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Antony LS, Monin L, Aarts M, Alarcon-Llado E. Unveiling Nanoscale Heterogeneities at the Bias-Dependent Gold-Electrolyte Interface. J Am Chem Soc 2024; 146:12933-12940. [PMID: 38591960 PMCID: PMC11099963 DOI: 10.1021/jacs.3c11696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/10/2024]
Abstract
Electrified solid-liquid interfaces (SLIs) are extremely complex and dynamic, affecting both the dynamics and selectivity of reaction pathways at electrochemical interfaces. Enabling access to the structure and arrangement of interfacial water in situ with nanoscale resolution is essential to develop efficient electrocatalysts. Here, we probe the SLI energy of a polycrystalline Au(111) electrode in a neutral aqueous electrolyte through in situ electrochemical atomic force microscopy. We acquire potential-dependent maps of the local interfacial adhesion forces, which we associate with the formation energy of the electric double layer. We observe nanoscale inhomogeneities of interfacial adhesion force across the entire map area, indicating local differences in the ordering of the solvent/ions at the interface. Anion adsorption has a clear influence on the observed interfacial adhesion forces. Strikingly, the adhesion forces exhibit potential-dependent hysteresis, which depends on the local gold grain curvature. Our findings on a model electrode extend the use of scanning probe microscopy to gain insights into the local molecular arrangement of the SLI in situ, which can be extended to other electrocatalysts.
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Affiliation(s)
| | | | - Mark Aarts
- Leiden
Institute of Chemistry, Leiden University, Leiden 2333 CC, The Netherlands
| | - Esther Alarcon-Llado
- AMOLF, Amsterdam 1098 XG, The Netherlands
- Van’t
Hoff Institute for Molecular Sciences, University
of Amsterdam, Amsterdam 1090, GD, The Netherlands
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2
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Kim SH, Choi PK, Lee YB, Kim TS, Jo MS, Lee SY, Min HW, Yoon JB. An experimental and numerical study on adhesion force at the nanoscale. NANOSCALE ADVANCES 2024; 6:2013-2025. [PMID: 38633052 PMCID: PMC11019507 DOI: 10.1039/d3na01044a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/14/2024] [Indexed: 04/19/2024]
Abstract
Adhesion has attracted great interest in science and engineering especially in the field pertaining to nano-science because every form of physical contact is fundamentally a macroscopic observation of interactions between nano-asperities under the adhesion phenomenon. Despite its importance, no practical adhesion prediction model has been developed due to the complexity of examining contact between nano-asperities. Here, we scrutinized the contact phenomenon and developed a contact model, reflecting the physical sequence in which adhesion develops. For the first time ever, our model analyzes the adhesion force and contact properties, such as separation distance, contact location, actual contact area, and the physical deformation of the asperities, between rough surfaces. Through experiments using atomic force microscopy, we demonstrated a low absolute percentage error of 2.8% and 6.55% between the experimental and derived data for Si-Si and Mo-Mo contacts, respectively, and proved the accuracy and practicality of our model in the analysis of the adhesion phenomenon.
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Affiliation(s)
- Su-Hyun Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
- Samsung Electronics Co., Ltd. 1, Samsungjeonja-ro Hwaseong-si Gyeonggi-do 18448 Republic of Korea
| | - Pan-Kyu Choi
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
- Samsung Electronics Co., Ltd. 1, Samsungjeonja-ro Hwaseong-si Gyeonggi-do 18448 Republic of Korea
| | - Yong-Bok Lee
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
| | - Tae-Soo Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
| | - Min-Seung Jo
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
| | - So-Young Lee
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
| | - Hyun-Woo Min
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
- Samsung Electronics Co., Ltd. 1, Samsungjeonja-ro Hwaseong-si Gyeonggi-do 18448 Republic of Korea
| | - Jun-Bo Yoon
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yuseong-gu Daejeon 34141 Republic of Korea
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3
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Lee SS, Micklow L, Tunell A, Chien KC, Mohanty S, Cates N, Furst S, Chang CH. Engineering Large-Area Antidust Surfaces by Harnessing Interparticle Forces. ACS APPLIED MATERIALS & INTERFACES 2023; 15:13678-13688. [PMID: 36811627 DOI: 10.1021/acsami.2c19211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Dust accumulation is detrimental to optical elements, electronic devices, and mechanical systems and is a significant problem in space missions and renewable energy deployment. In this paper, we report the demonstration of antidust nanostructured surfaces that can remove close to 98% of lunar particles solely via gravity. The dust mitigation is driven by a novel mechanism, whereby particle removal is facilitated by the formation of particle aggregates due to interparticle forces, allowing the particles to be removed in the presence of other particles. The structures are fabricated using a highly scalable nanocoining and nanoimprint process, where nanostructures with precise geometry and surface properties are patterned on polycarbonate substrates. The dust mitigation properties of the nanostructures have been characterized using optical metrology, electron microscopy, and image processing algorithms to demonstrate that the surfaces can be engineered to remove nearly all of the particles above 2 μm in size in the presence of Earth's gravity. Compared to the 35.0% area coverage on a smooth polycarbonate surface, the particle coverage on nanostructures with 500 nm period is significantly reduced to 2.4%, an improvement of 93%. This work enhances the understanding of the particulate adhesion on textured surfaces and demonstrates a scalable, effective solution to antidust surfaces that can be broadly applied to windows, solar panels, and electronics.
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Affiliation(s)
- Samuel S Lee
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Lauren Micklow
- Smart Material Solutions, Inc., Raleigh, North Carolina 27607, United States
| | - Andrew Tunell
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Kun-Chieh Chien
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Saurav Mohanty
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Nichole Cates
- Smart Material Solutions, Inc., Raleigh, North Carolina 27607, United States
| | - Stephen Furst
- Smart Material Solutions, Inc., Raleigh, North Carolina 27607, United States
| | - Chih-Hao Chang
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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4
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Lobel BT, Robertson H, Webber GB, Ireland PM, Wanless EJ. Impact of surface free energy on electrostatic extraction of particles from a bed. J Colloid Interface Sci 2022; 611:617-628. [PMID: 34974225 DOI: 10.1016/j.jcis.2021.12.117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 11/19/2022]
Abstract
HYPOTHESIS Electrostatic extraction of particles from a bed to a pendent droplet to form liquid marbles has previously been investigated with respect to particle conductivity, size and shape, however, interparticle forces have not been specifically interrogated. If cohesion is the dominant force within the particle bed, then particles will be more readily extracted with reduced surface free energy. EXPERIMENTS Glass particles were surface-modified using various alkyltrichlorosilanes. The surface free energy was measured for each sample using colloid probe atomic force microscopy (AFM) and sessile drop measurements on similarly modified glass slides. The ease of electrostatic particle extraction of each particle sample to a pendent droplet was compared by quantifying the electric field force required for successful extraction as a function of the measured surface free energy. FINDINGS Surface free energy calculated from sessile droplet measurements and AFM were not in agreement, as work of adhesion of a liquid droplet on a planar substrate is not representative of the contact between particles. Ease of electrostatic extraction of particles was observed to generally decrease as a function of AFM-derived surface free energy, confirming this is a critical factor in electrostatic delivery of particles to a pendent droplet. Roughness was also shown to inhibit particle extraction.
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Affiliation(s)
- Benjamin T Lobel
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Hayden Robertson
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B Webber
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Peter M Ireland
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Erica J Wanless
- College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia.
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5
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Jadidi B, Ebrahimi M, Ein-Mozaffari F, Lohi A. A comprehensive review of the application of DEM in the investigation of batch solid mixers. REV CHEM ENG 2022. [DOI: 10.1515/revce-2021-0049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Powder mixing is a vital operation in a wide range of industries, such as food, pharmaceutical, and cosmetics. Despite the common use of mixing systems in various industries, often due to the complex nature of mixing systems, the effects of operating and design parameters on the mixers’ performance and final blend are not fully known, and therefore optimal parameters are selected through experience or trial and error. Experimental and numerical techniques have been widely used to analyze mixing systems and to gain a detailed understanding of mixing processes. The limitations associated with experimental techniques, however, have made discrete element method (DEM) a valuable complementary tool to obtain comprehensive particle level information about mixing systems. In the present study, the fundamentals of solid-solid mixing, segregation, and characteristics of different types of batch solid mixers are briefly reviewed. Previously published papers related to the application of DEM in studying mixing quality and assessing the influence of operating and design parameters on the mixing performance of various batch mixing systems are summarized in detail. The challenges with regards to the DEM simulation of mixing systems, the available solutions to address those challenges and our recommendations for future simulations of solid mixing are also presented and discussed.
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Affiliation(s)
- Behrooz Jadidi
- Department of Chemical Engineering , Ryerson University , 350 Victoria Street , Toronto M5B 2K3 , Canada
| | - Mohammadreza Ebrahimi
- Department of Chemical Engineering , Ryerson University , 350 Victoria Street , Toronto M5B 2K3 , Canada
| | - Farhad Ein-Mozaffari
- Department of Chemical Engineering , Ryerson University , 350 Victoria Street , Toronto M5B 2K3 , Canada
| | - Ali Lohi
- Department of Chemical Engineering , Ryerson University , 350 Victoria Street , Toronto M5B 2K3 , Canada
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6
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Theoretical and Experimental Analysis of Surface Roughness and Adhesion Forces of MEMS Surfaces Using a Novel Method for Making a Compound Sputtering Target. COATINGS 2021. [DOI: 10.3390/coatings11121551] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Achieving a compound thin film with uniform thickness and high purity has always been a challenge in the applications concerning micro electro mechanical systems (MEMS). Controlling the adhesion force in micro/nanoscale is also critical. In the present study, a novel method for making a sputtering compound target is proposed for coating Ag–Au thin films with thicknesses of 120 and 500 nm on silicon substrates. The surface topography and adhesion forces of the samples were obtained using atomic force microscope (AFM). Rabinovich and Rumpf models were utilized to measure the adhesion force and compare the results with the obtained experimental values. It was found that the layer with a thickness of 500 nm has a lower adhesion force than the one with 120 nm thickness. The results further indicated that due to surface asperity radius, the adhesion achieved from the Rabinovich model was closer to the experimental values. This novel method for making a compound sputtering target has led to a lower adhesion force which can be useful for coating microgripper surfaces.
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7
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Bahramian A, Olazar M. Evaluation of elastic and inelastic contact forces in the flow regimes of Titania nanoparticle agglomerates in a bench-scale conical fluidized bed: A comparative study of CFD-DEM simulation and experimental data. Chem Eng Res Des 2021. [DOI: 10.1016/j.cherd.2021.09.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Rajupet S, Riet AA, Chen Q, Sow M, Lacks DJ. Relative importance of electrostatic and van der Waals forces in particle adhesion to rough conducting surfaces. Phys Rev E 2021; 103:042906. [PMID: 34005883 DOI: 10.1103/physreve.103.042906] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/06/2021] [Indexed: 11/06/2022]
Abstract
It is commonly assumed that van der Waals forces dominate adhesion in dry systems and electrostatic forces are of second order importance and can be safely neglected. This is unambiguously the case for particles interacting with flat surfaces. However, all surfaces have some degree of roughness. Here we calculate the electrostatic and van der Waals contributions to adhesion for a polarizable particle contacting a rough conducting surface. For van der Waals forces, surface roughness can diminish the force by several orders of magnitude. In contrast, for electrostatic forces, surface roughness affects the force only slightly, and in some regimes it actually increases the force. Since van der Waals forces decrease far more strongly with surface roughness than electrostatic forces, surface roughness acts to increase the relative importance of electrostatic forces to adhesion. We find that for a particle contacting a rough conducting surface, electrostatic forces can be dominant for particle sizes as small as ∼1-10 μm.
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Affiliation(s)
- Siddharth Rajupet
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Adriaan A Riet
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Qizan Chen
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Mamadou Sow
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES/SCA, Gif-sur-Yvette, 91192, France
| | - Daniel J Lacks
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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10
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Rajupet S, Sow M, Lacks DJ. Particle adhesion to rough surfaces. Phys Rev E 2020; 102:012904. [PMID: 32794996 DOI: 10.1103/physreve.102.012904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
While particle adhesion to smooth surfaces is well understood, real surfaces are not perfectly smooth, and the effects of surface roughness on adhesion are not easily characterized. We develop a theory for the effects of surface roughness on the strength of particle adhesion due to van der Waals forces, in the Derjaguin-Muller-Toporov (DMT)-type adhesion regime. We first address a well-defined rough surface created by embedding spheres in a smooth substrate, which had been previously examined experimentally. We derive an analytic expression for the adhesive force of particles to this well-defined surface, with the key distinction from the previous work being the inclusion of interactions from surface asperities not in direct contact with the particle. We show that our theory is in good agreement with experimental results in the DMT regime. Within appropriate limits, we extend our theory to general rough surfaces and verify the theory by comparing to the exact numerical results. We show that the interactions from surface asperities not in direct contact with the particle are the dominant contribution to the adhesive force under some conditions, and our theory predicts the experimental and numerical adhesion forces very accurately.
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Affiliation(s)
- Siddharth Rajupet
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Mamadou Sow
- Institut de Radioprotection et de Sûrete Nucleaire (IRSN), Gif-sur-Yvette 91192, France
| | - Daniel J Lacks
- Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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11
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A New Approach to Explore the Surface Profile of Clay Soil Using White Light Interferometry. SENSORS 2020; 20:s20113009. [PMID: 32466355 PMCID: PMC7309148 DOI: 10.3390/s20113009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/15/2020] [Accepted: 05/23/2020] [Indexed: 11/29/2022]
Abstract
In order to have a better understanding of the real contact area of granular materials, the white light interference method is applied to explore the real surface morphology of clay soils under high stress. Analysis of the surface profile indicates that there exists a support point height z0 with the highest distribution frequency. A concept of a real contact region (from z0 to z0 + d90; d90 represents the particle size corresponding to 90% of the volume fraction) is proposed by combining a surface profile with the particle size distribution of clay soil. It was found that under the compressive stress of 106 MPa–529 MPa, the actual contact area ratio of clay soil varies between 0.375 and 0.431. This demonstrates an increasing trend with the rise of stress. On the contrary, the apparent porosity decreases with an increasing stress, varying between 0.554 and 0.525. In addition, as the compressive stress increases, the cumulative frequency of apparent profile height (from z0 − d90 to z0 + d90) has a concentrated tendency with a limited value of 0.9.
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12
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Yeom SB, Ha ES, Kim MS, Jeong SH, Hwang SJ, Choi DH. Application of the Discrete Element Method for Manufacturing Process Simulation in the Pharmaceutical Industry. Pharmaceutics 2019; 11:E414. [PMID: 31443327 PMCID: PMC6723742 DOI: 10.3390/pharmaceutics11080414] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 12/15/2022] Open
Abstract
Process simulation using mathematical modeling tools is becoming more common in the pharmaceutical industry. A mechanistic model is a mathematical modeling tool that can enhance process understanding, reduce experimentation cost and improve product quality. A commonly used mechanistic modeling approach for powder is the discrete element method (DEM). Most pharmaceutical materials have powder or granular material. Therefore, DEM might be widely applied in the pharmaceutical industry. This review focused on the basic elements of DEM and its implementations in pharmaceutical manufacturing simulation. Contact models and input parameters are essential elements in DEM simulation. Contact models computed contact forces acting on the particle-particle and particle-geometry interactions. Input parameters were divided into two types-material properties and interaction parameters. Various calibration methods were presented to define the interaction parameters of pharmaceutical materials. Several applications of DEM simulation in pharmaceutical manufacturing processes, such as milling, blending, granulation and coating, were categorized and summarized. Based on this review, DEM simulation might provide a systematic process understanding and process control to ensure the quality of a drug product.
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Affiliation(s)
- Su Bin Yeom
- Department of Pharmaceutical Engineering, Inje University, Gyeongnam 621-749, Korea
| | - Eun-Sol Ha
- College of Pharmacy, Pusan National University, Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 46241, Korea
| | - Min-Soo Kim
- College of Pharmacy, Pusan National University, Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 46241, Korea.
| | | | - Sung-Joo Hwang
- College of Pharmacy, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, Korea
| | - Du Hyung Choi
- Department of Pharmaceutical Engineering, Inje University, Gyeongnam 621-749, Korea.
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13
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Lee HD, Ray KK, Tivanski AV. Solid, Semisolid, and Liquid Phase States of Individual Submicrometer Particles Directly Probed Using Atomic Force Microscopy. Anal Chem 2017; 89:12720-12726. [DOI: 10.1021/acs.analchem.7b02755] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Hansol D. Lee
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Kamal K. Ray
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Alexei V. Tivanski
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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14
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LaMarche CQ, Leadley S, Liu P, Kellogg KM, Hrenya CM. Method of quantifying surface roughness for accurate adhesive force predictions. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2016.09.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Perni S, Preedy EC, Landini P, Prokopovich P. Influence of csgD and ompR on Nanomechanics, Adhesion Forces, and Curli Properties of E. coli. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7965-7974. [PMID: 27434665 DOI: 10.1021/acs.langmuir.6b02342] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Curli are bacterial appendages involved in the adhesion of cells to surfaces; their synthesis is regulated by many genes such as csgD and ompR. The expression of the two curli subunits (CsgA and CsgB) in Escherichia coli (E. coli) is regulated by CsgD; at the same time, csgD transcription is under the control of OmpR. Therefore, both genes are involved in the control of curli production. In this work, we elucidated the role of these genes in the nanomechanical and adhesive properties of E. coli MG1655 (a laboratory strain not expressing significant amount of curli) and its curli-producing mutants overexpressing OmpR and CsgD, employing atomic force microscopy (AFM). Nanomechanical analysis revealed that the expression of these genes gave origin to cells with a lower Young's modulus (E) and turgidity (P0), whereas the adhesion forces were unaffected when genes involved in curli formation were expressed. AFM was also employed to study the primary structure of the curli expressed through the freely jointed chain (FJC) model for polymers. CsgD increased the number of curli on the surface more than OmpR did, and the overexpression of both genes did not result in a greater number of curli. Neither of the genes had an impact on the structure (total length of the polymer and number and length of Kuhn segments) of the curli. Our results further suggest that, despite the widely assumed role of curli in cell adhesion, cell adhesion force is also dictated by surface properties because no relation between the number of curli expressed on the surface and cell adhesion was found.
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Affiliation(s)
- Stefano Perni
- Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff University , Cardiff, U.K. CF10 3NB
| | - Emily Callard Preedy
- Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff University , Cardiff, U.K. CF10 3NB
| | - Paolo Landini
- Department of Biomolecular Sciences and Biotechnology, University of Milan , 20122 Milan, Italy
| | - Polina Prokopovich
- Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff University , Cardiff, U.K. CF10 3NB
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17
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Preedy EC, Brousseau E, Evans SL, Perni S, Prokopovich P. Adhesive forces and surface properties of cold gas plasma treated UHMWPE. Colloids Surf A Physicochem Eng Asp 2014; 460:83-89. [PMID: 25431523 PMCID: PMC4236083 DOI: 10.1016/j.colsurfa.2014.03.052] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 03/10/2014] [Accepted: 03/18/2014] [Indexed: 11/17/2022]
Abstract
Cold atmospheric plasma (CAP) treatment was used on ultra-high molecular weight polyethylene (UHMWPE), a common articulating counter material employed in hip and knee replacements. UHMWPE is a biocompatible polymer with low friction coefficient, yet does not have robust wear characteristics. CAP effectively cross-links the polymer chains of the UHMWPE improving wear performance (Perni et al., Acta Biomater. 8(3) (2012) 1357). In this work, interactions between CAP treated UHMWPE and spherical borosilicate sphere (representing model material for bone) were considered employing AFM technique. Adhesive forces increased, in the presence of PBS, after treatment with helium and helium/oxygen cold gas plasmas. Furthermore, a more hydrophilic surface of UHMWPE was observed after both treatments, determined through a reduction of up to a third in the contact angles of water. On the other hand, the asperity density also decreased by half, yet the asperity height had a three-fold decrease. This work shows that CAP treatment can be a very effective technique at enhancing the adhesion between bone and UHMWPE implant material as aided by the increased adhesion forces. Moreover, the hydrophilicity of the CAP treated UHMWPE can lead to proteins and cells adhesion to the surface of the implant stimulating osseointegration process.
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Key Words
- A.C., alternative current
- AFM
- AFM, atomic force microscopy
- Adhesion forces
- CAP, cold atmospheric plasma
- Cold atmospheric plasma-treatment
- ECM, extracellular matrix
- Material modification
- PBS, phosphate buffer solution
- PCTFE, polychlorofluoroethylene
- Surface topography
- TJA, total joint arthroplasty
- TJR, total joint replacement
- UHMWPE
- UHMWPE, ultra-high molecular weight polyethylene
- XLPE, highly cross-linked polyethylene
- sccm, standard cubic centimetre per minute
- slm, standard litre per minute
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Affiliation(s)
- Emily Callard Preedy
- Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
| | - Emmanuel Brousseau
- Cardiff School of Engineering, Cardiff University, Queen's Buildings, The Parade, Cardiff CF24 3AA, Wales, UK
| | - Sam L Evans
- Cardiff School of Engineering, Cardiff University, Queen's Buildings, The Parade, Cardiff CF24 3AA, Wales, UK
| | - Stefano Perni
- Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK ; Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, NE47-377, Cambridge, MA 02139, USA
| | - Polina Prokopovich
- Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK ; Cardiff School of Engineering, Cardiff University, Queen's Buildings, The Parade, Cardiff CF24 3AA, Wales, UK ; Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, NE47-377, Cambridge, MA 02139, USA
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18
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Smith RR, Williams DR, Burnett DJ, Heng JYY. A new method to determine dispersive surface energy site distributions by inverse gas chromatography. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8029-8035. [PMID: 24946213 DOI: 10.1021/la500688d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A computational model to predict the relative energy site contributions of a heterogeneous material from data collected by finite dilution-inverse gas chromatography (FD-IGC) is presented in this work. The methodology employed a multisolvent system site filling model utilizing Boltzmann statistics, expanding on previous efforts to calculate "experienced energies" at varying coverage, yielding a retention volume distribution allowing calculation of a surface free energy distribution. Surface free energy distributions were experimentally measured for racemic ibuprofen and β-mannitol powders, the energies of each were found in the ranges 43-52 and 40-55 mJ/m(2), respectively, over a surface coverage range of 0-8%. The computed contributions to surface energy values were found to match closely with data collected on macroscopic crystals by alternative techniques (±<1.5 mJ/m(2)).
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Affiliation(s)
- Robert R Smith
- Surfaces and Particle Engineering Laboratory, Department of Chemical Engineering, Imperial College London , South Kensington Campus, London SW7 2AZ, U.K
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You S, Wan MP. Modeling and experiments of the adhesion force distribution between particles and a surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6808-6818. [PMID: 24849548 DOI: 10.1021/la500360f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Due to the existence of surface roughness in real surfaces, the adhesion force between particles and the surface where the particles are deposited exhibits certain statistical distributions. Despite the importance of adhesion force distribution in a variety of applications, the current understanding of modeling adhesion force distribution is still limited. In this work, an adhesion force distribution model based on integrating the root-mean-square (RMS) roughness distribution (i.e., the variation of RMS roughness on the surface in terms of location) into recently proposed mean adhesion force models was proposed. The integration was accomplished by statistical analysis and Monte Carlo simulation. A series of centrifuge experiments were conducted to measure the adhesion force distributions between polystyrene particles (146.1 ± 1.99 μm) and various substrates (stainless steel, aluminum and plastic, respectively). The proposed model was validated against the measured adhesion force distributions from this work and another previous study. Based on the proposed model, the effect of RMS roughness distribution on the adhesion force distribution of particles on a rough surface was explored, showing that both the median and standard deviation of adhesion force distribution could be affected by the RMS roughness distribution. The proposed model could predict both van der Waals force and capillary force distributions and consider the multiscale roughness feature, greatly extending the current capability of adhesion force distribution prediction.
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Affiliation(s)
- Siming You
- School of Mechanical and Aerospace Engineering, Nanyang Technological University , Singapore 639798
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Perni S, Preedy EC, Prokopovich P. Success and failure of colloidal approaches in adhesion of microorganisms to surfaces. Adv Colloid Interface Sci 2014; 206:265-74. [PMID: 24342736 DOI: 10.1016/j.cis.2013.11.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 12/31/2022]
Abstract
Biofilms are communities of cells attached to surfaces, their contributions to biological process may be either a benefit or a threat depending on the microorganism involved and on the type of substrate and environment. Biofilm formation is a complex series of steps; due to the size of microorganisms, the initial phase of biofilm formation, the bacterial adhesion to the surface, has been studied and modeled using theories developed in colloidal science. In this review the application of approaches such as Derjaguin, Landau, Verwey, Overbeek (DLVO) theory and its extended version (xDLVO), to bacterial adhesion is described along with the suitability and applicability of such approaches to the investigation of the interface phenomena regulating cells adhesion. A further refinement of the xDLVO theory encompassing the brush model is also discussed. Finally, the evidences of phenomena neglected in colloidal approaches, such as surface heterogeneity and fluid flow, likely to be the source of failure are defined.
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Zhang Z, Morse AJ, Armes SP, Lewis AL, Geoghegan M, Leggett GJ. Nanoscale contact mechanics of biocompatible polyzwitterionic brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:10684-10692. [PMID: 23855771 DOI: 10.1021/la4018689] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Friction force microscopy has been used to demonstrate that biocompatible, lubricious poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC) brushes exhibit different frictional properties depending on the medium (methanol, ethanol, 2-propanol, and water; the latter also with different quantities of added salt). The chemical functionalization of the probe (amine-, carboxylic acid-, and methyl-terminated probes were used) is not as important as the medium in determining the contact mechanics. For solvents such as methanol, where the adhesion between AFM probe and PMPC brushes is negligible, a linear friction-load relationship is observed. In contrast, the friction-load plot is nonlinear in ethanol or water, media in which stronger adhesion is measured. For ethanol, the data indicate Johnson-Kendall-Roberts (JKR) mechanics, whereas the Derjaguin-Muller-Toporov (DMT) model provided a good fit for the data acquired in water. Contact mechanics on zwitterionic PMPC brushes immersed in aqueous solutions of varying ionic strength followed the same trend, with high adhesion energies being correlated with a nonlinear friction-load relationship. These results can be rationalized by treating the friction force as the sum of a load-dependent term, attributed to molecular plowing, and an area-dependent shear term. In a good solvent for PMPC such as methanol, the shear term is negligible and the sliding interaction is dominated by molecular plowing. However, the adhesion energy is significantly larger in water and ethanol and the shear term is no longer negligible.
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Affiliation(s)
- Zhenyu Zhang
- Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK
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Perni S, Kong MG, Prokopovich P. Cold atmospheric pressure gas plasma enhances the wear performance of ultra-high molecular weight polyethylene. Acta Biomater 2012; 8:1357-65. [PMID: 22202910 DOI: 10.1016/j.actbio.2011.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 12/03/2011] [Accepted: 12/06/2011] [Indexed: 12/28/2022]
Abstract
Ultra-high molecular weight polyethylene (UHMWPE) is frequently employed in joint replacements because of its high biocompatibility; however, this material does not exhibit particularly strong wear performance, thus potentially reducing the longevity of such devices. Numerous techniques have been investigated to increase the resistance to wear of UHMWPE, but they are all based on expensive machinery and require a high level of safety precautions. Cold atmospheric pressure gas plasma treatment is an inexpensive process that has been used as a surface modification method and as a sterilization technique. We demonstrate for the first time that a helium/oxygen cold atmospheric pressure gas plasma can be used to enhance the wear performance of UHMWPE without affecting the cytocompatibility of the material. The exposure to a cold atmospheric pressure gas plasma results in a greater level of crosslinking of the polyethylene chains. As a consequence of the higher crosslinking, the material stiffness of the treated surface is increased.
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Prokopovich P, Perni S, Fisher J, Hall RM. Spatial variation of wear on Charité lumbar discs. Acta Biomater 2011; 7:3914-26. [PMID: 21745608 DOI: 10.1016/j.actbio.2011.06.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Revised: 06/21/2011] [Accepted: 06/22/2011] [Indexed: 12/28/2022]
Abstract
Total disc replacement (TDR) is a modern technique employed to treat degenerative disc disease that has the benefit of preserving motion compared with the clinically established spinal fusion. The wear performance of implants based on articulating designs is a key factor that determines their longevity and it is hypothesized that this will be the case for TDR devices. A detailed analysis of the surface of Charité lumbar disc replacements during simulated wear for five million cycles (MC), with inputs defined by the ISO18192-1 standard, is presented. After each million cycles the disc asperity heights, asperity curvature radii and their distributions on the surface of the core of the implant were determined at different locations. Two distinct areas on the surface of Charité polyethylene disc were identified based on the surface topography change during the wear simulation process. Within the area corresponding to the dome the initial roughness decreased, but after 2 MC the surface appeared to roughen with material build-up. More peripherally on the dome the surface roughness decreased after the first MC and remained constant. No effect was noticed on the rim. Furthermore, no statistical difference was noticed between the inferior and superior sides of the core of the disc. The study demonstrated that the wear on the two surfaces of the disc was uneven. This spatial variation is important in modelling the wear processes and providing strategies for reducing wear through enhanced design and modifications to the biotribological properties of the device.
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Affiliation(s)
- P Prokopovich
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
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