 50% (v/v) in the reaction mixture. The mixture was incubated at 37 °C for 1, 2, 4, and 24 h. After the incubation, 3 μL ethylenediaminetetraacetic acid (EDTA 0.25 M) was added, and the mixture solution was heated to 80 °C for 2 min to quench the reaction. Subsequently, the samples were stored at 4 °C until the PAGE analysis. Serum-treated samples (6.5 μL) were applied to 10–20% linear gradient polyacrylamide gels (e-PAGEL gels; ATTO, Tokyo, Japan). Polyacrylamide gel electrophoresis was performed in Tris-glycine buffer (25 mM Tris, 192 mM glycine, pH 8.3) at a constant current of 21 mA for 65 min. An ultralow-range DNA ladder (Thermo Fisher Scientific) was used as a marker. The gel was stained with SYBR^® gold nucleic acid gel stain (Thermo Fisher Scientific) for 40 min. Quantification of non-degraded G4-CpG ODN was performed by determining the fluorescence intensity of the band in the gel using Image Studio Lite version 5.2 (Li-COR Biotechnology, Lincoln, NE, USA).