101
|
Wang W, Yang G, Cui H, Meng J, Wang S, Jiang L. Bioinspired Pollen-Like Hierarchical Surface for Efficient Recognition of Target Cancer Cells. Adv Healthc Mater 2017; 6. [PMID: 28471542 DOI: 10.1002/adhm.201700003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/27/2017] [Indexed: 12/17/2022]
Abstract
The efficient recognition and isolation of rare cancer cells holds great promise for cancer diagnosis and prognosis. In nature, pollens exploit spiky structures to realize recognition and adhesion to stigma. Herein, a bioinspired pollen-like hierarchical surface is developed by replicating the assembly of pollen grains, and efficient and specific recognition to target cancer cells is achieved. The pollen-like surface is fabricated by combining filtering-assisted assembly and soft lithography-based replication of pollen grains of wild chrysanthemum. After modification with a capture agent specific to cancer cells, the pollen-like surface enables the capture of target cancer cells with high efficiency and specificity. In addition, the pollen-like surface not only assures high viability of captured cells but also performs well in cell mixture system and at low cell density. This study represents a good example of constructing cell recognition biointerfaces inspired by pollen-stigma adhesion.
Collapse
Affiliation(s)
- Wenshuo Wang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science; CAS Center for Excellence in Nanoscience; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
- University of Chinese Academy of Sciences; Beijing 100049 P. R. China
| | - Gao Yang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science; CAS Center for Excellence in Nanoscience; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
- University of Chinese Academy of Sciences; Beijing 100049 P. R. China
| | - Haijun Cui
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science; CAS Center for Excellence in Nanoscience; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
- University of Chinese Academy of Sciences; Beijing 100049 P. R. China
| | - Jingxin Meng
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science; CAS Center for Excellence in Nanoscience; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
| | - Shutao Wang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science; CAS Center for Excellence in Nanoscience; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
- University of Chinese Academy of Sciences; Beijing 100049 P. R. China
| | - Lei Jiang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science; CAS Center for Excellence in Nanoscience; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
- University of Chinese Academy of Sciences; Beijing 100049 P. R. China
| |
Collapse
|
102
|
Poulcharidis D, Belfor K, Kros A, van Kasteren SI. A flow cytometry assay to quantify intercellular exchange of membrane components. Chem Sci 2017; 8:5585-5590. [PMID: 28970937 PMCID: PMC5618768 DOI: 10.1039/c7sc00260b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/20/2017] [Indexed: 12/12/2022] Open
Abstract
Membrane-compound exchange is vital for cell-to-cell communication, yet quantification of this process is difficult. Here we present a method using flow cytometry in combination with bioorthogonal and fluorescent labelling techniques to quantify the amount of exchange of cholesterol and sialylated compounds between cells. We demonstrate that direct cell-cell contact is the likely mechanism of sterol-exchange and show that by manipulating the contact time between cells using complementary coiled-coil peptides results in an enhanced exchange rate of membrane components between cells.
Collapse
Affiliation(s)
- Dimitrios Poulcharidis
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
- Division of Supramolecular and Biomaterials Chemistry , Leiden Institute of Chemistry , Leiden University , Einsteinweg 55 , 2333 CC Leiden , The Netherlands .
| | - Kimberley Belfor
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
| | - Alexander Kros
- Division of Supramolecular and Biomaterials Chemistry , Leiden Institute of Chemistry , Leiden University , Einsteinweg 55 , 2333 CC Leiden , The Netherlands .
| | - Sander I van Kasteren
- Division of Bio-organic Synthesis , Leiden Institute of Chemistry , Gorlaeus Laboratories , Leiden University , Leiden , The Netherlands .
| |
Collapse
|
103
|
Li M, Liu L, Xi N, Wang Y. Atomic force microscopy studies on cellular elastic and viscoelastic properties. SCIENCE CHINA-LIFE SCIENCES 2017; 61:57-67. [DOI: 10.1007/s11427-016-9041-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 04/07/2017] [Indexed: 01/03/2023]
|
104
|
Chang PS, McLane LT, Fogg R, Scrimgeour J, Temenoff JS, Granqvist A, Curtis JE. Cell Surface Access Is Modulated by Tethered Bottlebrush Proteoglycans. Biophys J 2017; 110:2739-2750. [PMID: 27332132 DOI: 10.1016/j.bpj.2016.05.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 05/04/2016] [Accepted: 05/13/2016] [Indexed: 12/18/2022] Open
Abstract
The hyaluronan-rich pericellular matrix (PCM) plays physical and chemical roles in biological processes ranging from brain plasticity, to adhesion-dependent phenomena such as cell migration, to the onset of cancer. This study investigates how the spatial distribution of the large negatively charged bottlebrush proteoglycan, aggrecan, impacts PCM morphology and cell surface access. The highly localized pericellular milieu limits transport of nanoparticles in a size-dependent fashion and sequesters positively charged molecules on the highly sulfated side chains of aggrecan. Both rat chondrocyte and human mesenchymal stem cell PCMs possess many unused binding sites for aggrecan, showing a 2.5x increase in PCM thickness from ∼7 to ∼18 μm when provided exogenous aggrecan. Yet, full extension of the PCM occurs well below aggrecan saturation. Hence, cells equipped with hyaluronan-rich PCM can in principle manipulate surface accessibility or sequestration of molecules by tuning the bottlebrush proteoglycan content to alter PCM porosity and the number of electrostatic binding sites.
Collapse
Affiliation(s)
- Patrick S Chang
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Louis T McLane
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas
| | - Ruth Fogg
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Jan Scrimgeour
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; Department of Physics, Clarkson University, Potsdam, New York
| | - Johnna S Temenoff
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Anna Granqvist
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Jennifer E Curtis
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia; Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.
| |
Collapse
|
105
|
Dokukin M, Ablaeva Y, Kalaparthi V, Seluanov A, Gorbunova V, Sokolov I. Pericellular Brush and Mechanics of Guinea Pig Fibroblast Cells Studied with AFM. Biophys J 2017; 111:236-46. [PMID: 27410750 DOI: 10.1016/j.bpj.2016.06.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 05/11/2016] [Accepted: 06/08/2016] [Indexed: 01/06/2023] Open
Abstract
The atomic force microscopy (AFM) indentation method combined with the brush model can be used to separate the mechanical response of the cell body from deformation of the pericellular layer surrounding biological cells. Although self-consistency of the brush model to derive the elastic modulus of the cell body has been demonstrated, the model ability to characterize the pericellular layer has not been explicitly verified. Here we demonstrate it by using enzymatic removal of hyaluronic content of the pericellular brush for guinea pig fibroblast cells. The effect of this removal is clearly seen in the AFM force-separation curves associated with the pericellular brush layer. We further extend the brush model for brushes larger than the height of the AFM probe, which seems to be the case for fibroblast cells. In addition, we demonstrate that an extension of the brush model (i.e., double-brush model) is capable of detecting the hierarchical structure of the pericellular brush, which, for example, may consist of the pericellular coat and the membrane corrugation (microridges and microvilli). It allows us to quantitatively segregate the large soft polysaccharide pericellular coat from a relatively rigid and dense membrane corrugation layer. This was verified by comparison of the parameters of the membrane corrugation layer derived from the force curves collected on untreated cells (when this corrugation membrane part is hidden inside the pericellular brush layer) and on treated cells after the enzymatic removal of the pericellular coat part (when the corrugations are exposed to the AFM probe). We conclude that the brush model is capable of not only measuring the mechanics of the cell body but also the parameters of the pericellular brush layer, including quantitative characterization of the pericellular layer structure.
Collapse
Affiliation(s)
- Maxim Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts
| | - Yulija Ablaeva
- Department of Biology, University of Rochester, Rochester, New York
| | | | - Andrei Seluanov
- Department of Biology, University of Rochester, Rochester, New York
| | - Vera Gorbunova
- Department of Biology, University of Rochester, Rochester, New York.
| | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts; Department of Physics, Tufts University, Medford, Massachusetts; Department of Biomedical Engineering, Tufts University, Medford, Massachusetts.
| |
Collapse
|
106
|
Abdelwahab MT, Kalyoncu E, Onur T, Baykara MZ, Seker UOS. Genetically-Tunable Mechanical Properties of Bacterial Functional Amyloid Nanofibers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:4337-4345. [PMID: 28388843 DOI: 10.1021/acs.langmuir.7b00112] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bacterial biofilms are highly ordered, complex, dynamic material systems including cells, carbohydrates, and proteins. They are known to be resistant against chemical, physical, and biological disturbances. These superior properties make them promising candidates for next generation biomaterials. Here we investigated the morphological and mechanical properties (in terms of Young's modulus) of genetically-engineered bacterial amyloid nanofibers of Escherichia coli (E. coli) by imaging and force spectroscopy conducted via atomic force microscopy (AFM). In particular, we tuned the expression and biochemical properties of the major and minor biofilm proteins of E. coli (CsgA and CsgB, respectively). Using appropriate mutants, amyloid nanofibers constituting biofilm backbones are formed with different combinations of CsgA and CsgB, as well as the optional addition of tagging sequences. AFM imaging and force spectroscopy are used to probe the morphology and measure the Young's moduli of biofilm protein nanofibers as a function of protein composition. The obtained results reveal that genetically-controlled secretion of biofilm protein components may lead to the rational tuning of Young's moduli of biofilms as promising candidates at the bionano interface.
Collapse
Affiliation(s)
- M Tarek Abdelwahab
- Department of Mechanical Engineering, Bilkent University , Ankara 06800, Turkey
- Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey
| | - Ebuzer Kalyoncu
- Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey
| | - Tugce Onur
- Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey
| | - Mehmet Z Baykara
- Department of Mechanical Engineering, Bilkent University , Ankara 06800, Turkey
- Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey
| | - Urartu Ozgur Safak Seker
- Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey
- National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey
| |
Collapse
|
107
|
Yang Y, Wang K, Gu X, Leong KW. Biophysical Regulation of Cell Behavior-Cross Talk between Substrate Stiffness and Nanotopography. ENGINEERING (BEIJING, CHINA) 2017; 3:36-54. [PMID: 29071164 PMCID: PMC5653318 DOI: 10.1016/j.eng.2017.01.014] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The stiffness and nanotopographical characteristics of the extracellular matrix (ECM) influence numerous developmental, physiological, and pathological processes in vivo. These biophysical cues have therefore been applied to modulate almost all aspects of cell behavior, from cell adhesion and spreading to proliferation and differentiation. Delineation of the biophysical modulation of cell behavior is critical to the rational design of new biomaterials, implants, and medical devices. The effects of stiffness and topographical cues on cell behavior have previously been reviewed, respectively; however, the interwoven effects of stiffness and nanotopographical cues on cell behavior have not been well described, despite similarities in phenotypic manifestations. Herein, we first review the effects of substrate stiffness and nanotopography on cell behavior, and then focus on intracellular transmission of the biophysical signals from integrins to nucleus. Attempts are made to connect extracellular regulation of cell behavior with the biophysical cues. We then discuss the challenges in dissecting the biophysical regulation of cell behavior and in translating the mechanistic understanding of these cues to tissue engineering and regenerative medicine.
Collapse
Affiliation(s)
- Yong Yang
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV 26506, USA
| | - Kai Wang
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV 26506, USA
| | - Xiaosong Gu
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Kam W. Leong
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| |
Collapse
|
108
|
Yun X, Tang M, Yang Z, Wilksch JJ, Xiu P, Gao H, Zhang F, Wang H. Interrogation of drug effects on HeLa cells by exploiting new AFM mechanical biomarkers. RSC Adv 2017. [DOI: 10.1039/c7ra06233h] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
New AFM mechanical biomarkers including cell brush length, adhesion work and the factor of viscosity are discovered for drug assays.
Collapse
Affiliation(s)
- Xiaoling Yun
- School of Life Science
- Inner Mongolia Agricultural University
- Hohhot 010018
- China
- Chongqing Key Laboratory of Multi-Scale Manufacturing Technology
| | - Mingjie Tang
- Chongqing Key Laboratory of Multi-Scale Manufacturing Technology
- Chongqing Institute of Green and Intelligent Technology
- Chinese Academy of Sciences
- Chongqing 400714
- China
| | - Zhongbo Yang
- Chongqing Key Laboratory of Multi-Scale Manufacturing Technology
- Chongqing Institute of Green and Intelligent Technology
- Chinese Academy of Sciences
- Chongqing 400714
- China
| | - Jonathan J. Wilksch
- Department of Microbiology and Immunology
- University of Melbourne
- Parkville
- Australia
| | - Peng Xiu
- Department of Engineering Mechanics
- Soft Matter Research Center
- Zhejiang University
- Hangzhou 310027
- China
| | - Haiyang Gao
- School of Life Science
- Inner Mongolia Agricultural University
- Hohhot 010018
- China
- Department of Biomedical Engineering
| | - Feng Zhang
- School of Life Science
- Inner Mongolia Agricultural University
- Hohhot 010018
- China
| | - Huabin Wang
- Chongqing Key Laboratory of Multi-Scale Manufacturing Technology
- Chongqing Institute of Green and Intelligent Technology
- Chinese Academy of Sciences
- Chongqing 400714
- China
| |
Collapse
|
109
|
Singh G, Bremmell K, Griesser HJ, Kingshott P. Colloid-probe AFM studies of the surface functionality and adsorbed proteins on binary colloidal crystal layers. RSC Adv 2017. [DOI: 10.1039/c6ra28491d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We demonstrate the applicability of colloid-probe AFM to detect different surface chemistries on binary colloidal crystal layers of different chemical and protein patterns.
Collapse
Affiliation(s)
- Gurvinder Singh
- Interdisciplinary Nanoscience Centre
- Faculty of Science
- Aarhus University
- Denmark
- Department of Materials Science and Engineering
| | - Kristen Bremmell
- School of Pharmacy and Medical Sciences
- University of South Australia
- Adelaide 5000
- Australia
| | - Hans J. Griesser
- Future Industries Institute
- University of South Australia
- Mawson Lakes
- Australia
| | - Peter Kingshott
- Interdisciplinary Nanoscience Centre
- Faculty of Science
- Aarhus University
- Denmark
- Department of Chemistry and Biotechnology
| |
Collapse
|
110
|
Guz NV, Patel SJ, Dokukin ME, Clarkson B, Sokolov I. AFM study shows prominent physical changes in elasticity and pericellular layer in human acute leukemic cells due to inadequate cell-cell communication. NANOTECHNOLOGY 2016; 27:494005. [PMID: 27834315 PMCID: PMC5221648 DOI: 10.1088/0957-4484/27/49/494005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Biomechanical properties of single cells in vitro or ex vivo and their pericellular interfaces have recently attracted a lot of attention as a potential biophysical (and possibly prognostic) marker of various diseases and cell abnormalities. At the same time, the influence of the cell environment on the biomechanical properties of cells is not well studied. Here we use atomic force microscopy to demonstrate that cell-cell communication can have a profound effect on both cell elasticity and its pericellular coat. A human pre-B p190BCR/ABL acute lymphoblastic leukemia cell line (ALL3) was used in this study. Assuming that cell-cell communication is inversely proportional to the distance between cells, we study ALL3 cells in vitro growing at different cell densities. ALL3 cells demonstrate a clear density dependent behavior. These cells grow very well if started at a relatively high cell density (HD, >2 × 105 cells ml-1) and are poised to grow at low cell density (LD, <1 × 104 cells ml-1). Here we observe ∼6× increase in the elastic (Young's) modulus of the cell body and ∼3.6× decrease in the pericellular brush length of LD cells compared to HD ALL3 cells. The difference observed in the elastic modulus is much larger than typically reported for pathologically transformed cells. Thus, cell-cell communication must be taken into account when studying biomechanics of cells, in particular, correlating cell phenotype and its biophysical properties.
Collapse
Affiliation(s)
- Nataliia V Guz
- Department of Chemistry, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699-5820, USA
| | | | | | | | | |
Collapse
|
111
|
Kim Y, Kim W, Park JW. Principles and Applications of Force Spectroscopy Using Atomic Force Microscopy. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.11022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Youngkyu Kim
- Department of Chemistry; Pohang University of Science and Technology; Pohang 37673 Korea
| | - Woong Kim
- Department of Chemistry; Pohang University of Science and Technology; Pohang 37673 Korea
| | - Joon Won Park
- Department of Chemistry; Pohang University of Science and Technology; Pohang 37673 Korea
| |
Collapse
|
112
|
Ciasca G, Sassun TE, Minelli E, Antonelli M, Papi M, Santoro A, Giangaspero F, Delfini R, De Spirito M. Nano-mechanical signature of brain tumours. NANOSCALE 2016; 8:19629-19643. [PMID: 27853793 DOI: 10.1039/c6nr06840e] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Glioblastoma (GBM) and meningothelial meningioma (MM) are the most frequent malignant and benign brain lesions, respectively. Mechanical cues play a major role in the progression of both malignancies that is modulated by the occurrence of aberrant physical interactions between neoplastic cells and the extracellular matrix (ECM). Here we investigate the nano-mechanical properties of human GBM and MM tissues by atomic force microscopy. Our measures unveil the mechanical fingerprint of the main hallmark features of both lesions, such as necrosis in GBM and dural infiltration in MM. These findings have the potential to positively impact on the development of novel AFM-based diagnostic methods to assess the tumour grade. Most importantly, they provide a quantitative description of the tumour-induced mechanical modifications in the brain ECM, thus being of potential help in the search for novel ECM targets for brain tumours and especially for GBM that, despite years of intense research, has still very limited therapeutic options.
Collapse
Affiliation(s)
- Gabriele Ciasca
- Istituto di Fisica, Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy.
| | - Tanya Enny Sassun
- Department of Neurology and Psychiatry, Division of Neurosurgery, Policlinico Umberto I, Sapienza University of Rome, Viale del Policlinico, 155 Rome, Italy 00161
| | - Eleonora Minelli
- Istituto di Fisica, Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy.
| | - Manila Antonelli
- Department of Radiological Sciences, Oncology and Anatomical Pathology, Sapienza University, Rome, Italy
| | - Massimiliano Papi
- Istituto di Fisica, Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy.
| | - Antonio Santoro
- Department of Neurology and Psychiatry, Division of Neurosurgery, Policlinico Umberto I, Sapienza University of Rome, Viale del Policlinico, 155 Rome, Italy 00161
| | - Felice Giangaspero
- Department of Radiological Sciences, Oncology and Anatomical Pathology, Sapienza University, Rome, Italy
| | - Roberto Delfini
- Department of Neurology and Psychiatry, Division of Neurosurgery, Policlinico Umberto I, Sapienza University of Rome, Viale del Policlinico, 155 Rome, Italy 00161
| | - Marco De Spirito
- Istituto di Fisica, Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy.
| |
Collapse
|
113
|
Lu Z, Li H, Hou C, Peng Y, Long J, Liu J. Endogenously generated amyloid-β increases stiffness in human neuroblastoma cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 46:415-424. [PMID: 27853822 DOI: 10.1007/s00249-016-1185-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 10/19/2016] [Accepted: 10/28/2016] [Indexed: 12/26/2022]
Abstract
Amyloid-β (Aβ) is widely recognized as toxic to neuronal cells. Its deposition on plasma and intracellular membranes and aggregation into amyloid plaques can disturb the composition and physiological function of neurons. Whether a physical property of cells, such as stiffness, is altered by endogenously overexpressed Aβ has not yet been investigated. In this study, we used human neuroblastoma cells stably overexpressing amyloid precursor protein (APP) and its Swedish mutant form (APPswe) to measure the changes in cell stiffness. Our results showed that the stiffness of cells overexpressing APP or APPswe was higher than that of control SH-SY5Y cells. Either reducing levels of Aβ with the γ secretase inhibitor DAPT or blocking the membrane calcium channel formed by Aβ with tromethamine decreased cell stiffness to a level close to the control SH-SY5Y cells. Our results suggested that Aβ, not APP, contributed to increased cell stiffness and that closure of calcium channels formed by Aβ can alleviate the effects of Aβ on membrane stiffness.
Collapse
Affiliation(s)
- Zhuoyang Lu
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Center for Mitochondrial Biology and Medicine, School of Life Science and Technology and Frontier Institute of Life Science, FIST, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Hua Li
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Center for Mitochondrial Biology and Medicine, School of Life Science and Technology and Frontier Institute of Life Science, FIST, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Chen Hou
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Center for Mitochondrial Biology and Medicine, School of Life Science and Technology and Frontier Institute of Life Science, FIST, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Yunhua Peng
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Center for Mitochondrial Biology and Medicine, School of Life Science and Technology and Frontier Institute of Life Science, FIST, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Jiangang Long
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Center for Mitochondrial Biology and Medicine, School of Life Science and Technology and Frontier Institute of Life Science, FIST, Xi'an Jiaotong University, 710049, Xi'an, China.
| | - Jiankang Liu
- The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Center for Mitochondrial Biology and Medicine, School of Life Science and Technology and Frontier Institute of Life Science, FIST, Xi'an Jiaotong University, 710049, Xi'an, China.
| |
Collapse
|
114
|
Cytoskeletal Configuration Modulates Mechanically Induced Changes in Mesenchymal Stem Cell Osteogenesis, Morphology, and Stiffness. Sci Rep 2016; 6:34791. [PMID: 27708389 PMCID: PMC5052530 DOI: 10.1038/srep34791] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/20/2016] [Indexed: 12/12/2022] Open
Abstract
Mesenchymal stem cells (MSC) responding to mechanical cues generated by physical activity is critical for skeletal development and remodeling. Here, we utilized low intensity vibrations (LIV) as a physiologically relevant mechanical signal and hypothesized that the confined cytoskeletal configuration imposed by 2D culture will enable human bone marrow MSCs (hBMSC) to respond more robustly when LIV is applied in-plane (horizontal-LIV) rather than out-of-plane (vertical-LIV). All LIV signals enhanced hBMSC proliferation, osteogenic differentiation, and upregulated genes associated with cytoskeletal structure. The cellular response was more pronounced at higher frequencies (100 Hz vs 30 Hz) and when applied in the horizontal plane. Horizontal but not vertical LIV realigned the cell cytoskeleton, culminating in increased cell stiffness. Our results show that applying very small oscillatory motions within the primary cell attachment plane, rather than perpendicular to it, amplifies the cell's response to LIV, ostensibly facilitating a more effective transfer of intracellular forces. Transcriptional and structural changes in particular with horizontal LIV, together with the strong frequency dependency of the signal, emphasize the importance of intracellular cytoskeletal configuration in sensing and responding to high-frequency mechanical signals at low intensities.
Collapse
|
115
|
Atomic force microscopy for the investigation of molecular and cellular behavior. Micron 2016; 89:60-76. [DOI: 10.1016/j.micron.2016.07.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/27/2016] [Indexed: 12/19/2022]
|
116
|
Carter C. The barrier, airway particle clearance, placental and detoxification functions of autism susceptibility genes. Neurochem Int 2016; 99:42-51. [DOI: 10.1016/j.neuint.2016.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/11/2016] [Accepted: 06/07/2016] [Indexed: 02/08/2023]
|
117
|
Gavara N. A beginner's guide to atomic force microscopy probing for cell mechanics. Microsc Res Tech 2016; 80:75-84. [PMID: 27676584 PMCID: PMC5217064 DOI: 10.1002/jemt.22776] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/17/2016] [Accepted: 08/22/2016] [Indexed: 12/17/2022]
Abstract
Atomic Force microscopy (AFM) is becoming a prevalent tool in cell biology and biomedical studies, especially those focusing on the mechanical properties of cells and tissues. The newest generation of bio-AFMs combine ease of use and seamless integration with live-cell epifluorescence or more advanced optical microscopies. As a unique feature with respect to other bionanotools, AFM provides nanometer-resolution maps for cell topography, stiffness, viscoelasticity, and adhesion, often overlaid with matching optical images of the probed cells. This review is intended for those about to embark in the use of bio-AFMs, and aims to assist them in designing an experiment to measure the mechanical properties of adherent cells. In addition to describing the main steps in a typical cell mechanics protocol and explaining how data is analysed, this review will also discuss some of the relevant contact mechanics models available and how they have been used to characterize specific features of cellular and biological samples. Microsc. Res. Tech. 80:75-84, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Núria Gavara
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 3NS, UK
| |
Collapse
|
118
|
Rianna C, Radmacher M. Comparison of viscoelastic properties of cancer and normal thyroid cells on different stiffness substrates. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 46:309-324. [DOI: 10.1007/s00249-016-1168-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/24/2016] [Accepted: 08/27/2016] [Indexed: 12/19/2022]
|
119
|
Costa L, Li-Destri G, Thomson NH, Konovalov O, Pontoni D. Real Space Imaging of Nanoparticle Assembly at Liquid-Liquid Interfaces with Nanoscale Resolution. NANO LETTERS 2016; 16:5463-5468. [PMID: 27571473 DOI: 10.1021/acs.nanolett.6b01877] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Bottom up self-assembly of functional materials at liquid-liquid interfaces has recently emerged as method to design and produce novel two-dimensional (2D) nanostructured membranes and devices with tailored properties. Liquid-liquid interfaces can be seen as a "factory floor" for nanoparticle (NP) self-assembly, because NPs are driven there by a reduction of interfacial energy. Such 2D assembly can be characterized by reciprocal space techniques, namely X-ray and neutron scattering or reflectivity. These techniques have drawbacks, however, as the structural information is averaged over the finite size of the radiation beam and nonperiodic isolated assemblies in 3D or defects may not be easily detected. Real-space in situ imaging methods are more appropriate in this context, but they often suffer from limited resolution and underperform or fail when applied to challenging liquid-liquid interfaces. Here, we study the surfactant-induced assembly of SiO2 nanoparticle monolayers at a water-oil interface using in situ atomic force microscopy (AFM) achieving nanoscale resolved imaging capabilities. Hitherto, AFM imaging has been restricted to solid-liquid interfaces because applications to liquid interfaces have been hindered by their softness and intrinsic dynamics, requiring accurate sample preparation methods and nonconventional AFM operational schemes. Comparing both AFM and grazing incidence X-ray small angle scattering data, we unambiguously demonstrate correlation between real and reciprocal space structure determination showing that the average interfacial NP density is found to vary with surfactant concentration. Additionally, the interaction between the tip and the interface can be exploited to locally determine the acting interfacial interactions. This work opens up the way to studying complex nanostructure formation and phase behavior in a range of liquid-liquid and complex liquid interfaces.
Collapse
Affiliation(s)
- Luca Costa
- ESRF-The European Synchrotron 71 , Avenue des Martyrs. 38100 Grenoble, France
| | - Giovanni Li-Destri
- ESRF-The European Synchrotron 71 , Avenue des Martyrs. 38100 Grenoble, France
| | - Neil H Thomson
- Department of Oral Biology, School of Dentistry and Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds , LS2 9JT Leeds, United Kingdom
| | - Oleg Konovalov
- ESRF-The European Synchrotron 71 , Avenue des Martyrs. 38100 Grenoble, France
| | - Diego Pontoni
- ESRF-The European Synchrotron 71 , Avenue des Martyrs. 38100 Grenoble, France
| |
Collapse
|
120
|
Koo H, Park I, Lee Y, Kim HJ, Jung JH, Lee JH, Kim Y, Kim JH, Park JW. Visualization and Quantification of MicroRNA in a Single Cell Using Atomic Force Microscopy. J Am Chem Soc 2016; 138:11664-71. [PMID: 27529574 DOI: 10.1021/jacs.6b05048] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
MicroRNAs (miRNAs) play critical roles in controlling various cellular processes, and the expression levels of individual miRNAs can be considerably altered in pathological conditions such as cancer. Accurate quantification of miRNA at the single-cell level will lead to a better understanding of miRNA function. Here, we present a direct and sensitive method for miRNA detection using atomic force microscopy (AFM). A hybrid binding domain (HBD)-tethered tip enabled mature miRNAs, but not premature miRNAs, to be located individually on an adhesion force map. By scanning several sections of a micrometer-sized DNA spot, we were able to quantify the copy number of miR-134 in a single neuron and demonstrate that the expression was increased upon cell activation. Moreover, we visualized individual miR-134s on fixed neurons after membrane removal and observed 2-4 miR-134s in the area of 1.0 × 1.0 μm(2) of soma. The number increased to 8-14 in stimulated neurons, and this change matches the ensemble-averaged increase in copy number. These findings indicate that miRNAs can be reliably quantified at the single cell level with AFM and that their distribution can be mapped at nanometric lateral resolution without modification or amplification. Furthermore, the analysis of miRNAs, mRNAs, and proteins in the same sample or region by scanning sequentially with different AFM tips would let us accurately understand the post-transcriptional regulation of biological processes.
Collapse
Affiliation(s)
- Hyunseo Koo
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Ikbum Park
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Yoonhee Lee
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Hyun Jin Kim
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Jung Hoon Jung
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Joo Han Lee
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Youngkyu Kim
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Joung-Hun Kim
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Joon Won Park
- Department of Chemistry, ‡Division of Integrative Biosciences and Biotechnology, and §Department of Life Sciences, Pohang University of Science and Technology , 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| |
Collapse
|
121
|
Shi L, Wang K, Yang Y. Adhesion-based tumor cell capture using nanotopography. Colloids Surf B Biointerfaces 2016; 147:291-299. [PMID: 27526289 DOI: 10.1016/j.colsurfb.2016.08.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 11/29/2022]
Abstract
Circulating tumor cells (CTCs) shed from primary tumors, transport through the blood stream to distant sites, and cause 90% of cancer deaths. Although different techniques have been developed to isolate CTCs for cancer detection, diagnosis and treatment, the heterogeneity of expression of the target antigen and the significant size variance in CTCs limit clinical applications of antibody- and size-based isolation techniques. Cell adhesion using nanotopography has been suggested as a promising approach to isolate CTCs independent of surface marker expression or size of CTCs. However, the nanotopographies studied are mainly nanopillars; the influence of other nanotopography such as nanogratings and their dimensions on tumor cell capture remains to be investigated. This study examined capture performance of several cancer cell lines of different types, surface marker expression and metastatic status on nanotopographies of various geometries and dimensions without antibody conjugation. The cancer cells exhibited differential capture performance on the nanotopographies with an efficiency up to 52%. Compared with flat surfaces and isotropic, discrete nanopillars, nanogratings favored cancer cell adhesion, thus improving the capture efficiency. The influence of nanotopography height studied, on the other hand, was less significant. This study provides useful information to optimize nanotopography for further improvement of CTC capture efficiency.
Collapse
Affiliation(s)
- Lin Shi
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, 26506, USA
| | - Kai Wang
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, 26506, USA
| | - Yong Yang
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, 26506, USA.
| |
Collapse
|
122
|
Pokharel D, Wijesinghe P, Oenarto V, Lu JF, Sampson DD, Kennedy BF, Wallace VP, Bebawy M. Deciphering Cell-to-Cell Communication in Acquisition of Cancer Traits: Extracellular Membrane Vesicles Are Regulators of Tissue Biomechanics. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2016; 20:462-9. [DOI: 10.1089/omi.2016.0072] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Deep Pokharel
- Discipline of Pharmacy, The Graduate School of Health, University of Technology Sydney, Australia
| | - Philip Wijesinghe
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Western Australia, Australia
| | - Vici Oenarto
- Discipline of Pharmacy, The Graduate School of Health, University of Technology Sydney, Australia
| | - Jamie F. Lu
- Discipline of Pharmacy, The Graduate School of Health, University of Technology Sydney, Australia
| | - David D. Sampson
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Western Australia, Australia
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Western Australia, Australia
| | - Brendan F. Kennedy
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Western Australia, Australia
- BRITElab, Harry Perkins Institute of Medical Research, Western Australia, Australia
| | - Vincent P. Wallace
- School of Physics, The University of Western Australia, Western Australia, Australia
| | - Mary Bebawy
- Discipline of Pharmacy, The Graduate School of Health, University of Technology Sydney, Australia
| |
Collapse
|
123
|
Guz NV, Patel SJ, Dokukin ME, Clarkson B, Sokolov I. Biophysical differences between chronic myelogenous leukemic quiescent and proliferating stem/progenitor cells. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2016; 12:2429-2437. [PMID: 27431055 DOI: 10.1016/j.nano.2016.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 06/26/2016] [Accepted: 06/29/2016] [Indexed: 11/18/2022]
Abstract
The treatment of chronic myeloid leukemia (CML), a clonal myeloproliferative disorder has improved recently, but most patients have not yet been cured. Some patients develop resistance to the available tyrosine kinase treatments. Persistence of residual quiescent CML stem cells (LSCs) that later resume proliferation is another common cause of recurrence or relapse of CML. Eradication of quiescent LSCs is a promising approach to prevent recurrence of CML. Here we report on new biophysical differences between quiescent and proliferating CD34+ LSCs, and speculate how this information could be of use to eradicate quiescent LSCs. Using AFM measurements on cells collected from four untreated CML patients, substantial differences are observed between quiescent and proliferating cells in the elastic modulus, pericellular brush length and its grafting density at the single cell level. The higher pericellular brush densities of quiescent LSCs are common for all samples. The significance of these observations is discussed.
Collapse
Affiliation(s)
- Nataliia V Guz
- Department of Chemistry, Clarkson University, Potsdam, NY, USA
| | - Sapan J Patel
- Department of Chemistry, Clarkson University, Potsdam, NY, USA; Memorial Sloan Kettering Cancer Center, Sloan Kettering Institute, Molecular Pharmacology and Chemistry Program, New York, NY
| | - Maxim E Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA
| | - Bayard Clarkson
- Memorial Sloan Kettering Cancer Center, Sloan Kettering Institute, Molecular Pharmacology and Chemistry Program, New York, NY.
| | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA; Department of Biomedical Engineering, Tufts University, Medford, MA, USA; Department of Physics and Astronomy, Tufts University, Medford, MA, USA.
| |
Collapse
|
124
|
Kann B, Spengler C, Coradini K, Rigo LA, Bennink ML, Jacobs K, Offerhaus HL, Beck RCR, Windbergs M. Intracellular Delivery of Poorly Soluble Polyphenols: Elucidating the Interplay of Self-Assembling Nanocarriers and Human Chondrocytes. Anal Chem 2016; 88:7014-22. [PMID: 27329347 DOI: 10.1021/acs.analchem.6b00199] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Increased molecular understanding of multifactorial diseases paves the way for novel therapeutic approaches requiring sophisticated carriers for intracellular delivery of actives. We designed and characterized self-assembling lipid-core nanocapsules for coencapsulation of two poorly soluble natural polyphenols curcumin and resveratrol. The polyphenols were identified as high-potential therapeutic candidates intervening in the intracellular inflammation cascade of chondrocytes during the progress of osteoarthritis. To elucidate the interplay between chondrocytes and nanocapsules and their therapeutic effect, we pursued a complementary analytical approach combining label-free visualization with biological assays. Primary human chondrocytes did not show any adverse effects upon nanocapsule application and coherent anti-Stokes Raman scattering images visualized their intracellular uptake. Further, by systematically blocking different uptake mechanisms, an energy independent uptake into the cells could be identified. Additionally, we tested the therapeutic effect of the polyphenol-loaded carriers on inflamed chondrocytes. Treatment with nanocapsules resulted in a major reduction of nitric oxide levels, a well-known apoptosis trigger during the course of osteoarthritis. For a more profound examination of this protective effect on joint cells, we pursued studies with atomic force microscopy investigations. Significant changes in the cell cytoskeleton as well as prominent dents in the cell membrane upon induced apoptosis were revealed. Interestingly, these effects could not be detected for chondrocytes which were pretreated with the nanocapsules. Overall, besides presenting a sophisticated carrier system for joint application, these results highlight the necessity of establishing combinatorial analytical approaches to elucidate cellular uptake, the interplay of codelivered drugs and their therapeutic effect on the subcellular level.
Collapse
Affiliation(s)
- Birthe Kann
- Saarland University , Department of Biopharmaceutics and Pharmaceutical Technology, Campus A4.1, 66123 Saarbruecken, Germany.,University of Twente , Optical Sciences Group, MESA+ Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Christian Spengler
- Saarland University , Experimental Physics, Campus E2.9, 66123 Saarbruecken, Germany
| | - Karine Coradini
- Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, Federal University of Rio Grande do Sul (UFRGS) , 90610-000, Porto Alegre, Rio Grande do Sul, Brazil
| | - Lucas A Rigo
- Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, Federal University of Rio Grande do Sul (UFRGS) , 90610-000, Porto Alegre, Rio Grande do Sul, Brazil
| | - Martin L Bennink
- University of Twente , Nanobiophysics Group, MESA+ Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Karin Jacobs
- Saarland University , Experimental Physics, Campus E2.9, 66123 Saarbruecken, Germany
| | - Herman L Offerhaus
- University of Twente , Optical Sciences Group, MESA+ Institute for Nanotechnology, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Ruy C R Beck
- Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, Federal University of Rio Grande do Sul (UFRGS) , 90610-000, Porto Alegre, Rio Grande do Sul, Brazil
| | - Maike Windbergs
- Saarland University , Department of Biopharmaceutics and Pharmaceutical Technology, Campus A4.1, 66123 Saarbruecken, Germany.,Helmholtz Centre for Infection Research and Helmholtz Institute for Pharmaceutical Research Saarland , Department of Drug Delivery, Campus E 8.1, 66123 Saarbruecken, Germany.,PharmBioTec GmbH , Department of Drug Delivery, Science Park 1, 66123 Saarbruecken, Germany
| |
Collapse
|
125
|
Abdelhady HG, Abdel-Salam HA, Niazy EM, Mueller A, Quast MJ, Effat AM, Elbehairi SEI. Spatiotemporal PFQNM visualization of the effect of suicide dendriplexes on dividing HeLa cells. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2016; 12:2365-2371. [PMID: 27389145 DOI: 10.1016/j.nano.2016.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/09/2016] [Accepted: 06/09/2016] [Indexed: 10/21/2022]
Abstract
Suicide gene delivery is significant in cancer therapy but has not been fully investigated on a cellular scale. Here, Peak Force Quantitative Nanomechanical atomic force microscopy (PFQNM-AFM) was applied to visualize the effect of herpes simplex virus thymidine kinase dendriplexes (G4AcFaHSTK) on the morphological and nanomechanical properties of individual live and dividing HeLa cells. Cells were then exposed to G4AcFaHSTK, followed by ganciclovir, and directly imaged by real-time PFQNM-AFM. Cell membrane liquefaction, cytoplasmic shrinkage, and cytoskeleton structure loss were observed during cell division. The average Young's modulus of the nuclear region increased with time as the cell continued from metaphase (6.29 kPa) to telophase (13.6 kPa) and then decreased (2.25 kPa) upon apoptosis. In contrast, cells exposed to either ganciclovir or G4AcFaHSTK alone have no changes. Thus, understanding the real-time effects of suicide dendriplexes on the cytoskeletal and nanomechanical behaviors of cancer cells may provide new methods for cancer treatment.
Collapse
Affiliation(s)
- Hosam G Abdelhady
- Pharmaceutics and Pharmaceutical Technology, College of Pharmacy-Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia; Bioavailability Center, National Organization for Drug Control and Research, Agouza, Giza, Egypt.
| | - Hassan A Abdel-Salam
- Pharmaceutics and Pharmaceutical Technology, College of Pharmacy-Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia; Department of Microbiology, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt
| | - Esmaeel M Niazy
- Pharmaceutics and Pharmaceutical Technology, College of Pharmacy-Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia
| | - Anja Mueller
- Department of Chemistry, Central Michigan University, Mount Pleasant, MI, USA
| | - Matthew J Quast
- Department of Chemistry, Central Michigan University, Mount Pleasant, MI, USA
| | - Ahmed M Effat
- Pharmaceutics and Pharmaceutical Technology, College of Pharmacy-Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia
| | - Serag-Eldin I Elbehairi
- Cell Culture Laboratory, Egyptian Organization for Biological Products and Vaccines, Agouza, Giza, Egypt; Biology Department, Faculty of Science, King Khalid University, Abha, Saudi Arabia
| |
Collapse
|
126
|
Li M, Liu L, Xiao X, Xi N, Wang Y. Viscoelastic Properties Measurement of Human Lymphocytes by Atomic Force Microscopy Based on Magnetic Beads Cell Isolation. IEEE Trans Nanobioscience 2016; 15:398-411. [DOI: 10.1109/tnb.2016.2547639] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
127
|
Lee Y, Kim Y, Lee D, Roy D, Park JW. Quantification of Fewer than Ten Copies of a DNA Biomarker without Amplification or Labeling. J Am Chem Soc 2016; 138:7075-81. [DOI: 10.1021/jacs.6b02791] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
| | | | | | - Dhruvajyoti Roy
- Nanogea Inc., 6162 Bristol Parkway, Culver City, California 90230, United States
| | | |
Collapse
|
128
|
Dong C, Hu X, Dinu CZ. Current status and perspectives in atomic force microscopy-based identification of cellular transformation. Int J Nanomedicine 2016; 11:2107-18. [PMID: 27274238 PMCID: PMC4876801 DOI: 10.2147/ijn.s103501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Understanding the complex interplay between cells and their biomechanics and how the interplay is influenced by the extracellular microenvironment, as well as how the transforming potential of a tissue from a benign to a cancerous one is related to the dynamics of both the cell and its surroundings, holds promise for the development of targeted translational therapies. This review provides a comprehensive overview of atomic force microscopy-based technology and its applications for identification of cellular progression to a cancerous phenotype. The review also offers insights into the advancements that are required for the next user-controlled tool to allow for the identification of early cell transformation and thus potentially lead to improved therapeutic outcomes.
Collapse
Affiliation(s)
- Chenbo Dong
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, USA
| | - Xiao Hu
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, USA
| | - Cerasela Zoica Dinu
- Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, USA
| |
Collapse
|
129
|
Aytac Korkmaz S. Diagnosis of cervical cancer cell taken from scanning electron and atomic force microscope images of the same patients using discrete wavelet entropy energy and Jensen Shannon, Hellinger, Triangle Measure classifier. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2016; 160:39-49. [PMID: 26921605 DOI: 10.1016/j.saa.2016.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 02/11/2016] [Indexed: 06/05/2023]
Abstract
The aim of this article is to provide early detection of cervical cancer by using both Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) images of same patient. When the studies in the literature are examined, it is seen that the AFM and SEM images of the same patient are not used together for early diagnosis of cervical cancer. AFM and SEM images can be limited when using only one of them for the early detection of cervical cancer. Therefore, multi-modality solutions which give more accuracy results than single solutions have been realized in this paper. Optimum feature space has been obtained by Discrete Wavelet Entropy Energy (DWEE) applying to the 3×180 AFM and SEM images. Then, optimum features of these images are classified with Jensen Shannon, Hellinger, and Triangle Measure (JHT) Classifier for early diagnosis of cervical cancer. However, between classifiers which are Jensen Shannon, Hellinger, and triangle distance have been validated the measures via relationships. Afterwards, accuracy diagnosis of normal, benign, and malign cervical cancer cell was found by combining mean success rates of Jensen Shannon, Hellinger, and Triangle Measure which are connected with each other. Averages of accuracy diagnosis for AFM and SEM images by averaging the results obtained from these 3 classifiers are found as 98.29% and 97.10%, respectively. It has been observed that AFM images for early diagnosis of cervical cancer have higher performance than SEM images. Also in this article, surface roughness of malign AFM images in the result of the analysis made for the AFM images, according to the normal and benign AFM images is observed as larger, If the volume of particles has found as smaller.
Collapse
Affiliation(s)
- Sevcan Aytac Korkmaz
- Engineering Faculty, Department of Electrical-Electronic Engineering, Firat University, 23100 Elazığ, Turkey.
| |
Collapse
|
130
|
Rana S, Elci SG, Mout R, Singla AK, Yazdani M, Bender M, Bajaj A, Saha K, Bunz UHF, Jirik FR, Rotello VM. Ratiometric Array of Conjugated Polymers-Fluorescent Protein Provides a Robust Mammalian Cell Sensor. J Am Chem Soc 2016; 138:4522-9. [PMID: 26967961 PMCID: PMC5846335 DOI: 10.1021/jacs.6b00067] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Supramolecular complexes of a family of positively charged conjugated polymers (CPs) and green fluorescent protein (GFP) create a fluorescence resonance energy transfer (FRET)-based ratiometric biosensor array. Selective multivalent interactions of the CPs with mammalian cell surfaces caused differential change in FRET signals, providing a fingerprint signature for each cell type. The resulting fluorescence signatures allowed the identification of 16 different cell types and discrimination between healthy, cancerous, and metastatic cells, with the same genetic background. While the CP-GFP sensor array completely differentiated between the cell types, only partial classification was achieved for the CPs alone, validating the effectiveness of the ratiometric sensor. The utility of the biosensor was further demonstrated in the detection of blinded unknown samples, where 121 of 128 samples were correctly identified. Notably, this selectivity-based sensor stratified diverse cell types in minutes, using only 2000 cells, without requiring specific biomarkers or cell labeling.
Collapse
Affiliation(s)
- Subinoy Rana
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
- Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
| | - S. Gokhan Elci
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
| | - Rubul Mout
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
| | - Arvind K. Singla
- Department of Biochemistry and Molecular Biology, The McCaig Institute for Bone and Joint Health, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
| | - Mahdieh Yazdani
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
| | - Markus Bender
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, FRG
| | - Avinash Bajaj
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
- Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology, 180 Udyog Vihar, Phase I, Gurgaon-122016, Haryana, India
| | - Krishnendu Saha
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
| | - Uwe H. F. Bunz
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, FRG
| | - Frank R. Jirik
- Department of Biochemistry and Molecular Biology, The McCaig Institute for Bone and Joint Health, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
| | - Vincent M. Rotello
- Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA
| |
Collapse
|
131
|
Yakubov GE, Bonilla MR, Chen H, Doblin MS, Bacic A, Gidley MJ, Stokes JR. Mapping nano-scale mechanical heterogeneity of primary plant cell walls. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2799-816. [PMID: 26988718 PMCID: PMC4861025 DOI: 10.1093/jxb/erw117] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nanoindentation experiments are performed using an atomic force microscope (AFM) to quantify the spatial distribution of mechanical properties of plant cell walls at nanometre length scales. At any specific location on the cell wall, a complex (non-linear) force-indentation response occurs that can be deconvoluted using a unique multiregime analysis (MRA). This allows an unambiguous evaluation of the local transverse elastic modulus of the wall. Nanomechanical measurements on suspension-cultured cells (SCCs), derived from Italian ryegrass (Lolium multiflorum) starchy endosperm, show three characteristic modes of deformation and a spatial distribution of elastic moduli across the surface. 'Soft' and 'hard' domains are found across length scales between 0.1 µm and 3 µm, which is well above a typical pore size of the polysaccharide mesh. The generality and wider applicability of this mechanical heterogeneity is verified through in planta characterization on leaf epidermal cells of Arabidopsis thaliana and L. multiflorum The outcomes of this research provide a basis for uncovering and quantifying the relationships between local wall composition, architecture, cell growth, and/or morphogenesis.
Collapse
Affiliation(s)
- Gleb E Yakubov
- Australian Research Council Centre of Excellence in Plant Cell Walls School of Chemical Engineering, The University of Queensland, Queensland, Australia
| | - Mauricio R Bonilla
- Australian Research Council Centre of Excellence in Plant Cell Walls School of Chemical Engineering, The University of Queensland, Queensland, Australia
| | - Huaying Chen
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Queensland, Australia
| | - Monika S Doblin
- Australian Research Council Centre of Excellence in Plant Cell Walls School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Antony Bacic
- Australian Research Council Centre of Excellence in Plant Cell Walls School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael J Gidley
- Australian Research Council Centre of Excellence in Plant Cell Walls Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Queensland, Australia
| | - Jason R Stokes
- Australian Research Council Centre of Excellence in Plant Cell Walls School of Chemical Engineering, The University of Queensland, Queensland, Australia
| |
Collapse
|
132
|
Synergistic Effect of Cold Atmospheric Plasma and Drug Loaded Core-shell Nanoparticles on Inhibiting Breast Cancer Cell Growth. Sci Rep 2016; 6:21974. [PMID: 26917087 PMCID: PMC4768177 DOI: 10.1038/srep21974] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/02/2016] [Indexed: 11/09/2022] Open
Abstract
Nano-based drug delivery devices allowing for effective and sustained targeted delivery of therapeutic agents to solid tumors have revolutionized cancer treatment. As an emerging biomedical technique, cold atmospheric plasma (CAP), an ionized non-thermal gas mixture composed of various reactive oxygen species, reactive nitrogen species, and UV photons, shows great potential for cancer treatment. Here we seek to develop a new dual cancer therapeutic method by integrating promising CAP and novel drug loaded core-shell nanoparticles and evaluate its underlying mechanism for targeted breast cancer treatment. For this purpose, core-shell nanoparticles were synthesized via co-axial electrospraying. Biocompatible poly (lactic-co-glycolic acid) was selected as the polymer shell to encapsulate anti-cancer therapeutics. Results demonstrated uniform size distribution and high drug encapsulation efficacy of the electrosprayed nanoparticles. Cell studies demonstrated the effectiveness of drug loaded nanoparticles and CAP for synergistic inhibition of breast cancer cell growth when compared to each treatment separately. Importantly, we found CAP induced down-regulation of metastasis related gene expression (VEGF, MTDH, MMP9, and MMP2) as well as facilitated drug loaded nanoparticle uptake which may aid in minimizing drug resistance-a major problem in chemotherapy. Thus, the integration of CAP and drug encapsulated nanoparticles provides a promising tool for the development of a new cancer treatment strategy.
Collapse
|
133
|
Simon M, Dokukin M, Kalaparthi V, Spedden E, Sokolov I, Staii C. Load Rate and Temperature Dependent Mechanical Properties of the Cortical Neuron and Its Pericellular Layer Measured by Atomic Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1111-1119. [PMID: 26727545 DOI: 10.1021/acs.langmuir.5b04317] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
When studying the mechanical properties of cells by an indentation technique, it is important to take into account the nontrivial pericellular interface (or pericellular "brush") which includes a pericellular coating and corrugation of the pericellular membrane (microvilli and microridges). Here we use atomic force microscopy (AFM) to study the mechanics of cortical neurons taking into account the presence of the above pericellular brush surrounding cell soma. We perform a systematic study of the mechanical properties of both the brush layer and the underlying neuron soma and demonstrate that the brush layer is likely responsible for the low elastic modulus (<1 kPa) typically reported for cortical neurons. When the contribution of the pericellular brush is excluded, the average elastic modulus of the cortical neuron soma is found to be 3-4 times larger than previously reported values measured under similar physiological conditions. We also demonstrate that the underlying soma behaves as a nonviscous elastic material over the indentation rates studied (1-10 μm/s). As a result, it seems that the brush layer is responsible for the previously reported viscoelastic response measured for the neuronal cell body as a whole, within these indentation rates. Due to of the similarities between the macroscopic brain mechanics and the effective modulus of the pericellular brush, we speculate that the pericellular brush layer might play an important role in defining the macroscopic mechanical properties of the brain.
Collapse
Affiliation(s)
- Marc Simon
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Maxim Dokukin
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Vivekanand Kalaparthi
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Elise Spedden
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Igor Sokolov
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| | - Cristian Staii
- Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States
| |
Collapse
|
134
|
Abstract
Currently, biomechanics of living cells is in the focus of interest due to noticeable capability of such techniques like atomic force microscopy (AFM) to probe cellular properties at the single cell level directly on living cells. The research carried out, so far, delivered data showing, on the one hand, the use of cellular mechanics as a biomarker of various pathological changes, which, on the other hand, reveal relative nature of biomechanics. In the AFM, the elastic properties of living cells are delivered from indentation experiments and described quantitatively by Young's modulus defined here as a measure of cellular deformability. Here, the AFM studies directly comparing the mechanical properties of normal and cancerous cells are summarized and presented together with a few important issues related to the relativeness of Young's modulus.
Collapse
Affiliation(s)
- Małgorzata Lekka
- Institute of Nuclear Physics, PAS, Radzikowskiego 152, 31-342 Kraków, Poland
| |
Collapse
|
135
|
Sokolov I, Zorn G, Nichols JM. A study of molecular adsorption of a cationic surfactant on complex surfaces with atomic force microscopy. Analyst 2016; 141:1017-26. [PMID: 26730682 DOI: 10.1039/c5an01941a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The study of molecular adsorption on solid surfaces is of broad interest. However, so far the study has been restricted to idealized flat smooth rigid surfaces which are rarely the case in real world applications. Here we describe a study of molecular adsorption on a complex surface of the submicron fibers of a fibrous membrane of regenerated cellulose in aqueous media. We use a cationic surfactant, cetyltrimethylammonium chloride (CTAC), as the adsorbing molecule. We study the equilibrium adsorption of CTAC molecules on the same area of the fibers by sequentially immersing the membrane in pure water, 1 mM and then a 20 mM solution of CTAC. Atomic force microscopy (AFM) is applied to study the adsorption. The force-volume mode is used to record the force-deformation curves of the adsorbed molecules on the fiber surface. We suggest a model to separate the forces due to the adsorbed molecules from the elastic deformation of the fiber. Interestingly, knowledge of the surface geometry is not required in this model provided the surface is made of elastically homogeneous material. Different models are investigated to estimate the amount of the adsorbed molecules based on the obtained force curves. The exponential steric repulsion model fits the force data the best. The amount of the adsorbed surfactant molecules and its dependence on the concentration are found to be reasonable compared to the data previously measured by means of Raman scattering done on a flat surface of silica.
Collapse
Affiliation(s)
- I Sokolov
- Departments of ME, BME, Physics, Tufts University, Medford, MA 02155, USA.
| | | | | |
Collapse
|
136
|
Single-Cell Mechanical Properties: Label-Free Biomarkers for Cell Status Evaluation. SERIES IN BIOENGINEERING 2016. [DOI: 10.1007/978-3-662-49118-8_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
137
|
Liu YX, Karsai A, Anderson DS, Silva RM, Uyeminami DL, Van Winkle LS, Pinkerton KE, Liu GY. Single-Cell Mechanics Provides an Effective Means To Probe in Vivo Interactions between Alveolar Macrophages and Silver Nanoparticles. J Phys Chem B 2015; 119:15118-29. [PMID: 26562364 DOI: 10.1021/acs.jpcb.5b07656] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single-cell mechanics, derived from atomic force microscopy-based technology, provides a new and effective means to investigate nanomaterial-cell interactions upon in vivo exposure. Lung macrophages represent initial and important responses upon introducing nanoparticles into the respiratory tract, as well as particle clearance with time. Cellular mechanics has previously proven effective to probe in vitro nanomaterial-cell interactions. This study extends technology further to probe the interactions between primary alveolar macrophages (AM) and silver nanoparticles (AgNPs) upon in vivo exposure. Two types of AgNPs, 20 and 110 nm, were instilled to rat lung at 0.5 mg AgNPs/kg body weight, and allowed 24 h interaction. The consequences of these interactions were investigated by harvesting the primary AMs while maintaining their biological status. Cellular mechanics measurements revealed the diverse responses among AM cells, due to variations in AgNP uptake and oxidative dissolving into Ag(+). Three major responses are evident: zero to low uptake that does not alter cellular mechanics, intracellular accumulation of AgNPs trigger cytoskeleton rearrangement resulting in the stiffening of mechanics, and damage of cytoskeleton that softens the mechanical profile. These effects were confirmed using confocal imaging of F-actin and measurements of reactive oxygen species production. More detailed intracellular interactions will also be discussed on the basis of this study in conjunction with prior knowledge of AgNP toxicity.
Collapse
Affiliation(s)
- Ying X Liu
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Arpad Karsai
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Donald S Anderson
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Rona M Silva
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Dale L Uyeminami
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Laura S Van Winkle
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Kent E Pinkerton
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| | - Gang-yu Liu
- Department of Chemistry, ‡Center for Health and the Environment, §Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, and ∥Department of Pediatrics, School of Medicine, University of California , Davis, California 95616, United States
| |
Collapse
|
138
|
Kilpatrick JI, Revenko I, Rodriguez BJ. Nanomechanics of Cells and Biomaterials Studied by Atomic Force Microscopy. Adv Healthc Mater 2015. [PMID: 26200464 DOI: 10.1002/adhm.201500229] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The behavior and mechanical properties of cells are strongly dependent on the biochemical and biomechanical properties of their microenvironment. Thus, understanding the mechanical properties of cells, extracellular matrices, and biomaterials is key to understanding cell function and to develop new materials with tailored mechanical properties for tissue engineering and regenerative medicine applications. Atomic force microscopy (AFM) has emerged as an indispensable technique for measuring the mechanical properties of biomaterials and cells with high spatial resolution and force sensitivity within physiologically relevant environments and timescales in the kPa to GPa elastic modulus range. The growing interest in this field of bionanomechanics has been accompanied by an expanding array of models to describe the complexity of indentation of hierarchical biological samples. Furthermore, the integration of AFM with optical microscopy techniques has further opened the door to a wide range of mechanotransduction studies. In recent years, new multidimensional and multiharmonic AFM approaches for mapping mechanical properties have been developed, which allow the rapid determination of, for example, cell elasticity. This Progress Report provides an introduction and practical guide to making AFM-based nanomechanical measurements of cells and surfaces for tissue engineering applications.
Collapse
Affiliation(s)
- Jason I. Kilpatrick
- Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Belfield Dublin 4 Ireland
| | - Irène Revenko
- Asylum Research an Oxford Instruments Company; 6310 Hollister Avenue Santa Barbara CA 93117 USA
| | - Brian J. Rodriguez
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin; Belfield, Dublin 4, Ireland; School of Physics; University College Dublin; Belfield Dublin 4 Ireland
| |
Collapse
|
139
|
Affiliation(s)
- Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, MA 02155, USA.,Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.,Department of Physics, Tufts University, Medford, MA 02155, USA
| |
Collapse
|
140
|
Geng L, Feng J, Sun Q, Liu J, Hua W, Li J, Ao Z, You K, Guo Y, Liao F, Zhang Y, Guo H, Han J, Xiong G, Zhang L, Han D. Nanomechanical clues from morphologically normal cervical squamous cells could improve cervical cancer screening. NANOSCALE 2015; 7:15589-93. [PMID: 26370304 DOI: 10.1039/c5nr03662c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Applying an atomic force microscope, we performed a nanomechanical analysis of morphologically normal cervical squamous cells (MNSCs) which are commonly used in cervical screening. Results showed that nanomechanical parameters of MNSCs correlate well with cervical malignancy, and may have potential in cancer screening to provide early diagnosis.
Collapse
Affiliation(s)
- Li Geng
- Peking University Third Hospital, Beijing, China 100191
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
141
|
Bui VC, Nguyen TH. The role of CD4 on mechanical properties of live cell membrane. J Biomed Mater Res A 2015; 104:239-44. [DOI: 10.1002/jbm.a.35559] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/13/2015] [Accepted: 09/03/2015] [Indexed: 01/21/2023]
Affiliation(s)
- Van-Chien Bui
- Center for Innovation Competence - Humoral Immune Reactions in Cardiovascular Diseases (ZIK HIKE); University of Greifswald; 17489 Greifswald Germany
| | - Thi-Huong Nguyen
- Center for Innovation Competence - Humoral Immune Reactions in Cardiovascular Diseases (ZIK HIKE); University of Greifswald; 17489 Greifswald Germany
| |
Collapse
|
142
|
Computer simulations of the mechanical response of brushes on the surface of cancerous epithelial cells. Sci Rep 2015; 5:13218. [PMID: 26315877 PMCID: PMC4551992 DOI: 10.1038/srep13218] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/21/2015] [Indexed: 11/29/2022] Open
Abstract
We report a model for atomic force microscopy by means of computer simulations of molecular brushes on surfaces of biological interest such as normal and cancerous cervical epithelial cells. Our model predicts that the force needed to produce a given indentation on brushes that can move on the surface of the cell (called “liquid” brushes) is the same as that required for brushes whose ends are fixed on the cell’s surface (called “solid” brushes), as long as the tip of the microscope covers the entire area of the brush. Additionally, we find that cancerous cells are softer than normal ones, in agreement with various experiments. Moreover, soft brushes are found to display larger resistance to compression than stiff ones. This phenomenon is the consequence of the larger equilibrium length of the soft brushes and the cooperative association of solvent molecules trapped within the brushes, which leads to an increase in the osmotic pressure. Our results show that a careful characterization of the brushes on epithelial cells is indispensable when determining the mechanical response of cancerous cells.
Collapse
|
143
|
Guz N, Dokukin M, Kalaparthi V, Sokolov I. If cell mechanics can be described by elastic modulus: study of different models and probes used in indentation experiments. Biophys J 2015; 107:564-575. [PMID: 25099796 DOI: 10.1016/j.bpj.2014.06.033] [Citation(s) in RCA: 197] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 06/03/2014] [Accepted: 06/16/2014] [Indexed: 10/25/2022] Open
Abstract
Here we investigated the question whether cells, being highly heterogeneous objects, could be described with the elastic modulus (effective Young's modulus) in a self-consistent way. We performed a comparative analysis of the elastic modulus derived from the indentation data obtained with atomic force microscopy (AFM) on human cervical epithelial cells (both normal and cancerous). Both sharp (cone) and dull (2500-nm radius sphere) AFM probes were used. The indentation data were processed through different elastic models. The cell was approximated as a homogeneous elastic medium that had either 1), smooth hemispherical boundary (Hertz/Sneddon models) or 2), the boundary covered with a layer of glycocalyx and membrane protrusions ("brush" models). Consistency of these approximations was investigated. Specifically, we tested the independence of the elastic modulus of the indentation depth, which is assumed in these models. We demonstrated that only one model showed consistency in treating cells as a homogeneous elastic medium, namely, the brush model, when processing the indentation data collected with the dull AFM probe. The elastic modulus demonstrated strong depth dependence in all models: Hertz/Sneddon models (no brush taken into account), and when the brush model was applied to the data collected with sharp conical probes. We conclude that it is possible to describe the elastic properties of the cell body by means of an effective elastic modulus, used in a self-consistent way, when using the brush model to analyze data collected with a dull AFM probe. The nature of these results is discussed.
Collapse
Affiliation(s)
- Nataliia Guz
- Department of Physics, Clarkson University, Potsdam, New York
| | - Maxim Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts
| | | | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts; Department of Biomedical Engineering, Tufts University, Medford, Massachusetts; Department of Physics, Tufts University, Medford, Massachusetts.
| |
Collapse
|
144
|
Studying biological membranes with extended range high-speed atomic force microscopy. Sci Rep 2015; 5:11987. [PMID: 26169348 PMCID: PMC4500952 DOI: 10.1038/srep11987] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/11/2015] [Indexed: 11/28/2022] Open
Abstract
High—speed atomic force microscopy has proven to be a valuable tool for the study of biomolecular systems at the nanoscale. Expanding its application to larger biological specimens such as membranes or cells has, however, proven difficult, often requiring fundamental changes in the AFM instrument. Here we show a way to utilize conventional AFM instrumentation with minor alterations to perform high-speed AFM imaging with a large scan range. Using a two—actuator design with adapted control systems, a 130 × 130 × 5 μm scanner with nearly 100 kHz open—loop small-signal Z—bandwidth is implemented. This allows for high-speed imaging of biologically relevant samples as well as high-speed measurements of nanomechanical surface properties. We demonstrate the system performance by real-time imaging of the effect of charged polymer nanoparticles on the integrity of lipid membranes at high imaging speeds and peak force tapping measurements at 32 kHz peak force rate.
Collapse
|
145
|
Nanoscale monitoring of drug actions on cell membrane using atomic force microscopy. Acta Pharmacol Sin 2015; 36:769-82. [PMID: 26027658 DOI: 10.1038/aps.2015.28] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 03/13/2015] [Indexed: 02/06/2023] Open
Abstract
Knowledge of the nanoscale changes that take place in individual cells in response to a drug is useful for understanding the drug action. However, due to the lack of adequate techniques, such knowledge was scarce until the advent of atomic force microscopy (AFM), which is a multifunctional tool for investigating cellular behavior with nanometer resolution under near-physiological conditions. In the past decade, researchers have applied AFM to monitor the morphological and mechanical dynamics of individual cells following drug stimulation, yielding considerable novel insight into how the drug molecules affect an individual cell at the nanoscale. In this article we summarize the representative applications of AFM in characterization of drug actions on cell membrane, including topographic imaging, elasticity measurements, molecular interaction quantification, native membrane protein imaging and manipulation, etc. The challenges that are hampering the further development of AFM for studies of cellular activities are aslo discussed.
Collapse
|
146
|
Cartagena-Rivera AX, Wang WH, Geahlen RL, Raman A. Fast, multi-frequency, and quantitative nanomechanical mapping of live cells using the atomic force microscope. Sci Rep 2015; 5:11692. [PMID: 26118423 PMCID: PMC4484408 DOI: 10.1038/srep11692] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 06/03/2015] [Indexed: 11/08/2022] Open
Abstract
A longstanding goal in cellular mechanobiology has been to link dynamic biomolecular processes underpinning disease or morphogenesis to spatio-temporal changes in nanoscale mechanical properties such as viscoelasticity, surface tension, and adhesion. This requires the development of quantitative mechanical microscopy methods with high spatio-temporal resolution within a single cell. The Atomic Force Microscope (AFM) can map the heterogeneous mechanical properties of cells with high spatial resolution, however, the image acquisition time is 1-2 orders of magnitude longer than that required to study dynamic cellular processes. We present a technique that allows commercial AFM systems to map quantitatively the dynamically changing viscoelastic properties of live eukaryotic cells at widely separated frequencies over large areas (several 10's of microns) with spatial resolution equal to amplitude-modulation (AM-AFM) and with image acquisition times (tens of seconds) approaching those of speckle fluorescence methods. This represents a ~20 fold improvement in nanomechanical imaging throughput compared to AM-AFM and is fully compatible with emerging high speed AFM systems. This method is used to study the spatio-temporal mechanical response of MDA-MB-231 breast carcinoma cells to the inhibition of Syk protein tyrosine kinase giving insight into the signaling pathways by which Syk negatively regulates motility of highly invasive cancer cells.
Collapse
Affiliation(s)
- Alexander X. Cartagena-Rivera
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA
| | - Wen-Horng Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Robert L. Geahlen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana, USA
| | - Arvind Raman
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA
| |
Collapse
|
147
|
Hung MS, Tsai MF. Investigating the Influence of Anti-Cancer Drugs on the Mechanics of Cells Using AFM. BIONANOSCIENCE 2015. [DOI: 10.1007/s12668-015-0174-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
148
|
Nano-Biomechanical Study of Spatio-Temporal Cytoskeleton Rearrangements that Determine Subcellular Mechanical Properties and Endothelial Permeability. Sci Rep 2015; 5:11097. [PMID: 26086333 PMCID: PMC4650616 DOI: 10.1038/srep11097] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/11/2015] [Indexed: 12/27/2022] Open
Abstract
The endothelial cell (EC) lining of the pulmonary vascular system forms a
semipermeable barrier between blood and the interstitium and regulates various
critical biochemical functions. Collectively, it represents a prototypical
biomechanical system, where the complex hierarchical architecture, from the
molecular scale to the cellular and tissue level, has an intimate and intricate
relationship with its biological functions. We investigated the mechanical
properties of human pulmonary artery endothelial cells (ECs) using atomic force
microscopy (AFM). Concurrently, the wider distribution and finer details of the
cytoskeletal nano-structure were examined using fluorescence microscopy (FM) and
scanning transmission electron microscopy (STEM), respectively. These correlative
measurements were conducted in response to the EC barrier-disrupting agent,
thrombin, and barrier-enhancing agent, sphingosine 1-phosphate (S1P). Our new
findings and analysis directly link the spatio-temporal complexities of cell
re-modeling and cytoskeletal mechanical properties alteration. This work provides
novel insights into the biomechanical function of the endothelial barrier and
suggests similar opportunities for understanding the form-function relationship in
other biomechanical subsystems.
Collapse
|
149
|
Guz NV, Dokukin ME, Woodworth CD, Cardin A, Sokolov I. Towards early detection of cervical cancer: Fractal dimension of AFM images of human cervical epithelial cells at different stages of progression to cancer. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2015; 11:1667-75. [PMID: 25959926 DOI: 10.1016/j.nano.2015.04.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 01/22/2023]
Abstract
UNLABELLED We used AFM HarmoniX modality to analyse the surface of individual human cervical epithelial cells at three stages of progression to cancer, normal, immortal (pre-malignant) and carcinoma cells. Primary cells from 6 normal strains, 6 cancer, and 6 immortalized lines (derived by plasmid DNA-HPV-16 transfection of cells from 6 healthy individuals) were tested. This cell model allowed for good control of the cell phenotype down to the single cell level, which is impractical to attain in clinical screening tests (ex-vivo). AFM maps of physical (nonspecific) adhesion are collected on fixed dried cells. We show that a surface parameter called fractal dimension can be used to segregate normal from both immortal pre-malignant and malignant cells with sensitivity and specificity of more than 99%. The reported method of analysis can be directly applied to cells collected in liquid cytology screening tests and identified as abnormal with regular optical methods to increase sensitivity. FROM THE CLINICAL EDITOR Despite cervical smear screening, sometimes it is very difficult to differentiate cancers cells from pre-malignant cells. By using AFM to analyze the surface properties of human cervical epithelial cells, the authors were able to accurately identify normal from abnormal cells. This method could augment existing protocols to increase diagnostic accuracy.
Collapse
Affiliation(s)
- Nataliia V Guz
- Department of Physics, Clarkson University, Potsdam, NY, USA
| | - Maxim E Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA
| | | | - Andrew Cardin
- Department of Physics, Clarkson University, Potsdam, NY, USA
| | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA; Department of Biomedical Engineering, Tufts University, Medford, MA, USA; Department of Physics, Tufts University, Medford, MA, USA.
| |
Collapse
|
150
|
Singh G, Bremmell KE, Griesser HJ, Kingshott P. Colloid-probe AFM studies of the interaction forces of proteins adsorbed on colloidal crystals. SOFT MATTER 2015; 11:3188-3197. [PMID: 25758979 DOI: 10.1039/c4sm02669a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In recent years, colloid-probe AFM has been used to measure the direct interaction forces between colloidal particles of different size or surface functionality in aqueous media, as one can study different forces in symmerical systems (i.e., sphere-sphere geometry). The present study investigates the interaction between protein coatings on colloid probes and hydrophilic surfaces decorated with hexagonally close packed single particle layers that are either uncoated or coated with proteins. Controlled solvent evaporation from aqueous suspensions of colloidal particles (coated with or without lysozyme and albumin) produces single layers of close-packed colloidal crystals over large areas on a solid support. The measurements have been carried out in an aqueous medium at different salt concentrations and pH values. The results show changes in the interaction forces as the surface charge of the unmodified or modified particles, and ionic strength or pH of the solution is altered. At high ionic strength or pH, electrostatic interactions are screened, and a strong repulsive force at short separation below 5 nm dominates, suggesting structural changes in the absorbed protein layer on the particles. We also study the force of adhesion, which decreases with an increment in the salt concentration, and the interaction between two different proteins indicating a repulsive interaction on approach and adhesion on retraction.
Collapse
Affiliation(s)
- Gurvinder Singh
- Interdisciplinary Nanoscience Centre, Faculty of Science, Aarhus University, Ny Munkegade, Aarhus C 8000, Denmark
| | | | | | | |
Collapse
|