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Title: Electrolyte-Mediated Assembly of Charged Nanoparticles

Abstract

Solutions at high salt concentrations are used to crystallize or segregate charged colloids, including proteins and polyelectrolytes via a complex mechanism referred to as “salting-out”. Here, we combine small-angle X-ray scattering (SAXS), molecular dynamics (MD) simulations, and liquid-state theory to show that salting-out is a long-range interaction, which is controlled by electrolyte concentration and colloid charge density. As a model system, we analyze Au nanoparticles coated with noncomplementary DNA designed to prevent interparticle assembly via Watson–Crick hybridization. SAXS shows that these highly charged nanoparticles undergo “gas” to face-centered cubic (FCC) to “glass-like” transitions with increasing NaCl or CaCl2 concentration. MD simulations reveal that the crystallization is concomitant with interparticle interactions changing from purely repulsive to a “long-range potential well” condition. Liquid-state theory explains this attraction as a sum of cohesive and depletion forces that originate from the interelectrolyte ion and electrolyte–ion–nanoparticle positional correlations. Our work provides fundamental insights into the effect of ionic correlations in the salting-out mechanism and suggests new routes for the crystallization of colloids and proteins using concentrated salts.

Authors:
 [1];  [2];  [1];  [1];  [3];  [4];  [5]
  1. Materials Science and Engineering Department, Northwestern University, Evanston, Illinois 60208, United States
  2. Materials Science and Engineering Department, Northwestern University, Evanston, Illinois 60208, United States, Instituto de Física, Universidad Autónoma de San Luis Potosí, Àlvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí, Mexico
  3. Materials Science and Engineering Department, Northwestern University, Evanston, Illinois 60208, United States, Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
  4. Materials Science and Engineering Department, Northwestern University, Evanston, Illinois 60208, United States, Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States, Physics and Astronomy Department, Northwestern University, Evanston, Illinois 60208, United States
  5. Materials Science and Engineering Department, Northwestern University, Evanston, Illinois 60208, United States, Physics and Astronomy Department, Northwestern University, Evanston, Illinois 60208, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Energy Frontier Research Centers (EFRC) (United States). Center for Bioinspired Energy Sciences (CBES); Northwestern Univ., Evanston, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); US Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF)
OSTI Identifier:
1245329
Alternate Identifier(s):
OSTI ID: 1470465
Grant/Contract Number:  
AC02-06CH11357; SC0000989; FA9550-11-1-0275; DMR-1121262
Resource Type:
Published Article
Journal Name:
ACS Central Science
Additional Journal Information:
Journal Name: ACS Central Science Journal Volume: 2 Journal Issue: 4; Journal ID: ISSN 2374-7943
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 59 BASIC BIOLOGICAL SCIENCES; Metal nanoparticles; Genetics; Nanoparticles; Ions; Electrolytes

Citation Formats

Kewalramani, Sumit, Guerrero-García, Guillermo I., Moreau, Liane M., Zwanikken, Jos W., Mirkin, Chad A., Olvera de la Cruz, Monica, and Bedzyk, Michael J. Electrolyte-Mediated Assembly of Charged Nanoparticles. United States: N. p., 2016. Web. doi:10.1021/acscentsci.6b00023.
Kewalramani, Sumit, Guerrero-García, Guillermo I., Moreau, Liane M., Zwanikken, Jos W., Mirkin, Chad A., Olvera de la Cruz, Monica, & Bedzyk, Michael J. Electrolyte-Mediated Assembly of Charged Nanoparticles. United States. doi:10.1021/acscentsci.6b00023.
Kewalramani, Sumit, Guerrero-García, Guillermo I., Moreau, Liane M., Zwanikken, Jos W., Mirkin, Chad A., Olvera de la Cruz, Monica, and Bedzyk, Michael J. Mon . "Electrolyte-Mediated Assembly of Charged Nanoparticles". United States. doi:10.1021/acscentsci.6b00023.
@article{osti_1245329,
title = {Electrolyte-Mediated Assembly of Charged Nanoparticles},
author = {Kewalramani, Sumit and Guerrero-García, Guillermo I. and Moreau, Liane M. and Zwanikken, Jos W. and Mirkin, Chad A. and Olvera de la Cruz, Monica and Bedzyk, Michael J.},
abstractNote = {Solutions at high salt concentrations are used to crystallize or segregate charged colloids, including proteins and polyelectrolytes via a complex mechanism referred to as “salting-out”. Here, we combine small-angle X-ray scattering (SAXS), molecular dynamics (MD) simulations, and liquid-state theory to show that salting-out is a long-range interaction, which is controlled by electrolyte concentration and colloid charge density. As a model system, we analyze Au nanoparticles coated with noncomplementary DNA designed to prevent interparticle assembly via Watson–Crick hybridization. SAXS shows that these highly charged nanoparticles undergo “gas” to face-centered cubic (FCC) to “glass-like” transitions with increasing NaCl or CaCl2 concentration. MD simulations reveal that the crystallization is concomitant with interparticle interactions changing from purely repulsive to a “long-range potential well” condition. Liquid-state theory explains this attraction as a sum of cohesive and depletion forces that originate from the interelectrolyte ion and electrolyte–ion–nanoparticle positional correlations. Our work provides fundamental insights into the effect of ionic correlations in the salting-out mechanism and suggests new routes for the crystallization of colloids and proteins using concentrated salts.},
doi = {10.1021/acscentsci.6b00023},
journal = {ACS Central Science},
number = 4,
volume = 2,
place = {United States},
year = {2016},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acscentsci.6b00023

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Cited by: 8 works
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