Thermoresponsive and Mechanical Properties of Poly(<scp>l</scp>-proline) Gels

Gkikas, Manos; Avery, Reginald K.; Olsen, Bradley D.

doi:10.1021/acs.biomac.5b01168

Cited by 27 publications

(30 citation statements)

References 75 publications

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“…These features are compared in 1D scattering profiles generated from radial sectors parallel and perpendicular to the tensile apparatus. The radial scattered intensity I as a function of the scattering vector q was fit to a broad peak model, which is commonly used to identify characteristic length scales in hydrogel systems with clustered domains [56,57,79,80]:…”

Section: A Structure Of Protein-based Physical Gelsmentioning

confidence: 99%

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Molecular anisotropy and rearrangement as mechanisms of toughness and extensibility in entangled physical gels

Edwards

Danielle

Tang

et al. 2020

Phys. Rev. Materials

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Dynamic networks formed by physically crosslinked, entangled polymers have emerged as self-healing, stretchable, and functional materials. Entangled associative gels with remarkable toughness and extensibility have been produced by several distinct chemical approaches, suggesting that these enhanced mechanical properties result from molecular-scale topology. Previously, artificially engineered associative proteins were designed to provide an ideal model system to investigate the role of entanglement on gel mechanics via welldefined entangled or unentangled physical gels. Herein, uniaxial strain-induced structural changes in these model gels were observed using in situ small-angle x-ray scattering (SAXS) and in situ polarized optical microscopy (POM) up to 2000% engineering strain. Anisotropic optical responses to uniaxial strain at the nano-, micro-, and macroscales suggest that stress dissipation mechanisms enable high extensibility and toughness. Nano-and microscopic anisotropy observed by SAXS indicate stretching and alignment of flexible polymer strands along the straining axis, and nonmonotonic macroscopic anisotropy observed by POM suggests relaxation within the hydrogel due to rearrangement of associative network junctions. Unentangled hydrogels exhibit low toughness and a strain-rate-dependent transition from ductile to brittle tensile behavior, which is typical for associative polymer solutions. These findings indicate that topological entanglements and the freedom of individual chains to align at the nanoscale due to junction relaxation are both critical to achieving high toughness and elongation in entangled physical gels.

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Section: A Structure Of Protein-based Physical Gelsmentioning

confidence: 99%

“…Radial profiles were analyzed in the context of the broad peak model [Eq. 2 peak position q 0 and correlation length ξ quantify nanostructural features of associative protein gels [56,57,79,80].…”

Section: Anisotropic Nanostructure Formation In Entangled Physicalmentioning

confidence: 99%

Molecular anisotropy and rearrangement as mechanisms of toughness and extensibility in entangled physical gels

Edwards

Danielle

Tang

et al. 2020

Phys. Rev. Materials

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“…[3][4][5][6] In materials science, there is also a rapidly growing interest in proline or hydroxyproline-derived polymers. [7][8][9] PLP derivatives have also demonstrate utility as mimics of antifreeze protein, 10 building blocks for hierarchical self-assembly, 11 templates for controlling nanoparticle growth, 12 gelators, 13 molecular identities controlling distances, 14 antimicrobial 15 and cell-penetrating agents, 16 etc.…”

Section: Introductionmentioning

confidence: 99%

Water-Assisted and Protein-Initiated Ring-Opening Polymerization of Proline N-Carboxyanhydride

Hu¹,

Tian²,

Xiong³

et al. 2021

Preprint

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The production of poly-L-proline (PLP) via the ring-opening polymerization (ROP) of L-proline N-carboxyanhydride (ProNCA) is challenging due to a combination of factors, including the stringent requirement of moisture-free conditions, slow monomer conversion, poor control of the molar mass, and premature precipitation of the product in the form of polyproline type I helix. Here, we report water-assisted ROP of ProNCA, which affords well-defined PLP in polyproline II helix in 2-5 minutes. Density functional theory reveals an as-yet-unreported role of water in facilitating proton shift that significantly lowered the energy barrier of the chain propagation. Protein-mediated ROP of ProNCA conveniently affords various protein-PLP conjugates via a grafting-from approach. PLP conjugation not only preserves the biological activities of the native proteins, but also enhances the stability of proteins against extreme conditions. This work provides a simple means and new mechanistic insight to solve a longstanding problem in PLP synthesis and will offer valuable guidance for the development of water-resistant ROP of other NCAs. The facile access of PLP can greatly boost the application potentials of PLP-based functional materials.

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“…[2][3][4][5][6][7][8] Among the OP hydrogels, taking advantage of the decomposition products released by nerve agents after reaction with oximes and the subsequent reaction with cross-linkers. [45][46][47][48] Recently, N,N-bis(acryloyl cystamine) (BAC) was used as the bridging molecule in radical polymerization, enabling numerous applications that are triggered by external stimuli such as pH, temperature, ionic strength, light, stress, and ligand binding (ligand-triggered actuators/sensors) to modulate the state of the disulfide bond. Many types of hydrogels have been engineered as building blocks for different stimuli-responsive materials due to their biocompatibility, biodegradability, tunability in mechanical properties, and molecular recognition abilities.…”

Section: Introductionmentioning

confidence: 99%

“…Many types of hydrogels have been engineered as building blocks for different stimuli-responsive materials due to their biocompatibility, biodegradability, tunability in mechanical properties, and molecular recognition abilities. [45][46][47][48] Recently, N,N-bis(acryloyl cystamine) (BAC) was used as the bridging molecule in radical polymerization, enabling numerous applications that are triggered by external stimuli such as pH, temperature, ionic strength, light, stress, and ligand binding (ligand-triggered actuators/sensors) to modulate the state of the disulfide bond. [49][50][51][52][53] Herein, the ability to couple oxime-based decontamination and disulfide chemistry is demonstrated, producing hydrogels that can decontaminate organophosphate compounds, sense the decontamination product, and transduce this sensing response into actuation of the gel which could be used to close pores in a gel layer or on a fabric coating.…”

Section: Introductionmentioning

confidence: 99%

Hydrogels That Actuate Selectively in Response to Organophosphates

Gkikas

Avery

Mills

et al. 2016

Adv Funct Materials

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1 of 10) 1602784 compounds, the V-type nerve agents are the most toxic, rendering the development of novel decontamination and protection technologies highly important. Decontamination or sequestration of high toxicity OP compounds can be accomplished through hydrolysis of the phosphate ester bond [9][10][11][12] with the enzyme organophosphorus hydrolase, [9][10][11][12][13][14][15] entrapment in nanoporous materials, [16,17] enzyme/ polymer conjugates [18][19][20][21][22][23][24] and highly bioactive enzyme/amphiphilic polymer formulations, [25] chemically modified fluorescent probes, [26][27][28] and oxime reactivators. [29][30][31][32] V-type organophosphates contain a P-S bond and a choline-like moiety and are hydrolyzed very slowly by natural enzymes. Therefore, new and efficient approaches that target VX are necessary for mitigation of the agent.A major challenge in the mitigation of threats from OP compounds is developing protective garments that can eliminate exposure of the wearer to the toxic chemical. Some rubbers can serve as effective barrier materials, [33] but in sufficient thickness they are not breathable and extremely uncomfortable to wear for an extended period of time. Therefore, there is a strong interest in a garment or barrier membrane that could remain in a porous state when it is not in the presence of an organophosphate, but close its pores autonomously in the presence of the toxic agent to prevent its passage. Such a smart barrier needs to be able to efficiently sense the OP compound and also transduce the sensing response into an actuated change of state without an external input of energy.The reactivity of oximes with OP compounds, yielding phosphorylated adducts, [34][35][36][37][38][39][40][41][42][43][44] provides a potential basis for detection and response in an autonomous material. As part of antidotal therapy against OP poisoning, oximes help reactivate phosphorylated AChE. Quaternary pyridine aldoximes substituted in the para position have been shown to be highly reactive in reversing poisoning from different OP compounds, screened over AChE of different origins. [36] Polymeric materials with enhanced nucleophilic activity provided by N-alkyl 4-pyridinium aldoximes also recently showed significant detoxification of diisopropyl fluorophosphate. [31] Coupling oxime decontamination with responsive crosslinkers could potentially enable the triggering of responsive Nerve agents and pesticides represent a category of extremely toxic organo phosphate compounds (OPs) that irreversibly inhibit the enzyme acetyl cholinesterase, disturbing transmission in the synaptic clefts of muscles and nerves. Protection from these compounds necessitates the development of breathable barriers that can selectively block the passage of OPs. Hydrogels prepared from acrylamide, N,N′methylenebis(acrylamide), N,N′bis(acryloyl) cystamine, and hydrophilic pendant oximes are herein prepared, showing the ability to decontaminate and respond to the presence of OPs through a change in swelling. The oximebased h...

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Thermoresponsive and Mechanical Properties of Poly(l-proline) Gels

Cited by 27 publications

References 75 publications

Molecular anisotropy and rearrangement as mechanisms of toughness and extensibility in entangled physical gels

Molecular anisotropy and rearrangement as mechanisms of toughness and extensibility in entangled physical gels

Water-Assisted and Protein-Initiated Ring-Opening Polymerization of Proline N-Carboxyanhydride

Hydrogels That Actuate Selectively in Response to Organophosphates

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