scholarly journals Synthesis of Thermo-Responsive Block-Graft Copolymer Based on PCL and PEG Analogs, and Preparation of Hydrogel via Click Chemistry

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 765 ◽  
Author(s):  
Pei Shang ◽  
Jie Wu ◽  
Xiaoyu Shi ◽  
Zhidan Wang ◽  
Fei Song ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graft Copolymer ◽  
Self Assembly ◽  
Three Dimensional ◽  
Cycloaddition Reaction ◽  
Temperature Response ◽  
Gel Permeation Chromatography ◽  
Proton Nuclear Magnetic Resonance ◽  
Fluorescence Probes ◽  
Different Temperatures

Thermo-responsive cross-linkable mPEG-b-[PCL-g-(MEO2MA-co-OEGMA)]-b-mPEG was synthesized by ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Then, the cross-linkable block-graft copolymer was used to prepare hydrogel via a copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition reaction. The chemical structure and composition of copolymer were characterized by proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behaviors of the copolymer in aqueous solution were studied by UV spectrophotometer, fluorescence probes, the surface tension method, dynamic light scattering, and transmission electron microscopy. The results proved that the copolymer has excellent solubility and better temperature response. The three-dimensional network structure of the gels, observed by scanning electron microscopy at different temperatures, indicated that the gels have temperature response.

scholarly journals Synthesis of Thermo-Responsive Block-Graft Copolymer Based on PCL and PEG Analogues, and Preparation of Hydrogel via Click Chemistry

2019 ◽  
Author(s):  
Pei Shang ◽  
Jie Wu ◽  
Xiaoyu Shi ◽  
Zhidan Wang ◽  
Fei Song ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Graft Copolymer ◽  
Water Solubility ◽  
Sol Gel ◽  
Cycloaddition Reaction ◽  
Gel Permeation Chromatography ◽  
Proton Nuclear Magnetic Resonance ◽  
Fluorescence Probes ◽  
Resonance Spectroscopy

The cross-linkable PCL-PEG analogues block-graft copolymer was designed and synthesized, which with the copolymer of the MEO2MA and OEGMA as graft chains to improve the mPEG-b-PCL-b-mPEG copolymer the aqueous solution properties. And successfully prepared two hydrogels via a copper-catalyzed 1, 3-dipolar azide-alkyne cycloaddition reaction of alkyne-terminated poly[glycidyl methacrylate-co-2-(2-methoxyethoxy) ethyl methacrylate-co-oligo (ethylene glycol) methacrylate] [P(GMA-co-MEO2MA-co-OEGMA)] with azide end-functionalized PCL-PEG analogues block-graft copolymer, and tetrakis (2-propynyloxymethyl) -methane (TPOM) and with azide end-functionalized PCL-PEG analogues block-graft copolymer. The copolymer's chemical structure was characterized by proton nuclear magnetic resonance spectroscopy and fourier transform infrared spectroscopy. The molecular weights of the copolymers were decided with gel permeation chromatography. The water solubility and temperature sensitivity of the copolymers were studied by taking digital photos and transmittance change measured by UV spectrophotometer at different temperatures. Fluorescence probes, surface tension, dynamic light scattering and transmission electron microscopy were used to analyze the micelles that copolymers self-assembly in aqueous solution. The sol-gel behavior of copolymer solutions at high concentrations was explored by vial inversion experiments. Finally, the network structure of the gels was observed by scanning electron microscopy. These conclusions indicate that these hydrogels are expected to be used as a new material in the field of biomedicine.

scholarly journals Synthesis, Characterization and Properties of Antibacterial Polyurethanes

Polymers ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 213
Author(s):  
Jihua Duan ◽  
Guichang Jiang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Gray Mold ◽  
Proton Nuclear Magnetic Resonance ◽  
Step Method ◽  
Chemical Structures ◽  
Physically Crosslinked ◽  
Scanning Electron

Novel physically crosslinked polyurethane (PUII), based on isophorone diisocyanates, was prepared by a conventional two-step method. The chemical structures of the PUII were characterized by fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), scanning electron microscopy (SEM) and DSC. The PUII hydrogels were subjected to solvent-induced self-assembly in THF + water to construct a variety of morphologies. The self-assembly morphology of the PUII was observed by scanning electron microscopy (SEM). The PUII films with different amounts (0.2%, 0.4%, 0.6%, 0.8%, 1.0%) of 1,3,5-Tris(2-hydroxyethyl)hexahydro-1,3,5-triazine (TNO) were challenged with Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Gray mold. The results showed that when a small amount of antibacterial agent were added, the antibacterial effect of films on Botrytis cinerea was more obvious. The mechanical evaluation shows that the antimicrobial polyurethane films exhibit good mechanical properties.

Reduction-Degradable Shell Cross-Linked Micelle with pH-Responsive Cores Prepared via Click Chemistry

2016 ◽  
Vol 848 ◽  
pp. 527-531
Author(s):  
Lu Bin Lin ◽  
Qing Yun Yu ◽  
Zhuo Qun Gu ◽  
Xiao Ze Jiang ◽  
Mei Fang Zhu
Keyword(s):  
Click Chemistry ◽  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Proton Nuclear Magnetic Resonance ◽  
Poly Ethylene Glycol ◽  
H Nmr ◽  
Transmission Electron ◽  
Assembly Behavior ◽  
Poly Ethylene ◽  
Novel Drug

A well-defined poly [(ethylene glycol)-block-2-(dimethylamino) ethyl methacrylate-block-2-(diethylamino) methacrylate] (PEG-b-DMA-b-DEA) triblock copolymer was synthesized via atom transfer radical polymerization (ATRP) by successively polymerization of DMA and DEA monomers using a PEG-based macroinitiator, and obtained copolymer was then converted to be PEG-b-P(DMA-co-QDMA)-b-PDEA copolymer with “clickable” moieties in the middle block by the quaternization with propargyl bromide. Those copolymers prepared were characterized by proton Nuclear Magnetic Resonance (1H NMR) and Gel Permeation Chromatography (GPC), and its self-assembly behavior and subsequently fixation with bis-(azidoethyl) disulfide via click chemistry resulting reduction-sensitive shell-cross-linked (SCL) micelle in purely aqueous solution were investigated by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The results show the micellar structure could be effectively cross-linked via click chemistry and also be dissociated at reduction condition, which may realize it's potential application as novel drug delivery carriers.

scholarly journals A Rapid Self-Assembly Peptide Hydrogel for Recruitment and Activation of Immune Cells

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 419
Author(s):  
Ruyue Luo ◽  
Yuan Wan ◽  
Xinyi Luo ◽  
Guicen Liu ◽  
Zhaoxu Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dendritic Cells ◽  
Self Assembly ◽  
Immune Cell ◽  
Three Dimensional ◽  
Hydrophobic Surface ◽  
Inhibitory Effect ◽  
Blue Staining ◽  
Peptide Hydrogel

Self-assembly peptide nanotechnology has attracted much attention due to its regular and orderly structure and diverse functions. Most of the existing self-assembly peptides can form aggregates with specific structures only under specific conditions and their assembly time is relatively long. They have good biocompatibility but no immunogenicity. To optimize it, a self-assembly peptide named DRF3 was designed. It contains a hydrophilic and hydrophobic surface, using two N-terminal arginines, leucine, and two c-terminal aspartate and glutamic acid. Meanwhile, the c-terminal of the peptide was amidated, so that peptide segments were interconnected to increase diversity. Its characterization, biocompatibility, controlled release effect on antigen, immune cell recruitment ability, and antitumor properties were examined here. Congo red/aniline blue staining revealed that peptide hydrogel DRF3 could be immediately gelled in PBS. The stable β-sheet secondary structure of DRF3 was confirmed by circular dichroism spectrum and IR spectra. The observation results of cryo-scanning electron microscopy, transmission electron microscopy, and atomic force microscopy demonstrated that DRF3 formed nanotubule-like and vesicular structures in PBS, and these structures interlaced with each other to form ordered three-dimensional nanofiber structures. Meanwhile, DRF3 showed excellent biocompatibility, could sustainably and slowly release antigens, recruit dendritic cells and promote the maturation of dendritic cells (DCs) in vitro. In addition, DRF3 has a strong inhibitory effect on clear renal cell carcinoma (786-0). These results provide a reliable basis for the application of peptide hydrogels in biomedical and preclinical trials.

Self-Assembly of Amphiphilic Graft Copolymer with Poly(acrylic Acid) Backbone and N-Octylphenyl Poly(oxyethylene) Side Chains in Water

2011 ◽  
Vol 233-235 ◽  
pp. 2138-2144 ◽  
Author(s):  
Fang Ping Wang ◽  
Xin Zhen Du ◽  
Hu Po Mu ◽  
Dong Xia Zhang ◽  
Yun Jun Ma
Keyword(s):  
Electron Microscopy ◽  
Graft Copolymer ◽  
Self Assembly ◽  
Inorganic Salt ◽  
The Self ◽  
Fluorescence Technique ◽  
Preparation Methods ◽  
Amphiphilic Graft Copolymer ◽  
Ph Values ◽  
Transmission Electron

The self-assembly of the amphiphilic graft copolymer AA-C8PhEO10Ac in water was investigated by fluorescence technique using 8-anilino-1-naphthalene sulfonate(ANS) as a probe and transmission electron microscopy (TEM), the effects of inorganic salt , copolymer concentration and pH on the micellar size and structures of AA-C8PhEO10Ac were discussed. It was found that the micelle morphologies and sizes were related with the micellar preparation methods. The sizes of micelles increased with the addition of NaCl and decreased at high pH values.

Controlling stiffness in nanostructured hydrogels produced by enzymatic dephosphorylation

2009 ◽  
Vol 37 (4) ◽  
pp. 660-664 ◽  
Author(s):  
Kate Thornton ◽  
Andrew M. Smith ◽  
Catherine L.R. Merry ◽  
Rein V. Ulijn
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Gelation Time ◽  
Three Dimensional ◽  
Precursor Solution ◽  
Cost Effective ◽  
Cd Spectroscopy ◽  
Phosphate Ester ◽  
Self Assembling ◽  
Oscillatory Rheology

In the present paper, we report on enzyme-initiated self-assembly of Fmoc (fluoren-9-ylmethoxycarbonyl)–tyrosine hydrogels by enzymatic dephosphorylation under physiological conditions and provide evidence for the ability to control the modulus. Upon enzyme action, a self-assembling network of interconnecting fibres is formed, observed by cryo-SEM (scanning electron microscopy) and TEM (transmission electron microscopy). The concentration of alkaline phosphatase added to the Fmoc–tyrosine phosphate ester precursor solution had a direct effect on the gelation time, mechanical properties and molecular arrangements as determined through oscillatory rheology, fluorescence spectroscopy and CD spectroscopy. This highly tuneable cost-effective gel system may have applications in three-dimensional cell culture.

Nano Aggregate Formation Through Self-Assembly of Poly(L-lysine)-Block-Poly(γ-benzyl-L-glutamate)-Graft-Poly(ethylene glycol) Copolymer

2020 ◽  
Vol 20 (11) ◽  
pp. 6968-6974
Author(s):  
Yu Zhang ◽  
Wenliang Song ◽  
Il Kim
Keyword(s):  
Ethylene Glycol ◽  
Volume Content ◽  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Deionized Water ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Exchange Reactions ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene

Polymeric nano aggregates based on poly(L-lysine)-block-PBLG-graft-poly(ethylene glycol) (PLL-b-PBLG-g-PEG) copolymers were prepared by a dialysis method in deionized water. PLL-b-PBLG-g-PEG copolymers with different degrees of PEG substitution were synthesized by combining the ring-opening polymerization of α-amino acid N-carboxyanhydrides and ester exchange reactions. Proton nuclear magnetic resonance spectroscopy and gel permeation chromatography were employed to confirm the polymer structures and molecular weights. Transmission electron microscopy and dynamic light scattering were used to observe the self-assembly behavior. The experimental results revealed that the volume content of deionized water in the mixture significantly affects the morphology and size of the aggregates formed by PLL-b-PBLG-g-PEG copolymers. Spherical, spindle-like, needle-like, and daisy-like aggregates were observed with an increase in the volume content of deionized water in the mixture.

scholarly journals Cryo-Electron microscopy for the study of self-assembled poly(ionic liquid) nanoparticles and protein supramolecular structures

2020 ◽  
Vol 298 (7) ◽  
pp. 707-717
Author(s):  
Zdravko Kochovski ◽  
Guosong Chen ◽  
Jiayin Yuan ◽  
Yan Lu
Keyword(s):  
Electron Microscopy ◽  
Ionic Liquid ◽  
Sample Preparation ◽  
Self Assembly ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Particle Analysis ◽  
Cryo Electron Microscopy ◽  
Self Assembled ◽  
Poly Ionic Liquid

Abstract Cryo-electron microscopy (cryo-EM) is a powerful structure determination technique that is well-suited to the study of protein and polymer self-assembly in solution. In contrast to conventional transmission electron microscopy (TEM) sample preparation, which often times involves drying and staining, the frozen-hydrated sample preparation allows the specimens to be kept and imaged in a state closest to their native one. Here, we give a short overview of the basic principles of Cryo-EM and review our results on applying it to the study of different protein and polymer self-assembled nanostructures. More specifically, we show how we have applied cryo-electron tomography (cryo-ET) to visualize the internal morphology of self-assembled poly(ionic liquid) nanoparticles and cryo-EM single particle analysis (SPA) to determine the three-dimensional (3D) structures of artificial protein microtubules.

Three-dimensional cell culture of chondrocytes on modified di-phenylalanine scaffolds

2007 ◽  
Vol 35 (3) ◽  
pp. 535-537 ◽  
Author(s):  
V. Jayawarna ◽  
A. Smith ◽  
J.E. Gough ◽  
R.V. Ulijn
Keyword(s):  
Electron Microscopy ◽  
Cell Culture ◽  
Cell Proliferation ◽  
Self Assembly ◽  
Three Dimensional ◽  
Building Blocks ◽  
Culture Conditions ◽  
The Self ◽  
Three Dimensions ◽  
Dimensional Cell

The design of self-assembled peptide-based structures for three-dimensional cell culture and tissue repair has been a key objective in biomaterials science for decades. In search of the simplest possible peptide system that can self-assemble, we discovered that combinations of di-peptides that are modified with aromatic stacking ligands could form nanometre-sized fibres when exposed to physiological conditions. For example, we demonstrated that a number of Fmoc (fluoren-9-ylmethyloxycarbonyl) modified di- and tri-peptides form highly ordered hydrogels via hydrogen-bonding and π–π interactions from the fluorenyl rings. These highly hydrated gels allowed for cell proliferation of chondrocytes in three dimensions [Jayawarna, Ali, Jowitt, Miller, Saiani, Gough and Ulijn (2006) Adv. Mater. 18, 611–614]. We demonstrated that fibrous architecture and physical properties of the resulting materials were dictated by the nature of the amino acid building blocks. Here, we report the self-assembly process of three di-phenylalanine analogues, Fmoc-Phe-Phe-OH, Nap (naphthalene)-Phe-Phe-OH and Cbz (benzyloxycarbonyl)-Phe-Phe-OH, to compare and contrast the self-assembly properties and cell culture conditions attributable to their protecting group difference. Fibre morphology analysis of the three structures using cryo-SEM (scanning electron microscopy) and TEM (transmission electron microscopy) suggested fibrous structures with dramatically varying fibril dimensions, depending on the aromatic ligand used. CD and FTIR (Fourier-transform IR) data confirmed β-sheet arrangements in all three samples in the gel state. The ability of these three new hydrogels to support cell proliferation of chondrocytes was confirmed for all three materials.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

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