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Saha D, Kumar S, Mata JP, Whitten AE, Aswal VK. Competitive effects of salt and surfactant on the structure of nanoparticles in a binary system of nanoparticle and protein. Phys Chem Chem Phys 2023; 25:22130-22144. [PMID: 37563993 DOI: 10.1039/d3cp02619a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) experiments have been carried out to study the competitive effects of NaCl and sodium dodecyl sulfate (SDS) surfactant on the evolution of the structure and interactions in a silica nanoparticle-Bovine serum albumin (BSA) protein system. The unique advantage of contrast-matching SANS has been utilized to particularly probe the structure of nanoparticles in the multi-component system. Silica nanoparticles and BSA protein both being anionic remain largely individual in the solution without significant adsorption. The non-adsorbing nature of protein is known to cause depletion attraction between nanoparticles at higher protein concentrations. The nanoparticles undergo immediate aggregation in the nanoparticle-BSA system on the addition of a small amount of salt [referred as the critical salt concentration (CSC)], much less than that required to induce aggregation in a pure nanoparticle dispersion. The salt ions screen the electrostatic repulsion between the nanoparticles, whereby the BSA-induced depletion attraction dominates the system and contributes to the nanoparticle aggregation of a mass fractal kind of morphology. Further, the addition of SDS in this system interestingly suppresses nanoparticle aggregation for salt concentrations lower than the CSC. The presence of SDS gives rise to additional electrostatic repulsion in the system by binding with the BSA protein via electrostatic and hydrophobic interactions. For salt concentrations higher than the CSC, the formation of clusters of nanoparticles is inevitable even in the presence of protein-surfactant complexes, but the mass fractal kind of branched aggregates transform to surface fractals. This has been attributed to the BSA-SDS complex induced depletion attraction along with salt-driven screening of electrostatic repulsion. Thus, the interplay of depletion and electrostatic and hydrophobic interactions has been utilized to tune the structures formed in a multicomponent silica nanoparticle-BSA-SDS/NaCl system.
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Affiliation(s)
- Debasish Saha
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
- Juelich Centre for Neutron Science-4, Forschungszentrum Juelich, Juelich-52425, Germany
| | - Sugam Kumar
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
- Homi Bhabha National Institute, Mumbai 400 094, India
| | - Jitendra P Mata
- Australian Centre for Neutron Scattering (ACNS), Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Andrew E Whitten
- Australian Centre for Neutron Scattering (ACNS), Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Vinod K Aswal
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
- Homi Bhabha National Institute, Mumbai 400 094, India
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2
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Wu J, Liu W, Ngai T. Total internal reflection microscopy: a powerful tool for exploring interactions and dynamics near interfaces. SOFT MATTER 2023. [PMID: 37314857 DOI: 10.1039/d3sm00085k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The occurrence of many micro/macrophenomena is closely related to interactions and dynamics near interfaces. Hence, developing powerful tools for characterizing near-interface interactions and dynamics has attached great importance among researchers. In this review, we introduce a noninvasive and ultrasensitive technique called total internal reflection microscopy (TIRM). The principles of TIRM are introduced first, demonstrating the characteristics of this technique. Then, typical measurements with TIRM and the recent development of the technique are reviewed in detail. At the end of the review, we highlight the great progress of TIRM during the past several decades and show its potential to be more influential in measuring interactions and dynamics near interfaces in various research fields.
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Affiliation(s)
- Jiahao Wu
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - Wei Liu
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education & School of Chemical and Material Engineering, Jiangnan University, Wuxi, China.
| | - To Ngai
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
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3
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Allahyarov E, Löwen H, Denton AR. Structural correlations in highly asymmetric binary charged colloidal mixtures. Phys Chem Chem Phys 2022; 24:15439-15451. [PMID: 35708479 DOI: 10.1039/d2cp01343f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We explore structural correlations of strongly asymmetric mixtures of binary charged colloids within the primitive model of electrolytes considering large charge and size ratios of 10 and higher. Using computer simulations with explicit microions, we obtain the partial pair correlation functions between the like-charged colloidal macroions. Interestingly the big-small correlation peak amplitude is smaller than that of the big-big and small-small macroion correlation peaks, which is unfamiliar for additive repulsive interactions. Extracting optimal effective microion-averaged pair interactions between the macroions, we find that on top of non-additive Yukawa-like repulsions an additional shifted Gaussian attractive potential between the small macroions is needed to accurately reproduce their correct pair correlations. For small Coulomb couplings, the behavior is reproduced in a coarse-grained theory with microion-averaged effective interactions between the macroions. However, the accuracy of the theory deteriorates with increasing Coulomb coupling. We emphasize the relevance of entropic interactions exerted by the microions on the macroions. Our results are experimentally verifiable in binary mixtures of micron-sized colloids and like-charge nanoparticles.
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Affiliation(s)
- Elshad Allahyarov
- Theoretical Department, Joint Institute for High Temperatures, Russian Academy of Sciences (IVTAN), 13/19 Izhorskaya Street, Moscow 125412, Russia. .,Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf, Germany.,Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7202, USA
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf, Germany
| | - Alan R Denton
- Department of Physics, North Dakota State University, Fargo, ND 58108-6050, USA
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Valdeperez D, Wutke N, Ackermann LM, Parak WJ, Klapper M, Pelaz B. Colloidal stability of polymer coated zwitterionic Au nanoparticles in biological media. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.120820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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5
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Jiryaei Z, Saidi MH. Effect of collision on self-assembly of nanoparticles in zirconia microparticle suspension. J DISPER SCI TECHNOL 2020. [DOI: 10.1080/01932691.2020.1845196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Zahra Jiryaei
- Department of Polymer Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mohammad Hassan Saidi
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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6
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Handel B, Dinkova VV, Ximendes E, Solé JG, Jaque D, Marin R. Investigation of the concentration- and temperature-dependent motion of colloidal nanoparticles. NANOSCALE 2020; 12:12561-12567. [PMID: 32500872 DOI: 10.1039/d0nr02995e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Although the motion of a single nanoparticle suspended in a fluid can be easily modeled, things get complicated for non-infinitely diluted systems. Coincidentally, these are the systems of interest in relevant fields such as, nanomedicine, microfluidics and miniaturized energy storage devices. Hence, a better understanding of the dynamics of colloidal nanoparticles is utterly needed. Herein, the motion of colloidal suspension of plasmonic nanoparticles (i.e., gold nanoshells) is investigated via laser speckle imaging. The method relies on the analysis of the speckle pattern generated by colloidal suspensions forced to flow at specific velocities. Temperature-dependent measurements corroborated that the dynamics of non-infinitely diluted nanoparticle suspensions are better described through a diffusive model rather than by the equipartition theorem. Under the tested experimental conditions, an average diffusion velocity between 0.37 and 1.57 mm s-1 was found. Most importantly, these values were largely dependent on the nanoparticle concentration. These results are in agreement with previous reports and indicate the existence of long-range interactions between nanoparticles.
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Affiliation(s)
- Barnaby Handel
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain.
| | - Vladislava Vladimirova Dinkova
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain.
| | - Erving Ximendes
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain. and Nanobiology Group, Instituto Ramón y Cajal de Investigación, Sanitaria Hospital Ramón y Cajal, Ctra. De Colmenar Viejo, Km. 9100, 28034 Madrid, Spain
| | - José García Solé
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain.
| | - Daniel Jaque
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain. and Nanobiology Group, Instituto Ramón y Cajal de Investigación, Sanitaria Hospital Ramón y Cajal, Ctra. De Colmenar Viejo, Km. 9100, 28034 Madrid, Spain
| | - Riccardo Marin
- Fluorescence Imaging Group (FIG), Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid 28049, Spain.
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7
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Meissner J, Wu Y, Jestin J, Shelton WA, Findenegg GH, Bharti B. pH-Induced reorientation of cytochrome c on silica nanoparticles. SOFT MATTER 2019; 15:350-354. [PMID: 30468443 DOI: 10.1039/c8sm01909f] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The orientation of cytochrome c molecules at the surface of silica nanoparticles was studied in a wide pH range by combining small-angle neutron scattering, adsorption measurements, and molecular dynamics simulations. The results indicate a reorientation of the ellipsoidal protein from head-on to side-on as the pH is increased. This is attributed to changes in the surface charge distribution of both the protein and the nanoparticles.
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Affiliation(s)
- Jens Meissner
- Stranski Laboratory of Physical and Theoretical Chemistry, Technical University Berlin, 10623 Berlin, Germany.
| | - Yao Wu
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Jacques Jestin
- Laboratoire Léon Brillouin, CEA Saclay 91191 Gif-sur-Yvette Cedex, France
| | - William A Shelton
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA. and Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Gerhard H Findenegg
- Stranski Laboratory of Physical and Theoretical Chemistry, Technical University Berlin, 10623 Berlin, Germany.
| | - Bhuvnesh Bharti
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.
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8
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Bacillus lipopeptides: powerful capping and dispersing agents of silver nanoparticles. APPLIED NANOSCIENCE 2018. [DOI: 10.1007/s13204-018-0852-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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9
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Weight BM, Denton AR. Structure and stability of charged colloid-nanoparticle mixtures. J Chem Phys 2018; 148:114904. [DOI: 10.1063/1.5004443] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Braden M. Weight
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050, USA
| | - Alan R. Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050, USA
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10
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Ojeda-Mendoza GJ, Moncho-Jordá A, González-Mozuelos P, Haro-Pérez C, Rojas-Ochoa LF. Evidence of electrostatic-enhanced depletion attraction in the structural properties and phase behavior of binary charged colloidal suspensions. SOFT MATTER 2018; 14:1355-1364. [PMID: 29379934 DOI: 10.1039/c7sm02220d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper we study the structure and phase behavior of binary mixtures of charged particles at low ionic strength. Due to the large size asymmetry between both species, light scattering measurements give us access only to the partial static structure factor that corresponds to the big particles. We observe that the addition of small charged colloids produces a decrease of the main peak of the measured static structure factor and a shift to larger scattering vector values. This finding is in agreement with theory based on integral equations with the Hypernetted-Chain Closure (HNC) relation. The effective interaction between two big particles due to the presence of small particles is obtained by a HNC inversion scheme and used in numerical simulations that adequately reproduce the experiments. We find that the presence of small particles induces an electrostatic depletion screening among the big colloids, creating around them an exclusion zone for the small charged colloids greater than that caused in the case of neutral small colloids, which in turn augments the depletion effect.
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Affiliation(s)
- G J Ojeda-Mendoza
- Departamento de Física, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico.
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11
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Denton AR. Effective electrostatic interactions in colloid-nanoparticle mixtures. Phys Rev E 2017; 96:062610. [PMID: 29347449 DOI: 10.1103/physreve.96.062610] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Indexed: 06/07/2023]
Abstract
Interparticle interactions and bulk properties of colloidal suspensions can be substantially modified by the addition of nanoparticles. Extreme asymmetries in size and charge between colloidal particles and nanoparticles present severe computational challenges to molecular-scale modeling of such complex systems. We present a statistical mechanical theory of effective electrostatic interactions that can greatly ease large-scale modeling of charged colloid-nanoparticle mixtures. By applying a sequential coarse-graining procedure, we show that a multicomponent mixture of charged colloids, nanoparticles, counterions, and coions can be mapped first onto a binary mixture of colloids and nanoparticles and then onto a one-component model of colloids alone. In a linear-response approximation, the one-component model is governed by a single effective pair potential and a one-body volume energy, whose parameters depend nontrivially on nanoparticle size, charge, and concentration. To test the theory, we perform molecular dynamics simulations of the two-component and one-component models and compute structural properties. For moderate electrostatic couplings, colloid-colloid radial distribution functions and static structure factors agree closely between the two models, validating the sequential coarse-graining approach. Nanoparticles of sufficient charge and concentration enhance screening of electrostatic interactions, weakening correlations between charged colloids and destabilizing suspensions, consistent with experiments.
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Affiliation(s)
- Alan R Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050, USA
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12
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Zubir MNM, Badarudin A, Kazi S, Misran M, Amiri A, Sadri R, Khalid S. Experimental investigation on the use of highly charged nanoparticles to improve the stability of weakly charged colloidal system. J Colloid Interface Sci 2015; 454:245-55. [DOI: 10.1016/j.jcis.2015.05.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/10/2015] [Accepted: 05/12/2015] [Indexed: 10/23/2022]
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13
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Keramati H, Saidi MH, Zabetian M. Stabilization of the Suspension of Zirconia Microparticle Using the Nanoparticle Halos Mechanism: Zeta Potential Effect. J DISPER SCI TECHNOL 2015. [DOI: 10.1080/01932691.2015.1015077] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Chen J, Kline SR, Liu Y. From the depletion attraction to the bridging attraction: The effect of solvent molecules on the effective colloidal interactions. J Chem Phys 2015; 142:084904. [DOI: 10.1063/1.4913197] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Jie Chen
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Center for Neutron Research, National Institute of Standards and Technology, Gaithursburg, Maryland 20899, USA
| | - Steven R. Kline
- Center for Neutron Research, National Institute of Standards and Technology, Gaithursburg, Maryland 20899, USA
| | - Yun Liu
- Center for Neutron Research, National Institute of Standards and Technology, Gaithursburg, Maryland 20899, USA
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
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16
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Xing X, Hua L, Ngai T. Depletion versus stabilization induced by polymers and nanoparticles: The state of the art. Curr Opin Colloid Interface Sci 2015. [DOI: 10.1016/j.cocis.2014.11.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Kazi SN, Badarudin A, Zubir MNM, Ming HN, Misran M, Sadeghinezhad E, Mehrali M, Syuhada NI. Investigation on the use of graphene oxide as novel surfactant to stabilize weakly charged graphene nanoplatelets. NANOSCALE RESEARCH LETTERS 2015; 10:212. [PMID: 25995712 PMCID: PMC4435691 DOI: 10.1186/s11671-015-0882-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 03/26/2015] [Indexed: 05/21/2023]
Abstract
This paper presents a unique synergistic behavior between a graphene oxide (GO) and graphene nanoplatelet (GnP) composite in an aqueous medium. The results showed that GO stabilized GnP colloid near its isoelectric point and prevented rapid agglomeration and sedimentation. It was considered that a rarely encountered charge-dependent electrostatic interaction between the highly charged GO and weakly charged GnP particles kept GnP suspended at its rapid coagulation and phase separation pH. Sedimentation and transmission electron microscope (TEM) micrograph images revealed the evidence of highly stable colloidal mixtures while zeta potential measurement provided semi-quantitative explanation on the mechanism of stabilization. GnP suspension was confirmed via UV-vis spectral data while contact angle measurement elucidated the close resemblance to an aqueous solution indicating the ability of GO to mediate the flocculation prone GnP colloids. About a tenfold increase in viscosity was recorded at a low shear rate in comparison to an individual GO solution due to a strong interaction manifested between participating colloids. An optimum level of mixing ratio between the two constituents was also obtained. These new findings related to an interaction between charge-based graphitic carbon materials would open new avenues for further exploration on the enhancement of both GO and GnP functionalities particularly in mechanical and electrical domains.
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Affiliation(s)
- Salim Newaz Kazi
- />Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Ahmad Badarudin
- />Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Mohd Nashrul Mohd Zubir
- />Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Huang Nay Ming
- />Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Misni Misran
- />Department of Chemistry, Faculty of Science, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Emad Sadeghinezhad
- />Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Mohammad Mehrali
- />Department of Mechanical Engineering and Advanced Material Research Centre, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
| | - Nur Ily Syuhada
- />Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, Jalan Universiti, 50603 Kuala Lumpur, Malaysia
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18
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Gong X, Hua L, Wei J, Ngai T. Tuning the particle-surface interactions in aqueous solutions by soft microgel particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13182-13190. [PMID: 25312378 DOI: 10.1021/la503573u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Due to the softness and deformability, interaction between colloidal surfaces induced by soft particles varies in a more complex way than for solid particles and thus has attracted much attention in recent years. In the present study, we use total internal reflection microscopy (TIRM) to directly measure the interaction between polystyrene (PS) microparticles and a flat glass surface in a poly(N-isopropylacrylamide) (PNIPAM) microgel dispersion with concentration varying from dilute (0.1 wt %) to highly concentrated regime (7.5 wt %). Our result shows that the PS particle-surface interactions mediated by the soft microgels are greatly affected by the particle concentration, the configuration of those microgels adsorbed on the surfaces, and the structure and packing of microgels in bulk solution. With increasing the microgel concentration (Cmicrogel), the interaction between the PS particle and surface turned from bridging attraction to steric repulsion, and then depletion attraction, which were mainly governed by the adsorption amount and configuration of microgels on the two surfaces. By further increasing Cmicrogel to condensed situation, structural force with oscillated energy wells was detected. The variation of interactions induced by the soft microgels was further confirmed by optical imaging. Crystallization of the PS microparticles appeared at moderate Cmicrogel; however, crystallization was hindered at higher Cmicrogel where the microgels are highly packed in the bulk solution. Furthermore, using TIRM, microgel packing with local energy well (0.1-1.0 kBT) at the highly condensed state (7.5 wt %) was resolved from the interaction profiles. Therefore, the shear force and modulus generated by such microgel packing can be determined as ∼0.2 pN and tens of mPa, respectively, which are much weaker than data given by conventional active methods.
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Affiliation(s)
- Xiangjun Gong
- Faculty of Materials Science and Engineering, South China University of Technology , Guangzhou, China , 510640
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Szilagyi I, Trefalt G, Tiraferri A, Maroni P, Borkovec M. Polyelectrolyte adsorption, interparticle forces, and colloidal aggregation. SOFT MATTER 2014; 10:2479-2502. [PMID: 24647366 DOI: 10.1039/c3sm52132j] [Citation(s) in RCA: 217] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This review summarizes the current understanding of adsorption of polyelectrolytes to oppositely charged solid substrates, the resulting interaction forces between such substrates, and consequences for colloidal particle aggregation. The following conclusions can be reached based on experimental findings. Polyelectrolytes adsorb to oppositely charged solid substrates irreversibly up to saturation, whereby loose and thin monolayers are formed. The adsorbed polyelectrolytes normally carry a substantial amount of charge, which leads to a charge reversal. Frequently, the adsorbed films are laterally heterogeneous. With increasing salt levels, the adsorbed mass increases leading to thicker and more homogeneous films. Interaction forces between surfaces coated with saturated polyelectrolyte layers are governed at low salt levels by repulsive electric double layer interactions, and particle suspensions are stable under these conditions. At appropriately high salt levels, the forces become attractive, principally due to van der Waals interactions, but eventually also through other forces, and suspensions become unstable. This situation can be rationalized with the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). Due to the irreversible nature of the adsorption process, stable unsaturated layers form in colloidal particle suspensions at lower polyelectrolyte doses. An unsaturated polyelectrolyte layer can neutralize the overall particle surface charge. Away from the charge reversal point, electric double layer forces are dominant and particle suspensions are stable. As the charge reversal point is approached, attractive van der Waals forces become important, and particle suspensions become unstable. This behaviour is again in line with the DLVO theory, which may even apply quantitatively, provided the polyelectrolyte films are sufficiently laterally homogeneous. For heterogeneous films, additional attractive patch-charge interactions may become important. Depletion interactions may also lead to attractive forces and suspension destabilization, but such interactions become important only at high polyelectrolyte concentrations.
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Affiliation(s)
- Istvan Szilagyi
- Department of Inorganic and Analytical Chemistry, University of Geneva, Sciences II, Quai Ernest-Ansermet 30, 1205 Geneva, Switzerland.
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Gong X, Wang Z, Ngai T. Direct measurements of particle–surface interactions in aqueous solutions with total internal reflection microscopy. Chem Commun (Camb) 2014; 50:6556-70. [DOI: 10.1039/c4cc00624k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This feature article reviews the experimental studies of the interactions between designed colloidal surfaces in the presence or absence of macromolecules/nanoparticles including depletion attraction, steric repulsion, bridging flocculation, and specific interactions by using Total Internal Reflection Microscopy.
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Affiliation(s)
- Xiangjun Gong
- Faculty of Materials Science and Engineering
- South China University of Technology
- Guangzhou, P. R. China
| | - Zhaohui Wang
- Department of Chemistry
- The Chinese University of Hong Kong
- Shatin, Hong Kong
| | - To Ngai
- Department of Chemistry
- The Chinese University of Hong Kong
- Shatin, Hong Kong
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Guerrero-García GI, González-Mozuelos P, Olvera de la Cruz M. Large counterions boost the solubility and renormalized charge of suspended nanoparticles. ACS NANO 2013; 7:9714-9723. [PMID: 24180597 DOI: 10.1021/nn404477b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Colloidal particles are ubiquitous in biology and in everyday products such as milk, cosmetics, lubricants, paints, or drugs. The stability and aggregation of colloidal suspensions are of paramount importance in nature and in diverse nanotechnological applications, including the fabrication of photonic materials and scaffolds for biological assemblies, gene therapy, diagnostics, targeted drug delivery, and molecular labeling. Electrolyte solutions have been extensively used to stabilize and direct the assembly of colloidal particles. In electrolytes, the effective electrostatic interactions among the suspended colloids can be changed over various length scales by tuning the ionic concentration. However, a major limitation is gelation or flocculation at high salt concentrations. This is explained by classical theories, which show that the electrostatic repulsion among charged colloids is significantly reduced at high electrolyte concentrations. As a result, these screened colloidal particles are expected to aggregate due to short-range attractive interactions or dispersion forces as the salt concentration increases. We discuss here a robust, tunable mechanism for colloidal stability by which large counterions prevent highly charged nanoparticles from aggregating in salt solutions with concentrations up to 1 M. Large counterions are shown to generate a thicker ionic cloud in the proximity of each charged colloid, which strengthens short-range repulsions among colloidal particles and also increases the corresponding renormalized colloidal charge perceived at larger separation distances. These effects thus provide a reliable stabilization mechanism in a broad range of biological and synthetic colloidal suspensions.
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