6533b85efe1ef96bd12bfaff

RESEARCH PRODUCT

Potassium Triggers a Reversible Specific Stiffness Transition of Polyethylene Glycol

Rubén Ahijado-guzmánFriederike SchmidLaura TütingWeixiang YeBernhard A. WolfCarsten SönnichsenGiovanni Settanni

subject

StereochemistryPotassiumchemistry.chemical_elementmacromolecular substances02 engineering and technologyPolyethylene glycol010402 general chemistry01 natural sciencesIonchemistry.chemical_compoundMolecular dynamicsmedicineMoleculePhysical and Theoretical ChemistrySpecific modulustechnology industry and agricultureStiffness021001 nanoscience & nanotechnology0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsGeneral EnergychemistryColloidal goldChemical physicsmedicine.symptom0210 nano-technology

description

We use plasmon rulers made from two connected gold nanoparticles to monitor the conformation and stiffness of single PEG molecules and their response to cations. By observing equilibrium fluctuations of the interparticle distance, we obtain the spring constants or stiffness of the connecting single-molecule tether with pico-Newton sensitivity. We observe a transition of the PEG molecules’ extension and stiffness above about 1.2 mM K+ ion concentration which is specific to potassium ions. Molecular dynamics simulations reveal the formation of crown-like structures as the most likely molecular mechanism responsible for this specific effect.

https://doi.org/10.1021/acs.jpcc.7b08987