(a) Simulation snapshot of a flexible polymer after equilibration but before translocation has started. The polymer experiences a good solvent in the left and a worse solvent in the right reservoir, where the conformation is hence more compact. (b) The radius of gyration of a flexible polymer in good-solvent scales as with (filled circles and full lines). When increasing the solvent-polymer repulsion by (hence decreasing the solvent quality), is reduced (open symbols) and a lower apparent scaling exponent is observed (dashed lines; cf. Table I). Mimicking bad-solvent conditions by reducing the monomer-monomer repulsion by yields similar effects on size scaling (crosslike symbols; shifted by a factor of 4 for better visibility; error bars are smaller than symbol size).
(a) The unbiased translocation time for good-solvent conditions (filled circles and full line; data shifted by factor of 1.5 for better visibility) scales as with . A very similar, yet weaker scaling is observed when decreasing the solvent quality by increasing (open symbols) or decreasing (crosslike symbols; shifted by a factor of 4). The apparent values for are summarized in Table I. (b) During the translocation process, a long polymer in good solvent shows a slight subdiffusion in the mean square displacement of the translocation coordinate (filled symbols) up to the polymer’s relaxation time (dashed line). The anomaly exponent is consistent with previous predictions (cf. main text). When decreasing the solvent quality via (, open symbols), the anomaly subsides and a diffusive scaling emerges, consistent with the scaling (cf. Table I; error bars are smaller than symbol size).
(a) The translocation time of a polymer of length between two reservoirs with different solvent qualities scales as with depending on the quality of the worse solvent (one reservoir is fixed to good-solvent conditions). For decreasing solvent quality an enhanced translocation is observed when the solvent quality is tuned by increasing (open symbols) or by decreasing (crosslike symbols; shifted by factor of 10). (b) While in both models an enhanced translocation is observed, the direction of the translocation is very different. While changing the polymer-solvent interactions via leads to a preferred translocation toward the good solvent , an enhancement of leads to translocation toward the worse solvent ; symbols as in (a); error bars are smaller than symbol size.
The scaling of the translocation time of a completely semiflexible polymer (rigidity ; open circles) is consistent with the limiting case of a stiff rod, (full line). Deviations for large are attributed to the finite stiffness of the polymer, i.e., for large bending modes perturb the scaling. The translocation becomes biased and is enhanced when the nanopore connects two reservoirs in one of which the polymer is flexible, while it is semiflexible in the other (filled circles). For the shown data set, we observe and a preferential translocation to the reservoir in which the polymer is flexible . Error bars are smaller than symbol size.
Apparent scaling exponents and of the polymers’ radius of gyration and translocation time , respectively, for decreasing solvent quality (increase in by ). Due to the soft-core nature of DPD beads, a size scaling exponent slightly smaller than the limiting value may occur (cf. last row).
Apparent scaling exponent of the translocation time when the solvent quality differs in the two reservoirs (worse solvent: increase in by ).
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