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Andrews JT, Baker KE, Handloser JT, Bridges N, Krone AA, Kett PJN. Formation of Supported Lipid Bilayers (SLBs) from Buffers Containing Low Concentrations of Group I Chloride Salts. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12819-12833. [PMID: 34699227 DOI: 10.1021/acs.langmuir.1c01707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Supported lipid bilayers (SLBs) are a useful tool for studying the interactions between lipids and other biomolecules that make up a cell membrane. SLBs are typically formed by the adsorption and rupture of vesicles from solution. Although it is known that many experimental factors can affect whether SLB formation is successful, there is no comprehensive understanding of the mechanism. In this work, we have used a quartz crystal microbalance (QCM) to investigate the role of the salt in the buffer on the formation of phosphatidylcholine SLBs on a silicon dioxide (SiO2) surface. We varied the concentration of sodium chloride in the buffer, from 5 to 150 mM, to find the minimum concentration of NaCl that was required for the successful formation of an SLB. We then repeated the experiments with other group I chloride salts (LiCl, KCl, and CsCl) and found that at higher salt concentrations (150 mM) SLB formation was successful for all of the salts used, and the degree of deformation of the adsorbed vesicles at the critical vesicle coverage was cation-dependent. The results showed that at an intermediate salt concentration (50 mM) the critical vesicle coverage was cation-dependent and at low salt concentrations (12.5 mM) the cation used determined whether SLB formation was successful. We found that the successful formation of SLBs could occur at lower electrolyte concentrations for KCl and CsCl than it did for NaCl. To understand these results, we calculated the magnitude of the vesicle-surface interaction energy using the Derjaguin-Landau-Verwey-Overbeek (DLVO) and extended-DLVO theory. We managed to explain the results obtained at higher salt concentrations by including cation-dependent surface potentials in the calculations and at lower salt concentrations by the addition of a cation-dependent hydration force. These results showed that the way that different cations in solution affect the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-SiO2 surface interaction energy depends on the ionic strength of the solution.
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Affiliation(s)
- J Tucker Andrews
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Kirstyn E Baker
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Jacob T Handloser
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Natalie Bridges
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Alexis A Krone
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Peter J N Kett
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
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Ito K, Ogawa Y, Yokota K, Matsumura S, Minamisawa T, Suga K, Shiba K, Kimura Y, Hirano-Iwata A, Takamura Y, Ogino T. Host Cell Prediction of Exosomes Using Morphological Features on Solid Surfaces Analyzed by Machine Learning. J Phys Chem B 2018; 122:6224-6235. [PMID: 29771528 DOI: 10.1021/acs.jpcb.8b01646] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Exosomes are extracellular nanovesicles released from any cells and found in any body fluid. Because exosomes exhibit information of their host cells (secreting cells), their analysis is expected to be a powerful tool for early diagnosis of cancers. To predict the host cells, we extracted multidimensional feature data about size, shape, and deformation of exosomes immobilized on solid surfaces by atomic force microscopy (AFM). The key idea is combination of support vector machine (SVM) learning for individual exosome particles and their interpretation by principal component analysis (PCA). We observed exosomes derived from three different cancer cells on SiO2/Si, 3-aminopropyltriethoxysilane-modified-SiO2/Si, and TiO2 substrates by AFM. Then, 14-dimensional feature vectors were extracted from AFM particle data, and classifiers were trained in 14-dimensional space. The prediction accuracy for host cells of test AFM particles was examined by the cross-validation test. As a result, we obtained prediction of exosome host cells with the best accuracy of 85.2% for two-class SVM learning and 82.6% for three-class one. By PCA of the particle classifiers, we concluded that the main factors for prediction accuracy and its strong dependence on substrates are incremental decrease in the PCA-defined aspect ratio of the particles with their volume.
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Affiliation(s)
- Kazuki Ito
- Yokohama National University , 79-5, Tokiwadai , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Yuta Ogawa
- Yokohama National University , 79-5, Tokiwadai , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Keiji Yokota
- Yokohama National University , 79-5, Tokiwadai , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Sachiko Matsumura
- Japanese Foundation for Cancer Research , 3-8-31 Ariake , Koto-ku, Tokyo 135-8550 , Japan
| | - Tamiko Minamisawa
- Japanese Foundation for Cancer Research , 3-8-31 Ariake , Koto-ku, Tokyo 135-8550 , Japan
| | - Kanako Suga
- Japanese Foundation for Cancer Research , 3-8-31 Ariake , Koto-ku, Tokyo 135-8550 , Japan
| | - Kiyotaka Shiba
- Japanese Foundation for Cancer Research , 3-8-31 Ariake , Koto-ku, Tokyo 135-8550 , Japan
| | - Yasuo Kimura
- Tokyo University of Technology , 1404-1, Katakura-Cho , Hachioji 192-0914 , Japan
| | - Ayumi Hirano-Iwata
- Tohoku University , 2-1-1, Katahira , Aoba-ku, Sendai , Miyagi 980-8577 , Japan
| | - Yuzuru Takamura
- Japan Advanced Institute of Science and Technology , 1-1, Asahi-Dai , Nomi , Ishikawa 923-1292 , Japan
| | - Toshio Ogino
- Yokohama National University , 79-5, Tokiwadai , Hodogaya-ku, Yokohama 240-8501 , Japan.,Japan Advanced Institute of Science and Technology , 1-1, Asahi-Dai , Nomi , Ishikawa 923-1292 , Japan
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Marr JM, Li F, Petlick AR, Schafer R, Hwang CT, Chabot A, Ruggiero ST, Tanner CE, Schultz ZD. The role of lateral tension in calcium-induced DPPS vesicle rupture. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11874-80. [PMID: 22799521 PMCID: PMC3422639 DOI: 10.1021/la301976s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We assess the role of lateral tension in rupturing anionic dipalmitoylphosphatidyserine (DPPS), neutral dipalmitoylphosphatidylcholine (DPPC), and mixed DPPS-DPPC vesicles. Binding of Ca(2+) is known to have a significant impact on the effective size of DPPS lipids and little effect on the size of DPPC lipids in bilayer structures. In the present work we utilized laser transmission spectroscopy (LTS) to assess the effect of Ca(2+)-induced stress on the stability of the DPPS and DPPC vesicles. The high sensitivity and resolution of LTS has permitted the determination of the size and shape of liposomes in solution. The results indicate a critical size after which DPPS single shell vesicles are no longer stable. Our measurements indicate Ca(2+) promotes bilayer fusion up to a maximum diameter of ca. 320 nm. These observations are consistent with a straightforward free-energy-based model of vesicle rupture involving lateral tension between lipids regulated by the binding of Ca(2+). Our results support a critical role of lateral interactions within lipid bilayers for controlling such processes as the formation of supported bilayer membranes and pore formation in vesicle fusion. Using this free energy model we are able to infer a lower bound for the area dilation modulus for DPPS (252 pN/nm) and demonstrate a substantial free energy increase associated with vesicle rupture.
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Affiliation(s)
- James M. Marr
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Frank Li
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Alexandra R. Petlick
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Robert Schafer
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Ching-Ting Hwang
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Adrienne Chabot
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Steven T. Ruggiero
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Carol E. Tanner
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Zachary D. Schultz
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Dimitrievski K. Deformation of adsorbed lipid vesicles as a function of vesicle size. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:3008-3011. [PMID: 20104868 DOI: 10.1021/la904743d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Experimental indications that adsorbed lipid vesicles are deformed on the surface (e.g., on SiO(2)) and that the deformation seems to be more pronounced for larger vesicles have been reported. In general, it has been assumed that larger vesicles should show a stronger tendency for spontaneous rupture, which is also backed up by thermodynamic considerations (Seifert, U.; Lipowsky, R. Phys. Rev. A 1990, 42, 4768; Seifert, U. Adv. Phys. 1997, 46, 13). However, using a newly developed model of a lipid bilayer, simulations were performed to study the shape of adsorbed lipid vesicles for different vesicle sizes, with the observation that larger vesicles indeed are more deformed on the surface, but that there is no additional tendency for larger vesicles to rupture spontaneously. It is shown here that the radius of curvature, on the portions of the vesicle membrane that are most strained, is practically independent of the vesicle size. A kinetic barrier for vesicle rupture is proposed to be the reason for the observed disagreement with thermodynamic theory.
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Affiliation(s)
- Kristian Dimitrievski
- Department of Applied Physics, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
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