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Non-contact bi-directional micropatterning of two-dimensional (2D) layered inorganic-organic (IO) perovskite [(R-NH3)2PbI4, R = organic moiety] thin films by direct laser writing (DLW) has been reported. These 2D materials are in the form of natural multiple quantum well (MQW) structures and show excitonic luminescence at room temperature because of quantum and dielectric confinement effects. Systematic optical and structural analyses of these laser processed hybrid systems provide an insight into laser-matter interaction and a pathway to develop technology to define complex 2D material based devices with new functionalities. These laser-matter interaction studies reveal several concurrent processes: single photon absorption, material ablation, melting and agglomeration of nanostructures and chemical/physical modifications. This study also provides an insight into chemical and optical changes in laser processed 2D perovskites which subsequently can be recovered by chemical processing. Apart from controllable feature sizes, the prolonged laser exposure results in material agglomeration in the form of nano-pillars at the laser track boundaries. Low-cost micro/nano-scaffolding of IO perovskites may have several important advantages in scalable optoelectronic devices, the realisation of luminescent photonic architectures (photonic crystals and waveguides), and light harvesting elements for IO LEDs and solar cells.
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Room-temperature photocurrent measurements in two-dimensional (2D) inorganic-organic perovskite devices reveal that excitons strongly contribute to the photocurrents despite possessing binding energies over 10 times larger than the thermal energies. The p-type (C6H9C2H4NH3)2PbI4 liberates photocarriers at metallic Schottky aluminum contacts, but incorporating electron- and hole-transport layers enhances the extracted photocurrents by 100-fold. A further 10-fold gain is found when TiO2 nanoparticles are directly integrated into the perovskite layers, although the 2D exciton semiconducting layers are not significantly disrupted. These results show that strong excitonic materials may be useful as photovoltaic materials despite high exciton binding energies and suggest mechanisms to better understand the photovoltaic properties of the related three-dimensional perovskites.
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Currently microorganisms are best identified using 16S rRNA and 18S rRNA gene sequencing. However, in recent years matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a potential tool for microbial identification and diagnosis. During the MALDI-TOF MS process, microbes are identified using either intact cells or cell extracts. The process is rapid, sensitive, and economical in terms of both labor and costs involved. The technology has been readily imbibed by microbiologists who have reported usage of MALDI-TOF MS for a number of purposes like, microbial identification and strain typing, epidemiological studies, detection of biological warfare agents, detection of water- and food-borne pathogens, detection of antibiotic resistance and detection of blood and urinary tract pathogens etc. The limitation of the technology is that identification of new isolates is possible only if the spectral database contains peptide mass fingerprints of the type strains of specific genera/species/subspecies/strains. This review provides an overview of the status and recent applications of mass spectrometry for microbial identification. It also explores the usefulness of this exciting new technology for diagnosis of diseases caused by bacteria, viruses, and fungi.
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The properties of layered inorganic semiconductors can be manipulated by the insertion of foreign molecular species via a process known as intercalation. In the present study, we investigate the phenomenon of organic moiety (R-NH3I) intercalation in layered metal-halide (PbI2)-based inorganic semiconductors, leading to the formation of inorganic-organic (IO) perovskites [(R-NH3)2PbI4]. During this intercalation strong resonant exciton optical transitions are created, enabling study of the dynamics of this process. Simultaneous in situ photoluminescence (PL) and transmission measurements are used to track the structural and exciton evolution. On the basis of the experimental observations, a model is proposed which explains the process of IO perovskite formation during intercalation of the organic moiety through the inorganic semiconductor layers. The interplay between precursor film thickness and organic solution concentration/solvent highlights the role of van der Waals interactions between the layers, as well as the need for maintaining stoichiometry during intercalation. Nucleation and growth occurring during intercalation matches a Johnson-Mehl-Avrami-Kolmogorov model, with results fitting both ideal and nonideal cases.
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BACKGROUND: Anti-angiogenesis targeting VEGFR2 has been considered as an important strategy for cancer therapy. Tylophorine is known to possess anti-inflammatory and antitumor activity, but its roles in tumor angiogenesis, the key step involved in tumor growth and metastasis, and the involved molecular mechanism is still unknown. Therefore, we examined its anti-angiogenic effects and mechanisms in vitro and in vivo. METHODS: We used tylophorine and analyzed its inhibitory effects on human umbilical vein endothelial cells (HUVEC) in vitro and Ehrlich ascites carcinoma (EAC) tumor in vivo. RESULTS: Tylophorine significantly inhibited a series of VEGF-induced angiogenesis processes including proliferation, migration, and tube formation of endothelial cells. Besides, it directly inhibited VEGFR2 tyrosine kinase activity and its downstream signaling pathways including Akt, Erk and ROS in endothelial cells. Using HUVECs we demonstrated that tylophorine inhibited VEGF-stimulated inflammatory responses including IL-6, IL-8, TNF-α, IFN-γ, MMP-2 and NO secretion. Tylophorine significantly inhibited neovascularization in sponge implant angiogenesis assay and also inhibited tumor angiogenesis and tumor growth in vivo. Molecular docking simulation indicated that tylophorine could form hydrogen bonds and aromatic interactions within the ATP-binding region of the VEGFR2 kinase unit. CONCLUSION: Tylophorine exerts anti-angiogenesis effects via VEGFR2 signaling pathway thus, may be a viable drug candidate in anti-angiogenesis and anti-cancer therapies.
Asunto(s)
Alcaloides/farmacología , Inhibidores de la Angiogénesis/farmacología , Antineoplásicos Fitogénicos/farmacología , Indolizinas/farmacología , Neovascularización Fisiológica/efectos de los fármacos , Fenantrenos/farmacología , Receptor 2 de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Alcaloides/administración & dosificación , Alcaloides/química , Inhibidores de la Angiogénesis/administración & dosificación , Inhibidores de la Angiogénesis/química , Animales , Antineoplásicos Fitogénicos/administración & dosificación , Antineoplásicos Fitogénicos/química , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Citocinas/metabolismo , Modelos Animales de Enfermedad , Femenino , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Humanos , Indolizinas/administración & dosificación , Indolizinas/química , Masculino , Metaloproteinasa 2 de la Matriz/metabolismo , Ratones , Conformación Molecular , Simulación del Acoplamiento Molecular , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/mortalidad , Neoplasias/patología , Óxido Nítrico/metabolismo , Fenantrenos/administración & dosificación , Fenantrenos/química , Unión Proteica/efectos de los fármacos , Dominios y Motivos de Interacción de Proteínas , Transducción de Señal/efectos de los fármacos , Carga Tumoral/efectos de los fármacos , Tylophora/química , Factor A de Crecimiento Endotelial Vascular/metabolismo , Receptor 2 de Factores de Crecimiento Endotelial Vascular/química , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Direct radioimmunoassay (RIA), based on the principle of competitive inhibition for the measurement of serum testosterone, using 3H as label, is described. Testosterone 3-O-carboxymethyloxime-bovine serum albumin (testosterone 3-O-CMO-BSA) was used as an immunogen and testosterone, labeled at positions 1, 2, 6, and 7 with 3H was used as tracer. To 12 x 75 mm glass tubes 100 microL of standard (250 to 10,000 pg/mL) and unknown samples were added in duplicate, followed by 100 microL of antibody and 600 microL of tracer (10,000 counts per minute [cpm]) in all the tubes and incubated overnight at 4 degrees C. The bound and free fraction of labeled were separated by adding 200 microL of charcoal followed by centrifugation. The bound radioactivity was measured in the supernatant by using a scintillation fluid containing 2,5-diphenyloxazole (PPO, primary scintillator) and p-bis[2-(5-phenyloxazolyl)]-benzene (POPOP, secondary scintillator). In this new strategy, high ionic strength and low pH of the buffer are utilized to release bound steroid from proteins. The sensitivity of the assay is 270 pg/mL. The analytical recovery ranged from 100.24% and 108.94%. The inter-assay and intra-assay coefficients of variation ranged from 3.38% to 9.56% and 5.69% to 9.84%, respectively. The serum testosterone values obtained by this method were correlated with those obtained by solid phase radioimmunoassay: r = 0.91 (n=34).
Asunto(s)
Radioinmunoensayo/métodos , Testosterona/sangre , Humanos , Marcaje Isotópico , Concentración Osmolar , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Testosterona/química , TritioRESUMEN
Direct radioimmunoassay (RIA), based on the principle of competitive inhibition for the measurement of serum progesterone using 3H as label, is described. Progesterone 3-O-carboxymethyloxime-bovine serum albumin (progesterone 3-O-CMO-BSA) was used as an immunogen and progesterone labeled at positions 1, 2, 6, and 7 with 3H was used as tracer. To 12 mm x 75 mm glass tubes, 100 microL of standard (250 pg to 50,000 pg/mL) and unknown samples were added, in duplicate, followed by 100 [LL of antibody and 600 microL of tracer (10,000 counts per minute [cpm]) in all of the tubes and incubated overnight at 4 degrees C. The bound and free fractions of labeled material were separated by adding 200 microL of charcoal followed by centrifugation. The bound radioactivity was measured in the supernatant by using a scintillation fluid containing 2,5-diphenyloxazole (PPO, primary scintillator) and p-Bis[2-(5-phenyloxazolyl)]-benzene (POPOP, secondary scintillator). In the present study, a high ionic strength, along with low and neutral pH of the buffer, is utilized to release bound steroid from proteins. The sensitivity of the assay is 732 pg/mL. The recovery ranged between 94.03% to 100.96%. The inter-assay and intra-assay coefficients of variation ranged from 3.89% to 7.59% and from 9.96% to 12.6%, respectively. The serum progesterone values, obtained by this method, were correlated with those obtained by enzyme linked immunosorbent assay; r = 0.96 (n=94).