Atomic force
microscopy (AFM) imaging was
performed using a tip-scan high-speed AFM (BIXAM, Olympus, Tokyo,
Japan) that was improved based on a previously developed prototype
AFM.45 (link),46 (link) A freshly cleaved mica surface was pretreated
with 0.05% 3-aminopropyltriethoxysilane (APTES).47 (link) A drop (2 μL) of the sample (about
1 nM) in the TAE-Mg buffer (40 mM Tris-acetate, 1 mM EDTA, 2 mM MgCl2,
pH 8.3) was deposited onto the APTES-treated mica surface and incubated
for 3 min. The surface was subsequently rinsed with 10 μL of
the TAE-Mg buffer. Small cantilevers (9 μm long, 2 μm
wide, and 100 nm thick; USC-F0.8-k0.1-T12, NanoWorld, Switzerland),
with a spring constant of ∼0.1 N/m and a resonant
frequency of ∼300–600 kHz in water, were used to scan
the sample surface. The 320 × 240 pixel2 images were
collected at a scan rate of 0.2 frames per second (fps). The imaged
sequences were analyzed using AFM
scanning software (Olympus) and ImageJ (http://imagej.nih.gov/ij/ )
software.
microscopy (AFM) imaging was
performed using a tip-scan high-speed AFM (BIXAM, Olympus, Tokyo,
Japan) that was improved based on a previously developed prototype
AFM.45 (link),46 (link) A freshly cleaved mica surface was pretreated
with 0.05% 3-aminopropyltriethoxysilane (APTES).47 (link) A drop (2 μL) of the sample (about
1 nM) in the TAE-Mg buffer (40 mM Tris-acetate, 1 mM EDTA, 2 mM MgCl2,
pH 8.3) was deposited onto the APTES-treated mica surface and incubated
for 3 min. The surface was subsequently rinsed with 10 μL of
the TAE-Mg buffer. Small cantilevers (9 μm long, 2 μm
wide, and 100 nm thick; USC-F0.8-k0.1-T12, NanoWorld, Switzerland),
with a spring constant of ∼0.1 N/m and a resonant
frequency of ∼300–600 kHz in water, were used to scan
the sample surface. The 320 × 240 pixel2 images were
collected at a scan rate of 0.2 frames per second (fps). The imaged
sequences were analyzed using AFM
scanning software (Olympus) and ImageJ (
software.
Free full text: Click here
