131 research outputs found

    Selective Light-Triggered Release of DNA from Gold Nanorods Switches Blood Clotting On and Off

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    Blood clotting is a precise cascade engineered to form a clot with temporal and spatial control. Current control of blood clotting is achieved predominantly by anticoagulants and thus inherently one-sided. Here we use a pair of nanorods (NRs) to provide a two-way switch for the blood clotting cascade by utilizing their ability to selectively release species on their surface under two different laser excitations. We selectively trigger release of a thrombin binding aptamer from one nanorod, inhibiting blood clotting and resulting in increased clotting time. We then release the complementary DNA as an antidote from the other NR, reversing the effect of the aptamer and restoring blood clotting. Thus, the nanorod pair acts as an on/off switch. One challenge for nanobiotechnology is the bio-nano interface, where coronas of weakly adsorbed proteins can obscure biomolecular function. We exploit these adsorbed proteins to increase aptamer and antidote loading on the nanorods.National Science Foundation (U.S.) (Grant DMR #0906838

    In situ measurement of bovine serum albumin interaction with gold nanospheres

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    Here we present in situ observations of adsorption of bovine serum albumin (BSA) on citratestabilized gold nanospheres. We implemented scattering correlation spectroscopy as a tool to quantify changes in the nanoparticle Brownian motion resulting from BSA adsorption onto the nanoparticle surface. Protein binding was observed as an increase in the nanoparticle hydrodynamic radius. Our results indicate the formation of a protein monolayer at similar albumin concentrations as those found in human blood. Additionally, by monitoring the frequency and intensity of individual scattering events caused by single gold nanoparticles passing the observation volume, we found that BSA did not induce colloidal aggregation, a relevant result from the toxicological viewpoint. Moreover, to elucidate the thermodynamics of the gold nanoparticle-BSA association, we measured an adsorption isotherm which was best described by an anti-cooperative binding model. The number of binding sites based on this model was consistent with a BSA monolayer in its native state. In contrast, experiments using poly-ethylene glycol capped gold nanoparticles revealed no evidence for adsorption of BSA

    Improved Cellular Specificity of Plasmonic Nanobubbles versus Nanoparticles in Heterogeneous Cell Systems

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    The limited specificity of nanoparticle (NP) uptake by target cells associated with a disease is one of the principal challenges of nanomedicine. Using the threshold mechanism of plasmonic nanobubble (PNB) generation and enhanced accumulation and clustering of gold nanoparticles in target cells, we increased the specificity of PNB generation and detection in target versus non-target cells by more than one order of magnitude compared to the specificity of NP uptake by the same cells. This improved cellular specificity of PNBs was demonstrated in six different cell models representing diverse molecular targets such as epidermal growth factor receptor, CD3 receptor, prostate specific membrane antigen and mucin molecule MUC1. Thus PNBs may be a universal method and nano-agent that overcome the problem of non-specific uptake of NPs by non-target cells and improve the specificity of NP-based diagnostics, therapeutics and theranostics at the cell level

    Psychology and aggression

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68264/2/10.1177_002200275900300301.pd

    Wie fair testet der WÜRT 1 die Rechtschreibleistungen von mehrsprachigen Kindern?

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    <jats:p> Zusammenfassung: Bei der Diskussion über Bildungsgerechtigkeit für mehrsprachige Kinder steht u. a. die Testfairness standardisierter Schulleistungstests im Fokus. So sollte eine Leistungsdiagnostik dieser Kinder auf Tests zurückgreifen, deren Fairness für Kinder mit nicht-deutscher Muttersprache empirisch abgesichert ist, denn nur so lassen sich die Testergebnisse in gleicher Weise interpretieren wie bei Kindern, die einsprachig deutsch aufwachsen. Ein Ziel bestand daher darin, die Testfairness des Würzburger Rechtschreibtests für 1. und 2. Klassen (WÜRT 1 – 2) zu überprüfen. Außerdem wurde analysiert, ob mehrsprachige Kinder die gleichen Fehlerschwerpunkte in der Rechtschreibung aufweisen wie einsprachige Kinder. Es nahmen 146 einsprachige und 107 mehrsprachige Kinder am Ende der ersten Klasse teil. Analysen zum Differential Item Functioning zeigten nur bei einem der insgesamt 36 Items Hinweise auf eine systematische Benachteiligung mehrsprachiger Kinder. Mit dem WÜRT 1 liegt somit ein faires Testverfahren vor, dessen Einsatz auch bei mehrsprachigen Kindern empfohlen werden kann. Die ein- und die mehrsprachigen Kinder unterschieden sich in der Fehleranzahl, nicht aber ihren qualitativen Fehlerprofilen. Dies legt nahe, dass eine Rechtschreibförderung für mehrsprachige Kinder an den gleichen Schwerpunkten ansetzen kann wie bei einsprachigen Kindern. </jats:p&gt
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