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2.
Nano Lett ; 23(14): 6497-6503, 2023 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-37450769

RESUMO

We report an experimental study of proximity induced superconductivity in planar Josephson junction devices made from free-standing InAs nanosheets. The nanosheets are grown by molecular beam epitaxy, and the Josephson junction devices are fabricated by directly contacting the nanosheets with superconductor Al electrodes. The fabricated devices are explored by low-temperature carrier transport measurements. The measurements show that the devices exhibit a gate-tunable supercurrent, multiple Andreev reflections, and a good quality superconductor-semiconductor interface. The superconducting characteristics of the Josephson junctions are investigated at different magnetic fields and temperatures and are analyzed based on the Bardeen-Cooper-Schrieffer (BCS) theory. The measurements of the ac Josephson effect are also conducted under microwave radiations with different radiation powers and frequencies, and integer Shapiro steps are observed. Our work demonstrates that InAs nanosheet based hybrid devices are desired systems for investigating the forefront of physics, such as two-dimensional topological superconductivity.

3.
Molecules ; 28(1)2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36615529

RESUMO

The abuse and residues of antibiotics have a great impact on the environment and organisms, and their determination has become very important. Due to their low contents, varieties and complex matrices, effective recognition, separation and enrichment are usually required prior to determination. Molecularly imprinted polymers (MIPs), a kind of highly selective polymer prepared via molecular imprinting technology (MIT), are used widely in the analytical detection of antibiotics, as adsorbents of solid-phase extraction (SPE) and as recognition elements of sensors. Herein, recent advances in MIPs for antibiotic residue analysis are reviewed. Firstly, several new preparation techniques of MIPs for detecting antibiotics are briefly introduced, including surface imprinting, nanoimprinting, living/controlled radical polymerization, and multi-template imprinting, multi-functional monomer imprinting and dummy template imprinting. Secondly, several SPE modes based on MIPs are summarized, namely packed SPE, magnetic SPE, dispersive SPE, matrix solid-phase dispersive extraction, solid-phase microextraction, stir-bar sorptive extraction and pipette-tip SPE. Thirdly, the basic principles of MIP-based sensors and three sensing modes, including electrochemical sensing, optical sensing and mass sensing, are also outlined. Fourthly, the research progress on molecularly imprinted SPEs (MISPEs) and MIP-based electrochemical/optical/mass sensors for the detection of various antibiotic residues in environmental and food samples since 2018 are comprehensively reviewed, including sulfonamides, quinolones, ß-lactams and so on. Finally, the preparation and application prospects of MIPs for detecting antibiotics are outlined.


Assuntos
Impressão Molecular , Polímeros Molecularmente Impressos , Antibacterianos , Extração em Fase Sólida/métodos , Microextração em Fase Sólida/métodos , Polímeros/química , Impressão Molecular/métodos
4.
Nat Prod Res ; 36(8): 1927-1933, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33107346

RESUMO

A new diarylheptanoid, (1 R,2S,3S,5S)-2,3-dihydroxy-3',3''-dimethoxy-4'-de-O-methylcentrolobine (1) and a new bisabolane-type sesquiterpenoid, (1 R,7S)-1,12,13-trihydroxybisabola-3,10-diene (2), together with nineteen known compounds (3-21) were isolated from the EtOH extract of the stems and branches of Viscum coloratum (Kom.) Nakai. Their structures were elucidated by extensive analysis of 1 D and 2 D NMR spectra and from the HRESIMS. All the compounds were evaluated for their cytotoxic activity against eight human tumor cell lines.


Assuntos
Antineoplásicos , Viscum , Diarileptanoides , Humanos , Espectroscopia de Ressonância Magnética , Viscum/química
5.
Nat Commun ; 12(1): 6279, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34725338

RESUMO

Van der Waals magnets have emerged as a fertile ground for the exploration of highly tunable spin physics and spin-related technology. Two-dimensional (2D) magnons in van der Waals magnets are collective excitation of spins under strong confinement. Although considerable progress has been made in understanding 2D magnons, a crucial magnon device called the van der Waals magnon valve, in which the magnon signal can be completely and repeatedly turned on and off electrically, has yet to be realized. Here we demonstrate such magnon valves based on van der Waals antiferromagnetic insulator MnPS3. By applying DC electric current through the gate electrode, we show that the second harmonic thermal magnon (SHM) signal can be tuned from positive to negative. The guaranteed zero crossing during this tuning demonstrates a complete blocking of SHM transmission, arising from the nonlinear gate dependence of the non-equilibrium magnon density in the 2D spin channel. Using the switchable magnon valves we demonstrate a magnon-based inverter. These results illustrate the potential of van der Waals anti-ferromagnets for studying highly tunable spin-wave physics and for application in magnon-base circuitry in future information technology.

6.
J Inflamm Res ; 14: 2681-2696, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34234502

RESUMO

PURPOSE: Euphorbia neriifolia Linn. has important medicinal value in the treatment of ulcers, tumors, inflammation, chronic respiratory troubles, and so on. Although many ingredients with anti-inflammatory activity have been discovered and isolated from the Euphorbia neriifolia, the current research still cannot explain its multivariate effects on the immune response. This article aims to introduce two Ingenane-type diterpenoids from Euphorbia neriifolia with macrophage regulatory effects and to investigate the mechanism of their action. METHODS: The stem bark of E. neriifolia was extracted with various separation methods to obtain ingenane-type diterpenoids. The RAW264.7 cells were treated with lipopolysaccharide (LPS, 1 µg/mL) to establish an inflammatory cell model. The cell viability was detected by MTT assay. The secretion of PGE2, TNF-α, IL-1ß, and IL-6 was tested with ELISA. The levels of iNOS, COX-2, IκBα, JNK, ERK, p38, p-IκBα, p-JNK, p-ERK, and p-p38 in cells were detected by Western blotting. The translocation of nuclear factor-kappa B (NF-κB)/p65 subunit were evaluated by Immunofluorescence staining. RESULTS: Ingenane-type diterpenoids, eurifoloid A (Euri A) and a new compound euphorneroid E (Euph E), were isolated from the EtOAc fraction of E. neriifolia stem bark extracts. Euph E and Euri A exhibited significant inhibition on the levels of pro-inflammatory mediators NO, IL-1ß, IL-6, and iNOS on LPS-induced macrophage RAW264.7. Cellular signaling pathway studies showed that they prevented the degradation of IκBα and the translocation of NF-κB/p65 subunit. Furthermore, the production of PGE2, TNFα, and COX-2 was dramatically increased under the influence of the compounds, which were closely related to the phosphorylation of protein kinase C δ (PKCδ) and activation of mitogen-activated protein kinase (MAPKs) signaling pathway. CONCLUSION: These results demonstrated that Euph E and Euri A exhibited multidirectional regulation on cytokines and immune function of macrophages, in addition to a good anti-inflammatory activity, and which was closely related to the regulation of PKCδ/MAPKs and NF-κB signal pathways.

7.
Mol Biol Rep ; 47(4): 3211-3219, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32086720

RESUMO

Vitiligo is a common chronic depigmented skin disease characterized by melanocyte loss or dysfunction in the lesion. The pathogenesis of vitiligo has not been fully clarified. Most studies have suggested that the occurrence and progression of vitiligo are due to multiple factors and gene interactions in which noncoding RNAs contribute to an individual's susceptibility to vitiligo. Noncoding RNAs, including microRNAs (miRNAs), are a hot topic in posttranscriptional regulatory mechanism research. miRNAs are noncoding RNAs with a length of approximately 22 nucleotides and play a negative regulatory role by binding to the 3'-UTR or 5'-UTR of the target mRNA to inhibit translation or initiate mRNA degradation. Previous studies have screened the differential expression profiles of miRNAs in the skin lesions, melanocytes, peripheral blood mononuclear cells (PBMCs) and sera of patients and mouse models with vitiligo. Moreover, several studies have focused on miRNA-25, miRNA-155 and other miRNAs involved in melanin metabolism, oxidative stress, and melanocyte proliferation and apoptosis. These miRNAs and regulatory processes further illuminate the pathogenesis of vitiligo and provide hope for the application of small molecules in the treatment of vitiligo. In this review, we summarize miRNA expression profiles in different tissues of vitiligo patients and the mechanisms by which key miRNAs mediate vitiligo development.


Assuntos
MicroRNAs/genética , Vitiligo/genética , Vitiligo/metabolismo , Regiões 3' não Traduzidas/genética , Animais , Apoptose/genética , Proliferação de Células/genética , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica/genética , Humanos , Leucócitos Mononucleares/metabolismo , Melaninas/genética , Melaninas/metabolismo , Melanócitos/metabolismo , Camundongos , MicroRNAs/fisiologia , Estresse Oxidativo/genética , Estresse Oxidativo/fisiologia , RNA Mensageiro/genética , Vitiligo/fisiopatologia
8.
Biomed Pharmacother ; 121: 109663, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31751870

RESUMO

P-glycoprotein (P-gp) plays a significant role in multi-drug resistance (MDR) of cancer cells, resulting in the failure of cancer chemotherapy. Lathyrane diterpene was a class of promising MDR modulator. The phytochemical investigation on the seeds of Euphorbia lathyris L. aff ;orded four new lathyrol-type diterpenoids (1-4), together with seventeen known ones (5-23). The structures of these compounds were elucidated by using 1D and 2D NMR spectroscopy. All the compounds were evaluated reversing MDR activity in HepG2/ADR cells. Compounds 2-4, 7-9, 11, 13-14, 16, 18-19, and 2 1-2 3 at 20 µM was able to reverse MDR of HepG2/ADR cells to adriamycin (reversal fold: 10.05-448.39). In the investigation of reversing the MDR mechanism, the most potent compound 21 facilitated the accumulation of intracellular adriamycin in HepG2/ADR cells in the time-dependent model. Although 21 neither affected the P-gp distribution nor expression in HepG2/ADR cells, the amount of P-gp monomer was induced by 21 and verapamil. Compound 21 has also activated the P-gp coupled ATPase activity in a dose-dependent model. The molecular docking analysis implied that 21 had lower binding energy than verapamil and adriamycin. The present data demonstrated that lathyrane diterpenes may act as a class of high-affinity P-gp substrate and was effluxed by P-gp monomer to reverse the MDR.


Assuntos
Diterpenos/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Euphorbia/química , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Linhagem Celular Tumoral , Doxorrubicina/farmacologia , Células Hep G2 , Humanos , Simulação de Acoplamento Molecular/métodos , Sementes/química
9.
ACS Appl Mater Interfaces ; 11(45): 42358-42364, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31633328

RESUMO

Two-dimensional material-based ferroelectric field-effect transistors (2D-FeFETs) hold great promise in information storage and processing. However, an often-observed and hard-to-control anti-hysteresis response of 2D-FeFETs, for example, hysteretic switching of the resistance states of the devices opposite to that of the actual polarization of the ferroelectric dielectric, represents a major issue in the industrial applications of such devices. Here, we demonstrate a van der Waals buffer technique that eliminates anti-hysteresis in black phosphorus (BP) 2D-FeFETs and restores their intrinsic hysteretic behavior. Our modified BP 2D-FeFETs showed outstanding performance including high room-temperature carrier mobility, robust bistable states with fast response to a gate, a large on/off ratio at zero gate voltage, a large and considerably more stable memory window, and a long retention time. During repeated gate operation, the memory window of the buffered device is ∼7000 times more stable than the unbuffered device. Such a method could be crucial in future information technological applications that utilize the intrinsic properties of 2D-FeFETs.

10.
J Exp Clin Cancer Res ; 37(1): 151, 2018 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-30005681

RESUMO

BACKGROUND: Colorectal cancer (CRC) is one of the most prevalent malignancies in the world and developed drug resistance has represented one of the most challenging tasks for management. The current therapeutic regimens may select and enrich cancer stem-like cells (CSCs) resulting in the increased resistance against treatment, metastatic potential and mortality. Regorafenib is a multi-kinase inhibitor, an FDA-approved last-of-line treatment for patients with chemo-refractory metastatic CRC. However, regorafenib's potential effects on CSCs have not been fully elucidated. METHODS: Here, we developed two 5-FU resistant CRC cell lines, HCT-116R and DLD-1R and showed the increased CSCs characteristics such as increased side-population cells, tumor sphere formation and expression of stemness markers. These cell lines and CSCs properties were used for evaluating the potential of regorafenib in suppressing CSCs. RESULTS: We showed that regorafenib treatment decreased the stemness phenotypes including tumor sphere formation, and side-population, of both HCT-116R and DLD-1R cells. Additionally, regorafenib suppressed the cell viability in both cell lines synergistically with 5-FU. In vivo, the combination of regorafenib and 5-FU significantly suppressed the tumorigenesis and stemness markers of 5-FU resistant DLD-1R. Mechanistically, regorafenib-mediated effects were associated with the induction of tumor suppressor miR-34a and suppression of WNT/ß-catenin signaling. Our findings demonstrated that regorafenib treatment was associated with the increased level of miR-34a, resulting in reversing drug resistance and cancer-initiating cell phenotypes by degrading WNT/ß-catenin in CRC. CONCLUSION: Regorafenib might be a potential drug for colon cancer stem-like cells and it should be investigated in future clinical trials.


Assuntos
Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/genética , MicroRNAs/metabolismo , Células-Tronco Neoplásicas/metabolismo , Compostos de Fenilureia/uso terapêutico , Piridinas/uso terapêutico , Carcinogênese , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Humanos , Compostos de Fenilureia/farmacologia , Piridinas/farmacologia , Transdução de Sinais
11.
Sci Rep ; 8(1): 1621, 2018 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-29374219

RESUMO

Trichostatin A (TSA) possess histone deacetylase (HDAC) inhibitory potential, can reverse the deactivation of tumor suppressor genes and inhibit tumor cell proliferation. We evaluated the effect of TSA on HDAC expression, tumor cell proliferation, and cancer stem cells (CSCs) activities in pancreatic ductal adenocarnoma (PDAC) cells. The PDAC cell lines MiaPaCa-2 and PANC-1 were distinctly sensitive to TSA, with enhanced apoptosis, compared to SAHA. TSA or SAHA inhibited vimentin, HDACs 1, 7 and 8, upregulated E-cadherin mRNA and protein levels in the PDAC cells, and time-dependently downregulated Oct-4, Sox-2, and Nanog, as well as inhibited PDAC tumorsphere formation. TSA also induces accumulation of acetylated histones, while increasing histone 3 lysine 4 or 9 dimethylation levels in PDAC cells and enhancing the epigenetic activity of SAHA. The anti-CSCs effect of TSA was like that obtained by silencing HDAC-1 or 7 using siRNA, and enhances Gemcitabine activity. Our study highlights the molecular targetability of HDACs 1, 7, and 8, confirm their PDAC-CSCs maintaining role, and demonstrate that compared to SAHA, TSA modulates the epigenetically- mediated oncogenic activity of PDAC-CSCs, and potentiate Gemcitabine therapeutic activity, making a case for further exploration of TSA activity alone or in combination with Gemcitabine in PDAC therapy.


Assuntos
Antimetabólitos Antineoplásicos/metabolismo , Desoxicitidina/análogos & derivados , Inibidores de Histona Desacetilases/metabolismo , Histona Desacetilases/metabolismo , Ácidos Hidroxâmicos/metabolismo , Células-Tronco Neoplásicas/efeitos dos fármacos , Neoplasias Pancreáticas/patologia , Apoptose , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Desoxicitidina/metabolismo , Humanos , Células-Tronco Neoplásicas/fisiologia , Gencitabina
12.
Phytochemistry ; 145: 40-47, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29080411

RESUMO

Six previously undescribed diterpenoids, named euphorantins S-T and euphorneroids A-D, including ingol and ent-atisane types, along with eleven known diterpenoids, were isolated from Euphorbia neriifolia. Their structures were elucidated on the basis of extensive NMR analysis and high resolution mass spectrometry. Euphorneroid D and ent-3-oxoatisan-16α,17-acetonide exhibited moderate anti-HIV-1 activities, with EC50 values of 34 µM (SI = 2.3) and 24 µM (SI = 1.9), respectively.


Assuntos
Fármacos Anti-HIV/farmacologia , Diterpenos/farmacologia , Euphorbia/química , HIV-1/efeitos dos fármacos , Casca de Planta/química , Caules de Planta/química , Fármacos Anti-HIV/química , Fármacos Anti-HIV/isolamento & purificação , Linhagem Celular , Diterpenos/química , Diterpenos/isolamento & purificação , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade
13.
Planta Med ; 83(17): 1368-1373, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28662527

RESUMO

Three new compounds (1 - 3), including a sesterterpenoid, aspterpenacid C (1), with an unusual 5/3/7/6/5 pentacyclic skeleton, together with seven known ones (4 - 10), were isolated from the ethanol extract of the traditional Chinese medicinal plant Swertia bimaculata. Their structures were elucidated on the basis of the methods of spectroscopic NMR, MS, and computational chemistry. The structure of 1 was further confirmed by single-crystal X-ray diffraction analysis. Compounds 1 - 10 were tested for activities on the inhibition of nitric oxide production and HIV-1 replication in vitro. Compound 1 exhibited moderate activity in inhibiting nitric oxide production (IC50 = 16.1 µM) and HIV-1 replication (EC50 = 1.35 µM).


Assuntos
Fármacos Anti-HIV/isolamento & purificação , Fármacos Anti-HIV/farmacologia , Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , HIV-1/efeitos dos fármacos , Swertia/química , Animais , Fármacos Anti-HIV/química , Anti-Inflamatórios/química , China , Medicamentos de Ervas Chinesas/química , Camundongos , Estrutura Molecular , Óxido Nítrico/antagonistas & inibidores , Células RAW 264.7 , Replicação Viral/efeitos dos fármacos
14.
Mater Sci Eng C Mater Biol Appl ; 63: 475-84, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27040241

RESUMO

The liver is the major organ of importance to determine drug dispositions in the body, thus the development of hepatocyte culture systems is of great scientific and practical interests to provide reliable and predictable models for in vitro drug screening. In the current study, to address the challenges of a rapid function loss of primary hepatocytes, the coculture of hepatocytes with fibroblasts and endothelial cells (Hep-Fib-EC) was established on micropatterned fibrous scaffolds. Liver-specific functions, such as the albumin secretion and urea synthesis, were well maintained in the coculture system, accompanied by a rapid formation of multicellular hepatocyte spheroids. The activities of phase I (CYP3A11 and CYP2C9) and phase II enzymes indicated a gradual increase for cocultured hepatocytes, and a maximum level was achieved after 5 days and maintained throughout 15 days of culture. The metabolism testing on model drugs indicated that the scaled clearance rates for hepatocytes in the Hep-Fib-EC coculture system were significantly higher than those of other culture methods, and a linear regression analysis indicated good correlations between the observed data of rats and in vitro predicted values during 15 days of culture. In addition, the enzyme activities and drug clearance rates of hepatocytes in the Hep-Fib-EC coculture model experienced sensitive responsiveness to the inducers and inhibitors of metabolizing enzymes. These results demonstrated the feasibility of micropatterned coculture of hepatocytes as a potential in vitro testing model for the prediction of in vivo drug metabolism.


Assuntos
Hepatócitos/metabolismo , Preparações Farmacêuticas/metabolismo , Animais , Células Cultivadas , Técnicas de Cocultura , Citocromo P-450 CYP2C9/genética , Citocromo P-450 CYP2C9/metabolismo , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/metabolismo , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Hepatócitos/citologia , Masculino , Microscopia Confocal , Microscopia Eletrônica de Varredura , Midazolam/metabolismo , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase em Tempo Real , Tolbutamida/metabolismo , Varfarina/metabolismo
15.
J Mater Chem B ; 4(44): 7155-7167, 2016 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-32263653

RESUMO

The establishment of a reliable in vitro liver model for drug screening remains challenging with respect to tethering the growth of hepatocyte spheroids and adapting to the current high-throughput system. In the current study, short fibers are utilized as scaffolds for the generation of size-controlled hepatocyte spheroids that recapitulate in vivo hepatic phenotypes and functions. The spheroid formation is modulated by the length and galactose/RGD grafts of short fibers, and short 50 µm long fibers motivate the spheroid formation with optimal hepatic function. Short fibers distribute throughout the entire spheroid for tethering hepatocyte growth to form compact spheroids. Compared with scaffold-free spheroid culture on agarose-coated plates, the spheroid culture with short fibers achieves higher clearance rates of model drugs and provides a better prediction of the in vivo drug clearance rate with a correlation value of 0.886. In addition, the drug metabolism capability is highly sensitive to the inducers and inhibitors of metabolizing enzymes, and the responsiveness is maintained during 20 days of culture, exhibiting an efficient in vitro model for determining drug-drug interactions. Therefore, the spheroid culture with short fibers provides an easily manipulated strategy to maintain hepatocyte functions for a prolonged period and enable ready deployment in conventional multiwell plates and diverse organ-on-a-chip devices for high-throughput drug screening.

16.
Acta Biomater ; 28: 138-148, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26409440

RESUMO

The identification of a biologic substrate for maintaining hepatocyte functions is essential to provide reliable and predictable models for in vitro drug screening. In the current study, a three-dimensional culture of hepatocytes was established on highly porous fibrous scaffolds with grafted galactose and RGD to afford extensive cell-cell and cell-scaffold interactions spatially. The pore size and ligand densities indicated significant effects on the formation of hepatocyte spheroids in balancing the cell retention, adhesion, and migration on fibrous scaffolds. Fibrous scaffolds with an average pore size of 60 µm and surface grafting densities of galactose at 5.9 nmol/cm(2) and RGD at 6.9 pmol/cm(2) provided optimal microenvironments for hepatocyte infiltration and multicellular spheroid formation. Significant promotions were also demonstrated in the syntheses of albumin and urea and the activities of phase I (CYP 3A11 and CYP 2C9) and phase II enzymes. The in vitro metabolism tests on testosterone and acetaminophen by hepatocytes on the optimal scaffolds indicated the predicated clearance rates of 50.7 and 22.6 ml/min/kg, respectively, which were comparable to the in vivo values of rats. The in vitro hepatotoxicity tests on amiodarone hydrochloride and acetaminophen predicted the half maximal effective concentrations (EC50) to reflect the in vivo toxic plasma concentrations in human. In addition, the enzyme activities, predicted clearance rates and hepatotoxicity values of hepatocytes on the optimal scaffolds experienced sensitive responsiveness to specific inducers or inhibitors of CYP 3A11 and phase II enzymes, exhibiting in vivo-in vitro correlations to a certain extent. These results demonstrate the feasibility of hepatocyte spheroid culture on fibrous scaffolds as an potential in vitro testing model to predict the in vivo drug metabolism, hepatotoxicity, and drug-drug interactions.


Assuntos
Hepatócitos/citologia , Alicerces Teciduais , Animais , Células Cultivadas , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Técnicas In Vitro , Ligantes , Microscopia Eletrônica de Varredura , Ratos , Ratos Sprague-Dawley
17.
Biomacromolecules ; 15(3): 1044-54, 2014 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-24547870

RESUMO

The maintenance of hepatocyte phenotype and functions remains as a great challenge in the generation of functional liver tissue and in vitro model for drug metabolism studies. The use of hepatocyte coculture systems plays essential roles in the establishment of cell-cell and cell-extracellular matrix communications similar to native liver tissues. In the current study, micropatterned electrospun fibrous mats were created to load hepatocytes, fibroblasts, and endothelial cells (ECs), which were precisely assembled to establish their spatially controlled coculture for mimicking the in vivo structure of hepatic lobules. Hepatocytes formed compact polyhedral spheroids with an average diameter of 80-100 µm, reorganized actin filaments in the cell-cell contact regions, and well-developed bile canaliculi. Compared with hepatocytes cultured alone, the coculture of hepatocytes with either fibroblasts or ECs led to significantly higher albumin secretion, urea synthesis and cytochrome P-450 expression, which were dramatically improved by the coculture of hepatocytes with both fibroblasts and ECs. The cocultured ECs well spread on patterned regions with little organized filamentous actin, and significantly higher densities and deeper penetration into patterned scaffolds were determined for ECs after coculture with fibroblasts and hepatocytes compared with those after cultured alone or coculture with either fibroblasts or hepatocytes. A Matrigel overlay assay showed that the capabilities of ECs to form capillary tubes were significantly enhanced by micropatterned coculture with fibroblasts and hepatocytes. Thus, the coculture of hepatocytes, fibroblasts, and ECs on micropatterned fibrous mats helps both hepatocytes in the maintenance of hepatic functions and ECs in the formation of capillary-like structures. It is suggested that the micropatterned coculture model described here not only provides functional hepatic tissues for predictions of drug metabolism profiles, but also will enable investigations on more complex and physiological cell-cell communications.


Assuntos
Comunicação Celular , Diferenciação Celular/genética , Células Endoteliais/citologia , Hepatócitos/citologia , Técnicas de Cocultura , Células Endoteliais/metabolismo , Matriz Extracelular/metabolismo , Fibroblastos/citologia , Hepatócitos/metabolismo , Humanos , Fígado/citologia , Fígado/crescimento & desenvolvimento , Óxido Nítrico Sintase Tipo II/metabolismo , Engenharia Tecidual
18.
J Mater Chem B ; 2(20): 3029-3040, 2014 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-32261678

RESUMO

It remains as a great challenge to maintain the viability and functions of hepatocytes in vitro, and the construction of various scaffold materials and establishment of hepatocyte coculture systems are essential for the reconstruction of engineered liver devices. In our previous study, micropatterned electrospun fibrous mats were developed to control cellular behaviors, indicating that the cell growth and extracellular matrix deposition were confined to patterned regions. In the current study, the coculture of primary rat hepatocytes and fibroblasts was established on micropatterned scaffolds to modulate hepatocyte phenotype and functions. The inoculation of lactosylated poly(dl-lactide) into fiber matrices stimulated hepatocyte spheroid formation, and enhanced the albumin secretion, urea synthesis and cytochrome P-450 expression. The micropatterned coculture of hepatocytes and fibroblasts was constructed through layer-by-layer assembly of cell-loaded patterned fibers. Hepatocyte spheroids were effectively formed in the patterned regions with strong cell-cell contact, and fibroblasts were elongated in a bipolar manner and linked up into a single stretch. Compared with random coculture on fibrous mats and monoculture on patterned fibers, the coculture of hepatocytes with fibroblasts on patterned scaffolds resulted in a significantly higher amount of albumin and urea secretions and P450 expressions. Among the patterning designs, the majority of hepatocytes formed into spheroids with an average diameter of 100 µm after coculture with fibroblasts alternately located in the patterned scaffolds. This coculture system may provide a useful in vitro platform to retain the phenotype of hepatocytes and realize their functions.

19.
J Biotechnol ; 168(1): 46-54, 2013 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-23968724

RESUMO

An accurate quantitation of ethanol is of great importance in clinical and forensic analyses. In the current study, alcohol oxidase (AOX) from Pichia pastoris, a multimeric enzyme consisting of eight identical subunits, was immobilized on electrospun polystyrene-co-maleic anhydride (PSMA) fibers for valid tests of alcoholic saliva. Branched polyethyleneimine (PEI) was grafted on PSMA fibers with a density of 0.15 nmol/cm(2) as tethers to allow multipoint covalent binding of enzyme molecules through glutaraldehyde activation, and the secondary and tertiary amino groups of PEI could intensify the interactions with AOX subunits to stabilize the quaternary structure. PSMA-PEI-AOX fibers were less sensitive than free AOX to the incubation temperature and pH, and indicated no detectable subunit release from the immobilized AOX after boiling in the presence of sodium dodecyl sulfate (SDS) and 2-mercaptoethanol. Color strips were established on PSMA-PEI-AOX fibrous mats dyed with indigo Carmine after incubation into ethanol solutions of different concentrations. The color fading ratio remained no significant change after repeat tests for 9 cycles after immersion in 0.2 and 0.8 mg/mL of alcoholic saliva. It was indicated that multipoint immobilization of the multimeric enzyme was essential to improve the enzyme stability by stabilizing both the quaternary structure of the enzyme and the structure of each individual subunit.


Assuntos
Oxirredutases do Álcool/química , Oxirredutases do Álcool/metabolismo , Álcoois/análise , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Saliva/química , Álcoois/metabolismo , Eletroquímica , Humanos
20.
Langmuir ; 28(49): 17134-42, 2012 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-23153038

RESUMO

Spatial arrangement of multiple cell types plays a critical role in maintaining the viability of cells and functionality of tissues. Micropatterning has been used to fabricate scaffolds to modulate cell distribution, growth, and functions for reconstructing the anisotropy in native tissues. In the current study, a glass substrate patterned with an electrically conductive circuit was prepared by lithography as a collector for electrospinning. Densely packed fibers were deposited on the top of silver strips and patterned fibrous mats were obtained with distinct ridge and groove areas. Orthogonal alignment was shown for fibers in the ridge and groove areas, and the pattern feature and fiber alignment were well maintained in the ridge during incubation of cells with patterned fibrous mats. Sequential confocal laser scanning from the top of cell-loaded fibrous mats indicated that a larger number of cells were spread in the ridge than that in the groove areas, and cells penetrated into the fibrous mats in the ridge. Microscopic observation and immunofluorescent staining indicated that cells and collagen deposition appeared to have distinct patterns on the fibrous scaffold and aligned along the directionality of fibers with an elongated morphology. It is concluded that lithography can provide the design flexibility of collectors with micrometer-scale precision patterning, and cells can be confined to precise locations, sizes, and shapes by the use of micropatterned fibrous scaffolds without any adverse effect on the cell viability and function. The results suggest the potential of patterned electrospun fibrous mats to construct complex tissues of well organized multiple cell types and with spatially distributed extracellular matrices.


Assuntos
Materiais Biocompatíveis/farmacologia , Colágeno/química , Poliésteres/farmacologia , Polietilenoglicóis/farmacologia , Animais , Materiais Biocompatíveis/química , Adesão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Técnicas Eletroquímicas , Matriz Extracelular/química , Imunofluorescência , Vidro/química , Camundongos , Microscopia Confocal , Células NIH 3T3 , Poliésteres/química , Polietilenoglicóis/química , Propriedades de Superfície , Engenharia Tecidual , Alicerces Teciduais
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