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Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM
We estimate the elasticity of single polymer chains using atomic force microscope (AFM)-based oscillatory experiments. An accurate estimate of elasticity using AFM is limited by assumptions in describing the dynamics of an oscillating cantilever. Here, we use a home-built fiber-interferometry-based...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8839736/ https://www.ncbi.nlm.nih.gov/pubmed/35159871 http://dx.doi.org/10.3390/nano12030526 |
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author | Ahlawat, Vikhyaat Deopa, Surya Pratap S. Patil, Shivprasad |
author_facet | Ahlawat, Vikhyaat Deopa, Surya Pratap S. Patil, Shivprasad |
author_sort | Ahlawat, Vikhyaat |
collection | PubMed |
description | We estimate the elasticity of single polymer chains using atomic force microscope (AFM)-based oscillatory experiments. An accurate estimate of elasticity using AFM is limited by assumptions in describing the dynamics of an oscillating cantilever. Here, we use a home-built fiber-interferometry-based detection system that allows a simple and universal point-mass description of cantilever oscillations. By oscillating the cantilever base and detecting changes in cantilever oscillations with an interferometer, we extracted stiffness versus extension profiles for polymers. For polyethylene glycol (PEG) in a good solvent, stiffness–extension data showed significant deviation from conventional force–extension curves (FECs) measured in constant velocity pulling experiments. Furthermore, modeling stiffness data with an entropic worm-like chain (WLC) model yielded a persistence length of (0.5 ± 0.2 nm) compared to anomaly low value (0.12 nm ± 0.01) in conventional pulling experiments. This value also matched well with equilibrium measurements performed using magnetic tweezers. In contrast, polystyrene (PS) in a poor solvent, like water, showed no deviation between the two experiments. However, the stiffness profile for PS in good solvent (8M Urea) showed significant deviation from conventional force–extension curves. We obtained a persistence length of (0.8 ± 0.2 nm) compared to (0.22 nm ± 0.01) in pulling experiments. Our unambiguous measurements using interferometer yield physically acceptable values of persistence length. It validates the WLC model in good solvents but suggests caution for its use in poor solvents. |
format | Online Article Text |
id | pubmed-8839736 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-88397362022-02-13 Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM Ahlawat, Vikhyaat Deopa, Surya Pratap S. Patil, Shivprasad Nanomaterials (Basel) Article We estimate the elasticity of single polymer chains using atomic force microscope (AFM)-based oscillatory experiments. An accurate estimate of elasticity using AFM is limited by assumptions in describing the dynamics of an oscillating cantilever. Here, we use a home-built fiber-interferometry-based detection system that allows a simple and universal point-mass description of cantilever oscillations. By oscillating the cantilever base and detecting changes in cantilever oscillations with an interferometer, we extracted stiffness versus extension profiles for polymers. For polyethylene glycol (PEG) in a good solvent, stiffness–extension data showed significant deviation from conventional force–extension curves (FECs) measured in constant velocity pulling experiments. Furthermore, modeling stiffness data with an entropic worm-like chain (WLC) model yielded a persistence length of (0.5 ± 0.2 nm) compared to anomaly low value (0.12 nm ± 0.01) in conventional pulling experiments. This value also matched well with equilibrium measurements performed using magnetic tweezers. In contrast, polystyrene (PS) in a poor solvent, like water, showed no deviation between the two experiments. However, the stiffness profile for PS in good solvent (8M Urea) showed significant deviation from conventional force–extension curves. We obtained a persistence length of (0.8 ± 0.2 nm) compared to (0.22 nm ± 0.01) in pulling experiments. Our unambiguous measurements using interferometer yield physically acceptable values of persistence length. It validates the WLC model in good solvents but suggests caution for its use in poor solvents. MDPI 2022-02-03 /pmc/articles/PMC8839736/ /pubmed/35159871 http://dx.doi.org/10.3390/nano12030526 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Ahlawat, Vikhyaat Deopa, Surya Pratap S. Patil, Shivprasad Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM |
title | Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM |
title_full | Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM |
title_fullStr | Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM |
title_full_unstemmed | Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM |
title_short | Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM |
title_sort | quantitative elasticity of flexible polymer chains using interferometer-based afm |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8839736/ https://www.ncbi.nlm.nih.gov/pubmed/35159871 http://dx.doi.org/10.3390/nano12030526 |
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