scholarly journals Responsive Adsorption of N-Isopropylacrylamide Based Copolymers on Polymer Brushes

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 153 ◽  
Author(s):  
Guillaume Sudre ◽  
Elodie Siband ◽  
Bruno Gallas ◽  
Fabrice Cousin ◽  
Dominique Hourdet ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Polymer Brushes ◽  
Electrostatic Interactions ◽  
Neutron Reflectivity ◽  
Ph Responsive ◽  
Temperature Responsive ◽  
Wide Range ◽  
Scaling Models ◽  
Solvophobic Interactions ◽  
Chain Lengths

We investigate the adsorption of pH- or temperature-responsive polymer systems by ellipsometry and neutron reflectivity. To this end, temperature-responsive poly (N-isopropylacrylamide) (PNIPAM) brushes and pH-responsive poly (acrylic acid) (PAA) brushes have been prepared using the “grafting onto” method to investigate the adsorption process of polymers and its reversibility under controlled environment. To that purpose, macromolecular brushes were designed with various chain lengths and a wide range of grafting density. Below the transition temperature (LCST), the characterization of PNIPAM brushes by neutron reflectivity shows that the swelling behavior of brushes is in good agreement with the scaling models before they collapse above the LCST. The reversible adsorption on PNIPAM brushes was carried out with linear copolymers of N-isopropylacrylamide and acrylic acid, P(NIPAM-co-AA). While these copolymers remain fully soluble in water over the whole range of temperature investigated, a quantitative adsorption driven by solvophobic interactions was shown to proceed only above the LCST of the brush and to be totally reversible upon cooling. Similarly, the pH-responsive adsorption driven by electrostatic interactions on PAA brushes was studied with copolymers of NIPAM and N,N-dimethylaminopropylmethacrylamide, P(NIPAM-co-MADAP). In this case, the adsorption of weak polycations was shown to increase with the ionization of the PAA brush with interactions mainly located in the upper part of the brush at pH 7 and more deeply adsorbed within the brush at pH 9.

The Design of Temperature and pH-Responsive Drug Delivery System Based on Cellulose and Aminated Cellulose by Computational and Experimental Methods

2020 ◽  
pp. 1-12
Author(s):  
Enayat Mohsenzadeh ◽  
Hassan Namazi ◽  
Rahim Ghadari
Keyword(s):  
Hydrogen Bonding ◽  
Electrostatic Interactions ◽  
Binding Free Energy ◽  
In Vitro Release ◽  
Md Simulations ◽  
Ph Responsive ◽  
Temperature Responsive ◽  
Repulsive Forces ◽  
Vitro Release

In this study, molecular dynamics (MD) simulations were performed on cellulose and aminated cellulose. Obtained results show the presence of amine moieties and their protonation, positive charges and repulsive forces increase. As a result, the van der Waals and electrostatic interactions and hydrogen bonding number decrease. Then, paclitaxel was loaded through docking into the structures and was studied by MD simulations. The simulations were performed in several protonation states along with 25°C, 37°C, 42°C and 50°C temperatures. The carrier/ligand system behaviors were analyzed. The results indicate the increase of temperature and protonation decrease hydrogen bonding number between drug and carrier and increase binding free energy. At last, to compare the simulations results, paclitaxel was loaded in cellulose and aminated cellulose and investigated in the in vitro release at two conditions (37°C, pH 7.4, and 42°C, pH 5). Experimental results prove computational results as pH/temperature-responsive system.

Selective Adsorption and Separation of Organic Dyes by Poly(acrylic acid) Hydrogels Formed with Spherical Polymer Brushes and Chitosan

2018 ◽  
Vol 71 (11) ◽  
pp. 846 ◽  
Author(s):  
Rui Zhang ◽  
Hongwei Peng ◽  
Tianxu Zhou ◽  
Min Li ◽  
Xuhong Guo ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Polymer Brushes ◽  
Electrostatic Interactions ◽  
Separation Efficiency ◽  
Organic Dyes ◽  
Selective Adsorption ◽  
Cationic Dyes ◽  
Order Kinetic ◽  
Double Network ◽  
Poly Acrylic Acid

Direct discharge of industry organic dyes has caused serious environmental pollution. In this study, a series of double network poly(acrylic acid) (PAA) hydrogels were fabricated with spherical polymer brushes (SPBs) and chitosan (CS) as crosslinker. Neutral spherical polyelectrolyte brushes of polystyrene–poly-N-isopropylacrylamide (PNIPAM@PS) in which poly(N-isopropylacrylamide) (PNIPAM) arms were grafted on polystyrene (PS) nanospheres, were employed as macro-crosslinkers. The innumerable hydrogen bonds both between the highly entangled PAA chains and between PNIPAM and the PAA chains composed the first network of the hydrogels. The electrostatic interactions between CS and the PAA chains formed the second network of the hydrogels. These double network hydrogels, named PNIPAM@PS/CS/PAA, achieve good compressive performance and a low swell ratio because of their compact structure through plentiful hydrogen bonding and electrostatic interactions. The hydrogel could absorb cationic dyes from water with high separation efficiency and selectivity due to the electrostatic interaction between the carboxy groups and dye molecules. The adsorption process fitted a pseudo-second-order kinetic model and Langmuir isotherm model very well. Moreover, the hydrogel can separate cationic dyes from mixed dye solutions through electrostatic interactions. After being loaded with silver nanoparticles, the obtained silver@hydrogel exhibited a good capacity for the photocatalytic degradation towards different dyes. The hydrogels are promising for dye-containing wastewater treatment.

scholarly journals Surface Modification of TFC-PA RO Membrane by Grafting Hydrophilic pH Switchable Poly(Acrylic Acid) Brushes

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Muhammad Asad Abbas ◽  
Shehla Mushtaq ◽  
Waqas A. Cheema ◽  
Hazim Qiblawey ◽  
Shenmin Zhu ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Polymer Brushes ◽  
Water Flux ◽  
Flux Rate ◽  
Ph Responsive ◽  
Salt Rejection ◽  
Pore Sizes ◽  
Ph Values ◽  
Membrane Surfaces ◽  
Poly Acrylic Acid

The grafting of pH-responsive poly(acrylic acid) (PAA) brushes was carried out on the surface of a commercial TFC-PA membrane using surface-initiated atom transfer radical polymerization (SI-ATRP). Poly(t-butyl acrylate) was polymerized through the SI-ATRP method followed by its acid hydrolysis to form PAA hydrophilic polymer brushes. Surface morphology, permeation flux, salt rejection, and pore sizes were investigated. The contact angle for water was reduced from 50° for a pristine membrane to 27° for the modified membrane due to a modification with the hydrophilic functional group and its brush on membrane surfaces. The flux rate also increased noticeably at lower pH values relative to higher pH for the modified membranes, while the flux remains stable in the case of pristine TFC-PA membranes. There is slight transition in the water flux rate that was also observed when going from pH values of 3 to 5. This was attributed to the pH-responsive conformational changes for the grafted PAA brushes. At these pH values, ionization of the COOH group takes place below and above pKa to influence the effective pore dimension of the modified membranes. At a lower pH value, the PAA brushes seem to permit tight structure conformation resulting in larger pore sizes and hence more flux. On the other hand, at higher pH values, PAA brushes appeared to be in extended conformation to induce smaller pore sizes and result in less flux. Further, pH values were observed to not significantly affect the NaCl salt rejection with values observed in between 98.8% and 95% and close to that of the pristine TFC-PA membranes. These experimental results are significant and have immediate implication for advances in polymer technology to design and modify the “switchable membrane surfaces” with controllable charge distribution and surface wettability, as well as regulation of water flux and salt.

Neutron Reflectivity Study of the Structure of pH-Responsive Polymer Brushes Grown from a Macroinitiator at the Sapphire−Water Interface

Langmuir ◽  
2010 ◽  
Vol 26 (15) ◽  
pp. 12684-12689 ◽  
Author(s):  
Mauro Moglianetti ◽  
John R. P. Webster ◽  
Steve Edmondson ◽  
Steven P. Armes ◽  
Simon Titmuss
Keyword(s):  
Polymer Brushes ◽  
Neutron Reflectivity ◽  
Water Interface ◽  
Ph Responsive ◽  
Responsive Polymer

scholarly journals Hairy Polydopamine Particles as Platforms for Photonic and Magnetic Materials

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 36 ◽  
Author(s):  
Michinari Kohri ◽  
Kanako Uradokoro ◽  
Yuri Nannichi ◽  
Ayaka Kawamura ◽  
Tatsuo Taniguchi ◽  
...  
Keyword(s):  
Magnetic Materials ◽  
Polymer Brushes ◽  
Electrostatic Interactions ◽  
Functional Materials ◽  
Amino Acid Derivative ◽  
Photonic Materials ◽  
Color Changes ◽  
Lanthanide Elements ◽  
Novel Approach ◽  
Wide Range

By selecting the core materials and grafted-hair polymers, hairy particles with polymer brushes can create various types of functional materials. In recent years, polydopamine (PDA) particles that are obtained by polymerizing dopamine, which is an amino acid derivative, have attracted attention for various applications. Herein, we present a novel approach for creating photonic and magnetic materials from hairy PDA particles. By grafting a hydrophilic hair polymer, we have succeeded in producing photonic materials capable of structural color changes. Furthermore, we have demonstrated the preparation of magnetic materials by immobilizing holmium, which is one of the lanthanide elements, by electrostatic interactions onto a cationic hair polymer. These results demonstrate the possibility of hairy PDA particles for a wide range of applications, such as for photonic and magnetic materials.

scholarly journals Probing pH-Responsive Interactions between Polymer Brushes and Hydrogels by Neutron Reflectivity

Langmuir ◽  
2014 ◽  
Vol 30 (32) ◽  
pp. 9700-9706 ◽  
Author(s):  
Guillaume Sudre ◽  
Dominique Hourdet ◽  
Costantino Creton ◽  
Fabrice Cousin ◽  
Yvette Tran
Keyword(s):  
Polymer Brushes ◽  
Neutron Reflectivity ◽  
Ph Responsive

Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

2019 ◽  
Author(s):  
Drew P. Harding ◽  
Laura J. Kingsley ◽  
Glen Spraggon ◽  
Steven Wheeler
Keyword(s):  
Gas Phase ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Binding Partner ◽  
Heavy Atoms ◽  
Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

Multi-Stimuli-Responsive Mesoporous Membranes and Effect of Molecular Architecture on Thermo- and pH-Responsive Behavior of the grafted Block Copolymer brushes

2019 ◽  
Author(s):  
Yanchun Tang ◽  
Kohzo Ito ◽  
Hideaki Yokoyama
Keyword(s):  
Polymer Brushes ◽  
Diblock Copolymers ◽  
Neutron Reflectivity ◽  
Molecular Architecture ◽  
Stimuli Responsive ◽  
Responsive Polymer ◽  
The Matrix ◽  
Stable Part ◽  
Copolymer Brushes ◽  
Mesoporous Membranes

In this study, we prepared ultrafiltration membranes with a decoupled responses of filtration property to temperature and pH. The membrane preparation method was developed based on our previous work. We utilized methanol-supercritical carbon dioxide (methanol-scCO<sub>2</sub>) selective swelling method to introduce nanopores to block copolymers containing poly(diethylene glycol) methyl ether methacrylate (PMEO<sub>2</sub>MA), poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and polystyrene (PS) blocks. Formation of the mesoporous barrier layer with PS being the mechanically stable part of the matrix was driven by selective swelling of the PMEO<sub>2</sub>MA-b-PDMAEMA domains. Due to the selective swelling of PMEO<sub>2</sub>MA or PDMAEMA domains to introduce pores, the interior of the pores are covered with PMEO<sub>2</sub>MA or PDMAEMA blocks after pore formation. The PMEO<sub>2</sub>MA-b-PDMAEMA polymer brushes are naturally attached on the pore walls and worked as functional gates. PMEO<sub>2</sub>MA is a non-toxic, neutral thermo-responsive polymer with LCST at 26 ᴼC. PDMAEMA is a typical weak polyelectrolyte with pK<sub>a</sub> value at 7.0-7.5 and also a thermo-responsive polymer revealed a LCST of 20-80 °C in aqueous solution. Therefore, these membranes were expected to have multi dimensions as function of the combination of temperature and pH. Moreover, to understand the detail of the temperature and pH depended conformation transitions of PMEO<sub>2</sub>MA-b-PDMAEMA brushes, those diblock copolymers were end-tethered on flat substrates and analyzed via neutron reflectivity (NR).

scholarly journals Self-assembling ferritin-dendrimer nanoparticles for targeted delivery of nucleic acids to myeloid leukemia cells

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Federica Palombarini ◽  
Silvia Masciarelli ◽  
Alessio Incocciati ◽  
Francesca Liccardo ◽  
Elisa Di Fabio ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Targeted Delivery ◽  
Myeloid Leukemia ◽  
Electrostatic Interactions ◽  
Archaeoglobus Fulgidus ◽  
Leukemia Cells ◽  
Cellular Delivery ◽  
Self Assembling ◽  
Wide Range ◽  
Hybrid Nanoparticle

Abstract Background In recent years, the use of ferritins as nano-vehicles for drug delivery is taking center stage. Compared to other similar nanocarriers, Archaeoglobus fulgidus ferritin is particularly interesting due to its unique ability to assemble-disassemble under very mild conditions. Recently this ferritin was engineered to get a chimeric protein targeted to human CD71 receptor, typically overexpressed in cancer cells. Results Archaeoglobus fulgidus chimeric ferritin was used to generate a self-assembling hybrid nanoparticle hosting an aminic dendrimer together with a small nucleic acid. The positively charged dendrimer can indeed establish electrostatic interactions with the chimeric ferritin internal surface, allowing the formation of a protein-dendrimer binary system. The 4 large triangular openings on the ferritin shell represent a gate for negatively charged small RNAs, which access the internal cavity attracted by the dense positive charge of the dendrimer. This ternary protein-dendrimer-RNA system is efficiently uptaken by acute myeloid leukemia cells, typically difficult to transfect. As a proof of concept, we used a microRNA whose cellular delivery and induced phenotypic effects can be easily detected. In this article we have demonstrated that this hybrid nanoparticle successfully delivers a pre-miRNA to leukemia cells. Once delivered, the nucleic acid is released into the cytosol and processed to mature miRNA, thus eliciting phenotypic effects and morphological changes similar to the initial stages of granulocyte differentiation. Conclusion The results here presented pave the way for the design of a new family of protein-based transfecting agents that can specifically target a wide range of diseased cells. Graphic abstract

scholarly journals Hybrid Acrylated Chitosan and Thiolated Pectin Cross-Linked Hydrogels with Tunable Properties

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 266
Author(s):  
Shaked Eliyahu ◽  
Alexandra Galitsky ◽  
Esther Ritov ◽  
Havazelet Bianco-Peled
Keyword(s):  
Electrostatic Interactions ◽  
Profile Analysis ◽  
Hybrid Hydrogel ◽  
Texture Profile ◽  
Ph Values ◽  
X Ray Scattering ◽  
Wide Range ◽  
Michael Type Addition ◽  
Physical And Chemical ◽  
Hydrogel System

We developed and characterized a new hydrogel system based on the physical and chemical interactions of pectin partially modified with thiol groups and chitosan modified with acrylate end groups. Gelation occurred at high pectin thiol ratios, indicating that a low acrylated chitosan concentration in the hydrogel had a profound effect on the cross-linking. Turbidity, Fourier transform infrared spectroscopy, and free thiol determination analyses were performed to determine the relationships of the different bonds inside the gel. At low pH values below the pKa of chitosan, more electrostatic interactions were formed between opposite charges, but at high pH values, the Michael-type addition reaction between acrylate and thiol took place, creating harder hydrogels. Swelling experiments and Young’s modulus measurements were performed to study the structure and properties of the resultant hydrogels. The nanostructure was examined using small-angle X-ray scattering. The texture profile analysis showed a unique property of hydrogel adhesiveness. By implementing changes in the preparation procedure, we controlled the hydrogel properties. This hybrid hydrogel system can be a good candidate for a wide range of biomedical applications, such as a mucosal biomimetic surface for mucoadhesive testing.

Sign in / Sign up

Export Citation Format

Share Document