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1.
Mol Pharm ; 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32437163

RESUMO

Tumor targeted drug delivery via chemotherapy is very effective on cancer treatment. For potential anti-cancer agent such as Camptothecin(CPT), high chemotherapeutic efficacy and accurate tumor targeting are equally crucial. Inspired by special CD44 binding capability from hyaluronic acid(HA), in this study, novel HA coated CPT nanocrystals were successfully prepared by an anti-solvent precipitation method for tumor targeted delivery of hydrophobic drug CPT. These HA coated CPT nanocrystals demonstrated high drug loading efficiency, improved aqueous dispersion, prolonged circulation and enhanced stability resulting from their nano-scaled sizes and hydrophilic HA layer. Moreover, as compared to crude CPT and Naked CPT nanocrystals, HA coated CPT nanocrystals displayed dramatically enhanced in vitro anti-cancer activity, apoptosis-inducing potency against CD44 overexpressed cancer cells and lower toxic effect towards normal cells due to pH-responsive drug release behavior and specific HA-CD44 mediated endocytosis. Additionally, HA coated CPT nanocrystals performed fairly better anti-migration activity and biocompatibility. The possible molecular mechanism regarding this novel drug formulation might be linked to intrinsic mitochondria-mediated apoptosis by an increase of Bax to Bcl-2 ratio and upregulation of P53. Consequently, HA coated CPT nanocrystals are expected to be an effective nanoplatform in drug delivery for cancer therapy.

2.
Cell Death Dis ; 11(4): 254, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32312949

RESUMO

Impairment of mitochondrial structure and function is strongly linked to glaucoma pathogenesis. Despite the widely appreciated disease relevance of mitochondrial dysfunction and loss, the molecular mechanisms underlying mitochondrial fragmentation and metabolic stress in glaucoma are poorly understood. We demonstrate here that glaucomatous retinal ganglion cells (RGCs) show loss of A-kinase anchoring protein 1 (AKAP1), activation of calcineurin (CaN) and reduction of dynamin-related protein 1 (Drp1) phosphorylation at serine 637 (Ser637). These findings suggest that AKAP1-mediated phosphorylation of Drp1 at Ser637 has a critical role in RGC survival in glaucomatous neurodegeneration. Male mice lacking AKAP1 show increases in CaN and total Drp1 levels, as well as a decrease in Drp1 phosphorylation at Ser637 in the retina. Ultrastructural analysis of mitochondria shows that loss of AKAP1 triggers mitochondrial fragmentation and loss, as well as mitophagosome formation in RGCs. Loss of AKAP1 deregulates oxidative phosphorylation (OXPHOS) complexes (Cxs) by increasing CxII and decreasing CxIII-V, leading to metabolic and oxidative stress. Also, loss of AKAP1 decreases Akt phosphorylation at Serine 473 (Ser473) and threonine 308 (Thr308) and activates the Bim/Bax signaling pathway in the retina. These results suggest that loss of AKAP1 has a critical role in RGC dysfunction by decreasing Drp1 phosphorylation at Ser637, deregulating OXPHOS, decreasing Akt phosphorylation at Ser473 and Thr308, and activating the Bim/Bax pathway in glaucomatous neurodegeneration. Thus, we propose that overexpression of AKAP1 or modulation of Drp1 phosphorylation at Ser637 are potential therapeutic strategies for neuroprotective intervention in glaucoma and other mitochondria-related optic neuropathies.

3.
J Neurosci ; 40(15): 3119-3129, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32144179

RESUMO

Mitochondrial fission catalyzed by dynamin-related protein 1 (Drp1) is necessary for mitochondrial biogenesis and maintenance of healthy mitochondria. However, excessive fission has been associated with multiple neurodegenerative disorders, and we recently reported that mice with smaller mitochondria are sensitized to ischemic stroke injury. Although pharmacological Drp1 inhibition has been put forward as neuroprotective, the specificity and mechanism of the inhibitor used is controversial. Here, we provide genetic evidence that Drp1 inhibition is neuroprotective. Drp1 is activated by dephosphorylation of an inhibitory phosphorylation site, Ser637. We identify Bß2, a mitochondria-localized protein phosphatase 2A (PP2A) regulatory subunit, as a neuron-specific Drp1 activator in vivo Bß2 KO mice of both sexes display elongated mitochondria in neurons and are protected from cerebral ischemic injury. Functionally, deletion of Bß2 and maintained Drp1 Ser637 phosphorylation improved mitochondrial respiratory capacity, Ca2+ homeostasis, and attenuated superoxide production in response to ischemia and excitotoxicity in vitro and ex vivo Last, deletion of Bß2 rescued excessive stroke damage associated with dephosphorylation of Drp1 S637 and mitochondrial fission. These results indicate that the state of mitochondrial connectivity and PP2A/Bß2-mediated dephosphorylation of Drp1 play a critical role in determining the severity of cerebral ischemic injury. Therefore, Bß2 may represent a target for prophylactic neuroprotective therapy in populations at high risk of stroke.SIGNIFICANCE STATEMENT With recent advances in clinical practice including mechanical thrombectomy up to 24 h after the ischemic event, there is resurgent interest in neuroprotective stroke therapies. In this study, we demonstrate reduced stroke damage in the brain of mice lacking the Bß2 regulatory subunit of protein phosphatase 2A, which we have shown previously acts as a positive regulator of the mitochondrial fission enzyme dynamin-related protein 1 (Drp1). Importantly, we provide evidence that deletion of Bß2 can rescue excessive ischemic damage in mice lacking the mitochondrial PKA scaffold AKAP1, apparently via opposing effects on Drp1 S637 phosphorylation. These results highlight reversible phosphorylation in bidirectional regulation of Drp1 activity and identify Bß2 as a potential pharmacological target to protect the brain from stroke injury.

4.
Cells ; 9(2)2020 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-31991888

RESUMO

Best known as the powerhouse of the cell, mitochondria have many other important functions such as buffering intracellular calcium and reactive oxygen species levels, initiating apoptosis and supporting cell proliferation and survival. Mitochondria are also dynamic organelles that are constantly undergoing fission and fusion to meet specific functional needs. These processes and functions are regulated by intracellular signaling at the mitochondria. A-kinase anchoring protein 1 (AKAP1) is a scaffold protein that recruits protein kinase A (PKA), other signaling proteins, as well as RNA to the outer mitochondrial membrane. Hence, AKAP1 can be considered a mitochondrial signaling hub. In this review, we discuss what is currently known about AKAP1's function in health and diseases. We focus on the recent literature on AKAP1's roles in metabolic homeostasis, cancer and cardiovascular and neurodegenerative diseases. In healthy tissues, AKAP1 has been shown to be important for driving mitochondrial respiration during exercise and for mitochondrial DNA replication and quality control. Several recent in vivo studies using AKAP1 knockout mice have elucidated the role of AKAP1 in supporting cardiovascular, lung and neuronal cell survival in the stressful post-ischemic environment. In addition, we discuss the unique involvement of AKAP1 in cancer tumor growth, metastasis and resistance to chemotherapy. Collectively, the data indicate that AKAP1 promotes cell survival throug regulating mitochondrial form and function. Lastly, we discuss the potential of targeting of AKAP1 for therapy of various disorders.

5.
Pharmacol Res ; 151: 104545, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31740384

RESUMO

A characteristic feature of leukemia cells is a blockade of differentiation in cellular maturation. All-trans-retinoic acid (ATRA) has been successfully applied for the treatment of M3-type AML (APL, 10 %), but it fails to demonstrate a significant efficacy on the remaining patients with non-APL AML (90 %). Therefore, the research for strategies to extend the efficacy of ATRA-based therapy to non-APL AML is a key avenue of investigation. Here, we evaluate the synergetic effect of CDK2 inhibition and ATRA in AML both in vitro and in vivo. We have determined that both the CDK2 depletion and pharmacological inhibitor of CDK2 significantly sensitize three subtypes of AML cells (including two non-APL cells) to ATRA-induced cell differentiation. RNA-sequence results indicate that transcription activation of differentiation and maturation pathways plays an important role in this synergetic effect. Furthermore, the down-regulation of CDK2 sensitized AML cells to ATRA-induced engraftment prevention of leukemia cells in NOD-SCID mice and promotes the primary AML blasts differentiation when combined with ATRA. Thus, our work not only provides relevant experimental evidence for further validating CDK2 as a target for differentiation therapy, but also uncovers the future clinical application of CDK2 inhibitors in ATRA-based differentiation therapeutics for AML.

6.
Nanotechnology ; 31(7): 075101, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31665708

RESUMO

The aqueous solubility of drug molecules is closely related to its bioactivity like bioavailability and subsequent therapeutic index, especially in the case of hydrophobic drugs like camptothecin (CPT), a potential broad-spectrum anti-cancer agent. Enhanced anti-cancer activity and selectivity of CPT are equally important. Inspired by host-guest effect and drug combination regimen, we developed a novel tumor lytic peptide incorporated drug delivery system by forming beta-cyclodextrin polymer (BCDp) based inclusion complex in nano-scaled size. In this study, BCDp formed inclusion complex with CPT and then a lytic-type peptide (ZH) was grafted. The resulting combinational formulation of BCDp, CPT and ZH, named as ZH-BCDp-CPT inclusion complex, demonstrated greater solubility resulting from its nano-scaled size, amorphous solid state and inclusion structure. Moreover, ZH facilitated quick internalization of conjugated drug via cell membrane lysis, leading to efficient intracellular drug delivery. This novel drug formulation was featured with prolonged circulation, enhanced anti-cancer efficacy, selectivity, anti-cell migration activity and better biocompatibility in comparison with crude CPT and binary BCDp-CPT inclusion complex, all of which were attributed to a cooperative action between ZH and BCDp-CPT inclusion complex. Our results suggested ZH-BCDp-CPT inclusion complex induced cell apoptosis by up-regulation of Bax and P53 and down-regulation of Bcl-2, primarily involved in the mitochondrial pathways.


Assuntos
Antineoplásicos Fitogênicos/química , Camptotecina/química , Celulose/química , Ciclodextrinas/química , Nanopartículas/química , Peptídeos/química , beta-Ciclodextrinas/química , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Disponibilidade Biológica , Camptotecina/farmacologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Sistemas de Liberação de Medicamentos/métodos , Células Hep G2 , Humanos , Células MCF-7 , Transdução de Sinais/efeitos dos fármacos , Solubilidade/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
7.
Food Chem ; 307: 125554, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31648176

RESUMO

The reaction of Nε-(carboxymethyl) lysine (CML) with eight kinds of non-flavonoid o-benzoquinones and five kinds of flavonoid o-benzoquinones were investigated by cyclic voltammetry at pH 5.0, 7.0 and 8.0 and scan rate of 10, 50 and 100 mV/s. The reactivity of o-benzoquinones towards CML is weakened by the electron-donating substituent and strengthened by the electron-withdrawing substituent on the o-benzoquinone rings. The steric hindrance of the substituents on o-benzoquinone rings also weakens the quinone reactivity. Reaction of 4-methylbenzoquinone with CML (38.0 ±â€¯1.3%) was found to be faster than that with l-lysine (31.3 ±â€¯1.5%) and Nα-acetyl-l-lysine (14.5 ±â€¯0.1%) but slower than that with l-cysteine (≥100.0%) and Nα-acetyl-l-cysteine (≥100.0%) at pH 7.0 and scan rate of 10 mV/s. Products obtained by the reaction of CML with o-benzoquinones were found to include a CML-quinone adduct according to the cyclic voltammetry and UPLC-QTOF-MS/MS analysis.


Assuntos
Benzoquinonas/química , Lisina/análogos & derivados , Catecóis , Cisteína/química , Flavonoides , Lisina/química
8.
Risk Manag Healthc Policy ; 12: 189-198, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31807099

RESUMO

Background: This study proposes the use of machine learning algorithms to improve the accuracy of type 2 diabetes predictions using non-invasive risk score systems. Methods: We evaluated and compared the prediction accuracies of existing non-invasive risk score systems using the data from the REACTION study (Risk Evaluation of Cancers in Chinese Diabetic Individuals: A Longitudinal Study). Two simple risk scores were established on the bases of logistic regression. Machine learning techniques (ensemble methods) were used to improve prediction accuracies by combining the individual score systems. Results: Existing score systems from Western populations performed worse than the scores from Eastern populations in general. The two newly established score systems performed better than most existing scores systems but a little worse than the Chinese score system. Using ensemble methods with model selection algorithms yielded better prediction accuracy than all the simple score systems. Conclusion: Our proposed machine learning methods can be used to improve the accuracy of screening the undiagnosed type 2 diabetes and identifying the high-risk patients.

9.
Artigo em Inglês | MEDLINE | ID: mdl-31714795

RESUMO

Mitochondria have an essential function in cell survival due to their role in bioenergetics, reactive oxygen species generation, calcium buffering, and other metabolic activities. Mitochondrial dysfunctions are commonly found in neurodegenerative diseases (NDs), and diabetes is a risk factor for NDs. However, the role of mitochondria in diabetic neurodegeneration is still unclear. In the current study, we reviewed the latest evidence on the role of mitochondrial dysfunctions in the development of diabetes-related NDs and the underlying molecular mechanisms. Hypoglycemic agents, especially metformin, have been proved to have neuroprotective effects in the treatment of diabetes, in which mitochondria could act as one of the underlying mechanisms. Other hypoglycemic agents, including thiazolidinedione (TZDs), dipeptidyl peptidase 4 (DPP-4) inhibitors, and glucagon-like peptide 1 (GLP-1) receptor agonists, have gained more attention due to their beneficial effects on NDs, presumably by improving mitochondrial function. Our review highlighted the notion that mitochondria could be a promising therapeutic target in the treatment of NDs in patients with diabetes.

10.
Infect Drug Resist ; 12: 2875-2883, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31686868

RESUMO

Objective: To study the association between glucose metabolism disorders and hepatotropic virus infection. Methods: A cross-sectional analysis was performed using data from the REACTION study (Risk Evaluation of Cancers in Chinese Diabetic Individuals: A Longitudinal Study). Outcomes of the analysis were test results of kidney function, liver function, lipid metabolism, and the prevalence of hepatitis B virus (HBV) infection and potential hepatitis C virus (HCV) infection (positive hepatitis C virus antibody) among individuals with and without diabetes mellitus (DM) or pre-diabetes mellitus (pre-DM). Results: Of the 10,080 patients who participated in the study, 7665 eligible subjects were included in the analysis. There was no significant difference in the prevalence of HBV infection between DM and normal subjects, pre-DM and normal subjects, and DM or pre-DM and normal subjects (p-values of 0.9180, 0.8154, and 0.6448, respectively). There was also no significant difference in the prevalence of potential HCV infection between DM and normal subjects, pre-DM and normal subjects, and DM or pre-DM and normal subjects (p-values of 0.1190, 0.0591, and 0.5591, respectively). Lipid metabolism showed a significant difference between DM or pre-DM subjects and normal subjects (p-values were less than 0.0221 in all cases). Multiple logistic regression analysis revealed hypertension as the leading significant variable associated with DM, pre-DM, and both. Other significant factors included gender, body mass index, age, and alanine aminotransferase. Conclusion: No significant association was detected between DM or pre-DM and HBV or potential HCV infection. Significant association was detected between lipid metabolism disorders and DM, but this association was absent in pre-DM patients when adjusting for other factors.

11.
Chem Asian J ; 14(23): 4179-4182, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31691478

RESUMO

Novel polyhedral structures were prepared with a butterfly-shape composed of oligosiloxane wings and a double-decker silsesquioxane (DDSQ) body. The compounds were synthesized in two steps from commercially available alkoxysilanes, and their structures were confirmed using spectroscopic methods and X-ray crystallography. Not like other phenyl-substituted cage silsesquioxanes, these butterfly cages show very good solubility in common organic solvents. The crystal structures clearly showed their unique features: a larger space with longer siloxane chains and a very flexible framework. Moreover, these compounds are thermally stable with a Td5 (5 % weight loss temperature) over 320 °C.

12.
CNS Neurol Disord Drug Targets ; 18(9): 695-704, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31577210

RESUMO

BACKGROUND: Carvedilol, which is considered as a nonselective ß-adrenoreceptor blocker, has many pleiotropic activities. It also causes great impact on neuroprotection because of its antioxidant ability, which suggested that carvedilol may be effective in protecting RGCs from increased oxidative stress. OBJECTIVE: To examine the effects of carvedilol on preventing Retinal Ganglion Cell (RGC) death in a mouse model of Optic Nerve Injury (ONI). METHODS: C57BL/6J mice were subjected to Optic Nerve Injury (ONI) model and treated with carvedilol or placebo. Histological and morphometric studies were performed; the RGC number, the amount of neurons in the ganglion cell layer and the thickness of the Inner Retinal Layer (IRL) was quantified. The average thickness of Ganglion Cell Complex (GCC) was determined by the Spectral- Domain OCT (SD-OCT) assay. Immunohistochemistry, western blot and quantitative real-time PCR analysis were also applied. RESULTS: Daily treatment of carvedilol reduced RGC death following ONI, and in vivo retinal imaging revealed that carvedilol can effectively prevent retinal degeneration. The expression of chemokines important for micorglia recruitment was deceased with carvedilol ingestion and the accumulation of retinal microglia is reduced consequently. In addition, the ONI-induced expression of inducible nitric oxide synthase in the retina was inhibited with carvedilol treatment in the retina. We also discovered that carvedilol suppressed ONI-induced activation of Apoptosis Signal-regulating Kinase-1 (ASK1) and p38 Mitogen-Activated Protein Kinase (MAPK) pathway. CONCLUSION: The results of this study indicate that carvedilol can stimulate neuroprotection and neuroregeneration, and may be useful for treatment of various neurodegenerative diseases.

13.
Tumori ; 105(6): 494-500, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31478461

RESUMO

BACKGROUND: An integral and well-functioning vascular system is essential for tumor progression and chemotherapy infusion. However, the lumen integrity of the microvessels and its significance in prognosis has not been studied. In this study, we found that the proportion of collapsed microvessels is suggested to be a novel biomarker for predicting prognosis in patients with non-small cell lung cancer (NSCLC). METHODS: In this study, immunohistochemical CD31 staining was performed to identify the microvessels in tumor specimens. Proportions of collapsed vessels were estimated in CD31-stained tumor specimens from 100 patients with NSCLC. The correlation between collapsed microvessel proportion and survival time were evaluated by univariate and multivariate analysis. RESULTS: Data from 99 patients were analyzed and a wide range of collapse-microvessel fraction was observed in 96 patients (1.4%-70%). Elevated collapse proportion (⩾6.5%) indicated poor overall survival in both univariate analysis (p = 0.042) and multivariate analysis (p = 0.014). CONCLUSIONS: Elevated proportion of collapsed microvessels indicted poor survival outcome in patients with NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/mortalidade , Carcinoma Pulmonar de Células não Pequenas/patologia , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/patologia , Microvasos/patologia , Neovascularização Patológica , Adulto , Idoso , Biomarcadores Tumorais , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , Análise de Sobrevida
14.
Micromachines (Basel) ; 10(8)2019 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-31398936

RESUMO

An integrated centrifugal microfluidic device was developed to preconcentrate and detect hazardous mercury (II) in water with ionic liquid as environmentally friendly extractant. An automatically salt-controlled ionic liquid dispersive liquid-liquid microextraction on a centrifugal microfluidic device was designed, fabricated, and characterized. The entire liquid transport mixing and separation process was controlled by rotation speed, siphon valves, and capillary valves. Still frame images on the rotating device showed the process in detail, revealing the sequential steps of mixing, siphon priming, transportation between chambers, and phase separation. The preconcentration of red dye could be clearly observed with the naked eye. By combining fluorescence probe and microscopy techniques, the device was tested to determine ppb-level mercury (II) in water, and was found to exhibit good linearity and low detection limit.

15.
J Cancer ; 10(15): 3397-3406, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31293643

RESUMO

Background: Sustained tumor growth and metastasis require sufficient blood supply, and microvessel area (MVA) has been reported that is related to prognosis of cancer patients. However, tumor cells may not be nourished enough by blood vessels when the cells are separated from vessels by thick stroma. Therefore we investigated whether stroma-area normalized MVA (SnMVA) is a more important prognostic factor than MVA. Materials and Methods: 100 NSCLC patients who underwent resection between July 2011 and October 2012 were randomly selected. We determined the MVA of the tumor tissues by anti-CD31 immunostaining of microvessels. Stroma-area normalized MVA (SnMVA) was a ratio of MVA to stromal area. Correlation of MVA and SnMVA with overall survival (OS) or progression-free survival (PFS) was assessed using multivariate analysis. Results: Median MVA was 0.0228 (range, 0.00393 to 0.172), and median SnMVA was 0.0441 × 10-6 (range, 0.00393 × 10-6 to 0.259 × 10-6). There was no significant difference in OS between groups of different MVA (HR 0.58, 95%CI 0.28 to 1.19, p = 0.148). In contrast, the risk of death was significantly decreased in high SnMVA group (at or below the median) than in group with low SnMVA (HR 0.47, 95%CI 0.23 to 0.97, p = 0.046). Furthermore, in multivariate analysis, high SnMVA, but not MVA, was an independent prognostic factor after adjusting for age, sex, tumor stage and other factors. OS was significantly associated with SnMVA in six of seven subgroup analysis, but with MVA in only three. Conclusions: Our study showed that the NSCLC patients with high SnMVA had higher OS. And SnMVA is a prognostic factor with greater accuracy than MVA. Since stroma exists widely in a variety of cancer tissues, we infer that SnMVA may also predict the prognostic of other types of cancers.

17.
Polymers (Basel) ; 11(2)2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30960325

RESUMO

Starch-based materials with reinforced properties were considered as one of the most promising materials to replace the petro-based packaging products, and actually, the molecular structures of starch usually determined the structures and properties of end-used starchy products. Here, starch-based nanocomposites were fabricated by starch esters derived from native starches with different amylose contents and organically modified montmorillonite (OMMT). The fractured surface under scanning electron microscopy (SEM) exhibited wrinkles formed by macromolecular aggregation owing to the interaction competition between the plasticizer and nanofiller with the starch ester. The more intense interaction within amylopectin-rich films promoted the formation of much randomly exfoliation of OMMT observed by Transmission electron microscopy (TEM). As the amylose content increased, the interaction between the starch ester and the nanofiller was weakened, leading to the dispersion morphology of an ordered arrangement and partly intercalated structures in the dimension of 12.92 to 19.77 nm. Meanwhile, such interaction also affected both the inner ordered structure integrity of starch ester and the layer structure consistency of nanofiller according to X-ray diffraction results. Further, the stronger interaction between amylopectin and the nanofiller endowed higher thermal stability to the amylopectin-rich starch-based nanocomposites. In short, these results are beneficial for the application of starch-based nanocomposites in the food packaging industry by regulating the interaction between starch and nanofillers.

18.
Inorg Chem ; 58(7): 4093-4098, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30895785

RESUMO

Novel tetravinyl- and tetraallyl-substituted closed double-decker siloxanes (DDSQs) were synthesized and characterized, and their structures were elucidated by X-ray crystallographic analysis. Moreover, it was shown that peripheral olefins could successfully undergo hydrosilylation quantitatively. Such tetrafunctionalizable DDSQs (DDSQ-Vinyl4 and DDSQ-Allyl4) thus constitute promising building blocks for more complex inorganic-organic hybrid materials.

19.
Carbohydr Polym ; 213: 304-310, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30879673

RESUMO

Chitin nanocrystal (ChiNC) was fabricated based on p-toluenesulfonic acid -choline chloride deep eutectic solvent treatment. The obtained ChiNC was about 12-44 nm in width and 206-399 nm in length. The crystalline structure and the functional groups of ChiNC were maintained during the preparation process. Moreover, porcine pancreas lipase (PPL) was successfully immobilized onto the ChiNC to form the immobilized PPL (PPL@ChiNC). The resulting PPL@ChiNC has enzyme loading and activity recovery of 35.6 mg/g and 82.5%, respectively. The thermal stability, pH and temperature adaptabilities of PPL@ChiNC was improved, comparing with free PPL. The demonstrated DES treatment process was efficient for ChiNC preparation and the as-prepared ChiNC exhibited great potentials in biocatalysis and biomedical field.


Assuntos
Benzenossulfonatos/química , Quitina/química , Colina/química , Nanopartículas/química , Quitina/síntese química , Hidrólise , Tamanho da Partícula , Solventes/química , Propriedades de Superfície
20.
J Org Chem ; 84(7): 4413-4420, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30665303

RESUMO

Ligand-free manganese-catalyzed homocoupling of arenes or aryl halides can be carried out under aerobic conditions via the in situ formation of the corresponding aryllithiums. A wide range of biaryls and derivatives has been obtained, and a mechanism involving monomeric manganese-oxo complexes has been proposed on the basis of DFT calculations.

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