Investigating the effect of mono‐ and multivalent counterions on the conformation of poly(styrenesulfonic acid) by nanopores

Abstract

Polyelectrolytes are useful materials that have many technical, medical, physiological and biological applications. The properties of polyelectrolytes are determined not only by their chemical composition but also by their conformational states. However, the conformations of polyelectrolytes in solution are very difficult to characterize. Herein, we propose to use a protein nanopore to investigate the effect of mono‐ and multivalent counterions on the conformational changes of a simple polyelectrolyte, sodium poly(styrenesulfonic acid) (NaPSS). High concentration of KCl induced a conformational transition of NaPSS from “swollen random coil” form in low salt concentration to “random coil” form and was evidenced by the changes of the translocation event pattern. Addition of Mg2+ in buffer solution did not cause notable changes of NaPSS translocation events, but Dy3+ and Y3+ were shown to have remarkable effects on the translocation profile of NaPSS. Bridging events caused by Dy3+ or Y3+ between polyelectrolyte chains largely affected current blockage and dwell time of the translocation events. Our results provide experimental evidence for the classical theories of conformational transitions of polyelectrolytes and may find applications in many other polyelectrolyte‐related researches.

Solution Properties of Polyelectrolytes with Divalent Counterions

“…Modeling the physicochemical behavior of polyelectrolytes in the presence of divalent (and higher valent) ions, even if specific interactions are not present, remains a challenging task with many open questions. ,,− It is generally assumed that multivalent counterions may form bridges between oppositely charged polymer chains. − However, this behavior has not been supported by conclusive experimental evidence or theoretical treatment and has not been established for a large set of systems …”

Design and Construction of a Multi-Tiered Minimal Actin Cortex for Structural Support in Lipid Bilayer Applications

“…A number of emerging sensing technologies critically depend on robust lipid bilayers, including those based on biological nanopores. − To work properly, analytes must be able to move from the bathing solution surrounding the interface to the mouth of the nanopore. Specific nanopore sensing applications include DNA sequencing, RNA sequencing, − nucleic acid detection, − polypeptide detection, RNA profiling, synthetic polymer characterization, − digital data storage, − disease detection, ion sensing, small molecule detection, and sensing of protein–drug interactions . Multiple types of nanopores with various pore sizes and channel structures can be employed.…”