Simulations of Time-Resolved X-Ray Diffraction in Laue Geometry

A method of computer simulation of Time-Resolved X-ray Diffraction (TRXD) in asymmetric Laue (transmission) geometry with an arbitrary propagating strain perpendicular to the crystal surface is presented. We present two case studies for possible strain generation by short-pulse laser irradiation: (i) a thermoelastic-like analytic model; (ii) a numerical model including effects of electron-hole diffusion, Auger recombination, deformation potential and thermal diffusion. A comparison with recent experimental results is also presented.Comment: 9 pages, 11 figure

A microfluidics tool for high-throughput, real-time multimodal imaging of nanoparticle-cell interactions

The increasing use of nanomaterials for biomedical applications has raised the need for efficient, robust and low-cost high-throughput assessment of nanotoxicity and cell-nanoparticle interactions. Microfluidics provides the tools for high-throughput single-cell functional monitoring, while gold nanorods have unique potential for intracellular tracking and can simultaneously be used as drug carriers. Presented here is a miniaturised platform that integrates these features with a multimodal approach to cell imaging. A microfluidic device allows for trapping of an array of singlecells, followed by the controlled delivery of nanoparticles into the cell array and subsequent real-time multimodal imaging of cellular interactions with functionalised nanoparticles. This system has been successfully used to assess cellnanoparticle interactions at the single-cell level

Time-lapse measurement of single-cell response to nanomaterial : a microfluidic approach

This work presents the successful application of a single-cell microfluidic platform for high-throughput, real-time screening of nanoparticle-cell interactions. Taking vaccine delivery as a proof-of-concept application, ovalbumin-conjugated gold nanorods were produced and controllably delivered to primary dendritic cells within the device. Time-lapse imaging enabled monitoring of hundreds of single-cells during exposure to a range of concentrations of nanoparticle conjugates and simultaneous quantification of specific cellular functions. This integrated system provides throughput and statistical data comparable to that obtained with flow cytometry but also offers a novel approach to determine the dynamics of nanoparticle-cell interactions and nanoparticle-mediated antigen delivery with single-cell resolution

Multilayered ordered mesoporous platinum/titania composite films: Does the photocatalytic activity benefit from the film thickness?

Multilayered films of TiO2 with ordered cubic mesoporosity were grown via layer-by-layer deposition on a conductive FTO (F-doped SnO 2) substrate by dip-coating and subsequent calcination at 400°C. Since platinum nanoparticles are known to enhance the photocatalytic activity, they were introduced into the TiO2 mesopores by pulsed electrodeposition. Additionally, sandwich-like layers with up to five alternating TiO2 and Pt layers were prepared. The photocatalytic gas-phase oxidation of acetaldehyde served as a test reaction to characterize the activity in the gas phase of both pristine TiO2 as well as Pt/TiO2 single- and multilayer films. The ordered mesoporous pristine TiO2 and Pt/TiO2 nanocomposites exhibited significantly higher photoactivity than commercial Pilkington Activ™ glass and dense TiO2 films. Moreover for pristine TiO2 films, those consisting of three layers (about 650 nm in thickness), were shown to be sufficient to achieve a maximum photonic efficiency of ζ = 0.45%. For the Pt/TiO2 system, however, a single-layer film with a total thickness of only about 220 nm exhibited an almost identical activity. Moreover, repetitive experiments demonstrated that the newly prepared photocatalyst films did not suffer from a decrease in the photocatalytic activity, evincing their potential for practical applications. © 2011 The Royal Society of Chemistry

Real-time assessment of nanoparticle-mediated antigen delivery and cell response

Nanomaterials are increasingly being developed for applications in biotechnology, including the delivery of therapeutic drugs and of vaccine antigens. However, there is a lack of screening systems that can rapidly assess the dynamics of nanoparticle uptake and their consequential effects on cells. Established in vitro approaches are often carried out on a single time point, rely on time-consuming bulk measurements and are based primarily on populations of cell lines. As such, these procedures provide averaged results, do not guarantee precise control over the delivery of nanoparticles to cells and cannot easily generate information about the dynamics of nanoparticle-cell interactions and/or nanoparticle-mediated compound delivery. Combining microfluidics and nanotechnology with imaging techniques, we present a microfluidic platform to monitor nanoparticle uptake and intracellular processing in real-time and at the single-cell level. As proof-of-concept application, the potential of such a system for understanding nanovaccine delivery and processing was investigated and we demonstrate controlled delivery of ovalbumin-conjugated gold nanorods to primary dendritic cells. Using time-lapse microscopy, our approach allowed monitoring of uptake and processing of nanoparticles across a range of concentrations over several hours on hundreds of single-cells. This system represents a novel application of single-cell microfluidics for nanomaterial screening, providing a general platform for studying the dynamics of cell-nanomaterial interactions and representing a cost-saving and time-effective screening tool for many nanomaterial formulations and cell types

Self-assembly of gold supraparticles with crystallographically aligned and strongly coupled nanoparticle building blocks for SERS and photothermal therapy

A new method is introduced for self-assembling citrate-capped gold nanoparticles into supraparticles with crystallographically aligned building blocks. It consists in confining gold nanoparticles inside a cellulos acetate membrane. The constituent nanoparticles are in close contact in the superstructure, and therefore generate hot spots leading to intense SERS signals. They also generate more plasmonic heat than the nanoparticle building blocks. The supraparticles are internalized by cells and show low cytotoxicity, but can kill cancer cells when irradiated with a laser. This, along with the improved plasmonic properties arising from their assembly, makes the gold supraparticles promising materials for applications in bioimaging and nanomedicine

Supersonic strain front driven by a dense electron-hole plasma

We study coherent strain in (001) Ge generated by an ultrafast laser-initiated high density electron-hole plasma. The resultant coherent pulse is probed by time-resolved x-ray diffraction through changes in the anomalous transmission. The acoustic pulse front is driven by ambipolar diffusion of the electron-hole plasma and propagates into the crystal at supersonic speeds. Simulations of the strain including electron-phonon coupling, modified by carrier diffusion and Auger recombination, are in good agreement with the observed dynamics.Comment: 4 pages, 6 figure

Detection and quantification of warfarin in pharmaceutical dosage form and in spiked human plasma using surface enhanced Raman scattering

Analytical approaches for the quantitation of warfarin in plasma are high in demand. In this study, a novel surface enhanced Raman scattering (SERS) technique for the quantification of the widely used anticoagulant warfarin sodium in pharmaceutical dosage form and in spiked human plasma was developed. The colloidal-based SERS measurements were carefully optimized considering the laser wavelength, the type of metal nanoparticles, their surface functionalization and concentration as well as the time required for warfarin to associate with the metal surface. Poly(diallyldimethylammonium chloride) coated silver nanoparticles (PDDA-AgNPs) were established as a substrate which greatly enhanced the weak warfarin Raman signal with high reproducibility. The limit of detection was calculated in both water and human plasma to be 0.56 nM (0.17 ngmL-1) and 0.25 nM (0.08 ngmL-1) respectively, with a high degree of accuracy and reproducibility. The proposed method is simple, economical, and easily applied for routine application requiring only small plasma samples and also could be potentially useful for pharmacokinetic research on warfarin

Influenza Vaccine Effectiveness against Hospitalisation with Confirmed Influenza in the 2010-11 Seasons: A Test-negative Observational Study

Immunisation programs are designed to reduce serious morbidity and mortality from influenza, but most evidence supporting the effectiveness of this intervention has focused on disease in the community or in primary care settings. We aimed to examine the effectiveness of influenza vaccination against hospitalisation with confirmed influenza. We compared influenza vaccination status in patients hospitalised with PCR-confirmed influenza with patients hospitalised with influenza-negative respiratory infections in an Australian sentinel surveillance system. Vaccine effectiveness was estimated from the odds ratio of vaccination in cases and controls. We performed both simple multivariate regression and a stratified analysis based on propensity score of vaccination. Vaccination status was ascertained in 333 of 598 patients with confirmed influenza and 785 of 1384 test-negative patients. Overall estimated crude vaccine effectiveness was 57% (41%, 68%). After adjusting for age, chronic comorbidities and pregnancy status, the estimated vaccine effectiveness was 37% (95% CI: 12%, 55%). In an analysis accounting for a propensity score for vaccination, the estimated vaccine effectiveness was 48.3% (95% CI: 30.0, 61.8%). Influenza vaccination was moderately protective against hospitalisation with influenza in the 2010 and 2011 seasons