Quartz glass capillaries

The nanobait was mixed with a sample (nucleic acid extract or purified viral targets at ten times excess) in 10 mM MgCl₂ and 100 mM NaCl. The mixture (5 μl) was incubated at room temperature (~10 min) until prepared for nanopore measurement. The difference in the target sequence composition and its physical characteristics might lead to variability in hybridization and hence the displacement efficiency of sensing sites^{21 (link)}. We have used htRNA (100 ng μl^–1; Invitrogen) as a background where indicated, to show that there are no non-specific signals induced by human native RNAs. For nanopore measurement, the sample was diluted to <0.5 nM nanobait (for purified viral targets) or 4.7 μl of RNase-H-cut patient sample was mixed with 0.3 μl of monovalent streptavidin (SAe1D3)^{18 (link)} (1 μM), 5 μl of LiCl (4.0 M) and 5.0 μl of LiCl (8.0 M). We have fabricated 14 ± 3 nm (mean ± standard deviation) nanopores^{12 (link)} using quartz glass capillaries with 0.5 mm outer diameter and 0.2 mm inner diameter (Sutter Instrument) by laser-assisted puller P-2000 (Sutter Instrument). The mix was pipetted in a nanopore polydimethylsiloxane chip, and all the measurements were performed at a constant voltage of 600 mV. Nanopore measurement details are shown in Supplementary Table 30.

Glass nanopores were produced from quartz glass capillaries with 0.5 mm outer diameter and 0.2 mm inner diameter (Sutter Instruments, USA) using a laser-assisted capillary puller P-2000 (Sutter Instruments, USA). The nanopores had diameters of 8 to 15 nm^{56 (link)}, achieved by using the following heating parameters of the instrument: HEAT, 470; VEL, 25; DEL, 170; and PUL, 200.