What Morphologies Do We Want? – TEM Images from Dilute Diblock Copolymer Solutions

Zhao, Hong; Chen, Qianjin; Hong, Liangzhi; Zhao, Lei; Wang, Jianfang; Wu, Chi

doi:10.1002/macp.201000696

Cited by 22 publications

(17 citation statements)

References 47 publications

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“…[3][4][5][6] During the sample preparation, the solvent evaporation leads to shrinkage, collapse, and even deformation of the micelles. 23 The increasing concentration resulting from the solvent evaporation may induce the fusion of micelles, which creates artefacts in TEM images.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly Kinetics of Amphiphilic Dendritic Copolymers

et al. 2017

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The self-assembly process of amphiphilic dendritic copolymers (ADPs) with a hydrophilic core and hydrophobic shell was investigated via laser light scattering. The self-assembly occurs via a fast step and a slow step with different relaxation times. At the critical micelle concentration (CMC), the fusion of small micelles results in the rapid increase of the micelle size in the fast step. The slow step is associated with equilibrium through the fission and fusion of the micelles. The micelle size increases with the unimer concentration, which leads to a lower micelle concentration. The lower micelle concentration and larger micelle size make the relaxation time of the fast step increase with increasing unimer concentration. The fusion of the larger micelles at higher concentration is more efficient for the increase of the micelle size, which contributes to the decrease of relaxation time in the slow step. Moreover, the fusion of small micelles with large micelles at higher concentration accelerates the approaching equilibrium of the micelle except for the fission and fusion of micelles. With the increasing degree of amidation (DA), the relaxation time in the fast step increases and in the slow step it decreases. website AUTHOR INFORMATION

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Section: Introductionmentioning

confidence: 99%

Self-Assembly Kinetics of Amphiphilic Dendritic Copolymers

et al. 2017

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“…Namely, conjugation affects fibril formation, confirming the results obtained from the ThT fluorescence assay. It is worth noting that we used liquid nitrogen to quickly freeze a drop of the solution and then removed the solvent by freezedrying, 55 which fixes the morphology in the solution state so that further oligomerization or aggregation is avoided during the solvent evaporation process. Such a combination of this special sample preparation and TEM enables us to imitate cryo-TEM.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The freeze-drying method was adopted for sample preparation for TEM imaging . A 10 μL portion of the protein solution taken at different times after dilution was placed on the cupper grid and frozen quickly by immersion in liquid nitrogen.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…The freezedrying method was adopted for sample preparation for TEM imaging. 55 A 10 μL portion of the protein solution taken at different times after dilution was placed on the cupper grid and frozen quickly by immersion in liquid nitrogen. The frozen sample on the cupper grid was then freeze-dried for ∼3 h. The dried sample was then subsequently stained with 10 μL of 1% uranyl acetate for 1 min and blotted gently with filter paper.…”

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Quantitative Study of the Oligomerization of Yeast Prion Sup35NM Proteins

Wang

2017

Biochemistry

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The fibrillation of misfolded neurodegenerative disease-related proteins has been extensively studied over the past few decades, but the initial oligomerization has been rarely examined even though some recent evidence indicated that small protein oligomers are more neurotoxic than long protein fibers. It is rather difficult to study the initial oligomerization (nucleation) because most experimental methods, such as the β-sheet-related fluorescence assay and X-ray diffraction, are unable to detect small structureless protein oligomers. In this study, we have successfully developed a method to link a short thermally sensitive poly(N-isopropylacrylamide) (PNIPAM) chain to a model protein, Sup35NM, at a specific 31st residue site (Sup35NM-31m-PNIPAM) via the efficient thiol-ene Michael addition reaction. The oligomerization was studied by a combination of laser light scattering, the thioflavin T assay, and transmission electron microscopy. We found that the lag phase of Sup35NM was delayed from 12 to >24 h under the physiological condition after the PNIPAM linkage. The oligomerization and fibrillation constants decreased from 5.0 × 10 to 1.5 × 10 h and from 3.0 × 10 to 1.8 × 10 μM h, respectively, presumably because of the steric hindrance introduced by the PNIPAM chain. Moreover, after initiating the oligomerization, we found that the oligomer distribution in the first 6 h repeatedly and quantitatively follows the Smoluchowski coagulation model. Our study paves the way for controllably and quantitatively studying the oligomerization kinetics of amyloidogenic proteins. In addition, by investigating the effects of different small molecules on the oligomerization kinetics, we should be able to screen potential drugs to slow the development of neurodegenerative diseases.

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“…Briefly, 5 mg of polymer was directly dissolved in 5 mL of Milli-Q water and stirred for 10 min before use. The sample for TEM observation was then prepared by a freeze–drying method. − The carbon-coated copper grid was placed on the bottom of a glass cell, which was then immediately transferred into liquid nitrogen. Subsequently, 10 μL of the polymer solution was dripped onto the grid, and the solvent in its frozen solid state was directly removed without melting in a freeze–dryer.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of PEGylated Ferrocene Nanoconjugates as the Radiosensitizer of Cancer Cells

Tian¹,

Chen

Ge³

et al. 2016

Bioconjugate Chem.

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Radiation is one of the most widely used methods for cancer diagnosis and therapy. Herein, we report a new type of radiation sensitizer (Fc-PEG) by a facile one-step reaction of conjugating the hydrophilic PEG chain with hydrophobic ferrocene molecule. The chemical composition and structure of Fc-PEG have been thoroughly characterized by FT-IR, NMR, GPC, and MALDI-TOF mass spectrometry. This Fc-PEG conjugate could self-assemble in aqueous solution into spherical aggregates, and it was found that the exposure to 4 Gy of X-ray radiation have little influence on the shape and size of these aggregates. After the chemical bonding with PEG chains, the uptake level of Fe element could be enhanced via the formation of aggregates. The live/dead, CCK-8, as well as apoptosis assays, indicated that the death of cancer cells can be obviously increased by X-ray radiation after the incubation of these Fc-based nanoconjugates, which might be served as the radiation sensitizer toward cancer cells. We suggest that this radiosensitizing effect comes from the enhancement of reactive oxygen specimen (ROS) level as denoted by both flow cytometric and fluorescence microscopic analysis. The enhanced radiation sensitivity of cancer cells is contributed by the synergic effect of Fe-induced radiation-sensitizing and the increased uptake of nanoconjugates after polymeric grafting.

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What Morphologies Do We Want? – TEM Images from Dilute Diblock Copolymer Solutions

Cited by 22 publications

References 47 publications

Self-Assembly Kinetics of Amphiphilic Dendritic Copolymers

Self-Assembly Kinetics of Amphiphilic Dendritic Copolymers

Quantitative Study of the Oligomerization of Yeast Prion Sup35NM Proteins

Synthesis of PEGylated Ferrocene Nanoconjugates as the Radiosensitizer of Cancer Cells

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