Glutaraldehyde tem grade

All samples were fixed with 0.1% of Glutaraldehyde TEM grade (Sigma Aldrich), washed with water, stained with 2% of filtered Uranyl acetate and finally washed with water.
All treated samples were deposited on a formvar carbon coated grid previously activated by plasma. Observation was carried out using a Philips CM120 TEM at 80 kV.

All samples were fixed with 0.1% of Glutaraldehyde TEM grade (Sigma Aldrich) and prepared as the method given by Gerling Cervantes for observing individual λ-DNA phage by AFM^{59 (link)} with some slight modifications. Samples were deposited with 10 mM of MgCl₂ onto a freshly cleaved mica previously mounted on a glass slide. The sample was left 2 minutes and spun with a spin coating system Mikasa 1H-D7 (Mikasa Co Ltd, Tokyo, Japan) for 20 seconds at 500 rpm and for 20 seconds at 7000 rpm. The unbound biomolecules were removed from mica surface by depositing a droplet of water and spun for 20 seconds at 500 rpm and for 2 minutes at 7000 rpm.
AFM observations were performed on a MFP-3D Infinity Asylum Research (Oxford Instruments, Tokyo, Japan) operated in tapping mode, using a silicon micro cantilever tip (Olympus, AC200TS-RS) with a height of 14 µm and a radius of 7 nm, a spring constant of 9 N/m and a resonance frequency of 180 kHz. Line scan rates were 0.5–1 Hz and images were acquired at 512 × 512 pixels.