1
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Liu S, Han Y, Kong L, Wang G, Ye Z. Atomic force microscopy in disease-related studies: Exploring tissue and cell mechanics. Microsc Res Tech 2024; 87:660-684. [PMID: 38063315 DOI: 10.1002/jemt.24471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 10/22/2023] [Accepted: 11/26/2023] [Indexed: 03/02/2024]
Abstract
Despite significant progress in human medicine, certain diseases remain challenging to promptly diagnose and treat. Hence, the imperative lies in the development of more exhaustive criteria and tools. Tissue and cellular mechanics exhibit distinctive traits in both normal and pathological states, suggesting that "force" represents a promising and distinctive target for disease diagnosis and treatment. Atomic force microscopy (AFM) holds great promise as a prospective clinical medical device due to its capability to concurrently assess surface morphology and mechanical characteristics of biological specimens within a physiological setting. This review presents a comprehensive examination of the operational principles of AFM and diverse mechanical models, focusing on its applications in investigating tissue and cellular mechanics associated with prevalent diseases. The findings from these studies lay a solid groundwork for potential clinical implementations of AFM. RESEARCH HIGHLIGHTS: By examining the surface morphology and assessing tissue and cellular mechanics of biological specimens in a physiological setting, AFM shows promise as a clinical device to diagnose and treat challenging diseases.
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Affiliation(s)
- Shuaiyuan Liu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, China
| | - Yibo Han
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, China
| | - Lingwen Kong
- Department of Cardiothoracic Surgery, Central Hospital of Chongqing University, Chongqing Emergency Medical Center, Chongqing, China
| | - Guixue Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, China
- JinFeng Laboratory, Chongqing, China
| | - Zhiyi Ye
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, China
- JinFeng Laboratory, Chongqing, China
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2
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Singh SB, Rajput SS, Patil S, Subramanyam D. Protocol for measuring mechanical properties of live cells using atomic force microscopy. STAR Protoc 2024; 5:102870. [PMID: 38329878 PMCID: PMC10865473 DOI: 10.1016/j.xpro.2024.102870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/18/2023] [Accepted: 01/19/2024] [Indexed: 02/10/2024] Open
Abstract
Atomic force microscope (AFM) is a powerful and versatile tool to determine the physical properties of cells. The force-distance curves obtained from AFM experiments can be used to determine the stiffness and viscoelastic properties of cells. Here, we present a protocol for the determination of viscoelasticity from live cells such as Drosophila hemocytes or mouse embryonic stem cells using AFM. This protocol has potential application in determining the physical properties of cells in healthy and diseased conditions. For complete details on the use and execution of this protocol, please refer to Mote et al. (2020),1 and Singh et al. (2023).2.
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Affiliation(s)
- Surya Bansi Singh
- National Centre for Cell Science, SP Pune University Campus, Pune 411007, India; SP Pune University, Pune 411007, India
| | - Shatruhan Singh Rajput
- Indian Institute of Science Education and Research, Pune 411008, India; Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, CB2 1GA Cambridge, UK
| | - Shivprasad Patil
- Indian Institute of Science Education and Research, Pune 411008, India.
| | - Deepa Subramanyam
- National Centre for Cell Science, SP Pune University Campus, Pune 411007, India.
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3
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Chiodini S, Borbone F, Oscurato SL, Garcia PD, Ambrosio A. Light-induced modulation of viscoelastic properties in azobenzene polymers. NANOPHOTONICS 2024; 13:229-238. [PMID: 38283896 PMCID: PMC10808048 DOI: 10.1515/nanoph-2023-0728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 12/21/2023] [Indexed: 01/30/2024]
Abstract
Photo-induced isomerization of azobenzene molecules drives mass migrations in azopolymer samples. The resulting macroscopic directional photo-deformation of the material morphology has found many applications in literature, although the fundamental mechanisms behind this mass transfer are still under debate. Hence, it is of paramount importance to find quantitative observables that could drive the community toward a better understanding of this phenomenon. In this regard, azopolymer mechanical properties have been intensively studied, but the lack of a nanoscale technique capable of quantitative viscoelastic measurements has delayed the progress in the field. Here, we use bimodal atomic force microscopy (AFM) as a powerful technique for nanomechanical characterizations of azopolymers. With this multifrequency AFM approach, we map the azopolymer local elasticity and viscosity, with high resolution, after irradiation. We find that, while in the (previously) illuminated region, a general photo-softening is measured; locally, the Young modulus and the viscosity depend upon the inner structuring of the illuminating light spot. We then propose a possible interpretation based on a light-induced expansion plus a local alignment of the polymer chains (directional hole-burning effect), which explains the experimental observations. The possibility to access, in a reliable and quantitative way, both Young modulus and viscosity could trigger new theoretical-numerical investigations on the azopolymer mass migration dynamics since, as we show, both parameters can be considered measurable. Furthermore, our results provide a route for engineering the nanomechanical properties of azopolymers, which could find interesting applications in cell mechanobiology research.
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Affiliation(s)
- Stefano Chiodini
- Center for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Via Rubattino 81, 20134, Milan, Italy
| | - Fabio Borbone
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cinthia Complesso Universitario di Monte Sant’Angelo, Via Cintia, 80126Naples, Italy
| | - Stefano L. Oscurato
- Center for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Via Rubattino 81, 20134, Milan, Italy
- Physics Department “E. Pancini”, University of Naples “Federico II”, Via Cinthia Complesso Universitario di Monte Sant’Angelo, Via Cintia, 80126Naples, Italy
| | - Pablo D. Garcia
- BYM-Ingema, Centro de Empresas del Caudal, Polígono Vega de Arriba, 33600, Mieres, Spain
| | - Antonio Ambrosio
- Center for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Via Rubattino 81, 20134, Milan, Italy
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4
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Gisbert VG, Garcia R. Insights and guidelines to interpret forces and deformations at the nanoscale by using a tapping mode AFM simulator: dForce 2.0. SOFT MATTER 2023; 19:5857-5868. [PMID: 37305960 DOI: 10.1039/d3sm00334e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Amplitude modulation (tapping mode) AFM is the most versatile AFM mode for imaging surfaces at the nanoscale in air and liquid environments. However, it remains challenging to estimate the forces and deformations exerted by the tip. We introduce a new simulator environment to predict the values of the observables in tapping mode AFM experiments. The relevant feature of dForce 2.0 is the incorporation of contact mechanics models aimed to describe the properties of ultrathin samples. These models were essential to determine the forces applied on samples such as proteins, self-assembled monolayers, lipid bilayers, and few-layered materials. The simulator incorporates two types of long-range magnetic forces. The simulator is written in an open-source code (Python) and it can be run from a personal computer.
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Affiliation(s)
- Victor G Gisbert
- Instituto de Ciencia de Materiales de Madrid, CSIC c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
| | - Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
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5
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Chen SWW, Teulon JM, Kaur H, Godon C, Pellequer JL. Nano-structural stiffness measure for soft biomaterials of heterogeneous elasticity. NANOSCALE HORIZONS 2022; 8:75-82. [PMID: 36314544 DOI: 10.1039/d2nh00390b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Measuring the structural stiffness aims to reveal the impact of nanostructured components or various physiological circumstances on the elastic response of material to an external indentation. With a pyramidal tip at a nano-scale, we employed the atomic force microscopy (AFM) to indent the surfaces of two compositions of polyacrylamide gels with different softness and seedling roots of Arabidopsis thaliana. We found that the stiffness-depth curve derived from the measured force exhibits a heterogeneous character in elasticity. According to the tendency of stiffness-depth curve, we decomposed the responding force into depth-impact (FC), Hookean (FH) and tip-shape (FS) components, called trimechanic, where FS and its gradient should be offset at the surface or subsurfaces of the indented material. Thereby, trimechnic theory allows us to observe how the three restoring nanomechanics change with varied depth. Their strengths are represented by the respective spring constants (kC, kH, kS) of three parallel-connected spring (3PCS) analogs to differentiate restoring nanomechansims of indented materials. The effective Young's modulus Ê and the total stiffness kT (= kH + kS) globally unambiguously distinguish the softness between the two gel categories. Data fluctuations were observed in the elasticity parameters of individual samples, reflecting nanostructural variations in the gel matrix. Similar tendencies were found in the results from growing plant roots, though the data fluctuations are expectedly much more dramatic. The zone-wise representation of stiffness by the trimechanic-3PCS framework demonstrates a stiffness measure that reflects beneath nanostructures encountered by deepened depth. The trimechanic-3PCS framework can apply any mechanical model of power-law based force-depth relationship and is compatible with thin layer corrections. It provides a new paradigm for analyzing restoring nanomechanics of soft biomaterials in response to indenting forces.
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Affiliation(s)
- Shu-Wen W Chen
- Université Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France.
- Rue Cyprien Jullin, Vinay, 38470, France
| | - Jean-Marie Teulon
- Université Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France.
| | - Harinderbir Kaur
- Université Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France.
| | - Christian Godon
- Aix Marseille University, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, Cadarache, France
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6
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Zhao O, Collinson DW, Ohshita S, Naito M, Nakano N, Tortissier G, Nomura T, Dauskardt RH. Insights into the Mechanical Properties of Ultrathin Perfluoropolyether-Silane Coatings. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6435-6442. [PMID: 35543410 DOI: 10.1021/acs.langmuir.2c00625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ultrathin perfluoropolyether-silane (PFPE-silane) films offer excellent functionality as antifingerprint coatings for display touchscreens due to their oleophobic, hydrophobic, and good adhesion properties. During smartphone use, PFPE-silane coatings undergo many abrasion cycles which limit the coating lifetime, so a better understanding of how to optimize the film structure for improved mechanical durability is desired. However, the hydrophobic and ultrathin (1-10 nm) nature of PFPE-silane films renders them very difficult to experimentally characterize. In this study, the cohesive fracture energy and elastic modulus, which are directly correlated with hardness and better wear resistance of 3.5 nm-thick PFPE-silane films were, respectively, measured by double cantilever beam testing and atomic force microscopy indentation. Both the cohesive fracture energy and modulus are shown to be highly dependent on the underlying film structure. Both values increase with optimal substrate conditions and a higher number of silane groups in the PFPE-silane precursor. The higher cohesive fracture energy and modulus values are suggested to be the result of the changes in the film chemistry and structure, leading to higher cross-linking density. Therefore, future work on optimizing PFPE-silane film wear resistance should focus on pathways to improve the cross-linking density. Subcritical fracture testing in humid environments reveals that humidity negatively affects the fracture properties of PFPE-silane films.
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Affiliation(s)
- Oliver Zhao
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305-2205, United States
| | - David W Collinson
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305-2205, United States
| | - Shinsuke Ohshita
- Daikin Industries Limited, 1-1, Nishihitotsuya, Settsu, Osaka 566-8585, Japan
| | - Masato Naito
- Daikin Industries Limited, 1-1, Nishihitotsuya, Settsu, Osaka 566-8585, Japan
| | - Nozomi Nakano
- Daikin Industries Limited, 1-1, Nishihitotsuya, Settsu, Osaka 566-8585, Japan
| | - Gregory Tortissier
- Daikin Industries Limited, 1-1, Nishihitotsuya, Settsu, Osaka 566-8585, Japan
| | - Takashi Nomura
- Daikin Industries Limited, 1-1, Nishihitotsuya, Settsu, Osaka 566-8585, Japan
| | - Reinhold H Dauskardt
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305-2205, United States
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7
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Wang G, Najafi F, Ho K, Hamidinejad M, Cui T, Walker GC, Singh CV, Filleter T. Mechanical Size Effect of Freestanding Nanoconfined Polymer Films. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02270] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Guorui Wang
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Farzin Najafi
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Kevin Ho
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Mahdi Hamidinejad
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Teng Cui
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Gilbert C. Walker
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Chandra Veer Singh
- Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4, Canada
| | - Tobin Filleter
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
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8
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Gisbert VG, Garcia R. Accurate Wide-Modulus-Range Nanomechanical Mapping of Ultrathin Interfaces with Bimodal Atomic Force Microscopy. ACS NANO 2021; 15:20574-20581. [PMID: 34851086 DOI: 10.1021/acsnano.1c09178] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The nanoscale determination of the mechanical properties of interfaces is of paramount relevance in materials science and cell biology. Bimodal atomic force microscopy (AFM) is arguably the most advanced nanoscale method for mapping the elastic modulus of interfaces. Simulations, theory, and experiments have validated bimodal AFM measurements on thick samples (from micrometer to millimeter). However, the bottom-effect artifact, this is, the influence of the rigid support on the determination of the Young's modulus, questions its accuracy for ultrathin materials and interfaces (1-15 nm). Here we develop a bottom-effect correction method that yields the intrinsic Young's modulus value of a material independent of its thickness. Experiments and numerical simulations validate the accuracy of the method for a wide range of materials (1 MPa to 100 GPa). Otherwise, the Young's modulus of an ultrathin material might be overestimated by a 10-fold factor.
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Affiliation(s)
- Victor G Gisbert
- Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
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9
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Lin CH, Luo SC. Combination of AFM and Electrochemical QCM-D for Probing Zwitterionic Polymer Brushes in Water: Visualization of Ionic Strength and Surface Potential Effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12476-12486. [PMID: 34648298 DOI: 10.1021/acs.langmuir.1c02230] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The surface modification of soft zwitterionic polymer brushes with antifouling properties represents a facile approach to enhancing the performance of bioelectronics. Ionic strength and applied potentials play a crucial role in controlling polymer brushes' conformation and hydration states. In this study, we quantitatively investigated and compared poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(sulfobetaine methacrylate) (PSBMA) brushes at different salt concentrations and applied surface potentials. Initiator-containing poly(3,4-ethylenedioxythiophene) films (poly(EDOT-Br)) were prepared by electropolymerization. After the conducting polymer was deposited, polymer brushes grew from the electrode surface through surface-initiated atom-transfer radical polymerization (SI-ATRP). Polymer brushes were carefully characterized for their surface morphologies using an atomic force microscope (AFM). The force volume method measured using AFM enabled the analysis of the Young's modulus of the two polymer brushes. Hydration states and protein binding behaviors of polymer brushes were examined using quartz crystal microbalance with dissipation (QCM-D). We further integrated a potentiostat with the QCM-D to conduct an electrochemical QCM-D study. The energy dissipation and frequency changes corresponded to the ion adsorption on the film surface under different ionic strengths. The results of both hydration states and nonspecific protein binding behavior indicate that PMPC brushes have greater ionic strength independency, implying the conformation of the unchanged PMPC brushes. Moreover, we illustrated how the surface potential influences nonspecific and specific binding behavior on PMPC brushes on PEDOT films compared with electrified poly(EDOT-PC) electrodes. We concluded that PMPC brushes exhibit unique behaviors that are barely affected by ion concentration, and that the brushes' modification results in less influence by surface potential due to the finite Debye length influencing the electrode surface to outer environment in an NaCl aqueous solution.
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Affiliation(s)
- Chia-Hsuan Lin
- Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Shyh-Chyang Luo
- Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes (NHRI), Miaoli County, 35053 Taiwan
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10
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Cortelli G, Patruno L, Cramer T, Murgia M, Fraboni B, de Miranda S. Atomic Force Microscopy Nanomechanics of Hard Nanometer-Thick Films on Soft Substrates: Insights into Stretchable Conductors. ACS APPLIED NANO MATERIALS 2021; 4:8376-8382. [PMID: 34485845 PMCID: PMC8411650 DOI: 10.1021/acsanm.1c01590] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/06/2021] [Indexed: 05/14/2023]
Abstract
The nanomechanical properties of ultrathin and nanostructured films of rigid electronic materials on soft substrates are of crucial relevance to realize materials and devices for stretchable electronics. Of particular interest are bending deformations in buckled nanometer-thick films or patterned networks of rigid materials as they can be exploited to compensate for the missing tensile elasticity. Here, we perform atomic force microscopy indentation experiments and electrical measurements to characterize the nanomechanics of ultrathin gold films on a polydimethylsiloxane (PDMS) elastomer. The measured force-indentation data can be analyzed in terms of a simple analytical model describing a bending plate on a semi-infinite soft substrate. The resulting method enables us to quantify the local Young's modulus of elasticity of the nanometer-thick film. Systematic variation of the gold layer thickness reveals the presence of a diffuse interface between the metal film and the elastomer substrate that does not contribute to the bending stiffness. The effect is associated with gold clusters that penetrate the silicone and are not directly connected to the ultrathin film. Only above a critical layer thickness, percolation of the metallic thin film happens, causing a linear increase in bending stiffness and electrical conductivity.
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Affiliation(s)
- Giorgio Cortelli
- Department
of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy
| | - Luca Patruno
- Department
of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy
| | - Tobias Cramer
- Department
of Physics and Astronomy, University of
Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
| | - Mauro Murgia
- Department
of Physics and Astronomy, University of
Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
| | - Beatrice Fraboni
- Department
of Physics and Astronomy, University of
Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
| | - Stefano de Miranda
- Department
of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy
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11
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Wang X, Ismael A, Almutlg A, Alshammari M, Al-Jobory A, Alshehab A, Bennett TLR, Wilkinson LA, Cohen LF, Long NJ, Robinson BJ, Lambert C. Optimised power harvesting by controlling the pressure applied to molecular junctions. Chem Sci 2021; 12:5230-5235. [PMID: 34163759 PMCID: PMC8179551 DOI: 10.1039/d1sc00672j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 02/22/2021] [Indexed: 11/21/2022] Open
Abstract
A major potential advantage of creating thermoelectric devices using self-assembled molecular layers is their mechanical flexibility. Previous reports have discussed the advantage of this flexibility from the perspective of facile skin attachment and the ability to avoid mechanical deformation. In this work, we demonstrate that the thermoelectric properties of such molecular devices can be controlled by taking advantage of their mechanical flexibility. The thermoelectric properties of self-assembled monolayers (SAMs) fabricated from thiol terminated molecules were measured with a modified AFM system, and the conformation of the SAMs was controlled by regulating the loading force between the organic thin film and the probe, which changes the tilt angle at the metal-molecule interface. We tracked the thermopower shift vs. the tilt angle of the SAM and showed that changes in both the electrical conductivity and Seebeck coefficient combine to optimize the power factor at a specific angle. This optimization of thermoelectric performance via applied pressure is confirmed through the use of theoretical calculations and is expected to be a general method for optimising the power factor of SAMs.
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Affiliation(s)
- Xintai Wang
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- The Blackett Laboratory, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Ali Ismael
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Education for Pure Science, Tikrit University Tikrit Iraq
| | - Ahmad Almutlg
- Physics Department, Lancaster University Lancaster LA1 4YB UK
| | | | - Alaa Al-Jobory
- Physics Department, Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Science, University of Anbar Anbar Iraq
| | | | - Troy L R Bennett
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
| | - Luke A Wilkinson
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
- Department of Chemistry, University of York Heslington York YO10 5DD UK
| | - Lesley F Cohen
- The Blackett Laboratory, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Nicholas J Long
- Department of Chemistry, Imperial College London, MSRH White City London W12 0BZ UK
| | | | - Colin Lambert
- Physics Department, Lancaster University Lancaster LA1 4YB UK
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12
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Eid J, Greige-Gerges H, Monticelli L, Jraij A. Elastic moduli of lipid membranes: Reproducibility of AFM measures. Chem Phys Lipids 2020; 234:105011. [PMID: 33217391 DOI: 10.1016/j.chemphyslip.2020.105011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 10/26/2020] [Accepted: 11/15/2020] [Indexed: 11/29/2022]
Abstract
Membrane elastic properties play a major role in membrane remodeling events, such as vesicle fusion and fission. They are also crucial in drug delivery by liposomes. Different experimental techniques are available to measure elastic properties. Among them, atomic force microscopy (AFM) presents the unique advantage of being directly applicable to nano-sized liposomes. Unfortunately, different AFM measures reported in the literature show little agreement among each other and are difficult to compare with measures of bending modulus obtained by other experimental techniques or by molecular simulations. In this work we determine the bending rigidity of Egg PC liposomes in terms of Young modulus via AFM measurements, using two different tip shapes and different cantilever force constants. We interpret the measures using the Hertz and Shell models, and observe a clear dependency of the Young modulus values on the tip properties and on the interpretative theory. The effect of the AFM tip shape is less important than the effect of the cantilever force constant, and the mathematical model has a major effect on the interpretation of the data. The Shell theory provides the closest agreement between AFM data and other experimental data for the membrane bending modulus. Finally, we compare the results to calculations of bending modulus from molecular dynamics simulations of membrane buckles. Simulations provide values of bending modulus consistent with literature data, but the agreement with AFM experiments is reasonable only for some specific experimental conditions.
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Affiliation(s)
- Jad Eid
- Bioactive Molecules Research Laboratory, Doctoral School of Sciences and Technologies, Faculty of Sciences, Lebanese University, Lebanon; Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS / University Claude Bernard Lyon1, Lyon, France
| | - Hélène Greige-Gerges
- Bioactive Molecules Research Laboratory, Doctoral School of Sciences and Technologies, Faculty of Sciences, Lebanese University, Lebanon
| | - Luca Monticelli
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS / University Claude Bernard Lyon1, Lyon, France
| | - Alia Jraij
- Bioactive Molecules Research Laboratory, Doctoral School of Sciences and Technologies, Faculty of Sciences, Lebanese University, Lebanon.
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13
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Nanofabrication Techniques in Large-Area Molecular Electronic Devices. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10176064] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The societal impact of the electronics industry is enormous—not to mention how this industry impinges on the global economy. The foreseen limits of the current technology—technical, economic, and sustainability issues—open the door to the search for successor technologies. In this context, molecular electronics has emerged as a promising candidate that, at least in the short-term, will not likely replace our silicon-based electronics, but improve its performance through a nascent hybrid technology. Such technology will take advantage of both the small dimensions of the molecules and new functionalities resulting from the quantum effects that govern the properties at the molecular scale. An optimization of interface engineering and integration of molecules to form densely integrated individually addressable arrays of molecules are two crucial aspects in the molecular electronics field. These challenges should be met to establish the bridge between organic functional materials and hard electronics required for the incorporation of such hybrid technology in the market. In this review, the most advanced methods for fabricating large-area molecular electronic devices are presented, highlighting their advantages and limitations. Special emphasis is focused on bottom-up methodologies for the fabrication of well-ordered and tightly-packed monolayers onto the bottom electrode, followed by a description of the top-contact deposition methods so far used.
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