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Chu B, Marchioro A, Roke S. Size dependence of second-harmonic scattering from nanoparticles: Disentangling surface and electrostatic contributions. J Chem Phys 2023; 158:094711. [PMID: 36889968 DOI: 10.1063/5.0135157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
Polarimetric angle-resolved second-harmonic scattering (AR-SHS) is an all-optical tool enabling the study of unlabeled interfaces of nano-sized particles in an aqueous solution. As the second harmonic signal is modulated by interference between nonlinear contributions originating at the particle's surface and those originating in the bulk electrolyte solution due to the presence of a surface electrostatic field, the AR-SHS patterns give insight into the structure of the electrical double layer. The mathematical framework of AR-SHS has been previously established, in particular regarding changes in probing depth with ionic strength. However, other experimental factors may influence the AR-SHS patterns. Here, we calculate the size dependence of the surface and electrostatic geometric form factors for nonlinear scattering, together with their relative contribution to the AR-SHS patterns. We show that the electrostatic term is stronger in the forward scattering direction for smaller particle sizes, while the ratio of the electrostatic to surface terms decreases with increasing size. Besides this competing effect, the total AR-SHS signal intensity is also weighted by the particle's surface characteristics, given by the surface potential Φ0 and the second-order surface susceptibility χs,2 2. The weighting effect is experimentally demonstrated by comparing SiO2 particles of different sizes in NaCl and NaOH solutions of varying ionic strengths. For NaOH, the larger χs,2 2 values generated by deprotonation of surface silanol groups prevail over the electrostatic screening occurring at high ionic strengths; however, only for larger particle sizes. This study establishes a better connection between the AR-SHS patterns and surface properties and predicts trends for arbitrarily-sized particles.
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Affiliation(s)
- Bingxin Chu
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), École polytechnique fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Arianna Marchioro
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), École polytechnique fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), École polytechnique fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Glikman D, Braunschweig B. Nanoscale Effects on the Surfactant Adsorption and Interface Charging in Hexadecane/Water Emulsions. ACS NANO 2021; 15:20136-20147. [PMID: 34898170 DOI: 10.1021/acsnano.1c08038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nanoscale properties at interfaces play a key role in the colloidal stability of emulsions and other soft matter materials where physical properties need to be controlled from the nano to macroscopically visible length scales. Our molecular level understanding of oil-water interfaces arises mostly from results at extended interfaces and the common view that emulsions are stabilized by a large number of surfactant molecules at the droplet's interface which, however, has been recently challenged. In this work, we show that the particle size and the curvature of oil droplets at the nanoscale is of great importance for the interface adsorption of dodecyl sulfate surfactants and possible counterion condensation at the charged hexadecane-water interface. Using second-harmonic scattering, we have studied the surface charge of oil droplets in nanoemulsions where we systematically varied the particle size R between 80 and 270 nm and demonstrate that the surface charge density σ changes drastically with size: For sizes >200 nm, σ is similar to what can be expected at flat extended interfaces, while σ is dramatically reduced by almost an order of magnitude when the particle size of the oil droplet is 80 nm. Using a theoretical approach that considers counterion condensation, we quantify the nanoscale effects on the change in surface charge with particle size and find excellent agreement with our experimental result. Modeling of the experimental results also implies that the charge per particle remains constant and depends on a critical balance of surfactant adsorption and ion condensation.
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Affiliation(s)
- Dana Glikman
- Institute of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
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Marchioro A, Bischoff M, Lütgebaucks C, Biriukov D, Předota M, Roke S. Surface Characterization of Colloidal Silica Nanoparticles by Second Harmonic Scattering: Quantifying the Surface Potential and Interfacial Water Order. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:20393-20404. [PMID: 35692558 PMCID: PMC9182216 DOI: 10.1021/acs.jpcc.9b05482] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Revised: 07/25/2019] [Indexed: 05/11/2023]
Abstract
The microscopic description of the interface of colloidal particles in solution is essential to understand and predict the stability of these systems, as well as their chemical and electrochemical reactivity. However, this description often relies on the use of simplified electrostatic mean field models for the structure of the interface, which give only theoretical estimates of surface potential values and do not provide properties related to the local microscopic structure, such as the orientation of interfacial water molecules. Here we apply polarimetric angle-resolved second harmonic scattering (AR-SHS) to 300 nm diameter SiO2 colloidal suspensions to experimentally determine both surface potential and interfacial water orientation as a function of pH and NaCl concentration. The surface potential values and interfacial water orientation change significantly over the studied pH and salt concentration range, whereas zeta-potential (ζ) values remain constant. By comparing the surface and ζ-potentials, we find a layer of hydrated condensed ions present in the high pH case, and for NaCl concentrations ≥1 mM. For milder pH ranges (pH < 11), as well as for salt concentrations <1 mM, no charge condensation layer is observed. These findings are used to compute the surface charge densities using the Gouy-Chapman and Gouy-Chapman-Stern models. Furthermore, by using the AR-SHS data, we are able to determine the preferred water orientation in the layer directly in contact with the silica interface. Molecular dynamics simulations confirm the experimental trends and allow deciphering of the contributions of water layers to the total response.
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Affiliation(s)
- Arianna Marchioro
- Laboratory
for Fundamental BioPhotonics
(LBP), Institute of Bioengineering (IBI), and Institute of Materials
Science (IMX), School of Engineering (STI), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marie Bischoff
- Laboratory
for Fundamental BioPhotonics
(LBP), Institute of Bioengineering (IBI), and Institute of Materials
Science (IMX), School of Engineering (STI), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Cornelis Lütgebaucks
- Laboratory
for Fundamental BioPhotonics
(LBP), Institute of Bioengineering (IBI), and Institute of Materials
Science (IMX), School of Engineering (STI), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Denys Biriukov
- Institute
of Physics, Faculty of Science, University
of South Bohemia, 370 05 České Budějovice, Czech
Republic
| | - Milan Předota
- Institute
of Physics, Faculty of Science, University
of South Bohemia, 370 05 České Budějovice, Czech
Republic
| | - Sylvie Roke
- Laboratory
for Fundamental BioPhotonics
(LBP), Institute of Bioengineering (IBI), and Institute of Materials
Science (IMX), School of Engineering (STI), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- (S.R.) E-mail:
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Remsing RC, Duignan TT, Baer MD, Schenter GK, Mundy CJ, Weeks JD. Water Lone Pair Delocalization in Classical and Quantum Descriptions of the Hydration of Model Ions. J Phys Chem B 2018; 122:3519-3527. [DOI: 10.1021/acs.jpcb.7b10722] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Richard C. Remsing
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Timothy T. Duignan
- Chemical and Materials Science Division, Pacific Northwest National Laboratory, Richland, Washington, United States
| | - Marcel D. Baer
- Chemical and Materials Science Division, Pacific Northwest National Laboratory, Richland, Washington, United States
| | - Gregory K. Schenter
- Chemical and Materials Science Division, Pacific Northwest National Laboratory, Richland, Washington, United States
| | - Christopher J. Mundy
- Chemical and Materials Science Division, Pacific Northwest National Laboratory, Richland, Washington, United States
- Affiliate Professor, Department of Chemical Engineering, University of Washington, Seattle, Washington, United States
| | - John D. Weeks
- Institute for Physical Science and Technology and Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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Moreno Ostertag L, Ling X, Domke KF, Parekh SH, Valtiner M. Characterizing the hydrophobic-to-hydrophilic transition of electrolyte structuring in proton exchange membrane mimicking surfaces. Phys Chem Chem Phys 2018; 20:11722-11729. [DOI: 10.1039/c8cp01625a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The surface density of charged sulfonic acid head groups in a perfluorosulfonic acid (PFSA) proton exchange membrane determines the hydrophilicity of the ionic channels and is thus critical for the structuring and transport of water and protons.
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Affiliation(s)
- Laila Moreno Ostertag
- Interface Chemistry and Surface Engineering
- Max-Planck-Institut für Eisenforschung GmbH
- D-40237 Düsseldorf
- Germany
- Institute of Applied Physics
| | - Xiao Ling
- Department of Molecular Spectroscopy
- Max-Planck-Institut für Polymerforschung
- D-55128 Mainz
- Germany
| | - Katrin F. Domke
- Department of Molecular Spectroscopy
- Max-Planck-Institut für Polymerforschung
- D-55128 Mainz
- Germany
| | - Sapun H. Parekh
- Department of Molecular Spectroscopy
- Max-Planck-Institut für Polymerforschung
- D-55128 Mainz
- Germany
| | - Markus Valtiner
- Interface Chemistry and Surface Engineering
- Max-Planck-Institut für Eisenforschung GmbH
- D-40237 Düsseldorf
- Germany
- Institute of Applied Physics
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Xiao M, Wei S, Li Y, Jasensky J, Chen J, Brooks CL, Chen Z. Molecular interactions between single layered MoS 2 and biological molecules. Chem Sci 2017; 9:1769-1773. [PMID: 29675220 PMCID: PMC5885976 DOI: 10.1039/c7sc04884j] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 11/29/2017] [Indexed: 11/21/2022] Open
Abstract
In this research, molecular interactions between several de novo designed alpha-helical peptides and monolayer MoS2 have been studied.
Two-dimensional (2D) materials such as graphene, molybdenum disulfide (MoS2), tungsten diselenide (WSe2), and black phosphorous are being developed for sensing applications with excellent selectivity and high sensitivity. In such applications, 2D materials extensively interact with various analytes including biological molecules. Understanding the interfacial molecular interactions of 2D materials with various targets becomes increasingly important for the progression of better-performing 2D-material based sensors. In this research, molecular interactions between several de novo designed alpha-helical peptides and monolayer MoS2 have been studied. Molecular dynamics simulations were used to validate experimental data. The results suggest that, in contrast to peptide–graphene interactions, peptide aromatic residues do not interact strongly with the MoS2 surface. It is also found that charged amino acids are important for ensuring a standing-up pose for peptides interacting with MoS2. By performing site-specific mutations on the peptide, we could mediate the peptide–MoS2 interactions to control the peptide orientation on MoS2.
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Affiliation(s)
- Minyu Xiao
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
| | - Shuai Wei
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
| | - Yaoxin Li
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
| | - Joshua Jasensky
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
| | - Junjie Chen
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
| | - Charles L Brooks
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
| | - Zhan Chen
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , USA .
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