scholarly journals pH-Responsive Properties of Asymmetric Nanopapers of Nanofibrillated Cellulose

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1380
Author(s):  
Maud Chemin ◽  
Baptiste Beaumal ◽  
Bernard Cathala ◽  
Ana Villares
Keyword(s):  
Carboxylic Acid ◽  
Reaction Times ◽  
Nanofibrillated Cellulose ◽  
Ph Responsive ◽  
Tempo Oxidation ◽  
Ph Changes ◽  
Charge Concentration ◽  
Amine Groups ◽  
Layer Composition ◽  
Electrostatic Repulsions

Inspired by plant movements driven by the arrangement of cellulose, we have fabricated nanopapers of nanofibrillated cellulose (NFC) showing actuation under pH changes. Bending was achieved by a concentration gradient of charged groups along the film thickness. Hence, the resulting nanopapers contained higher concentration of charged groups on one side of the film than on the opposite side, so that pH changes resulted in charge-dependent asymmetric deprotonation of the two layers. Electrostatic repulsions separate the nanofibers in the nanopaper, thus facilitating an asymmetric swelling and the subsequent expanding that results in bending. Nanofibrillated cellulose was modified by 2,2,6,6-tetramethylpiperidin-1-yloxyl radical (TEMPO) oxidation at two reaction times to get different surface concentrations of carboxylic acid groups. TEMPO-oxidized NFC was further chemically transformed into amine-modified NFC by amidation. The formation of graded nanopapers was accomplished by successive filtration of NFC dispersions with varying charge nature and/or concentration. The extent of bending was controlled by the charge concentration and the nanopaper thickness. The direction of bending was tuned by the layer composition (carboxylic acid or amine groups). In all cases, a steady-state was achieved within less than 25 s. This work opens new routes for the use of cellulosic materials as actuators.

Chlorosulfonic Acid Supported Piperidine-4-carboxylic Acid (PPCA) Functionalized Fe3O4 Nanoparticles (Fe3O4-PPCA): The Efficient, Green and Reusable Nanocatalyst for the Synthesis of Pyrazolyl Coumarin Derivatives under Solvent-Free Conditions

2019 ◽  
Vol 22 (2) ◽  
pp. 123-128
Author(s):  
Setareh Habibzadeh ◽  
Hassan Ghasemnejad-Bosra ◽  
Mina Haghdadi ◽  
Soheila Heydari-Parastar
Keyword(s):  
Carboxylic Acid ◽  
Fe3o4 Nanoparticles ◽  
High Efficiency ◽  
Reaction Times ◽  
Chlorosulfonic Acid ◽  
Aromatic Aldehydes ◽  
Solvent Free ◽  
Magnetic Nanocatalyst ◽  
One Pot ◽  
Solvent Free Conditions

Background: In this study, we developed a convenient methodology for the synthesis of coumarin linked to pyrazolines and pyrano [2,3-h] coumarins linked to 3-(1,5-diphenyl-4,5- dihydro-1H-pyrazol-3-yl)-chromen-2-one derivatives using Chlorosulfonic acid supported Piperidine-4-carboxylic acid (PPCA) functionalized Fe3O4 nanoparticles (Fe3O4-PPCA) catalyst. Materials and Methods:: Fe3O4-PPCA was investigated as an efficient and magnetically recoverable Nanocatalyst for the one-pot synthesis of substituted coumarins from the reaction of coumarin with a variety of aromatic aldehydes in high to excellent yield at room temperature under solvent-free conditions. The magnetic nanocatalyst can be easily recovered by applying an external magnet device and reused for at least 10 reaction runs without considerable loss of reactivity. Results and Conclusion: The advantages of this protocol are the use of commercially available materials, simple and an inexpensive procedure, easy separation, and an eco-friendly procedure, and it shows good reaction times, good to high yields, inexpensive and practicability procedure, and high efficiency.

Dual-temperature and pH responsive (ethylene glycol)-based nanogels via structural design

2014 ◽  
Vol 5 (8) ◽  
pp. 3061-3070 ◽  
Author(s):  
Yohei Kotsuchibashi ◽  
Ravin Narain
Keyword(s):  
Carboxylic Acid ◽  
Ethylene Glycol ◽  
Salt Concentration ◽  
Structural Design ◽  
Solution Temperature ◽  
Ph Responsive ◽  
Solution Ph ◽  
Critical Solution Temperature ◽  
Carboxylic Acid Groups ◽  
The Core

Dual-temperature and pH responsive (ethylene glycol)-based nanogels were synthesized. Both the core and the shell of the nanogels showed a lower critical solution temperature (LCST) and the LCST of the shell was strongly affected by the solution pH and salt concentration due to the presence of carboxylic acid groups at the nanogel surface.

scholarly journals Nanofibrillated Cellulose from Appalachian Hardwoods Logging Residues as Template for Antimicrobial Copper

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Masoumeh Hassanzadeh ◽  
Ronald Sabo ◽  
Alan Rudie ◽  
Richard Reiner ◽  
Roland Gleisner ◽  
...  
Keyword(s):  
Oxidation Process ◽  
Metallic Copper ◽  
Nanofibrillated Cellulose ◽  
Strength Properties ◽  
Red Oak ◽  
Northern Red Oak ◽  
Yellow Poplar ◽  
Tempo Oxidation ◽  
Mechanical Fibrillation ◽  
Appalachian Hardwoods

TEMPO nanofibrillated cellulose (TNFC) from two underutilized Appalachian hardwoods, Northern red oak (Quercus rubra) and yellow poplar (Liriodendron tulipifera), was prepared to determine its feasibility to be used as template for antimicrobial metallic copper particles. In addition, a comparison of the TNFC from the two species in terms of their morphological, chemical, thermal, and mechanical properties was also performed. The woody biomass was provided in the form of logging residue from Preston County, West Virginia. A traditional kraft process was used to produce the pulp followed by a five-stage bleaching. Bleached pulps were then subjected to a TEMPO oxidation process using the TEMPO/NaBr/NaClO system to facilitate the final mechanical fibrillation process and surface incorporation of metallic copper. The final TNFC diameters for red oak and yellow poplar presented similar dimensions, 3.8±0.74 nm and 3.6±0.85 nm, respectively. The TNFC films fabricated from both species exhibited no statistical differences in both Young’s modulus and the final strength properties. Likely, after the TEMPO oxidation process both species exhibited similar carboxyl group content, of approximately 0.8 mmol/g, and both species demonstrated excellent capability to incorporate antimicrobial copper on their surfaces.

scholarly journals Engineering pH-responsive switching of donor–π–acceptor chromophore alignments along a peptide nanotube scaffold

RSC Advances ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 3588-3592 ◽  
Author(s):  
Yuki Tabata ◽  
Yusuke Kamano ◽  
Shunsaku Kimura ◽  
Hirotaka Uji
Keyword(s):  
Cyclic Peptides ◽  
Ph Responsive ◽  
Ph Changes ◽  
Left Handed ◽  
Peptide Nanotube

pH-Responsive switching between a left-handed chiral and random alignments of D–π–A naphthalimides along a peptide nanotube (PNT) composed of tri-β-cyclic peptides was attained in response to repeated pH changes.

A stimuli responsive two component supramolecular hydrogelator with aggregation-induced emission properties

Soft Matter ◽  
2019 ◽  
Vol 15 (36) ◽  
pp. 7117-7121 ◽  
Author(s):  
Dennis Aschmann ◽  
Steffen Riebe ◽  
Thorben Neumann ◽  
Dennis Killa ◽  
Jan-Erik Ostwaldt ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Stimuli Responsive ◽  
Ph Responsive ◽  
Aggregation Induced Emission ◽  
Emission Properties ◽  
Two Component

A dual pH-responsive two component hydrogelator with aggregation-induced emission properties is described. The orchestration of supramolecular guadiniumcarbonylpyrrole dimerisation and the recognition of carboxylic acid is reason for the gelation.

One-shot synthesis and solution properties of ROS/pH responsive methoxy poly(ethylene glycol)-b-polycarbonate

2019 ◽  
Vol 10 (17) ◽  
pp. 2143-2151 ◽  
Author(s):  
Yan Zhang ◽  
Yue Xu ◽  
Chao Wei ◽  
Chuanhao Sun ◽  
Bingkun Yan ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Tertiary Amine ◽  
Solution Properties ◽  
Ph Responsive ◽  
Poly Ethylene Glycol ◽  
Amine Groups ◽  
Poly Ethylene

A one-shot method was employed to synthesize ROS/pH responsive methoxy poly(ethylene glycol)-b-polycarbonate (mPEG-b-poly(MN-co-MSe)) with the selenide and tertiary amine groups situated on the backbone.

scholarly journals Ultrasensitive (Co)polymers Based on Poly(methacrylamide) Structure with Fining-Tunable pH Responsive Value

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1870 ◽  
Author(s):  
Haiming Fan ◽  
Po Li ◽  
Wei Li ◽  
Hui Li ◽  
Xiaonan Huang
Keyword(s):  
Hydrophobic Effect ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Ph Responsive ◽  
Responsive Polymers ◽  
Novel Approach ◽  
Pka Value ◽  
Methacrylate Monomers ◽  
Amine Groups ◽  
Ph Responsive Polymers

Novel pH responsive copolymers with tertiary amine groups were prepared by free radical polymerization with 2-(dialkylamino)ethyl methacrylate monomers. These polymers were pH sensitive with the ability to be responsively fine-tuned in aqueous solution, which was proven through titration, transmittance measurements, and proton nuclear magnetic resonance spectroscopy. The polymers were soluble in water at low pH values, induced by electrostatic repulsion between amine groups, and aggregated above their pKa value due to the hydrophobic effect of the alkyls. The pH responsive values were precisely tuned from 7.4 to 4.8 by increasing the hydrophobic monomer ratio. Our work provides a novel approach for the development of ultrasensitive pH-responsive polymers for application in biomedical materials.

Relationship between intracellular pH and ammonia metabolism in LLC-PK1 cells

1990 ◽  
Vol 258 (1) ◽  
pp. F103-F108 ◽  
Author(s):  
A. Sahai ◽  
E. Laughrey ◽  
R. L. Tannen
Keyword(s):  
Intracellular Ph ◽  
Cultured Cells ◽  
Ph Responsive ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Ammonia Metabolism ◽  
Ph Changes ◽  
Concentration Measurements ◽  
Significant Change ◽  
Alanine Production

Previous studies from our laboratory have confirmed that cultures of LLC-PK1 cells exhibit pH-responsive alterations in ammonia metabolism produced by changes in media bicarbonate concentration. To further elucidate the mechanism of ammonia regulation, studies were carried out using parallel cultures of still and rocked LLC-PK1 cells subjected to acute alterations in media pH by either metabolic or respiratory acid-base manipulations. When media pH was altered by modifying PCO2 levels, the response of ammonia and alanine production by rocked culture was identical to the changes observed with metabolic acid-base maneuvers. Furthermore, both metabolic and respiratory acute acidosis resulted in a fall of intracellular alpha-ketoglutarate concentrations in these cells. In contrast, standard still cultures subjected to acute acidosis/alkalosis by metabolic and respiratory manipulations did not exert any significant change in ammonia and alanine production or in intracellular alpha-ketoglutarate concentration. Measurements of intracellular pH (pHi) by the 5,5-[2-14C]dimethyloxazolidine-2,4-dione method in rocked cells demonstrated changes in pHi parallel to media pH changes induced by both metabolic and respiratory acid-base maneuvers. Despite the absence of pH-responsive ammonia-genesis in still cultured cells the pHi values were altered in a fashion similar to their rocked counterparts, indicating the lack of an effect of the pHi signal on ammonia metabolism.

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