75 research outputs found

    Controlled side-by-side assembly of gold nanorods and dye molecules into polymer-wrapped SERRS-active clusters

    Get PDF
    The controlled side-by-side assembly of gold nanorods in solution together with Raman reporter dye molecules to create small SERRS-active clusters stabilised by a surrounding polymer layer is demonstrated. This promising new class of nanotags offers several advantages over spherical nanoparticles for bioimaging and is of potential importance for a wide range of plasmon-enhanced spectroscopies and can also serve as building blocks for more complex solution-phase nanostructures

    Cathodoluminescence hyperspectral imaging on the nanometre scale

    Get PDF
    Extending cathodoluminescence microscopy into the hyperspectral imaging mode brings significant benefits to an already powerful nano-scale characterization tool. In this paper, we give an introduction to the technique, and illustrate its potential with examples of its application to both semiconducting and plasmonic nanostructures

    Methods for nanoparticle labeling of ricin and effect on toxicity

    Get PDF
    The unique optical properties associated with nanostructured materials that support the excitation of surface plasmons offer many new opportunities for the enhanced optical investigation of biological materials that pose a security threat. In particular, ricin is considered a significant bioterrorism risk due to its high toxicity combined with its ready availability as a byproduct in castor oil production. Therefore, the development of optical techniques capable of rapid on-site toxin detection with high molecular specificity and sensitivity continues to be of significant importance. Furthermore, understanding of the ricin cell entry and intracellular pathways remains poor due to a lack of suitable bioanalytical techniques. Initial work aimed at simultaneously tackling both these issues is described where different approaches for the nanoparticle labeling of ricin are investigated along with changes in ricin toxicity associated with the labeling process

    Bioaffinity detection of pathogens on surfaces

    Get PDF
    The demand for improved technologies capable of rapidly detecting pathogens with high sensitivity and selectivity in complex environments continues to be a significant challenge that helps drive the development of new analytical techniques. Surface-based detection platforms are particularly attractive as multiple bioaffinity interactions between different targets and corresponding probe molecules can be monitored simultaneously in a single measurement. Furthermore, the possibilities for developing new signal transduction mechanisms alongside novel signal amplification strategies aremuchmore varied. In this article, we describe some of the latest advances in the use of surface bioaffinity detection of pathogens. Three major sections will be discussed: (i) a brief overview on the choice of probe molecules such as antibodies, proteins and aptamers specific to pathogens and surface attachment chemistries to immobilize those probes onto various substrates, (ii) highlighting examples among the current generation of surface biosensors, and (iii) exploring emerging technologies that are highly promising and likely to form the basis of the next generation of pathogenic sensors

    Stabilized gold nanorod–dye conjugates with controlled resonance coupling create bright surface-enhanced resonance Raman nanotags

    Get PDF
    The preparation and characterization of stable and non-aggregated colloidal suspensions of gold nanorod–molecular dye complexes which exhibit very bright surface-enhanced resonance Raman scattering (SERRS) signals is described. A systematic study was performed where both the localized surface plasmon resonance (LSPR) of the nanorod and the molecular resonance of dyes adsorbed onto the rod surface were selectively tuned with respect to the laser excitation wavelengths. Resonance coupling was found to be a significant factor in the overall SERRS enhancement. The polymer stabilized nanorod–dye conjugates were prepared without the added complexity of nanoparticle aggregation as well as having good control over the surface coverage and orientation of the dye molecules. Furthermore, we demonstrate that this new class of Raman nanotags greatly outperforms an approach based on quasi-spherical gold nanoparticles

    Femtomolar detection of Tau proteins in undiluted plasma using surface plasmon resonance

    Get PDF
    The ability to directly detect Tau protein and other neurodegenerative biomarkers in human plasma at clinically relevant concentrations continues to be a significant hurdle for the establishment of diagnostic tests for Alzheimer’s disease (AD). In this article, we introduce a new DNA aptamer/antibody sandwich assay pairing and apply it for the detection of human Tau 381 in undiluted plasma at concentrations as low as 10 fM. This was achieved on a multichannel surface plasmon resonance (SPR) platform with the challenge of working in plasma overcome through the development of a tailored mixed monolayer surface chemistry. In addition, a robust methodology was developed involving various same chip control measurements on reference channels to which the detection signal was normalized. Comparative measurements in plasma between SPR and enzyme-linked immunosorbent assay (ELISA) measurements were also performed to highlight both the 1000-fold performance enhancement of SPR and the ability to measure both spiked and native concentrations that are not achievable with ELISA

    Gel electrophoretic analysis of differently shaped interacting and non-interacting bioconjugated nanoparticles

    Get PDF
    The use of a simple gel electrophoretic method to study mixtures of differently shaped biofunctionalized nanoparticles (NP's) that undergo bioaffinity interactions is demonstrated. Both gold nanorods (NR's) and quasi-spherical nanoparticles (qNS's) were functionalized with an interacting antigen and antibody pairing (alpha-1 antitrypsin (AAT) protein and antiAAT) or non-interacting antibody controls (antiBNP). Gel-based measurements were accompanied with transmission electron microscopy (TEM) and UV-vis spectroscopy analysis before and after separation. Initial measurements of NR and qNS bioconjugates suspended individually were applied to optimize the gel separation conditions and it was demonstrated that higher particle uniformities could be obtained relative to the initial stock solutions. A series of NR and qNS mixtures prepared at various stoichiometric ratios were then compared for both interacting (antiAAT–AAT) and non-interacting (antiAAT–antiBNP) particle conjugates. Both gel images and extinction measurements were utilized to demonstrate reduced NP concentrations transported along the gel due to bioaffinity-induced NP assembly. This confirmed that gel electrophoresis can be extended to identifying particle aggregation associated with protein bioaffinity interactions as well as being an established tool for separating particles based on size, shape and surface chemistry

    Attomolar detection of protein biomarkers using biofunctionalized gold nanorods with surface plasmon resonance

    Get PDF
    This paper describes an ultrasensitive surface plasmon resonance (SPR) detection method using biofunctionalized gold nanorods for the direct detection of protein biomarkers. Immunoglobulin E (IgE), which has separate antibody and DNA aptamer binding sites, was chosen as a model protein for which a sandwich assay platform was designed. Detection was achieved via the specific adsorption of unlabelled IgE proteins onto the surface immobilized aptamer followed by the specific adsorption of anti-IgE coated gold nanorods (Au-NRs). Using the biofunctionalized nanorods in conjunction with SPR, we were able to directly measure IgE proteins at attomolar concentrations. This is a remarkable 108 enhancement compared to conventional SPR measurements of the same surface sandwich assay format ‘anti-IgE/IgE/surface bound IgE-aptamer’ in the absence of gold nanorod signal amplification

    The effect of prosthesis-related loading on soft tissue health

    Get PDF
    Worldwide, one individual loses a limb every 30 seconds because of complications of diabetes [1]. Considering our aging population, this is expected to worsen over the decades to come [2]. To mitigate the negative impact of an amputation on the individual, restoring mobility is key. Often a prosthesis is fitted that replaces the lost limb. One of its most important parts is the socket, which forms the direct connection between the prosthesis and the leg. However, designing and fitting a good prosthetic socket is a considerable challenge: Most amputees report discomfort and pain when using their prosthesis, which often leads to reduced functionality and low acceptance rates. A major reason is our limited understanding of how compressing soft tissues like muscle between the rigid socket and the bone affects soft tissue health. Whilst researchers have explored how prolonged, static loading, for example when standing with a prosthesis, impacts on soft tissue health [3], dynamic loading scenarios like walking and running, have been neglected [4]. We therefore aim to compare the effect of static and dynamic loading representative of prosthetic use on muscle tissue. We developed an ex vivo experiment that uses two different muscles from the hindlimb of Sprague Dawley rats (extensor digitorum longus and soleus). The muscles were dissected and compressed with a pressure of 100kPa for 1 hour either statically, representing standing and sitting, or dynamically, representing walking and running (frequencies of 1.42Hz and 4Hz). Subsequently, the tissues were stained with Procion Yellow MX4R (ProY) for 1 hour before being processed for microscopy. ProY is a fluorescent stain that enters cells that have lost their membrane integrity. Accordingly, we could detect mechanically damaged cells under the microscope (Leica SP8 system). The number of dead cells was counted across five samples for each experimental group in a semi-automated process with ImageJ software. The results were tested for statistically significant differences (p ≀ 0.05) with Mann-Whittney-tests. Both dynamic loading scenarios induced more cellular damage than static loading (median number of dead cells: 79.5 (static), 90 (1.42Hz), 135.5 (4Hz)). However, results were only statistically significant between the static and 4Hz (p=0.011), and the 1.42Hz and 4Hz group (p=0.044). Interpreting these results in a clinical context, sitting, standing, and walking seem to bare a similar risk of damage for the muscle tissue in the residual limb. Fast walking or running however is potentially more harmful to the tissues, which could result in pain and tissue damage. To avoid these issues, adjusting socket fit to minimise soft tissue deformation is crucial. Additionally, identifying threshold levels for damage-inducing loading levels related to the activity performed by an amputee would be helpful. This information can not only inform clinical guidelines on prosthetic socket fit and use, but also be integrated into home-monitoring systems to allow for patient-specific risk assessment beyond the hospital

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

    Get PDF
    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
    • 

    corecore