title: Hydration Repulsion between Carbohydrate Surfaces Mediated by Temperature and Specific Ions.
abstract: Stabilizing colloids or nanoparticles in solution involves a fine balance between surface charges, steric repulsion of coating molecules, and hydration forces against van der Waals attractions. At high temperature and electrolyte concentrations, the colloidal stability of suspensions usually decreases rapidly. Here, we report a new experimental and simulation discovery that the polysaccharide (dextran) coated nanoparticles show ion-specific colloidal stability at high temperature, where we observed enhanced colloidal stability of nanoparticles in CaCl2 solution but rapid nanoparticle-nanoparticle aggregation in MgCl2 solution. The microscopic mechanism was unveiled in atomistic simulations. The presence of surface bound Ca(2+) ions increases the carbohydrate hydration and induces strongly polarized repulsive water structures beyond at least three hydration shells which is farther-reaching than previously assumed. We believe leveraging the binding of strongly hydrated ions to macromolecular surfaces represents a new paradigm in achieving absolute hydration and colloidal stability for a variety of materials, particularly under extreme conditions.
authors.affiliation: Aramco Services Company: Aramco Research Center - Boston, Cambridge, MA 02139, USA.
authors.forename: Hsieh
authors.initials: H
authors.lastname: Chen
authors.affiliation: Aramco Services Company: Aramco Research Center - Boston, Cambridge, MA 02139, USA.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Cox
authors.affiliation: Aramco Services Company: Aramco Research Center - Boston, Cambridge, MA 02139, USA.
authors.forename: Hooisweng
authors.initials: H
authors.lastname: Ow
authors.affiliation: Aramco Services Company: Aramco Research Center - Boston, Cambridge, MA 02139, USA.
authors.forename: Rena
authors.initials: R
authors.lastname: Shi
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Athanassios Z
authors.initials: AZ
authors.lastname: Panagiotopoulos
mesh_terms: D002118:Calcium / Q000737:chemistry; D002122:Calcium Chloride / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D007477:Ions / Q000737:chemistry*; D015636:Magnesium Chloride / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D003102:Colloids; D003911:Dextrans; D004573:Electrolytes; D007477:Ions; D015636:Magnesium Chloride; D014867:Water; D002122:Calcium Chloride; D002118:Calcium