Detection of ssRNA, ssDNA, and α-synuclein
in the nanobridge
configuration. (a) Current–time trace for a 1 kb ssRNA ladder
(2 μg/mL) in 100 mM KCl at an applied bias of 400 mV. For visualization
purposes, approximate levels are designated for each fragment size
(0.5, 1, 2, 3, 5, 7, 9 kb). (b) Peak current histogram and (c) corresponding
equivalent charge plot. (d) Current time trace for a 100 pM sample
of M13mp18 ssDNA in 100 mM KCl at an applied bias of 200 mV. (e) Current–dwell
time contour plots are shown for voltages of 200 mV, 300 mV, and 400
mV, respectively. Similar to dsDNA, the dwell times increase with
voltage due to compacting of the DNA in the nanobridge. Events as
slow as 40 ms could be detected which is substantially slower than
in a conventional nanopore configuration. (f) Current–time
trace for monomeric α-synuclein for a concentration of 700 pM
in 100 mM KCl and recorded at an applied bias of 400 mV. (g) Current–dwell
time contour plots are shown for voltages of 400 mV, 500 mV, and 600
mV, respectively.