Ac240ts afm probe

The GT15mir19 sensor was incubated overnight at 20 mg/L with 10 uM of the miR-19-hairpin or 10 uM of the R23-hairpin in saline sodium citrate diluted 20x in 20 mM HEPES + 5 mM MgCl₂. The sample was plated on a freshly cleaved mica substrate (SPI) for 4 minutes before washing with 10 mL of dH2O and blowing dry with argon gas. An Asylum Research MFP-3D-Bio instrument was used with an Olympus AC240TS AFM probe in AC mode. Data was captured at 2.93 nm/pixel XY resolution and 15.63 pm Z resolution. For AFM under aqueous conditions, 20 mg/L of the GT15mir19 sensor was incubated with 10 uM of the miR-19-hairpin, R23-hairpin, or buffer overnight. All three conditions were spin-filtered 3x with 100 kDa Amicon centrifuge filters, and resuspended with 5 mM NiCl₂, 20 mM HEPES pH 6.7 buffer. The samples were plated onto freshly cleaved mica for 2 minutes before gently washing with the same buffer. Samples were imaged in a droplet of the buffer using an Asylum Research Cypher ES + BlueDrive AFM with an Olympus AC55 probe and imaged using BlueDrive excitation at the ambient temperature of 31°C within the AFM enclosure. All three samples were imaged with the same probe, consecutively, with the same scan settings, starting with the miR-19-hairpin sample, followed by the R23-hairpin control and the buffer control.