A Fully-Flexible Solution-Processed Autonomous Glucose Indicator

We present the first demonstration of a fully-flexible, self-powered glucose indicator system that synergizes two flexible electronic technologies: a flexible self-powering unit in the form of a biofuel cell, with a flexible electronic device - a circuit-board decal fabricated with biocompatible microbial nanocellulose. Our proof-of-concept device, comprising an enzymatic glucose fuel cell, glucose sensor and a LED indicator, does not require additional electronic equipment for detection or verification; and the entire structure collapses into a microns-thin, self-adhering, single-centimeter-square decal, weighing less than 40 mg. The flexible glucose indicator system continuously operates a light emitting diode (LED) through a capacitive charge/discharge cycle, which is directly correlated to the glucose concentration. Our indicator was shown to operate at high sensitivity within a linear glucose concentration range of 1 mM-45 mM glucose continuously, achieving a 1.8 VDC output from a flexible indicator system that deliver sufficient power to drive an LED circuit. Importantly, the results presented provide a basis upon which further development of indicator systems with biocompatible diffusing polymers to act as buffering diffusion barriers, thereby allowing them to be potentially useful for low-cost, direct-line-of-sight applications in medicine, husbandry, agriculture, and the food and beverage industries

Functional characterization of a melon alcohol acyl-transferase gene family involved in the biosynthesis of ester volatiles. Identification of the crucial role of a threonine residue for enzyme activity

Volatile esters, a major class of compounds contributing to the aroma of many fruit, are synthesized by alcohol acyl-transferases (AAT). We demonstrate here that, in Charentais melon (Cucumis melo var. cantalupensis), AAT are encoded by a gene family of at least four members with amino acid identity ranging from 84% (Cm-AAT1/Cm-AAT2) and 58% (Cm-AAT1/Cm-AAT3) to only 22% (Cm-AAT1/Cm-AAT4). All encoded proteins, except Cm-AAT2, were enzymatically active upon expression in yeast and show differential substrate preferences. Cm-AAT1 protein produces a wide range of short and long-chain acyl esters but has strong preference for the formation of E-2-hexenyl acetate and hexyl hexanoate. Cm-AAT3 also accepts a wide range of substrates but with very strong preference for producing benzyl acetate. Cm-AAT4 is almost exclusively devoted to the formation of acetates, with strong preference for cinnamoyl acetate. Site directed mutagenesis demonstrated that the failure of Cm-AAT2 to produce volatile esters is related to the presence of a 268-alanine residue instead of threonine as in all active AAT proteins. Mutating 268-A into 268-T of Cm-AAT2 restored enzyme activity, while mutating 268-T into 268-A abolished activity of Cm-AAT1. Activities of all three proteins measured with the prefered substrates sharply increase during fruit ripening. The expression of all Cm-AAT genes is up-regulated during ripening and inhibited in antisense ACC oxidase melons and in fruit treated with the ethylene antagonist 1-methylcyclopropene (1-MCP), indicating a positive regulation by ethylene. The data presented in this work suggest that the multiplicity of AAT genes accounts for the great diversity of esters formed in melon

Electrocatalytic activity of Au nanoparticles onto TiO2 nanotubular layers in oxygen electroreduction reaction: size and support effects

Electrocatalytic activity of both bare high-ordered TiO2 nanotubes (TNTs) and gold nanoparticles (Au NPs) loaded TNTs toward oxygen reduction reaction (ORR) has been examined by cyclic voltammetry (CV). Cyclic voltammograms for Au NPs-TNT electrodes are characterized by an additional wave observed at less negative potentials which is responsible for oxygen electroreduction on the surface of gold NPs. The overpotential for O-2 reduction on the Au surface grows with increasing the temperature of TNT annealing and the Au NPs size. The nature of the effects observed was explained by peculiarities of the electron transport through Schottky barrier formed at the Au NPs - TiO2 interface. The width of the Schottky barrier, determined by semiconductor doping level and Au NPs size, plays a key role in the mechanism of electron transport through the space charge region. (C) 2016 Elsevier Ltd. All rights reserved

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Sustainability, nutrition, and scientific advances of functional foods under the new EU and global legislation initiatives

The health of the general population is one of the various factors at stake in the 2020′s generation: food security, safety, nutrition, and responsible, sustainable production and consumption are also part of the priorities of governments and enterprises. Under that prism, the new EU legislation (Green Deal – Farm to Fork) building on the top of the UN’s Sustainable Development Goals groundwork has brought about a revamped focus on sustainability in the food industry, emphasising reducing food production's environmental impact and promoting sustainable food systems. Here, an integrative approach between scientific and technological advancement, policymakers, consumers, and society, to design sustainable, functional foods is presented, focusing on food innovation for developing bioactive-rich ingredients and tackling non-communicable diseases (NCD). We also critically analyse how these findings fit within the new policy frameworks of the EU and the UN under the common goal of achieving global food security and sustainable growth

Statistical Analysis of Plating Variable Effects on the Electrical Conductivity of Electroless Copper Patterns on Paper

We describe a process for selective metallization of paper substrates bearing inkjet printed patterns of a commercial Pd/Sn colloidal catalyst ink plated using a commercial electroless Cu bath. The electrical conductivity of the Cu films is analyzed as a function of feature geometry (line dimensions (<i>L</i>) and spacing (<i>S</i>)), type of paper (<i>P</i>), age of the Pd/Sn patterns (<i>A</i>), plating time (<i>T</i>), and plating temperature (<i>H</i>) using a two-level factorial design. Conductivity is influenced predominantly by the <i>P</i>, <i>T</i>, and <i>H</i> factors, with lesser contributions attributed to pair-wise interactions among several of the variables studied. Increases in <i>T</i> and/or <i>H</i> enhance conductivity of the Cu films, whereas increases in <i>P</i>, corresponding to the use of rougher, more porous, paper substrates, yield Cu films exhibiting decreased conductivity. Our analysis leads to a model that predicts Cu film conductivity well over the ranges of variables examined, provides guidelines for identification of optimum conditions for plating highly conductive Cu films, and identifies areas for further process improvement

Integrating Paper Chromatography with Electrochemical Detection for the Trace Analysis of TNT in Soil

We report on the development of an electrochemical probe for the trace analysis of 2,4,6-trinitrotoluene (TNT) in soil samples. The probe is a combination of graphite electrodes, filter paper, with ethylene glycol and choline chloride as the solvent/electrolyte. Square wave chromatovoltammograms show the probes have a sensitivity for TNT of 0.75 nA/ng and a limit of detection of 100 ng. In addition, by taking advantage of the inherent paper chromatography step, TNT can be separated in both time and cathodic peak potential from 4-amino-dinitrotolene co-spotted on the probe or in soil samples with the presence of methyl parathion as a possible interferent

A Simple and Inexpensive Electrochemical Assay for the Identification of Nitrogen Containing Explosives in the Field

We report a simple and inexpensive electrochemical assay using a custom built hand-held potentiostat for the identification of explosives. The assay is based on a wipe test and is specifically designed for use in the field. The prototype instrument designed to run the assay is capable of performing time-resolved electrochemical measurements including cyclic square wave voltammetry using an embedded microcontroller with parts costing roughly $250 USD. We generated an example library of cyclic square wave voltammograms of 12 compounds including 10 nitroaromatics, a nitramine (RDX), and a nitrate ester (nitroglycine), and designed a simple discrimination algorithm based on this library data for identification

Effect of high gold salt concentrations on the size and polydispersity of gold nanoparticles prepared by an extended Turkevich-Frens method

The Turkevich-Frens synthesis starting conditions are expanded, ranging the gold salt concentrations up to 2 mM and citrate/gold(III) molar ratios up to 18:1. For each concentration of the initial gold salt solution, the citrate/gold(III) molar ratios are systematically varied from 2:1 to 18:1 and both the size and size distribution of the resulting gold nanoparticles are compared. This study reveals a different nanoparticle size evolution for gold salt solutions ranging below 0.8 mM compared to the case of gold salt solutions above 0.8 mM. In the case of Au3+]<0.8 mM, both the size and size distribution vary substantially with the citrate/gold(III) ratio, both displaying plateaux that evolve inversely to Au3+] at larger ratios. Conversely, for Au3+]>= 0.8 mM, the size and size distribution of the synthesized gold nanoparticles continuously rise as the citrate/gold(III) ratio is increased. A starting gold salt concentration of 0.6 mM leads to the formation of the most monodisperse gold nanoparticles (polydispersity index<0.1) for a wide range of citrate/gold(III) molar ratios (from 4:1 to 18:1). Via a model for the formation of gold nanoparticles by the citrate method, the experimental trends in size could be qualitatively predicted:the simulations showed that the destabilizing effect of increased electrolyte concentration at high initial Au3+] is compensated by a slight increase in zeta potential of gold nanoparticles to produce concentrated dispersion of gold nanoparticles of small sizes

Development and evaluation of single domain antibodies for vaccinia and the L1 antigen.

There is ongoing interest to develop high affinity, thermal stable recognition elements to replace conventional antibodies in biothreat detection assays. As part of this effort, single domain antibodies that target vaccinia virus were developed. Two llamas were immunized with killed viral particles followed by boosts with the recombinant membrane protein, L1, to stimulate the immune response for envelope and membrane proteins of the virus. The variable domains of the induced heavy chain antibodies were selected from M13 phage display libraries developed from isolated RNA. Selection via biopanning on the L1 antigen produced single domain antibodies that were specific and had affinities ranging from 4×10(-9) M to 7.0×10(-10) M, as determined by surface plasmon resonance. Several showed good ability to refold after heat denaturation. These L1-binding single domain antibodies, however, failed to recognize the killed vaccinia antigen. Useful vaccinia binding single domain antibodies were isolated by a second selection using the killed virus as the target. The virus binding single domain antibodies were incorporated in sandwich assays as both capture and tracer using the MAGPIX system yielding limits of detection down to 4×10(5) pfu/ml, a four-fold improvement over the limit obtained using conventional antibodies. This work demonstrates the development of anti-vaccinia single domain antibodies and their incorporation into sandwich assays for viral detection. It also highlights the properties of high affinity and thermal stability that are hallmarks of single domain antibodies