Conformational dynamic behavior of single polyelectrolyte chains confined in micro and nanochannels

Conformational dynamic behavior of single polyelectrolyte chains confined in micro and nanochannels
Conformation; Polyelectrolyte; Microchannel; Nanochannel; Rheology; Simulations
Issue Date
85th Society of Rheology
VOL 85
Polyelectrolytes in the confined spaces exhibit distinguished structure and rheology compared to their behavior in the bulk, due to the interactions with bounding surfaces originated in the charged polymer chains and mobile counterions. We investigated the confinement-induced conformational dynamics of the polyelectrolyte chain by employing the coarse-grained Brownian dynamics simulations [1] as well as by considering the blob theory [2]. Submicron-sized biopolymer xanthan was chosen as a model polyelectrolyte taking into account both flexible and semiflexible chains for comparison. It is available to identify three primary regimes (i.e., weakly confined, de Gennes, and Odijk regimes) according to a competition between length scales with the three dimensional radius of gyration in bulk, the persistence length, and the channel width. Confined flexible and semiflexible chains exhibit a nonmonotonic variation in size in the weak confinements, where the relative radius of gyration interestingly shows a dip and then increases with decreasing the channel width. The rigid chain, realized at low Debye screening with a low ionic concentration, exhibits a sigmoidal transition without minima in size. Major attention should be on the dependence of scaling law exponents on the screening effect of the aqueous solution in the moderate confinement of the de Gennes regime. For experimental verifications, we also present the single xanthan visualization using a fluorescence microscope and the displacing motion of an individual molecule in slitlike channels. Our findings are expected to provide useful information and design platform aiming to develop the micro total analysis system, inter alia, DNA sequencing, genome analysis, and manipulations of soft-matters [3].
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