Dual Enlargement of Gold Nanoparticles: From Mechanism to Scanometric Detection of Pathogenic Bacteria

A mechanism of dual enlargement of gold nanoparticles (AuNPs) comprising two steps is described. In the first step, the AuNPs are enlarged by depositing Au atoms on their crystalline faces. In this process, the particles are not only enlarged but they are also observed to multiply: new Au nuclei are formed by the budding and division of the enlarged particles. In the second step, a silver enhancement is subsequently performed by the deposition of silver atoms on the enlarged and newly formed AuNPs to generate bimetallic Au@Ag core-shell structures. The dual nanocatalysis greatly enhances the electron density of the nanostructures, leading to a stronger intensity for colorimetric discrimination as well as better sensitivity for quantitative measurement. Based on this, a simple scanometric assay for the on-slide detection of the food-born pathogen Campylobacter jejuni is developed. After capturing the target bacteria, gold-tagged immunoprobes are added to create a signal on a solid substrate. The signal is then amplified by the dual enlargement process, resulting in a strong color intensity that can easily be recognized by the unaided eye, or measured by an inexpensive flatbed scanner. In this paper, dual nanocatalysis is reported for the first time. It provides a valuable mechanistic insight into the development of a simple and cost-effective detection format.

Pre-storage of gelified reagents in a lab-on-a-foil system for rapid nucleic acid analysis

Reagent pre-storage in a microfluidic chip can enhance operator convenience, simplify the system design, reduce the cost of storage and shipment, and avoid the risk of cross-contamination. Although dry reagents have long been used in lateral flow immunoassays, they have rarely been used for nucleic acid-based point-of-care (POC) assays due to the lack of reliable techniques to dehydrate and store fragile molecules involved in the reaction. In this study, we describe a simple and efficient method for prolonged on-chip storage of PCR reagents. The method is based on gelification of all reagents required for PCR as a ready-to-use product. The approach was successfully implemented in a lab-on-a-foil system, and the gelification process was automated for mass production. Integration of reagents on-chip by gelification greatly facilitated the development of easy-to-use lab-on-a-chip (LOC) devices for fast and cost-effective POC analysis.

Gold Nanoparticles-Coated SU-8 for Sensitive Fluorescence-Based Detections of DNA

SU-8 epoxy-based negative photoresist has been extensively employed as a structural material for fabrication of numerous biological microelectro-mechanical systems (Bio-MEMS) or lab-on-a-chip (LOC) devices. However, SU-8 has a high autofluorescence level that limits sensitivity of microdevices that use fluorescence as the predominant detection workhorse. Here, we show that deposition of a thin gold nanoparticles layer onto the SU-8 surface significantly reduces the autofluorescence of the coated SU-8 surface by as much as 81% compared to bare SU-8. Furthermore, DNA probes can easily be immobilized on the Au surface with high thermal stability. These improvements enabled sensitive DNA detection by simple DNA hybridization down to 1 nM (a two orders of magnitude improvement) or by solid-phase PCR with sub-picomolar sensitivity. The approach is simple and easy to perform, making it suitable for various Bio-MEMs and LOC devices that use SU-8 as a structural material.

Isolation and detection of Campylobacter jejuni from chicken fecal samples by immunomagnetic separation–PCR

Campylobacter jejuni (C. jejuni) is one of the leading causes of bacterial food-borne disease worldwide. The presence of Campylobacter in chicken feces poses a high risk for contamination of chicken meat and for Campylobacter infections in human. Detection of this bacterium in chicken fecal specimens before slaughter is therefore vital to prevent disease transmission. By combining two techniques – immunomagnetic separation (IMS) and polymerase chain reaction (PCR), this study developed a reliable and specific method for rapid detection of C. jejuni in chicken fecal samples. The specificity of the assay was assured by two selection steps: 1) Dynabeads®M-270 Amine microbeads (2.8 µm in diameter) coated with C. jejuni monoclonal antibodies were used as the primary selection to isolate bacteria from fecal samples. 2) A PCR assay amplifying the Hippuricase gene was performed as the specific selection to accurately confirm the presence of C. jejuni. Without pre-enrichment, this method was able to detect approximately 10 CFU of C. jejuni in 1 µl of spiked feces within 3 h.

Au Nanoparticles for Applications in Analysis of Cellular and Biomolecular Recognitions

Au nanoparticles (AuNPs) have attracted a great interest in fabrication of various biosensor systems for analysis of cellular and biomolecular recognitions. In conjunction with vast conjugation chemistry available, the materials are easily coupled with biomolecules such as nucleic acids, antigens or antibodies in order to achieve their many potential applications as ligand carriers or transducing platforms for preparation, detection and quantification purposes. Furthermore, the nanoparticles possess easily tuned and unique optical/ physical/ chemical characteristics, and high surface areas, making them ideal candidates to this end. In this topic, sensing mechanisms based on localized surface plasmon resonance (LSPR), particle aggregation, catalytic property, and Fluorescence Resonance Energy Transfer (FRET) of AuNPs as well as barcoding technologies including DNA biobarcodes will be discussed.

A Trip from a Tube to a Chip Applied Micro and Nanotechnology in Biotechnology, Veterinary and Life Sciences

More than 200 known diseases are transmitted via foods or food products. In the United States, food-borne diseases are responsible for 76 million cases of illness, 32,500 cases of hospitalisation and 5000 cases of death yearly. The ongoing increase in worldwide trade in livestock, food, and food products in combination with increase in human mobility (business- and leisure travel, emigration etc.) will increase the risk of emergence and spreading of such pathogens. There is therefore an urgent need for development of rapid, efficient and reliable methods for detection and identification of such pathogens.

Microchipfabrication has had a major impact on electronics and is expected to have an equally pronounced effect on life sciences. By combining micro-fluidics with micromechanics, micro-optics, and microelectronics, systems can be realized to perform complete chemical or biochemical analyses. These socalled ’Lab-on-a-Chip’ will completely change the face of laboratories in the future where smaller, fully automated devices will be able to perform assays faster, more accurately, and at a lower cost than equipment of today. A general introduction of food safety and applied micro-nanotechnology in life sciences will be given. In addition, examples of DNA micro arrays, micro fabricated integrated PCR chips and total integrated lab-on-achip systems from different National and EU research projects being carried out at the Laboratory of Applied Micro- Nanotechnology (LAMINATE) group at the National Veterinary Institute (DTU-Vet) Technical University of Denmark and the BioLabchip group at the Department of Micro and Nanotechnology (DTU-Nanotech), Technical University of Denmark (DTU), Ikerlan-IK4 (Spain) and other 16 partners from different European countries will be presented.

GELIFICATION - A SIMPLE AND EFFICIENT METHOD FOR ON-CHIP STORAGE OF REAGENTS: TOWARDS LAB-ON-A-CHIP SYSTEMS FOR POINT-OF-CARE DIAGNOSTICS

In this study, we describe a simple and efficient method for on-chip storage of reagents for point-of-care (POC) diagnostics. The method is based on gelification of all reagents required for on-chip PCR-based diagnostics as a ready-to-use product. The result reported here is a key step towards the development of a ready and easy to use fully integrated Lab-on-a-chip (LOC) system for fast, cost-effective and efficient POC diagnostics analysis.

Is it worthwhile to conduct a randomized controlled trial of glaucoma screening in the United Kingdom?

To assess the value of conducting a glaucoma screening randomized controlled trial in the UK.

Genome-wide association analysis identifies 13 new risk loci for schizophrenia

Schizophrenia is an idiopathic mental disorder with a heritable component and a substantial public health impact. We conducted a multi-stage genome-wide association study (GWAS) for schizophrenia beginning with a Swedish national sample (5,001 cases and 6,243 controls) followed by meta-analysis with previous schizophrenia GWAS (8,832 cases and 12,067 controls) and finally by replication of SNPs in 168 genomic regions in independent samples (7,413 cases, 19,762 controls and 581 parent-offspring trios). We identified 22 loci associated at genome-wide significance; 13 of these are new, and 1 was previously implicated in bipolar disorder. Examination of candidate genes at these loci suggests the involvement of neuronal calcium signaling. We estimate that 8,300 independent, mostly common SNPs (95% credible interval of 6,300-10,200 SNPs) contribute to risk for schizophrenia and that these collectively account for at least 32% of the variance in liability. Common genetic variation has an important role in the etiology of schizophrenia, and larger studies will allow more detailed understanding of this disorder.

The Next Generation Transit Survey (NGTS)

The Next Generation Transit Survey (NGTS) is a new ground-based sky survey designed to find transiting Neptunes and super-Earths. By covering at least sixteen times the sky area of Kepler we will find small planets around stars that are sufficiently bright for radial velocity confirmation, mass determination and atmospheric characterisation. The NGTS instrument will consist of an array of twelve independently pointed 20cm telescopes fitted with red-sensitive CCD cameras. It will be constructed at the ESO Paranal Observatory, thereby benefiting from the very best photometric conditions as well as follow up synergy with the VLT and E-ELT. Our design has been verified through the operation of two prototype instruments, demonstrating white noise characteristics to sub-mmag photometric precision. Detailed simulations show that about thirty bright super-Earths and up to two hundred Neptunes could be discovered. Our science operations are due to begin in 2014.

SN 2009ip á la PESSTO:No evidence for core-collapse yet

We present observations of the interacting transient SN 2009ip, from the start of the outburst in October 2012 until the end of the 2012 observing season. The transient reached a peak of $M_V$=-17.7 mag before fading rapidly, with a total integrated luminosity of 1.9$\times10^{49}$ erg over the period of August-December 2012. The optical and near infrared spectra are dominated by narrow emission lines, signaling a dense circumstellar environment, together with multiple components of broad emission and absorption in H and He at velocities between 0.5-1.2$\times10^4$ km s$^{-1}$\. We see no evidence for nucleosynthesized material in SN 2009ip, even in late-time pseudo-nebular spectra. We set a limit of $

The superluminous supernova PS1-11ap: bridging the gap between low and high redshift

We present optical photometric and spectroscopic coverage of the superluminous supernova (SLSN) PS1-11ap, discovered with the Pan-STARRS1 Medium Deep Survey at z = 0.524. This intrinsically blue transient rose slowly to reach a peak magnitude of Mu = −21.4 mag and bolometric luminosity of 8 × 1043 erg s−1 before settling on to a relatively shallow gradient of decline. The observed decline is significantly slower than those of the SLSNe-Ic which have been the focus of much recent attention. Spectroscopic similarities with the lower redshift SN2007bi and a decline rate similar to 56Co decay time-scale initially indicated that this transient could be a candidate for a pair instability supernova (PISN) explosion. Overall the transient appears quite similar to SN2007bi and the lower redshift object PTF12dam. The extensive data set, from 30 d before peak to 230 d after, allows a detailed and quantitative comparison with published models of PISN explosions. We find that the PS1-11ap data do not match these model explosion parameters well, supporting the recent claim that these SNe are not pair instability explosions. We show that PS1-11ap has many features in common with the faster declining SLSNe-Ic, and the light-curve evolution can also be quantitatively explained by the magnetar spin-down model. At a redshift of z = 0.524, the observer-frame optical coverage provides comprehensive rest-frame UV data and allows us to compare it with the SLSNe recently found at high redshifts between z = 2 and 4. While these high-z explosions are still plausible PISN candidates, they match the photometric evolution of PS1-11ap and hence could be counterparts to this lower redshift transient.

Variation of clinical outcomes used in glaucoma randomised controlled trials:a systematic review

Purpose: In randomised clinical trials (RCTs) the selection of appropriate outcomes is crucial to the assessment of whether one intervention is better than another. The purpose of this review is to identify different clinical outcomes reported in glaucoma trials.

Methods We conducted a systematic review of glaucoma RCTs. A sample or selection of glaucoma trials were included bounded by a time frame (between 2006 and March 2012). Only studies in English language were considered. All clinical measured and reported outcomes were included. The possible variations of clinical outcomes were defined prior to data analysis. Information on reported clinical outcomes was tabulated and analysed using descriptive statistics. Other data recorded included type of intervention and glaucoma, duration of the study, defined primary outcomes, and outcomes used for sample size calculation, if nominated.

Results The search strategy identified 4323 potentially relevant abstracts. There were 315 publications retrieved, of which 233 RCTs were included. A total of 967 clinical measures were reported. There were large variations in the definitions used to describe different outcomes and their measures. Intraocular pressure was the most commonly reported outcome (used in 201 RCTs, 86%) with a total of 422 measures (44%). Safety outcomes were commonly reported in 145 RCTs (62%) whereas visual field outcomes were used in 38 RCTs (16%).

Conclusions There is a large variation in the reporting of clinical outcomes in glaucoma RCTs. This lack of standardisation may impair the ability to evaluate the evidence of glaucoma interventions.

Outcome Measures in Glaucoma:A Systematic Review of Cochrane Reviews and Protocols

In clinical trials, the selection of appropriate outcomes is crucial for the assessment of whether one intervention is better than another. Selection of inappropriate outcomes can compromise the utility of a trial. However, the process of selecting the most suitable outcomes to include can be complex. Ideally, glaucoma trials aim to evaluate important outcomes for clinicians and patients. A high variability in the selection of outcomes suggests that there is no consensus on how best to evaluate the effect of glaucoma interventions. Further, it makes evidence synthesis difficult. The purpose of this review is to determine the extent of clinical outcome measures used in published glaucoma Cochrane Reviews and Protocols.