RESUMO
Guanine-quadruplex, consisting of several stacked guanine-quartets (GQs), has emerged as an important category of novel molecular targets with applications from nanoelectronic devices to anticancer drugs. Incorporation of metal cations into a GQ structure is utilized to form stable G-quadruplexes, while formation of a cation-free GQ network has been challenging. Here we report the room temperature (RT) molecular self-assembly of extended pristine GQ networks on an Au(111) surface. An implanted molybdenum atom within the Au(111) surface is used to nucleate and stabilize the cation-free GQ network. Additionally, decoration of the Au(111) surface with 7-armchair graphene nanoribbons (7-AGNRs) enhances the GQ domain size by suppressing the influence of the disordered phase nucleated from Au step edges. Scanning tunneling microscopy/spectroscopy (STM/STS) and density functional theory (DFT) calculations confirm the formation of GQ networks and unravel the nucleation and growth mechanism. Our work, utilizing a hetero-atom doped substrate, provides a facile approach to enhance the stability and domain size of the GQ self-assembly, which would be applicable for other molecular structures.
RESUMO
PURPOSE: Epidemiological and intervention studies have attempted to link the health effects of a diet rich in fruits and vegetables with the consumption of polyphenols and their impact in neurodegenerative diseases. Studies have shown that polyphenols can cross the intestinal barrier and reach concentrations in the bloodstream able to exert effects in vivo. However, the effective uptake of polyphenols into the brain is still regarded with some reservations. Here we describe a combination of approaches to examine the putative transport of blackberry-digested polyphenols (BDP) across the blood-brain barrier (BBB) and ultimate evaluation of their neuroprotective effects. METHODS: BDP was obtained by in vitro digestion of blackberry extract and BDP major aglycones (hBDP) were obtained by enzymatic hydrolysis. Chemical characterization and BBB transport of extracts were evaluated by LC-MSn. BBB transport and cytoprotection of both extracts was assessed in HBMEC monolayers. Neuroprotective potential of BDP was assessed in NT2-derived 3D co-cultures of neurons and astrocytes and in primary mouse cerebellar granule cells. BDP-modulated genes were evaluated by microarray analysis. RESULTS: Components from BDP and hBDP were shown to be transported across the BBB. Physiologically relevant concentrations of both extracts were cytoprotective at endothelial level and BDP was neuroprotective in primary neurons and in an advanced 3D cell model. The major canonical pathways involved in the neuroprotective effect of BDP were unveiled, including mTOR signaling and the unfolded protein response pathway. Genes such as ASNS and ATF5 emerged as novel BDP-modulated targets. CONCLUSIONS: BBB transport of BDP and hBDP components reinforces the health benefits of a diet rich in polyphenols in neurodegenerative disorders. Our results suggest some novel pathways and genes that may be involved in the neuroprotective mechanism of the BDP polyphenol components.
Assuntos
Barreira Hematoencefálica/metabolismo , Fármacos Neuroprotetores/farmacologia , Extratos Vegetais/farmacologia , Polifenóis/farmacologia , Rubus/metabolismo , Animais , Células Cultivadas , Cromatografia Líquida , Humanos , Técnicas In Vitro , Espectrometria de Massas , Camundongos , Camundongos Endogâmicos BALB C , Modelos Animais , Fármacos Neuroprotetores/metabolismo , Extratos Vegetais/metabolismo , Reação em Cadeia da Polimerase , Polifenóis/metabolismoRESUMO
The effective capture and storage of radioactive iodine is of importance for nuclear waste storage during nuclear power station accidents. Here we report Fe3O4@PPy powder containing â¼12nm magnetite (Fe3O4) nanoparticles encapsulated in the polypyrrole (PPy) matrix. It shows 1627mg/g uptake of iodine dissolved in water, within 2h at room temperature. Fe3O4@PPy is ferromagnetic in nature and can be separated from water using external magnetic field. The nitrogen gas sweeping test at 30°C shows release of 2% iodine from iodine adsorbed Fe3O4@PPy, revealing stable storage of iodine for a moderate period. The iodine-adsorbed magnetic powder can be regenerated by washing with ethanol. The XPS spectrum of iodine adsorbed Fe3O4@PPy confirmed the presence of polyiodides (I3- and I5-) bound to the PPy surface. This excellent iodine capture and storage from iodine contaminated water is an environment friendly, inexpensive and large scale method.
RESUMO
Diatomic halogen molecules X2 (X = Cl/Br) favor the edge-to-face conformation on benzene with significant electrostatic interaction via halogen bonding. In contrast, they favor the stacked conformation on graphene with negligible electrostatic interaction. As the aromatic ring expands, the inner facial side becomes almost electrostatically neutral. On coronene, the two conformations are compatible.
RESUMO
Human bone marrow-derived mesenchymal stem cells (hBMSCs) present promising opportunities for therapeutic medicine. Carbon derivatives showed only marginal enhancement in stem cell differentiation toward bone formation. Here we report that red-light absorbing carbon nitride (C3N4) sheets lead to remarkable proliferation and osteogenic differentiation by runt-related transcription factor 2 (Runx2) activation, a key transcription factor associated with osteoblast differentiation. Accordingly, highly effective hBMSCs-driven mice bone regeneration under red light is achieved (91% recovery after 4 weeks compared to 36% recovery in the standard control group in phosphate-buffered saline without red light). This fast bone regeneration is attributed to the deep penetration strength of red light into cellular membranes via tissue and the resulting efficient cell stimulation by enhanced photocurrent upon two-photon excitation of C3N4 sheets near cells. Given that the photoinduced charge transfer can increase cytosolic Ca2+ accumulation, this increase would promote nucleotide synthesis and cellular proliferation/differentiation. The cell stimulation enhances hBMSC differentiation toward bone formation, demonstrating the therapeutic potential of near-infrared two-photon absorption of C3N4 sheets in bone regeneration and fracture healing.
Assuntos
Regeneração Óssea/efeitos dos fármacos , Nanoestruturas/química , Nitrilas/farmacologia , Fótons , Fármacos Fotossensibilizantes/farmacologia , Animais , Diferenciação Celular/efeitos dos fármacos , Suturas Cranianas/efeitos dos fármacos , Modelos Animais de Doenças , Células HeLa , Humanos , Masculino , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Nitrilas/síntese química , Nitrilas/química , Osteogênese/efeitos dos fármacos , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/químicaRESUMO
Various types of interactions between halogen (X) and π moiety (X-π interaction) including halogen bonding play important roles in forming the structures of biological, supramolecular, and nanomaterial systems containing halogens and aromatic rings. Furthermore, halogen molecules such as X2 and CX4 (X = Cl/Br) can be intercalated in graphite and bilayer graphene for doping and graphene functionalization/modification. Due to the X-π interactions, though recently highly studied, their structures are still hardly predictable. Here, using the coupled-cluster with single, double, and noniterative triple excitations (CCSD(T)), the Møller-Plesset second-order perturbation theory (MP2), and various flavors of density functional theory (DFT) methods, we study complexes of benzene (Bz) with halogen-containing molecules X2 and CX4 (X = Cl/Br) and analyze various components of the interaction energy using symmetry adapted perturbation theory (SAPT). As for the lowest energy conformers (S1), X2-Bz is found to have the T-shaped structure where the electropositive X atom-end of X2 is pointing to the electronegative midpoint of CC bond of the Bz ring, and CX4-Bz has the stacked structure. In addition to this CX4-Bz (S1), other low energy conformers of X2-Bz (S2/S3) and CX4-Bz (S2) are stabilized primarily by the dispersion interaction, whereas the electrostatic interaction is substantial. Most of the density functionals show noticeable deviations from the CCSD(T) complete basis set (CBS) limit binding energies, especially in the case of strongly halogen-bonded conformers of X2-Bz (S1), whereas the deviations are relatively small for CX4-Bz where the dispersion is more important. The halogen bond shows highly anisotropic electron density around halogen atoms and the DFT results are very sensitive to basis set. The unsatisfactory performance of many density functionals could be mainly due to less accurate exchange. This is evidenced from the good performance by the dispersion corrected hybrid and double hybrid functionals. B2GP-PLYP-D3 and PBE0-TS(Tkatchenko-Scheffler)/D3 are well suited to describe the X-π interactions adequately, close to the CCSD(T)/CBS binding energies (within â¼1 kJ/mol). This understanding would be useful to study diverse X-π interaction driven structures such as halogen containing compounds intercalated between 2-dimensional layers.
RESUMO
Natural food sources constitute a promising source of new compounds with neuroprotective properties, once they have the ability to reach the brain. Our aim was to evaluate the brain accessibility of quercetin, epigallocatechin gallate (EGCG) and cyanidin-3-glucoside (C3G) in relation to their neuroprotective capability. Primary cortical neuron cultures were exposed to oxidative insult in the absence and presence of the selected compounds, and neuroprotection was assessed through evaluation of apoptotic-like and necrotic-like cell death. The brain accessibility of selected compounds was assessed using an optimised human blood-brain barrier model. The blood-brain barrier model was crossed rapidly by EGCG and more slowly by C3G, but not by quercetin. EGCG protected against oxidation-induced neuronal necrotic-like cell death by ~40%, and apoptosis by ~30%. Both quercetin and C3G were less effective, since only the lowest quercetin concentration was protective, and C3G only prevented necrosis by ~37%. Quercetin, EGCG and C3G effectively inhibited α-synuclein fibrillation over the relevant timescale applied here. Overall, EGCG seems to be the most promising neuroprotective compound. Thus, inclusion of this polyphenol in the diet might provide an affordable means to reduce the impact of neurodegenerative diseases.
Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Flavonoides/farmacologia , Flavonoides/farmacocinética , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/farmacocinética , Animais , Antocianinas/farmacocinética , Antocianinas/farmacologia , Antioxidantes/farmacocinética , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Catequina/análogos & derivados , Catequina/farmacocinética , Catequina/farmacologia , Células Cultivadas , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Estabilidade de Medicamentos , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Glucosídeos/farmacocinética , Glucosídeos/farmacologia , Humanos , Necrose/tratamento farmacológico , Necrose/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Multimerização Proteica/efeitos dos fármacos , Quercetina/farmacocinética , Quercetina/farmacologia , Ratos Wistar , Proteínas Recombinantes/metabolismo , alfa-Sinucleína/metabolismoRESUMO
Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π-π stacking between the H3BTB moieties. The material can be viewed as a well-ordered array of cages, which are tight packed with each other so that the cages are inaccessible from outside. Thus, the host is practically nonporous. Despite the absence of permanent pathways connecting the empty cages, they are permeable to CO2 at high temperatures due to thermally activated molecular gating, and the weakly confined CO2 molecules in the cages allow direct detection by in situ single-crystal X-ray diffraction at 323 K. Variable-temperature in situ synchrotron powder X-ray diffraction studies also show that the CO2 sorption is reversible and driven by temperature increase. Solid-state magic angle spinning NMR defines the interactions of CO2 with the organic framework and dynamic motion of CO2 in cages. The reversible sorption is attributed to the dynamic motion of the DMF molecules combined with the axial motions/angular fluctuations of CO2 (a series of transient opening/closing of compartments enabling CO2 molecule passage), as revealed from NMR and simulations. This temperature-driven transient molecular gating can store gaseous molecules in ordered arrays toward unique collective properties and release them for ready use.
RESUMO
Mesenchymal stromal/stem cells (MSCs) have the potential to differentiate into neuron-like cells under specific conditions and to secrete paracrine factors for neuroprotection and regeneration. Previously, Rho-kinase inhibitors have been reported to potentiate differentiation of rodent bone marrow MSCs into neuron-like cells induced by CoCl2 (HIF-1α activation-mimicking agent). Here, a strategy of priming MSCs with fasudil, a Rho-kinase inhibitor, was investigated using Wharton's jelly-derived MSCs (WJ-MSCs) to improve recovery in a rat model of intracranial hemorrhage (ICH). In vitro culture of WJ-MSCs by co-treatment with fasudil (30 µM) and CoCl2 provoked morphological changes of WJ-MSCs into neuron-like cells and increased the expression of neuronal markers. Assessment of the secretion profiles showed that fasudil (30 µM) specifically increased glial cell line-derived neurotrophic factor (GDNF) among the secreted proteins at the transcription and secretion levels. For in vivo experiments, WJ-MSCs primed with fasudil (10 µM, exposure for 6 h) were transplanted into ICH rats with HIF-1α upregulation 1 week after injury, and neurological function was assessed via rotarod and limb placement tests for 7 weeks after transplantation. The group with WJ-MSCs primed with fasudil showed improved functional performance compared with the non-primed group. Accordingly, the primed group showed stronger expression of GDNF and higher levels of microtubule-associated protein 2 and neurofilament-H positive-grafted cells in the ICH lesion 3 weeks after transplantation compared with the non-primed group. Therefore, this work suggests that priming WJ-MSCs with fasudil is a possible application for enhanced cell therapy in stroke, with additional beneficial effect of up-regulation of GDNF.
Assuntos
Hemorragia Cerebral/terapia , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Geleia de Wharton/citologia , Quinases Associadas a rho/antagonistas & inibidores , 1-(5-Isoquinolinasulfonil)-2-Metilpiperazina/análogos & derivados , 1-(5-Isoquinolinasulfonil)-2-Metilpiperazina/farmacologia , Animais , Western Blotting , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Hemorragia Cerebral/fisiopatologia , Cobalto/farmacologia , Modelos Animais de Doenças , Expressão Gênica/efeitos dos fármacos , Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Humanos , Masculino , Células-Tronco Mesenquimais/enzimologia , Células-Tronco Mesenquimais/metabolismo , Microscopia Confocal , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Ratos Sprague-Dawley , Recuperação de Função Fisiológica , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Quinases Associadas a rho/metabolismoRESUMO
Amyotrophic lateral sclerosis (ALS) is the most common adult onset motor neuron disease. The etiology and pathogenic mechanisms of the disease remain unknown, and there is no effective treatment. Here we show that intrathecal transplantation of human motor neurons derived from neural stem cells (NSCs) in spinal cord of the SOD1G93A mouse ALS model delayed disease onset and extended life span of the animals. When HB1.F3.Olig2 (F3.Olig2) cells, stable immortalized human NSCs encoding the human Olig2 gene, were treated with sonic hedgehog (Shh) protein for 5-7 days, the cells expressed motor neuron cell type-specific phenotypes Hb9, Isl-1 and choline acetyltransferase (ChAT). These F3.Olig2-Shh human motor neurons were transplanted intrathecally in L5-L6 spinal cord of SOD1G93A mice, and at 4 weeks post-transplantation, transplanted F3.Olig2-Shh motor neurons expressing the neuronal phenotype markers NF, MAP2, Hb9, and ChAT were found in the ventral horn of the spinal cord. Onset of clinical signs in ALS mice with F3.Olig2-Shh motor neuron implants was delayed for 7 days and life span of animals was significantly extended by 20 days. Our results indicate that this treatment modality of intrathecal transplantation of human motor neurons derived from NSCs might be of value in the treatment of ALS patients without significant adverse effects.
Assuntos
Esclerose Lateral Amiotrófica/terapia , Diferenciação Celular , Neurônios Motores/metabolismo , Neurônios Motores/transplante , Células-Tronco Neurais/metabolismo , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Antígenos de Diferenciação/metabolismo , Linhagem Celular Transformada , Feminino , Xenoenxertos , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Neurônios Motores/patologia , Células-Tronco Neurais/patologia , Fatores de TempoRESUMO
Cationic cyclophanes with bridging and spacer groups possess well-organized semirigid cavities and are able to encapsulate and stabilize anionic species through diverse molecular interactions. We highlight the precise tuning of functionalized cyclophanes toward selective recognition of AMP, GTP, and pyrophosphate (PPi) using fluorescence, NMR spectroscopy, and density functional theory (DFT).
Assuntos
Modelos Moleculares , Compostos Organofosforados/química , Hidrocarbonetos Policíclicos Aromáticos/química , Monofosfato de Adenosina/química , Ânions , Cátions , Fluorescência , Guanosina Trifosfato/química , Espectroscopia de Ressonância Magnética , Estrutura MolecularRESUMO
Intercalation of magnetic iron atoms through graphene formed on the SiC(0001) surface is found to induce significant changes in the electronic properties of graphene due mainly to the Fe-induced asymmetries in charge as well as spin distribution. From our synchrotron-based photoelectron spectroscopy data together with ab initio calculations, we observe that the Fe-induced charge asymmetry results in the formation of a quasi-free-standing bilayer graphene while the spin asymmetry drives multiple spin-split bands. We find that Fe adatoms are best intercalated upon annealing at 600 °C, exhibiting split linear π-bands, characteristic of a bilayer graphene, but much diffused. Subsequent changes in the C 1s, Si 2p, and Fe 3p core levels are consistently described in terms of Fe-intercalation. Our calculations together with a spin-dependent tight binding model ascribe the diffuse nature of the π-bands to the multiple spin-split bands originated from the spin-injected carbon atoms residing only in the lower graphene layer.
Assuntos
Grafite/química , Substâncias Intercalantes/química , Ferro/química , Magnetismo , Teoria Quântica , Propriedades de SuperfícieRESUMO
Laser-driven molecular spectroscopy of low spatial resolution is widely used, while electronic current-driven molecular spectroscopy of atomic scale resolution has been limited because currents provide only minimal information. However, electron transmission of a graphene nanoribbon on which a molecule is adsorbed shows molecular fingerprints of Fano resonances, i.e., characteristic features of frontier orbitals and conformations of physisorbed molecules. Utilizing these resonance profiles, here we demonstrate two-dimensional molecular electronics spectroscopy (2D MES). The differential conductance with respect to bias and gate voltages not only distinguishes different types of nucleobases for DNA sequencing but also recognizes methylated nucleobases which could be related to cancerous cell growth. This 2D MES could open an exciting field to recognize single molecule signatures at atomic resolution. The advantages of the 2D MES over the one-dimensional (1D) current analysis can be comparable to those of 2D NMR over 1D NMR analysis.
Assuntos
DNA de Neoplasias/metabolismo , Análise de Sequência de DNA/métodos , Análise Espectral/métodos , DNA de Neoplasias/químicaRESUMO
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that selectively affects motor neurons in the cortex, brain stem, and spinal cord. The precise pathogenic mechanism remains unknown, and there is currently no effective therapy. We evaluated the therapeutic effects of human adipose tissue-derived stem cells (ASCs) in an animal model of ALS. Human abdominal subcutaneous fat tissues were obtained by simple liposuction from donors, and ASCs were isolated from the fat stromal vascular fraction. ASCs were found to differentiate into adipocytes, chondrocytes, osteocytes, and neurons. SOD1G93A ALS mice were divided into three groups: sham, intravenous (IV), and intracerebroventricular (ICV) groups. Human ASCs were transplanted in the ALS mice at 70 postnatal days before the appearance of clinical symptoms. Behavior of transplanted animals was assessed by rotarod test, paw grip endurance (PaGE), and reflex index. Mice in every group were sacrificed after 4 weeks posttransplantation. Transplanted ASCs were identified in the lumbar spinal cords with an antihuman mitochondria antibody and cell type-specific markers for neurons or astrocytes. Delayed onset of clinical symptoms (26 days) and extended survival of animals (24 days) were observed in ALS mice transplanted with ASCs via ICV route. ASCs were found to secrete high levels of neurotrophic factors such as NGF, BDNF, IGF-1, and VEGF. Reduction of apoptotic cell death by these factors was confirmed in cultured CNS cells and in the ALS spinal cord. These results indicate that transplantation of ASCs in ALS mice provides neuroprotective effects by production of cytokines/growth factors, delays disease progression, and prolongs the life span of ALS mice.
Assuntos
Tecido Adiposo/citologia , Esclerose Lateral Amiotrófica/terapia , Longevidade , Transplante de Células-Tronco , Células-Tronco/citologia , Idoso , Idoso de 80 Anos ou mais , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Comportamento Animal , Diferenciação Celular/efeitos dos fármacos , Sobrevivência Celular , Citocinas/metabolismo , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Peróxido de Hidrogênio/farmacologia , Injeções Intravenosas , Injeções Intraventriculares , Masculino , Camundongos , Pessoa de Meia-Idade , Atividade Motora/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/patologia , Fármacos Neuroprotetores/metabolismo , Medula Espinal/efeitos dos fármacos , Medula Espinal/patologia , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Doadores de TecidosRESUMO
Japanese encephalitis virus (JEV) is a single stranded RNA virus that infects the central nervous system leading to acute encephalitis in children. Alterations in brain endothelial cells have been shown to precede the entry of this flavivirus into the brain, but infection of endothelial cells by JEV and their consequences are still unclear. Productive JEV infection was established in human endothelial cells leading to IFN-ß and TNF-α production. The MHC genes for HLA-A, -B, -C and HLA-E antigens were upregulated in human brain microvascular endothelial cells, the endothelial-like cell line, ECV 304 and human foreskin fibroblasts upon JEV infection. We also report the release/shedding of soluble HLA-E (sHLA-E) from JEV infected human endothelial cells for the first time. This shedding of sHLA-E was blocked by an inhibitor of matrix metalloproteinases (MMP). In addition, MMP-9, a known mediator of HLA solubilisation was upregulated by JEV. In contrast, human fibroblasts showed only upregulation of cell-surface HLA-E. Addition of UV inactivated JEV-infected cell culture supernatants stimulated shedding of sHLA-E from uninfected ECV cells indicating a role for soluble factors/cytokines in the shedding process. Antibody mediated neutralization of TNF-α as well as IFNAR receptor together not only resulted in inhibition of sHLA-E shedding from uninfected cells, it also inhibited HLA-E and MMP-9 gene expression in JEV-infected cells. Shedding of sHLA-E was also observed with purified TNF-α and IFN-ß as well as the dsRNA analog, poly (I:C). Both IFN-ß and TNF-α further potentiated the shedding when added together. The role of soluble MHC antigens in JEV infection is hitherto unknown and therefore needs further investigation.
Assuntos
Vírus da Encefalite Japonesa (Espécie)/fisiologia , Células Endoteliais/metabolismo , Células Endoteliais/virologia , Linhagem Celular , Citocinas/biossíntese , Citocinas/farmacologia , Células Endoteliais/imunologia , Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Imunofenotipagem , Interferon beta/biossíntese , Interferon beta/farmacologia , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Fatores de Tempo , Transcrição Gênica , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/farmacologia , Liberação de Vírus , Antígenos HLA-ERESUMO
This review deals with wide-ranging environmental studies of graphene-based materials on the adsorption of hazardous materials and photocatalytic degradation of pollutants for water remediation and the physisorption, chemisorption, reactive adsorption, and separation for gas storage. The environmental and biological toxicity of graphene, which is an important issue if graphene composites are to be applied in environmental remediation, is also addressed.
Assuntos
Poluentes Ambientais/isolamento & purificação , Recuperação e Remediação Ambiental/instrumentação , Recuperação e Remediação Ambiental/métodos , Grafite/química , Nanocompostos/química , Poluição da Água , Adsorção , Gases/isolamento & purificação , HumanosRESUMO
A graphene-nanoparticle (NP) hybrid biosensor that utilizes an electrical hysteresis change to detect the enzymatic activity and concentration of Carboxypeptidase B was developed. The results indicate that the novel graphene-NP hybrid biosensor, utilizing electrical hysteresis, has the ability to detect concentrations of targeted enzyme on the micromolar scale. Furthermore, to the knowledge of the authors, this is the first demonstration of a graphene-based biosensor that utilizes a hysteresis change resulting from metallic NPs assembled on a graphene surface.
Assuntos
Técnicas Biossensoriais/instrumentação , Carboxipeptidase B/análise , Carboxipeptidase B/química , Condutometria/instrumentação , Grafite/química , Nanopartículas/química , Peptídeos/química , Ativação Enzimática , Desenho de Equipamento , Análise de Falha de Equipamento , Nanotecnologia/instrumentação , Coloração e RotulagemRESUMO
A new water-soluble and fluorescent imidazolium-anthracene cyclophane 1 effectively recognizes and differentiates the biologically important GTP and ATP in 100% aqueous solution of physiological pH 7.4. Fluorescence, (1)H-NMR spectra and ab initio calculations demonstrate that excimer formation and fluorescence enhancement occur upon GTP and ATP binding, respectively, through (C-H)(+)···A(-) hydrogen bond interactions.
Assuntos
Antracenos/química , Corantes Fluorescentes/química , Guanosina Trifosfato/química , Imidazóis/química , Trifosfato de Adenosina/química , Concentração de Íons de Hidrogênio , Modelos Moleculares , Espectrometria de Fluorescência , Água/químicaRESUMO
N-doped porous carbon produced via chemical activation of polypyrrole functionalized graphene sheets shows selective adsorption of CO(2) (4.3 mmol g(-1)) over N(2) (0.27 mmol g(-1)) at 298 K. The potential for large scale production and facile regeneration makes this material useful for industrial applications.
RESUMO
The mechanism of Cronobacter pathogenesis in neonatal meningitis and potential virulence factors (aside from host cell invasion ability) remain largely unknown. To ascertain whether Cronobacter can invade and transcytose across intestinal epithelial cells, enter into the blood stream and then transcytose across the blood-brain-barrier, we have utilized human intestinal INT407 and Caco-2 cells and brain microvascular endothelial cell (HBMEC) monolayers on Transwell filters as experimental model systems. Our data indicate a wide range of heterogeneity with respect to invasion efficiency among twenty-three Cronobacter isolates screened. For selected isolates, we observed significant levels of transcytosis for Cronobacter sakazakii across tight monolayers of both Caco-2 and HBMEC, mimicking in vivo ability to cross the intestine as well as the blood brain barrier, and at a frequency equivalent to that of a control meningitis-causing Escherichia coli K1 strain. Finally, EM analysis demonstrated intracellular Cronobacter bacteria within host vacuoles in HBMEC, as well as transcytosed bacteria at the basolateral surface. These data reveal that certain Cronobacter isolates can invade and translocate across both cultured human intestinal epithelial cells and HBMEC, thus demonstrating a potential path for neonatal infections of the central nervous system (CNS) following oral ingestion.