High-resolution environmental AFM was used to characterize the DNA assemblies. DNA assemblies in DMEM at 37°C were fixed at room temperature on a freshly cleaved mica surfaces (Nano-Tec V-1 grade Muscovite, Micro to Nano innovative Microscopy Supplies) that was pre-treated with 20 µL of 0.1M spermine tetrahydrochloride solution for 10 min before being washed with deionized water and a buffered saline solution (Tris-Acetate pH 8, 100 mM NaCl). 15 µL of DNA solution was deposited on the treated mica and left for 10 min adsorption. The solution was blotted off and the mica surface was gently rinsed with the buffered saline solution, and kept moist in this solution. The samples were observed with a Cypher ES AFM Microscope (Oxford Instruments) in tapping mode with 17-45 kHz resonance frequency in liquid and 0.09 N/m force constant tip (BL-AC40TS, Olympus), using the blueDrive TM photothermal excitation mode. Raw images were subjected to polynomial background subtraction, plane level correction, rows alignment using various methods and horizontal scars correction in Gwyddion.