Cellulose nanofibers to improve the sensitivit…

Cellulose nanofibers to improve the sensitivity of lateral flow tests

Lateral flow tests are used across a wide range of sectors including human health and pharma, environmental testing, animal health, food and feed testing, and plant and crop health. They are paper-based biosensors that fulfil all the demands of the World Health Organization for devices: the ASSURED criteria require them to be affordable, sensitive, selective, user-friendly, rapid and robust and derivable to the end-user. Paradoxically, sensitivity is not always assured.

Their way of working is simple: a fluid sample, with or without a specific analyte, is put in one end of the strip. Certain particles (transducers) prepared to attach to that analyte are dragged along by the fluid. A large amount of antibodies are placed in the test line to retain the analyte marked with the transducers. In case the analyte is present in the sample, the test line will be coloured because of the transducers. Otherwise, the particles will continue their journey to the end of the strip.

Researchers from the ICN2, in collaboration with University of Girona, have found a way to increase remarkably the sensitivity of the test with only a slight increase in time. The research has been led by ICREA Prof. Arben Merkoçi, Group Leader of the ICN2 Nanobioelectronics and Biosensors Group, and counted with the participation of the ICN2 Advanced AFM Laboratory too, led by Dr Neus Domingo. The results have been published in Biosensors and Bioelectronics with Dr Daniel Quesada-González, now researcher at the spin-off Paperdropdx, as its first author.

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qingzinano: Five-needle Electrospinning Device…

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Five-needle Electrospinning Device With An Auxiliary Electrode

Kim et al. designed a five-needle electrospinning device with an auxiliary electrode (Fig. 6.5) and compared its spinning process to a five-needle electrospinning process without an auxiliary electrode. It was found that the initial jet and the entire electrospinning process were more stable when an auxiliary electrode was added. The mutual electric field interference between the jets was obviously reduced and the diameter and yield of the nanofibers both increased. In addition, Kim et al. also studied an electrospinning process that utilized different numbers of needles with auxiliary electrodes and found that the nanofiber deposition weight of each needle was similar to that of singleneedle electrospinning under the same spinning conditions. Therefore, the nanofiber yield increases linearly with the increase in the number of needles when an auxiliary electrode is added to the electrospinning system.

Biosynthesized fibers inspired strong and to…

Biosynthesized fibers inspired strong and tough artificial nanocomposite fibers

High-performance biomass-based nanocomposites are emerging as promising materials for future structural and functional applications due to their environmentally friendly, renewable and sustainable characteristics. Bio-sourced nanocelluloses (a kind of nanofibers) obtained from plants and bacterial fermentation are the most abundant raw materials on earth. They have attracted tremendous attention recently due to their attractive inherent merits including biodegradability, low density, thermal stability, global availability from renewable resources, as well as impressive mechanical properties. These features make them appropriate building blocks for spinning the next generation of advanced macrofibers for practical applications.

In past decades, various strategies have been pursued to gain cellulose-based macrofibers with improved strength and stiffness. However, nearly all of them have been achieved at the expense of elongation and toughness, because strength and toughness are always mutually exclusive for man-made structural materials. Therefore, this dilemma is quite common for previously reported cellulose-based macrofibers, which greatly limited their practical applications.

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Researcher uses canola to create biodegradab…

Researcher uses canola to create biodegradable cling wrap

A University of Alberta researcher has found a new use for a canola byproduct, providing potential for diverse markets beyond China.

Canola straw—the fibrous stalk left in the field after the plant is harvested for its oil—is proving useful in strengthening a plant-based cling wrap developed by Marleny Saldaña, a researcher in food and bioengineering processing.

In a new study, Saldaña and her research team used cellulose nanofibres from canolastraw to make the clear, plastic-like film, which is 12 times stronger than what they’ve already developed from cassava starch. The straw, which has little other use except as bedding for soil nutrients, contains cellulose and lignin, two components that support the canola plant.

Using canola straw this way demonstrates potential value-added options for the crop residue besides obtaining oil and protein from its seed, said Saldaña, who believes her and her team’s discovery to be the first application of its kind.

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Capturing real-time data as nanofibers form …

Capturing real-time data as nanofibers form makes electrospinning more affordable and effective

Electrospinning, a nanofiber fabrication method, can produce nanometer- to micrometer-diameter ceramic, polymer, and metallic fibers of various compositions for a wide spectrum of applications: tissue engineering, filtration, fuel cells and lithium batteries. These materials have unique properties because of their high-aspect-ratio morphology and large surface area.

Yet their development has largely been by trial and error, making it difficult to reproduce reliably in industrial settings. This challenge stems from a lack of understanding of the underlying dynamics during the process, which involves more than 10 control parameters.

The U.S. Department of Energy’s (DOE) Argonne National Laboratory is taking the guesswork out of electrospinning by leveraging its unique suite of capabilities to build a database that correlates electrospinning machine parameters with nanofiber properties. The suite will allow companies to design materials optimized for specific applications at top speed, while also making possible real-time feedback and control on the manufacturing floor.

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qingzinano: Touch Spinning of Nanofibers …

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Touch Spinning of Nanofibers

A further modification is a scalable method called touch spinning (Fig. 4.12). Nano/microfibers from 40 nm to 5 mm in diameter can be made by adjusting the rotational speed and polymer concentration (Tokarev et al., 2015). A glass rod (0.3 mm to a few millimeters in diameter) is glued to a rotating stage. A polymer solution is supplied, for example, from the needle of a syringe pump that faces the glass rod. The distance between the droplet of polymer solution and the tip of the glass rod is adjusted so that the glass rod contacts the polymer droplet as it rotates. Following the initial “touch,” the polymer droplet forms a liquid bridge. As the stage rotates, the bridge stretches and fiber length increases, with the diameter decreasing owing to mass conservation. Polyethylene nanofibers can be made by this method.

Cooling wood: Engineers create strong, sustain…

Cooling wood: Engineers create strong, sustainable solution for passive cooling

What if the wood your house was made of could save your electricity bill? In the race to save energy, using a passive cooling method that requires no electricity and is built right into your house could save even chilly areas of the US some cash. Now, researchers at the University of Maryland and the University of Colorado have harnessed nature’s nanotechnology to help solve the problem of finding a passive way for buildings to dump heat that is sustainable and strong.

Wood solves the problem—it is already used as a building material, and is renewable and sustainable. Using tiny structures found in wood—cellulose nanofibers and the natural chambers that grow to pass water and nutrients up and down inside a living tree—that specially processed wood has optical properties that radiate heat away. The results of this study were published May 9 in the journal Science.

“This work has greatly extended the use of wood towards high performance energy efficient applications and provided a sustainable route to combat the energy crisis,” said Northeast Forestry University Professor Jian Li, a member of Chinese Academy of Engineering, who is not associated with the research.

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New way to beat the heat in electronics: Rice …

New way to beat the heat in electronics: Rice University lab’s flexible insulator offers high strength and superior thermal conduction

A nanocomposite invented at Rice University’s Brown School of Engineering promises to be a superior high-temperature dielectric material for flexible electronics, energy storage and electric devices. A lab video shows how quickly heat disperses from a composite of a polymer nanoscale fiber layer and boron nitride nanosheets. When exposed to light, both materials heat up, but the plain polymer nanofiber layer on the left retains the heat far longer than the composite at right.

[…]

The nanocomposite combines one-dimensional polymer nanofibers and two-dimensional boron nitride nanosheets. The nanofibers reinforce the self-assembling material while the “white graphene” nanosheets provide a thermally conductive network that allows it to withstand the heat that breaks down common dielectrics, the polarized insulators in batteries and other devices that separate positive and negative electrodes.

The discovery by the lab of Rice materials scientist Pulickel Ajayan is detailed in Advanced Functional Materials.

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qingzinano: Nano-microfiber Composites For F…

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Nano-microfiber Composites For Filtration

Nanofibers prepared by molecular self-assembly are in general not self-supporting and therefore require stabilizing scaffold structures. In fact, a lot of research in the past has been done with supramolecular self-assembly of molecules forming a network of nanofibers used as organo/hydrogelators. But efforts to use them as a self-standing membrane or as free fibers were not strong. Therefore, the self-assembly of trisamides was also tried on a substrate, i.e., other microfiber nonwovens, leading to microenanofiber composites (Fig. 4.4) used for filtration (Weiss et al., 2016).

qingzinano: Polymer/Carbon Nanotube Composit…

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Polymer/Carbon Nanotube Composite Nanofibers

To improve the compatibility between CNTs and polymers, the surface functionalization of CNTs has been developed (Kharaziha et al., 2014; Molnar et al., 2008; Ra et al., 2005; Mazinani et al., 2009;
Yee et al., 2012; Subagia et al., 2014; Diouri et al., 2014). For instance, Kharaziha et al. established a simple strategy to prepare electrospun gelatin/CNT composite nanofibers by using carboxyl acid groupemodified CNTs, and the well-dispersed CNTs aligned along the fibrous axis could be observed (Fig. 3.15B). This work demonstrated CNTs as a component of tough and flexible scaffolds with outstanding electrical properties (Kharaziha et al., 2014). Molnar et al. (2008) synthesized PVA/CNT composite nanofibers with diverse types of CNTs and different functional groups via electrospinning. Furthermore, other synthetic methods such as electrospinning combined with electrospraying and a surface adsorption approach have been developed as well (Xuyen et al., 2009; Kim et al., 2006b; Vaisman et al., 2007; Dai et al., 2011; Rana and Cho, 2011).

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