Morphology of hybrid polystyrene-block-poly(ethylene oxide) micelles: Analytical ultracentrifugation and SANS studies

Bronstein, Lyudmila M.; Khotina, Irina A.; Chernyshov, Dmitrii M.; Valetsky, Pyotr M.; Тимофеева, Г. И.; Dubrovina, L.V.; Stein, Barry D.; Karlinsey, Robert L.; Triolo, Alessandro; Weidenmann, A.; Celso, Fabrizio Lo; Triolo, R.; Khokhlov, Alexei R.

doi:10.1016/j.jcis.2006.02.050

Cited by 8 publications

(5 citation statements)

References 47 publications

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“…Diblock co‐oligomers with various hydrophobic block lengths ( m PEG 16 ‐ b ‐PS 2 , m PEG 16 ‐ b ‐PS 4 , and m PEG 16 ‐ b ‐PS 6 ) were produced and their self‐assembly studied. While the synthesis and the self‐assembly properties of PEG‐ b ‐PS (and PEO‐ b ‐PS) have been explored,1, 26, 53–62 the study presented here is the first to synthesize and self‐assemble such short chain lengths of m PEG‐ b ‐PS diblock co‐oligomers. The final product, m PEG‐ b ‐PS, has a butyltrithiocarbonate end group at the PS end, and therefore will be presented in the core of the nanostructures resulting from micellization in aqueous media.…”

Section: Resultsmentioning

confidence: 99%

Genetic alterations in the RAS/RAF/mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase/Akt signaling pathways in the follicular variant of papillary thyroid carcinoma

Santarpia

Myers

Sherman

et al. 2010

Cancer

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BACKGROUND:The follicular variant of papillary thyroid carcinoma (FVPTC) is the second most common histotype among papillary thyroid cancers (PTCs). Although the prognosis of FVPTC is similar to the conventional phenotype, differential diagnostic difficulties may not be uncommon with other follicular thyroid neoplasms, and little is known about their genetic alterations. Defining these alterations may lead to the identification of diagnostic and biologic markers. METH-ODS: In this study, the authors evaluated genetic alterations and downstream-activated signals of the Ras/Raf-mitogenactivated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene (Akt) (PI3K/Akt) signaling pathways in 30 FVPTC tissue specimens. Tumors and matched normal thyroid samples were tested for RAS, for the v-raf murine sarcoma viral oncogene (BRAF) substitution of valine (V) for glutamate (E) at codon 600 (the V600E mutation), for phosphatase and tensin homolog (PTEN), for catalytic PI3k p110 subunit alpha (PIK3CA), for AKT, and for the presence of rearranged during transfection (ret) proto-oncogene/PTC (RET-PTC) and paired box-8 (PAX8)/peroxisome proliferator-activated receptor c (PPARc) fusion protein (PAX8-PPARc) rearrangements by direct sequencing and reverse transcriptase-polymerases chain reaction analyses, respectively. Western blot analysis was used to assess the effects of these gene abnormalities on the activation of the 2 pathways. RESULTS: Genetic alterations were identified in 70% of FVPTCs. Activation of the MAPK and PI3K pathways was observed in 74% and 22% of tumors, respectively. The alterations that were identified in the genes of the 2 pathways were mutually exclusive. Chromosomal RET-PTC and PAX8-PPARc rearrangements were observed in 20% and 17% of tumors, respectively. It was noteworthy that some FVPTCs with RET-PTC had the coactivation of both pathways. CONCLUSIONS: RET-PTC and PAX8-PPARc rearrangements and mutations of the neuroblastoma RAS viral oncogene homolog N-RAS at codon 61 were the most common genetic alterations in FVPTCs. Activation of the MAPK pathway was a frequent event in FVPTCs, and the PI3K signaling pathway could be coactivated in RET-PTC tumors. These findings may have important therapeutic implication in patients with FVPTC. Cancer 2010;116:2974-83.

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Section: Resultsmentioning

confidence: 99%

Genetic alterations in the RAS/RAF/mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase/Akt signaling pathways in the follicular variant of papillary thyroid carcinoma

Santarpia

Myers

Sherman

et al. 2010

Cancer

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“…[11][12][13][14][15][16][17][18][19][20][21][22][23] The extension of this work to polymeric nanoparticles is straightforward, and investigators often use it to evaluate the dispersion and purity of these samples in suspension. 11,[24][25][26][27][28][29] Careful analysis of AU data has been particularly important for determining the densities of spherical polymers using the buoyant density method pioneered by Edelstein and Schachman. 11,12,29,30 AU was historically applied to gold colloids, and more recent examples include nanocrystals of TiO 2 , Fe 3 O 4 , CdS, ZrSO 4 , FePt, Pt, ZnO, and various other metal clusters stabilized by micelles or polymers.…”

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confidence: 99%

“…Analytical ultracentrifugation (AU) uses optical tools to evaluate samples during a centrifugation procedure, ultimately providing a direct visualization of the sedimentation of particles. It has emerged as an important tool in characterizing complex macromolecules and their assemblies in both polymer science and biochemistry. – The extension of this work to polymeric nanoparticles is straightforward, and investigators often use it to evaluate the dispersion and purity of these samples in suspension. ,– Careful analysis of AU data has been particularly important for determining the densities of spherical polymers using the buoyant density method pioneered by Edelstein and Schachman. ,,, AU was historically applied to gold colloids, and more recent examples include nanocrystals of TiO 2 , Fe 3 O 4 , CdS, ZrSO 4 , FePt, Pt, ZnO, and various other metal clusters stabilized by micelles or polymers. – In all of these cases, AU data were employed as a comparative tool, usually with the aim of evaluating particle growth or aggregation under varying conditions. Our group, for example, recently applied AU to examine the formation of bionanoconjugates and to determine the concentration at which gold nanoparticles were saturated with proteins .…”

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confidence: 99%

Size-Dependent Sedimentation Properties of Nanocrystals

et al. 2008

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Centrifugation is an increasingly important technique for nanomaterial processing. Here, we examine this process for gold, cadmium selenide, and iron oxide nanocrystals using an analytical ultracentrifuge. Such data provide an accurate measure of the sedimentation coefficients for these materials, and we find that this parameter has a significant dependence on the size and surface coating. Conventional models for particle sedimentation cannot capture the behavior of these nanocrystals unless the density of the nanocrystals is described by a size-dependent term that accounts for both the inorganic core and the organic coating. Using this modification in the particle sedimentation framework, it is possible to estimate sedimentation coefficients from information about the nanocrystal core and surface coating dimensions. Such data are useful in choosing the speeds for a centrifugation process and are particularly important when bimodal nanocrystal distributions are present.

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“…We believe that the mediocre properties of the SPEs based on PS 10 -b-PEO 23 are due to the low mobility of the PS block. We found that the T g of very short PS blocks is still above room temperature, 35 which affects the mobility of the PEO blocks. Soo et al showed that when both blocks of phase-separated block copolymer are in the rubbery state (T g s are well below room temperature), these materials exhibit improved conductivities over those of glassy-rubbery block copolymer systems.…”

Section: Introductionmentioning

confidence: 87%

Composite Solid Polymer Electrolytes Based on Pluronics: Does Ordering Matter?

et al. 2007

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Composite solids polymer electrolytes (SPEs) based on Pluronic block copolymers, PEO x -b-PPO y -b-PEO x , and silicate organic-inorganic component (OIC) formed in situ have been synthesized and characterized using solid-state NMR, Raman spectroscopy, differential scanning calorimetry (DSC), smallangle X-ray scattering (SAXS), rheology, and electrochemical measurements. Raman spectroscopy, DSC, and rheological data reveal that the block copolymer and OIC are intermixed in the composite SPEs, and the degree of intermixing determines the SPE properties. Comparison of the SAXS and electrochemical results leads us to conclude that ordering in block copolymer-based composite SPEs is not a crucial parameter for the improved conductivity, while the combination of the ratios of the SPE components and their intermixing gives rise to extended interfaces that control the electrochemical performance.

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Morphology of hybrid polystyrene-block-poly(ethylene oxide) micelles: Analytical ultracentrifugation and SANS studies

Cited by 8 publications

References 47 publications

Genetic alterations in the RAS/RAF/mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase/Akt signaling pathways in the follicular variant of papillary thyroid carcinoma

Genetic alterations in the RAS/RAF/mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase/Akt signaling pathways in the follicular variant of papillary thyroid carcinoma

Size-Dependent Sedimentation Properties of Nanocrystals

Composite Solid Polymer Electrolytes Based on Pluronics: Does Ordering Matter?

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