Surface and Biomolecular Forces of Conducting Polymers

Higgins, Michael J.; Wallace, Gordon G.

doi:10.1080/15583724.2013.813856

Cited by 31 publications

(48 citation statements)

References 70 publications

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“…1b ). During oxidation, the negatively charged sulfonate groups coordinate with the positively charged polymer, causing the hydrophobic groups to orientate to the polymer-liquid interface 26 . The sulfonate groups and hydrophobic groups can then switch orientation during reduction, with the hydrophobic groups preferring to coordinate with the neutral polymer backbone.…”

Section: Resultsmentioning

confidence: 99%

Quantifying Molecular-Level Cell Adhesion on Electroactive Conducting Polymers using Electrochemical-Single Cell Force Spectroscopy

Zhang

Molino

Wallace

et al. 2015

Sci Rep

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Single Cell Force Spectroscopy was combined with Electrochemical-AFM to quantify the adhesion between live single cells and conducting polymers whilst simultaneously applying a voltage to electrically switch the polymer from oxidized to reduced states. The cell-conducting polymer adhesion represents the non-specific interaction between cell surface glycocalyx molecules and polymer groups such as sulfonate and dodecylbenzene groups, which rearrange their orientation during electrical switching. Single cell adhesion significantly increases as the polymer is switched from an oxidized to fully reduced state, indicating stronger cell binding to sulfonate groups as opposed to hydrophobic groups. This increase in single cell adhesion is concomitant with an increase in surface hydrophilicity and uptake of cell media, driven by cation movement, into the polymer film during electrochemical reduction. Binding forces between the glycocalyx and polymer surface are indicative of molecular-level interactions and during electrical stimulation there is a decrease in both the binding force and stiffness of the adhesive bonds. The study provides insight into the effects of electrochemical switching on cell adhesion at the cell-conducting polymer interface and is more broadly applicable to elucidating the binding of cell adhesion molecules in the presence of electrical fields and directly at electrode interfaces.

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Section: Resultsmentioning

confidence: 99%

Quantifying Molecular-Level Cell Adhesion on Electroactive Conducting Polymers using Electrochemical-Single Cell Force Spectroscopy

Zhang

Molino

Wallace

et al. 2015

Sci Rep

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“…During electrical stimulation, the redox switching mechanism for PPy-DBSA involves rearrangement of the sulfonate and dodecylbenzene groups of the DBSA molecules within the conducting polymer. 41 During oxidation (yellow), the negatively charged sulfonate groups coordinate with the positively charged polymer, causing the hydrophobic groups to orientate to the polymer-liquid interface [ Fig. 1(b)].…”

Section: A Electrical Stimulation Schemes Of Conducting Polymermentioning

confidence: 99%

Effect of electrochemical oxidation and reduction on cell de-adhesion at the conducting polymer–live cell interface as revealed by single cell force spectroscopy

Zhang

Wallace

et al. 2018

Biointerphases

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Cell adhesion on conducting polymers is important in organic bioelectronics, including applications such as electronically switchable surfaces and electrochemical transistors. There is a fundamental interest in understanding the conducting polymer-cellular interface though as yet no direct measurements to quantify the cell adhesion forces and energies, particularly at the molecular level, have been undertaken. Here, the authors apply electrochemical-single cell force spectroscopy (EC-SCFS) to directly quantify the de-adhesion forces between single L929 fibroblast cells and polypyrrole doped with dodecylbenzene sulfonate (PPy-DBSA) under electrical stimulation. The EC-SCFS reveals single cell de-adhesion forces of 0.65 nN on PPy-DBSA films with adsorbed fibronectin (FN) protein. Blocking experiments by introducing antibodies show that cell de-adhesion is largely due to the binding (∼60% of interactions) of cell-surface α5β1 integrin receptors. Electrochemical oxidation and reduction of PPy-DBSA during initial adsorption of fibronectin cause a significant decrease in the single cell de-adhesion forces to ∼0.4 nN, which is suggested to relate to electrical stimulation effects on reducing FN adsorption on the polymer. In contrast, when electrical stimulation is applied after protein adsorption is established and during the EC-SCFS measurements, the single cell de-adhesion is significantly enhanced on the oxidized polymer compared to the reduced and nonbiased polymer. The study highlights the use of EC-SCFS to directly quantify cell adhesion on electrode surfaces, as well as the ability to probe molecular-level interactions such as integrin receptor-FN complexes with forces of ∼50-100 pN.

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“…Upon reduction, positive Na + ions enter the polymer for charge neutralization of the excess sulfonate groups. Benzene groups then switch back to coordinate with the neutral polymer, while excess sulfonate groups rearrange toward the polymer surface 40 [Fig. 1(b)].…”

Section: B Effect Of Electrical Stimulation On Interfacial Redox Promentioning

confidence: 99%

Effect of monophasic pulsed stimulation on live single cell de-adhesion on conducting polymers with adsorbed fibronectin as revealed by single cell force spectroscopy

2019

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The force required to detach a single fibroblast cell in contact with the conducting polymer, polypyrrole doped with dodecylbenzene, was quantified using the Atomic Force Microscope-based technique, Single Cell Force Spectroscopy. The de-adhesion force for a single cell was 0.64 ± 0.03 nN and predominately due to unbinding of α5β1 integrin complexes with surface adsorbed fibronectin, as confirmed by blocking experiments using antibodies. Monophasic pulsed stimulation (50 μs pulse duration) superimposed on either an applied oxidation (+500) or reduction (−500 mV) constant voltage caused a significant decrease in the de-adhesion force by 30%-45% to values ranging from 0.34 to 0.43 nN (±0.02 nN). The electrical stimulation caused a reduction in the molecular-level jump and plateau interactions, while an opposing increase in nonspecific interactions was observed during the cell de-adhesion process. Due to the monophasic pulsed stimulation, there is an apparent change or weakening of the cell membrane properties, which is suggested to play a role in reducing the cell de-adhesion. Based on this study, pulsed stimulation with optimized threshold parameters represents a possible approach to tune cell interactions and adhesion on conducting polymers.

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Surface and Biomolecular Forces of Conducting Polymers

Cited by 31 publications

References 70 publications

Quantifying Molecular-Level Cell Adhesion on Electroactive Conducting Polymers using Electrochemical-Single Cell Force Spectroscopy

Quantifying Molecular-Level Cell Adhesion on Electroactive Conducting Polymers using Electrochemical-Single Cell Force Spectroscopy

Effect of electrochemical oxidation and reduction on cell de-adhesion at the conducting polymer–live cell interface as revealed by single cell force spectroscopy

Effect of monophasic pulsed stimulation on live single cell de-adhesion on conducting polymers with adsorbed fibronectin as revealed by single cell force spectroscopy

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