Elasticity of single flexible polymer chains in good and poor solvents

Ahlawat, Vikhyaat; Rajput, Shatruhan Singh; Patil, Shivprasad

doi:10.1016/j.polymer.2021.124031

Cited by 12 publications

(7 citation statements)

References 54 publications

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“…The persistence length of 0.12 nm is again lower than the c-c bond length and raises the question on the validity of fitting the data with the WLC model. The Kuhn length of 0.24 nm coincides with the value obtained in other polar solvents like 2-propanol [ 21 ] and others [ 36 ] but is about five times lower than its measurement with magnetic tweezers [ 37 , 38 ]. It is noted that an earlier work by Oesterhelt et al [ 33 ] reported a Kuhn length of 0.7 nm in large size solvent molecule like hexadecane.…”

Section: Resultssupporting

confidence: 83%

“…Instead of global pulling experiments, a local oscillatory protocol is better suited for the sampling of the conformational landscape. This is due to two reasons: (1) the oscillatory technique is bidirectional in nature and hence is accurate in sampling the conformational space [ 20 ], (2) extracting an oscillatory response allows for a simple interpretation of intrinsic elasticity from the convolution of instrument effects [ 21 ]. However, oscillating the cantilever base end with a piezo and using the optical beam deflection scheme to detect oscillations necessitates viewing the cantilever as a continuum beam.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM

2022

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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.

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Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM

2022

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“…In addition, Kawakami et al 38) and Humphrisy et al 39,40) studied the dynamics of conformational transitions such as folding-unfolding of proteins and DNA by applying periodic forces driven by magnetism, and Mcleish et al 41,42) investigated the mechanism of internal friction in the high elongation expansion of polypeptide chains. Patil et al 43,44) measured the dynamic elastic response of single molecules by using a nonresonant oscillation method and discussed the differences in these responses in good and poor solvents. The study of viscoelasticity for single polymer chains will aid in our understanding of the origins of nonequilibrium properties in polymer solutions and polymeric materials.…”

Section: Dynamic Mechanical Properties Of Single Molecule Chainsmentioning

confidence: 99%

Static and Dynamic Mechanical Properties of Single Polymer Chains

Liang

2022

J. Soc. Rheol., Jpn

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Since the invention of atomic force microscopy (AFM), researchers have been able to study the statistical mechanical properties of individual polymer chains by using a technique known as single molecule force spectroscopy (SMFS), which stretches a single polymer chain by attaching one end of the chain to a substrate and the other end to the AFM tip. SMFS is used to obtain static information about single polymer chains, mainly through a quasistatic stretching process. With technological developments in recent years, dynamic SMFS measurements under nonequilibrium conditions have also been realized. The dynamic viscoelasticity of single molecule chains can also be measured, which will benefit our understanding of the nonequilibrium dynamic properties of polymeric materials.

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“…Atomic force microscopy (AFM)-based single molecule force spectroscopy (SMFS) is a powerful tool to investigate the properties of biomacromolecules (such as DNA, proteins and cellulose) from the single molecule level. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] AFM has been used to study the successful in this study, AFM-based SMFS was used to study the single-chain elasticity of chitin and chitosan in different conditions to investigate the similarities and differences from chitin to chitosan. The force measurements results indicate that these two polysaccharides present the same strength of intrachain H-bonds in the same solvents (nonane or DMSO), which results in these two polysaccharides present the same single-chain natural and backbone elasticity in the same solvents.…”

Section: Introductionmentioning

confidence: 99%