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1.
Front Oncol ; 13: 1294037, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38098502

RESUMO

The aim of this study was to examine the characteristics and prognosis of patients with myelodysplastic syndrome (MDS) accompanied by TP53 abnormalities and explore potential prognostic factors and treatment responses. This retrospective analysis included 95 patients with MDS and TP53 abnormalities and 173 patients with MDS without TP53 abnormalities at the Fujian Medical University Union Hospital between January 2016 and June 2023. Among patients with TP53 abnormalities, 26 (27.4%) developed AML during the disease course, with a median transformation time of 5.7 months. Complex karyotypes were observed in 73.1% of patients, and the proportions of -5 or del(5q), -7 or del(7q), +8, and -20 or del(20q) were 81.8%, 54.5%, 30.7%, and 25.0%, respectively. These patients exhibited poor survival, with a median overall survival (OS) of 7.3 months, and had 1- and 2-year OS rates of 42.2% and 21.5%, respectively. The complete response rates for azacitidine monotherapy, venetoclax combined with azacitidine, decitabine monotherapy, and decitabine combined with low-dose chemotherapy were 9.1%, 41.7%, 37.5%, and 33.3%, respectively. Long-term survival was similar among the four treatment groups. Patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) had a median OS of 21.3 months, which trended to be longer than that of patients who did not undergo allo-HSCT (5.6 months; P = 0.1449). Patients with pulmonary infection at diagnosis experienced worse OS than those without pulmonary infection (2.3 months vs. 15.4 months; P < 0.0001). Moreover, 61.9% of patients with pulmonary infection had immune dysfunction, with a ratio of CD4+ to CD8+ T lymphocytes below two. Pulmonary infections and complex karyotypes were independent adverse prognostic factors for OS. In conclusion, TP53 abnormalities in patients with MDS were frequently accompanied by complex karyotypes, and treatments based on hypomethylating agents or venetoclax have limited efficacy. Pulmonary infections associated with immune dysfunction is associated with poor prognosis.

2.
J Phys Chem A ; 127(31): 6400-6411, 2023 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-37498222

RESUMO

Al-containing catalysts, e.g., Al(OTf)3, show good catalytic performance toward the conversion of cellulose to fructose in methanol solution. Here, we report the catalytic isomerization and alcoholysis mechanisms for the conversion of cellobiose to fructose at the PBE0/6-311++G(d,p), aug-cc-pVTZ theoretical level, combining the relevant experimental verifications of electrospray ionization mass spectrometry (ESI-MS), high-performance liquid chromatography (HPLC), and the attenuated total reflection-infrared (ATR-IR) spectra. From the alcoholysis of Al(OTf)3 in methanol solution, the catalytically active species involves both the [CH3OH2]+ Brønsted acid and the [Al(CH3O)(OTf)(CH3OH)4]+ Lewis acid. There are two reaction pathways, i.e., one through glucose (glycosidic bond cleavage followed by isomerization, w-G) and another through cellobiulose (isomerization followed by glycosidic bond cleavage, w-L). The Lewis acid ([Al(CH3O)(OTf)(CH3OH)4]+) is responsible for the aldose-ketose tautomerization, while the Brønsted acid ([CH3OH2]+) is in charge of ring-opening, ring-closure, and glycosidic bond cleavage. For both w-G and w-L, the rate-determining steps are related to the intramolecular [1,2]-H shift between C1-C2 for the aldose-ketose tautomerization catalyzed by the [Al(CH3O)(OTf)(CH3OH)4]+ species. The Lewis acid ([Al(CH3O)(OTf)(CH3OH)4]+) exhibits higher catalytic activity toward the aldose-ketose tautomerization of glycosyl-chain-glucose to glycosyl-chain-fructose than that of chain-glucose to chain-fructose. Besides, the Brønsted acid ([CH3OH2]+) shows higher catalytic activity toward the glycosidic bond cleavage of cellobiulose than that of cellobiose. Kinetically, the w-L pathway is predominant, whereas the w-G pathway is minor. The theoretically proposed mechanism has been experimentally testified. These insights may advance on the novel design of the catalytic system toward the conversion of cellulose to fructose.

3.
Phys Chem Chem Phys ; 25(12): 8507-8514, 2023 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-36883477

RESUMO

In a solution of sorbitol (SBT) and Ga(OTf)3 compounds, the coordination of sorbitol (SBT) to [Ga(OTf)n]3-n (n = 0-3) has been investigated, using both ESI-MS spectra and density functional theory (DFT) calculations at the M06/6-311++g(d,p), aug-cc-pvtz level using a polarized continuum model (PCM-SMD). In sorbitol solution, the most stable conformer of sorbitol includes three intramolecular H-bonds, i.e., O2H⋯O4, O4H⋯O6, and O5H⋯O3. Through ESI-MS spectra, in a tetrahydrofuran solution of both SBT and Ga(OTf)3 compounds, five main species are observed, i.e., [Ga(SBT)]3+, [Ga(OTf)]2+, [Ga(SBT)2]3+, [Ga(OTf)(SBT)]2+, and [Ga(OTf)(SBT)2]2+. Through DFT calculations, in a solution of sorbitol (SBT) and Ga(OTf)3 compounds, the Ga3+ cation tends to form five six-coordination complexes, i.e., [Ga(η2O,O-OTf)3], [Ga(η3O2-O4-SBT)2]3+, [(η2O,O-OTf)Ga(η4O2-O5-SBT)]2+, [(η1O-OTf)(η2O2,O4-SBT)Ga(η3O3-O5-SBT)]2+, and [(η1O-OTf)(η2O,O-OTf)Ga(η3O3-O5-SBT)]+, which are in good agreement with the experimental observation of the ESI-MS spectra. For both [Ga(OTf)n]3-n (n = 1-3) and [Ga(SBT)m]3+ (m = 1, 2) complexes, the negative charge transfer from ligands to the Ga3+-center plays an important role in their stability, because of the strong polarization of the Ga3+ cation. For [Ga(OTf)n(SBT)m]3-n (n = 1, 2; m = 1, 2) complexes, the negative charge transfer from ligands to the Ga3+-center plays an essential role in their stability, accompanied by an electrostatic interaction between the Ga3+-center and ligands and/or spatial inclusion of ligands toward the Ga3+-center.

4.
Carbohydr Polym ; 309: 120692, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-36906373

RESUMO

The main bottleneck in the direct conversion of cellulose to levulinic acid (LA), a promising bio-based platform chemical, lies in the severe formation of humins, especially at high substrate loading (>10 wt%). Herein, we report an efficient catalytic system consisting of a 2-methyltetrahydrofuran/water (MTHF/H2O) biphasic solvent with NaCl and cetyltrimethylammonium bromide (CTAB) as additives for converting cellulose (15 wt%) to LA in the presence of a benzenesulfonic acid catalyst. We show that both NaCl and CTAB accelerated the depolymerization of cellulose and formation of LA. However, NaCl favored the humin formation via degradative condensations, whereas CTAB inhibited humin formation by restraining the routes of both degradative and dehydrated condensations. A synergistic role of NaCl and CTAB on suppressing humin formations is illustrated. The combined use of NaCl and CTAB led to an increased LA yield (60.8 mol%) from microcrystalline cellulose in MTHF/H2O (VMTHF/VH2O = 2/1) at 453 K for 2 h. Moreover, it was efficient for converting cellulose fractioned from several kinds of lignocellulosic biomass, wherein a high LA yield of 81.0 mol% was achieved from wheat straw cellulose. This work presents a new strategy for advancing LA biorefinery by synergistically promoting cellulose depolymerization with orientated inhibition of undesired humin formation.

5.
ChemSusChem ; 13(18): 4812-4832, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-32667707

RESUMO

Biomass-derived hexose constitutes the main component of lignocellulosic biomass for producing value-added chemicals and biofuels. However, the reaction network of hexose is complicated, which makes the highly selective synthesis of one particular product challenging in biorefinery. This Review focuses on the selective production of 5-hydroxymethylfurfural (HMF) from glucose on account of its potential significance as an important platform molecule. The complex reaction network involved in glucose-to-HMF transformations is briefly summarized. Special emphasis is placed on analyzing the complexities of feedstocks, intermediates, (side-) products, catalysts, solvents, and their impacts on the reaction network. The strategies and representative examples for adjusting the reaction pathway toward HMF by developing multifunctional catalysts and promoters, taking advantage of solvent effects and process intensification, and synergizing all measures are comprehensively discussed. An outlook is provided to highlight the challenges and opportunities faced in this promising field. It is expected to provide guidance to design practical catalytic processes for advancing HMF biorefinery.

6.
ChemSusChem ; 13(3): 438, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31961486

RESUMO

Invited for this month's cover is the group of Liangfang Zhu and Changwei Hu at Sichuan University. The image shows a general understanding on the solvent-controlled formation of oligomers (the possible precursors of humins) accompanying with formation of small-molecular carboxylic acids as by-products in the initial reaction stage of fructose dehydration. The Full Paper itself is available at 10.1002/cssc.201902309.

7.
ChemSusChem ; 13(3): 501-512, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31557412

RESUMO

The degradative condensation of hexose, which originates from the C-C cleavage of hexose and condensation of degraded hexose fragment, is one of the possible reaction pathways for the formation of humins in hexose dehydration to 5-hydroxymethylfurfural (HMF). Herein, the impacts of several polar aprotic solvents on the degradative condensation of fructose to small-molecule carboxylic acids and oligomers (possible precursors of humins) are reported. In particular, a close relationship between the tautomeric distribution of fructose in solvents and the mechanism of degradative condensation is demonstrated. Typically, α-fructofuranose in 1,4-dioxane and acyclic open-chain fructose in THF favor the conversion of fructose to formic acid and oligomers; α-fructopyranose in γ-valerolactone or N-methylpyrrolidone favors levulinic acid and oligomers, whereas ß-fructopyranose in 4-methyl-2-pentanone favors acetic acid and corresponding oligomers. This close correlation highlights a general understanding of the solvent-controlled formation of oligomers, which represents an important step toward the rational design of effective solvent systems for HMF production.

8.
Phys Chem Chem Phys ; 21(7): 3795-3804, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30714064

RESUMO

The selective removal of oxygen from 5-hydroxymethylfurfural (HMF) is challenging for the effective utilization of biomass. The catalytic mechanisms of palladium acetate toward the conversion of HMF to furfuryl alcohol (FFA), 5-methylfurfural (5-MF) and 2,5-dihydroxymethyl furan (DHMF) have been theoretically investigated. The decarbonylation of HMF to FFA includes (i) migratory extrusion, (ii) metal-acetate-co-assisted deprotonation, (iii) decarbonylation, (iv) metal-assisted deprotonation, and (v) migratory extrusion and catalyst regeneration. Both hydrogenation and deoxidation of HMF with HCOOH as the H-source involve (i) migratory extrusion, (ii) oxidative addition, (iii) reductive elimination, (iv) metal-assisted deprotonation, and (v) migratory extrusion and catalyst regeneration. The C-H bond cleavage is the crucial reaction step, in which the metal-acetate-co-assisted deprotonation is kinetically more preferable than the oxidative addition. Both FFA and DHMF are kinetically superior to 5-MF. In terms of selectivity, increasing the temperature is beneficial to decarbonylation and decreasing the temperature is advantageous to hydrogenation. The present finding provides molecular-level insight into the functions of both the metal-center and coordinated-ligand in the Pd(OAc)2 catalyst, which may drive the novel design of catalytic systems toward both decarbonylation and hydrogenation reactions.

9.
Genomics ; 109(5-6): 331-335, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28533192

RESUMO

OBJECTIVE: Our study aims to explore the in vitro effects of reprogramming factors on the expressions of pluripotent genes and CD34 gene in HL-60 cells. METHODS: According to the construction of lentiviral vector LV-OSCK of reprogramming factors (Oct-4, Sox2, Klf4, c-Myc), 293T cells were transfected to detect virus titer. The endogenous pluripotent genes (Oct4, SOX2, c-Myc and Klf4) and CD34 mRNA and protein expressions were detected by AP staining, immunofluorescence staining, qRT-PCR and flow cytometry. RESULTS: Expressions of Oct4, SOX2, c-Myc and Klf4 were 0.220±0.013, 0.186±0.009, 0.287±0.015 and 0.153±0.007. These levels were significantly higher in the experimental group than the control and blank groups. CD34 protein expression in the experimental group was also discovered to be significantly higher than the other two groups. CONCLUSION: The reprogramming factors could increase the expressions of pluripotent genes and CD34 gene in HL-60 cells.


Assuntos
Antígenos CD34/genética , Proteínas de Ligação a DNA/genética , Leucemia Promielocítica Aguda/genética , Regulação para Cima , Antígenos CD34/metabolismo , Reprogramação Celular , Proteínas de Ligação a DNA/metabolismo , Regulação Leucêmica da Expressão Gênica , Células HEK293 , Células HL-60 , Humanos , Fator 4 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Lentivirus/fisiologia , Leucemia Promielocítica Aguda/metabolismo , Fator 3 de Transcrição de Octâmero/genética , Fator 3 de Transcrição de Octâmero/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo
10.
Cell Physiol Biochem ; 41(4): 1661-1674, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28359056

RESUMO

OBJECTIVE: The present study aimed to establish an induced pluripotent stem cell (iPSC) line from acute myelogenous leukemia (AML) cells in vitro and identify their biological characteristics. METHODS: Cells from the AML-infiltrated skin from an M6 patient were infected with a lentivirus carrying OCT4, SOX2, KLF4 and C-MYC to induce iPSCs. The characteristics of the iPSCs were confirmed by alkaline phosphatase (ALP) staining. The proliferation ability of iPSCs was detected with a CCK-8 assay. The expression of pluripotency markers was measured by immunostaining, and the expression of stem cell-related genes was detected by qRT-PCR; distortion during the induction process was detected by karyotype analysis; the differentiation potential of iPSCs was determined by embryoid body-formation and teratoma-formation assays. ALP staining confirmed that these cells exhibited positive staining and had the characteristics of iPSCs. RESULTS: The CCK-8 assay showed that the iPSCs had the ability to proliferate. Immunostaining demonstrated that iPSC clones showed positive expression of NANOG, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. qRT-PCR results revealed that the mRNA expression of Nanog, Lin28, Cripto, FOX3, DNMT3b, DPPA2, and DPPA4 significantly increased in iPSCs. Karyotype analysis found no chromosome aberration in the iPSCs. The results of the embryoid body-formation and teratoma-formation assays indicated that the iPSCs had the potential to differentiate into all three germ layers. CONCLUSION: Our study provided evidence that an iPSC line derived from AML cells was successfully established.


Assuntos
Regulação Leucêmica da Expressão Gênica , Células-Tronco Pluripotentes Induzidas/metabolismo , Leucemia Eritroblástica Aguda/metabolismo , Proteínas de Neoplasias/biossíntese , Neoplasias Cutâneas/metabolismo , Fatores de Transcrição/biossíntese , Adulto , Humanos , Células-Tronco Pluripotentes Induzidas/patologia , Fator 4 Semelhante a Kruppel , Leucemia Eritroblástica Aguda/genética , Leucemia Eritroblástica Aguda/patologia , Masculino , Proteínas de Neoplasias/genética , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Fatores de Transcrição/genética
11.
ChemSusChem ; 9(16): 2174-81, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27453215

RESUMO

We report an unprecedented solid organic-base catalyst, formyl-modified polyaniline (FS-PAN), for the dehydration of fructose to 5-hydroxymethylfurfural (HMF) with a high yield of 90.4 mol %. We demonstrate that the nitrogen atoms incorporated between the phenyl rings in the backbone of the polyaniline chain contribute to the basicity of the catalyst. The grafting of electron-withdrawing formyl groups to the imine nitrogen atoms leads to a significant increase of basicity of the polymer catalyst owing to the greater localization of electrons at the amide nitrogen atom formed. A linear dependence of the yield of HMF on the grafting level of formyl groups in FS-PAN indicates that the amide acts as the active phase. A possible reaction mechanism for this organic-base-catalyzed dehydration reaction is proposed. The side-reaction of HMF rehydration is inhibited thoroughly, and the condensation of any reaction intermediates to undesirable oligomers is restrained by this base catalyst. This organic-base catalyst can be recycled completely without loss of activity. This research highlights the first application of a highly effective and stable solid base catalyst for the transformation of renewable carbohydrates into fine chemicals.


Assuntos
Compostos de Anilina/química , Frutose/química , Furaldeído/análogos & derivados , Catálise , Furaldeído/química , Concentração de Íons de Hidrogênio , Iminas/química , Solventes/química , Temperatura , Água/química
12.
ChemSusChem ; 7(12): 3541-7, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25351364

RESUMO

In this work, a one-pot strategy for directly converting fructose into 2,5-diformylfuran (DFF) over Mo-containing Keggin heteropolyacids (HPAs) in open air is developed. H3 PMo12 O40 HPA is found to show high activity and selectivity to the formation of DFF owing to its higher Brønsted acidity and moderate redox potential. The partial substitution of the H(+) in H3 PMo12 O40 with Cs(+) leads to the heterogenization of the HPA by forming its cesium salts Csx H3-x PMo12 (x=0.5, 1.5, and 2.5). A satisfactory yield of 69.3% to DFF is obtained over Cs0.5 H2.5 PMo12 polyoxometalate after deliberate optimization of the reaction conditions. The heterogenized polyoxometalate could be recycled and reused without significant loss of catalytic activity for five runs. The produced DFF could be separated from the resulting mixture by an adsorption-desorption method using activated carbon as the adsorbent and furfural as the desorbent. A highest isolated yield of 58.2% is obtained.


Assuntos
Ácidos/química , Carboidratos/química , Furanos/síntese química , Molibdênio/química
13.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 21(6): 1413-22, 2013 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-24370022

RESUMO

This study was aimed to investigate the reversing effects of emodin on multidrug resistance (MDR) in resistant HL-60/ADR cells, and to explore the underlying mechanisms. The MTT assay was used to assess the chemoresistance of HL-60/ADR cells to emodin and 8 chemotherapeutic agents commonly used in clinic. The reversal effects of emodin on MDR of HL-60/ADR cells were also evaluated by MTT method. DNA ploidy analysis and DNA Ladder assay were used to detect apoptosis-induced effects on HL-60/ADR cells via the adriamycin (ADR) and emodin combination. The expression changes of the drug resistance-associated genes and proteins were detected by RT-PCR and Western Blot respectively. The intracellular accumulation and subcellular distribution of ADR and DNR were measured by flow cytometry and confocal laser scanning microscopy. The results showed that emodin inhibited HL-60/ADR cell proliferation with an average IC50 value of 24.09 ± 1.72 µmol/L, which was similar to that of the parental HL-60 cells (average IC50 = 23.18 ± 0.87 µmol/L). HL-60/ADR cells were resistant to a variety of chemotherapeutic agents, such as ADR, DNR, VP16, VCR,Ara-C, HHT, MTZ and THP. The reversal multiple were between 1.58 and 4.12 after the treatment with low concentration of emodin combined with the above mentioned different agents. The combination of ADR with emodin showed the best reversal effects, and the typical hypodiploid peak (apoptotic peak) and DNA ladder could be detected after the co-treatment.In addition, emodin down-regulated the mRNA and protein expression levels of MRP1, TOPOIIß, GST π and BCL-2. Furthermore, the addition of emodin enhanced ADR and DNR intracellular accumulation and subcellular distribution in HL-60/ADR cells in dose-dependent manner. It is concluded that the emodin shows reversing effects on the multidrug resistant HL-60/ADR cells, possibly via decreasing the expression levels of drug resistance-associated genes, increasing the intracellular accumulation of chemotherapeutic agents and activating the apoptosis pathway.


Assuntos
Antineoplásicos/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Emodina/farmacologia , Apoptose , Doxorrubicina/farmacologia , Células HL-60 , Humanos
14.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 21(1): 1-6, 2013 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-23484680

RESUMO

This study was aimed to compare the expression level of eIF4E in patients with leukemia and normal controls, and to explore its role in leukemogenesis. White blood cells were collected in 76 leukemia patients and 10 healthy volunteers. The mRNA and protein expressions of eIF4E were detected by QT-PCR and Western blot in 39 cases of acute myeloid leukemia (AML), 15 cases of chronic myeloid leukemia (CML), 22 cases of acute lymphocytic leukemia (ALL) and 10 healthy volunteers as normal controls. The results demonstrated that compared with normal controls, the absolute expression levels of eIF4E mRNA increased in patients with AML, ALL and CML in blastic phase (P < 0.05), but had no significant change between groups of CML in chronic and accelerated phase although some increasing in group of CML in accelerated phase. The relative expression level of eIF4E mRNA had no significant change in AML, ALL, CML groups except the two subtypes of leukemia M4 and M5. Furthermore, the protein expression level in group of CML in accelerated phase and blastic phase and all acute leukemia patients including AML and ALL were higher than that in normal controls (P < 0.05). It is concluded that although its mRNA relative expressions had no significant change in most leukemia patients, the absolute expression level of eIF4E mRNA and its protein expression is up-regulated in most leukemia patients, which may play an important role in leukemogenesis, so the eIF4E may be a promising target for leukemia therapy and eIF4E-targeted therapy may be an option especially for the relapse and refractory leukemia.


Assuntos
Fator de Iniciação 4E em Eucariotos/genética , Fator de Iniciação 4E em Eucariotos/metabolismo , Leucemia/genética , Leucemia/metabolismo , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Leucemia/patologia , Leucemia Mielogênica Crônica BCR-ABL Positiva , Leucemia Mieloide Aguda , Masculino , Pessoa de Meia-Idade , Leucemia-Linfoma Linfoblástico de Células Precursoras , RNA Mensageiro/genética , Adulto Jovem
16.
ACS Nano ; 6(7): 6033-9, 2012 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-22712429

RESUMO

Growth of polythiophene (PTh) on five-fold twinned Ag nanowires (NWs) is not symmetrical due to preferred etching of their intrinsic defects. This imbalance of polymer formation leads to consistent bending action along the etched NWs, coiling the resulting Ag-PTh nanocomposites into planar spirals. We studied the etching intermediates and also the effects of the surface ligands in order to understand the symmetry-breaking action. The defect-dependent etching chemistry offers a new means to induce motion and a novel perspective in the ordered occurrence of certain defects. We demonstrate that Ag can be deposited back onto the coiled Ag-PTh composite to form metallic spirals.

17.
Small ; 8(12): 1857-62, 2012 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-22467175

RESUMO

New methods to self-assemble polystyrene-block-poly(acrylic acid) (PSPAA) on silica via electrostatic interaction and to deposit silica on PSPAA shells are developed. The mutual encapsulation of silica and PSPAA allows versatile syntheses of well-controlled nanohybrids.


Assuntos
Acrilatos/química , Metais/química , Polímeros/química , Poliestirenos/química , Dióxido de Silício/química , Materiais Biocompatíveis/química , Catálise , Sistemas de Liberação de Medicamentos , Desenho de Equipamento , Humanos , Microscopia Eletrônica de Transmissão/métodos , Nanoestruturas/química , Nanotecnologia/métodos , Propriedades de Superfície , Termodinâmica
18.
J Am Chem Soc ; 134(4): 2004-7, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22239595

RESUMO

We show that embedding of a surface ligand can dramatically affect the metal-metal interfacial energy, making it possible to create nanostructures in defiance of traditional wisdom. Despite matching Au-Ag lattices, Au-Ag hybrid NPs can be continuously tuned from concentric core-shell, eccentric core-shell, acorn, to dimer structures. This method can be extended to tune even Au-Au and Ag-Ag interfaces.

19.
ACS Nano ; 5(10): 8426-33, 2011 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-21942743

RESUMO

We show that the microstructures of polycrystalline ice can serve as a confining template for one-dimensional assembly of colloidal nanoparticles. Upon simply freezing an aqueous colloid, the nanoparticles are excluded from ice grains and form chains in the ice veins. The nanoparticle chains are transferable and can be strengthened by polymer encapsulation. After coating with polyaniline shells, simple sedimentation is used to remove large aggregates, enriching single-line chains of 40 nm gold nanoparticles with a total length of several micrometers. When gold nanorods were used, they formed one-dimensional aggregates with specific end-to-end conformation, indicating the confining effects of the nanoscale ice veins at the final stage of freezing. The unbranched and ultralong plasmonic chains are of importance for future study of plasmonic coupling and development of plasmonic waveguides.


Assuntos
Ouro/química , Gelo , Nanopartículas/química , Coloides , Congelamento
20.
J Am Chem Soc ; 133(30): 11422-5, 2011 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-21732677

RESUMO

We demonstrate that the silica shell on nanoparticles formed by a typical Stöber method is inhomogeneous in nature. The outer layer of the shell is chemically more robust than the inner layer, which can be selectively etched by hot water. Methods are developed to "harden" the soft silica shells. These new understandings are exploited to develop versatile and template-free approaches for fabricating sophisticated yolk-shell nanostructures.

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