scholarly journals Bioinspired Histidine–Zn2+ Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels

Biomimetics ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 25 ◽  
Author(s):  
Isabell Tunn ◽  
Matthew J. Harrington ◽  
Kerstin G. Blank
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Ethylenediaminetetraacetic Acid ◽  
Coiled Coil ◽  
Higher Order ◽  
Metal Coordination ◽  
Cross Linking ◽  
Self Healing ◽  
Poly Ethylene ◽  
Tunable Mechanical Properties

Natural biopolymeric materials often possess properties superior to their individual components. In mussel byssus, reversible histidine (His)–metal coordination is a key feature, which mediates higher-order self-assembly as well as self-healing. The byssus structure, thus, serves as an excellent natural blueprint for the development of self-healing biomimetic materials with reversibly tunable mechanical properties. Inspired by byssal threads, we bioengineered His–metal coordination sites into a heterodimeric coiled coil (CC). These CC-forming peptides serve as a noncovalent cross-link for poly(ethylene glycol)-based hydrogels and participate in the formation of higher-order assemblies via intermolecular His–metal coordination as a second cross-linking mode. Raman and circular dichroism spectroscopy revealed the presence of α-helical, Zn2+ cross-linked aggregates. Using rheology, we demonstrate that the hydrogel is self-healing and that the addition of Zn2+ reversibly switches the hydrogel properties from viscoelastic to elastic. Importantly, using different Zn2+:His ratios allows for tuning the hydrogel relaxation time over nearly three orders of magnitude. This tunability is attributed to the progressive transformation of single CC cross-links into Zn2+ cross-linked aggregates; a process that is fully reversible upon addition of the metal chelator ethylenediaminetetraacetic acid. These findings reveal that His–metal coordination can be used as a versatile cross-linking mechanism for tuning the viscoelastic properties of biomimetic hydrogels.

Investigating the Effect of Thermoelectric Processing on Ionic Aggregation in Thermoplastic Ionomers

2017 ◽  
Author(s):  
Prasant Vijayaraghavan ◽  
Vishnu-Baba Sundaresan
Keyword(s):  
Mechanical Properties ◽  
Electrostatic Field ◽  
Thermal Studies ◽  
Effect Of Temperature ◽  
Self Healing ◽  
Polymer Backbone ◽  
Ionic Dissociation ◽  
Dissociation Temperature ◽  
Aggregate Morphology ◽  
Poly Ethylene

Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn 8940 which a poly-ethylene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution. Thermal Analysis is performed using a Differential Scanning Calorimeter and the resulting thermogram analysis shows that thermoelectric processing increases the peak temperature and onset temperature of melting by 4 C and 20 C respectively. The peak width at half maximum of the melting endotherm is reduced by 10 C due to thermoelectric processing. This serves as a measure of the increased crystallinity. A parametric study on the effect of field duration and field strength is also performed.

scholarly journals Cross-linking reveals laminin coiled-coil architecture

2016 ◽  
Vol 113 (47) ◽  
pp. 13384-13389 ◽  
Author(s):  
Gad Armony ◽  
Etai Jacob ◽  
Toot Moran ◽  
Yishai Levin ◽  
Tevie Mehlman ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Self Assembly ◽  
Quaternary Structure ◽  
Coiled Coil ◽  
Surface Proteins ◽  
Cross Linking ◽  
Single Particle Reconstruction ◽  
Cross Links ◽  
Particle Reconstruction ◽  
Key Questions

Laminin, an ∼800-kDa heterotrimeric protein, is a major functional component of the extracellular matrix, contributing to tissue development and maintenance. The unique architecture of laminin is not currently amenable to determination at high resolution, as its flexible and narrow segments complicate both crystallization and single-particle reconstruction by electron microscopy. Therefore, we used cross-linking and MS, evaluated using computational methods, to address key questions regarding laminin quaternary structure. This approach was particularly well suited to the ∼750-Å coiled coil that mediates trimer assembly, and our results support revision of the subunit order typically presented in laminin schematics. Furthermore, information on the subunit register in the coiled coil and cross-links to downstream domains provide insights into the self-assembly required for interaction with other extracellular matrix and cell surface proteins.

Injectable Self-Healing Zwitterionic Hydrogels Based on Dynamic Benzoxaborole–Sugar Interactions with Tunable Mechanical Properties

2018 ◽  
Vol 19 (2) ◽  
pp. 596-605 ◽  
Author(s):  
Yangjun Chen ◽  
Wenda Wang ◽  
Di Wu ◽  
Masanori Nagao ◽  
Dennis G. Hall ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Healing ◽  
Tunable Mechanical Properties

Ternary hydrogels with tunable mechanical and self-healing properties based on the synergistic effects of multiple dynamic  bonds

2020 ◽  
Vol 8 (21) ◽  
pp. 4660-4671 ◽  
Author(s):  
Kun Li ◽  
Jingxi Wang ◽  
Ping Li ◽  
Yubo Fan
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonds ◽  
Synergistic Effects ◽  
Self Healing ◽  
Tunable Mechanical Properties

Ternary hydrogels with tunable mechanical properties were prepared based on the synergistic effects of hydrogen bonds and imine bonds.

scholarly journals The effect of Poly(Ethylene oxide) cross-linking structure on the mechanical properties and CO2 separation performance of an ion gel membrane

Polymer ◽  
2019 ◽  
Vol 180 ◽  
pp. 121666 ◽  
Author(s):  
Victor A. Kusuma ◽  
Christina Chen ◽  
James S. Baker ◽  
Megan K. Macala ◽  
David Hopkinson
Keyword(s):  
Mechanical Properties ◽  
Ethylene Oxide ◽  
Cross Linking ◽  
Co2 Separation ◽  
Separation Performance ◽  
Poly Ethylene Oxide ◽  
Ion Gel ◽  
Poly Ethylene

Injectable and Self-Healing Dynamic Hydrogels Based on Metal(I)-Thiolate/Disulfide Exchange as Biomaterials with Tunable Mechanical Properties

2015 ◽  
Vol 16 (11) ◽  
pp. 3552-3561 ◽  
Author(s):  
Pablo Casuso ◽  
Ibon Odriozola ◽  
Adrián Pérez-San Vicente ◽  
Iraida Loinaz ◽  
Germán Cabañero ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Healing ◽  
Disulfide Exchange ◽  
Tunable Mechanical Properties

scholarly journals Dynamic cross-linking of an alginate–acrylamide tough hydrogel system: time-resolved in situ mapping of gel self-assembly

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 10710-10726
Author(s):  
Akanksha Pragya ◽  
Suhas Mutalik ◽  
Muhammad Waseem Younas ◽  
Siu-Kwong Pang ◽  
Pui-Kin So ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Formation Process ◽  
Self Assembly ◽  
Cross Linking ◽  
Time Resolved ◽  
System Time ◽  
Dynamic Formation ◽  
Hydrogel System

In situ, time-resolved characterisation of an alginate–acrylamide tough hydrogel dynamic formation process indicate routes to intervention and modification of chemo-physico-mechanical properties.

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