A crowded
cellular environment is highly associated with many significant
biological processes. However, the effect of molecular crowding on
the translocation behavior of DNA through a pore has not been explored.
Here, we use nanopore single-molecule analytical technique to quantify
the thermodynamics and kinetics of DNA transport under heterogeneous
cosolute PEGs. The results demonstrate that the frequency of the translocation
event exhibits a nonmonotonic dependence on the crowding agent size,
while both the event frequency and translocation time increase monotonically
with increasing crowder concentration. In the presence of PEGs, the
rate of DNA capture into the nanopore elevates 118.27-fold, and at
the same time the translocation velocity decreases from 20 to 120
μs/base. Interestingly, the impact of PEG 4k on the DNA-nanopore
interaction is the most notable, with up to ΔΔG = 16.27 kJ mol–1 change in free energy
and 764.50-fold increase in the binding constant at concentration
of 40% (w/v). The molecular crowding effect will has broad applications
in nanopore biosensing and nanopore DNA sequencing in which the strategy
to capture analyte and to control the transport is urgently required.
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