X -Ray Absorption Fine Structure (EXAFS and XANES) and Microscopic Investigations of Supramolecular Systems.

Self-assembled monolayers of n-alkanethiols, CH3-(CH 2)x-SH, on Au, Ag, and Cu have been studied with Grazing incidence EXAFS (GIXAFS) at the sulfur K-edge. Characterization of the bonding of self-assembled monolayers is of great interest because of their ability to tailor physical and chemical properties of surfaces. For both pentanethiol and decanethiol monolayers on Ag and Cu, the three-fold hollow site is found to be the most probable sulfur binding site. However, observations for octadecanethiol indicate that the three-fold-hollow site is not the exclusive binding site. In addition, the possible existence of disulfide bonds on the metal surface (adsorbed dialkyldisulfides) is not supported by the data. In addition, careful examination of the systems by XANES clearly demonstrate the peculiar behavior of octadecanethiol on surfaces. Preliminary results from monolayers on Au are also reported and constitute the first ever reported EXAFS data for alkanethiol monolayers on gold. These findings represent a great advance for the investigation of thin films on surfaces, and also present the possibility to study mixed monolayers as a complement to scanning probe microscopy. Recently, dendritic systems, and especially dendrimer-metal complexes, have been shown to have outstanding properties which make them suitable for applications in catalysis and biology. Our long-term plans include investigations of adsorbed dendrimer-metal complexes on metal surfaces through the use of grazing incidence EXAFS. Preliminary X-ray absorption studies of poly(propylene imine) dendrimer-copper(II) complexes of generation 1--5 in powder form and methanolic solution are presented here. XANES allows determination of the oxidation state of the copper species and the geometry of the copper complex whereas EXAFS gives us information about bond distances, coordination number and nature of the neighbor atoms. When reacted with NaBH4, these dendrimer-copper complexes undergo reduction which leads to the formation of Cu(0) nanoclusters. We investigated these clusters by EXAFS, XANES, ultra violet-visible spectroscopy and high resolution transmission electron microscopy (HR-TEM) and discuss their geometry, composition and size depending on the dendrimer generation. The synthesis of metallic nanoclusters by the dendrimer route has been successful to produce nanoclusters of reduced size and increased monodispersity

Programmable bio-nanochip-based cytologic testing of oral potentially malignant disorders in Fanconi anemia

Fanconi anemia (FA) is caused by mutations of DNA repair genes. The risk of oral squamous cell carcinoma (OSCC) among FA patients is 800-folds higher than in the general population. Early detection of OSCC, preferably at it precursor stage, is critical in FA patients to improve their survival. In an ongoing clinical trial, we are evaluating the effectiveness of the programmable bio-nanochip (p-BNC)-based oral cytology test in diagnosing oral potentially malignant disorders (OPMD) in non-FA patients. We used this test to compare cytomorphometric and molecular biomarkers in OSCC cell lines derived from FA and non-FA patients to brush biopsy samples of a FA patient with OPMD and normal mucosa of healthy volunteers. Our data showed that expression patterns of molecular biomarkers were not notably different between sporadic and FA-OSCC cell lines. The p-BNC assay revealed significant differences in cytometric parameters and biomarker MCM2 expression between cytobrush samples of the FA patient and cytobrush samples of normal oral mucosa obtained from healthy volunteers. Microscopic examination of the FA patient's OPMD confirmed the presence of dysplasia. Our pilot data suggests that the p-BNC brush biopsy test recognized dysplastic oral epithelial cells in a brush biopsy sample of a FA patient

A Microchip CD4 Counting Method for HIV Monitoring in Resource-Poor Settings

BACKGROUND: More than 35 million people in developing countries are living with HIV infection. An enormous global effort is now underway to bring antiretroviral treatment to at least 3 million of those infected. While drug prices have dropped considerably, the cost and technical complexity of laboratory tests essential for the management of HIV disease, such as CD4 cell counts, remain prohibitive. New, simple, and affordable methods for measuring CD4 cells that can be implemented in resource-scarce settings are urgently needed. METHODS AND FINDINGS: Here we describe the development of a prototype for a simple, rapid, and affordable method for counting CD4 lymphocytes. Microliter volumes of blood without further sample preparation are stained with fluorescent antibodies, captured on a membrane within a miniaturized flow cell and imaged through microscope optics with the type of charge-coupled device developed for digital camera technology. An associated computer algorithm converts the raw digital image into absolute CD4 counts and CD4 percentages in real time. The accuracy of this prototype system was validated through testing in the United States and Botswana, and showed close agreement with standard flow cytometry (r = 0.95) over a range of absolute CD4 counts, and the ability to discriminate clinically relevant CD4 count thresholds with high sensitivity and specificity. CONCLUSION: Advances in the adaptation of new technologies to biomedical detection systems, such as the one described here, promise to make complex diagnostics for HIV and other infectious diseases a practical global reality

Application of programmable bio-nano-chip system for the quantitative detection of drugs of abuse in oral fluids

Objective: There is currently a gap in on-site drug of abuse monitoring. Current detection methods involve invasive sampling of blood and urine specimens, or collection of oral fluid, followed by qualitative screening tests using immunochromatographic cartridges. While remote laboratories then may provide confirmation and quantitative assessment of a presumptive positive, this instrumentation is expensive and decoupled from the initial sampling making the current drug-screening program inefficient and costly. The authors applied a noninvasive oral fluid sampling approach integrated with the in-development chip-based Programmable bio-nano-chip (p-BNC) platform for the detection of drugs of abuse. Method: The p-BNC assay methodology was applied for the detection of tetrahydrocannabinol, morphine, amphetamine, methamphetamine, cocaine, methadone and benzodiazepines, initially using spiked buffered samples and, ultimately, using oral fluid specimen collected from consented volunteers. Results: Rapid (∼10 min), sensitive detection (∼ng/mL) and quantitation of 12 drugs of abuse was demonstrated on the p-BNC platform. Furthermore, the system provided visibility to time-course of select drug and metabolite profiles in oral fluids; for the drug cocaine, three regions of slope were observed that, when combined with concentration measurements from this and prior impairment studies, information about cocaine-induced impairment may be revealed. Conclusions: This chip-based p-BNC detection modality has significant potential to be used in the future by law enforcement officers for roadside drug testing and to serve a variety of other settings, including outpatient and inpatient drug rehabilitation centers, emergency rooms, prisons, schools, and in the workplace

Porous Bead-Based Diagnostic Platforms: Bridging the Gaps in Healthcare

Advances in lab-on-a-chip systems have strong potential for multiplexed detection of a wide range of analytes with reduced sample and reagent volume; lower costs and shorter analysis times. The completion of high-fidelity multiplexed and multiclass assays remains a challenge for the medical microdevice field; as it struggles to achieve and expand upon at the point-of-care the quality of results that are achieved now routinely in remote laboratory settings. This review article serves to explore for the first time the key intersection of multiplexed bead-based detection systems with integrated microfluidic structures alongside porous capture elements together with biomarker validation studies. These strategically important elements are evaluated here in the context of platform generation as suitable for near-patient testing. Essential issues related to the scalability of these modular sensor ensembles are explored as are attempts to move such multiplexed and multiclass platforms into large-scale clinical trials. Recent efforts in these bead sensors have shown advantages over planar microarrays in terms of their capacity to generate multiplexed test results with shorter analysis times. Through high surface-to-volume ratios and encoding capabilities; porous bead-based ensembles; when combined with microfluidic elements; allow for high-throughput testing for enzymatic assays; general chemistries; protein; antibody and oligonucleotide applications

Ni crisis ni panaceas: dinámicas y transformaciones de los sistemas partidarios en América Latina

A nivel global, tanto en la literatura especializada como en el debate público, la desafección ciudadana hacia la cosa pública, el debilitamiento de los partidos políticos y el aumento de la abstención contribuyeron a asentar la idea de una crisis de los sistemas de partidos y de la democracia. Diferentes indicadores darían cuenta de esta crisis: el desarraigo social de los partidos que consagró el modelo del partido cartel (Katz y Mair 1995); el declive de la militancia (Van Biezen, Mair y Poguntke 2012; Whiteley 2011); la erosión de las estructuras partidarias tradicionales capturadas por el lobby corporativo (Crouch 2004 [2014], 112) o la tecnocracia; la pérdida de capacidad de los líderes para construir partidos programáticos que expresaran identidades políticas duraderas (Cheresky 2006; Dalton 2004; Luna 2014b); o su incapacidad para responder con una mayor deliberación interna a los desafíos de la representación política (Accetti y Wolkenstein 2017).Fil: Alenda, Stéphanie. Universidad Andrés Bello; ChileFil: Varetto, Carlos Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martin. Escuela de Politica y Gobierno. Centro de Estudios Federales y Electorales; Argentin

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15–20 July 2017

This work was produced as part of the activities of FAPESP Research,\ud Disseminations and Innovation Center for Neuromathematics (grant\ud 2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud supported by a CNPq fellowship (grant 306251/2014-0)

Nanopore integrated nanogaps for DNA detection

International audienc

Methods and compositions related to determination and use of white blood cell counts

Described herein is an analyte detection device and method related to a portable instrument suitable for point-of-care analyses. In some embodiments, a portable instrument may include a disposable cartridge, an optical detector, a sample collection device and/or sample reservoir, reagent delivery systems, fluid delivery systems, one or more channels, and/or waste reservoirs. Use of a portable instrument may reduce the hazard to an operator by reducing an operator's contact with a sample for analysis. The device is capable of obtaining diagnostic information using cellular- and/or particle-based analyses and may be used in conjunction with membrane- and/or particle-based analysis cartridges. Analytes, including proteins and cells and/or microbes may be detected using the membrane and/or particle based analysis system.Board of Regents, University of Texas Syste