SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Selectivity

139

Reliable environmental monitoring requires cost effective but highly sensitive and selective gas sensors. While the sensitivity of the sensors is improved by reducing the characteristic dimensions of the gas-sensing material, the selectivity is often approached by combining the sensors into multisensor arrays. The development of scalable methods to manufacture such arrays based on low-dimensional structures offers new perspectives for gas sensing applications. Here we examine an approach to produce multisensor array chips based on the TiOx nanotube layers segmented by multiple Pt strip electrodes. We study the sensitivity and selectivity of the developed chip at operating temperatures up to 400 °C towards organic vapors in the ppm range. The results indicate that the titania nanotubes are a promising material platform for novel cost-effective and powerful gas-analytical multisensor units.

Concepts: Cost-effectiveness analysis, Array, Costs, Titanium dioxide, Oxygen, Selectivity, Temperature, Sensitivity and specificity

78

The recent outbreak of Zika virus (ZIKV) infection in the Americas and its devastating impact on fetal development have prompted WHO to declare the ZIKV pandemic as a Public Health Emergency of International Concern. Rapid and reliable diagnostics for ZIKV are vital since ZIKV-infected individuals display no symptoms or nonspecific symptoms similar to other viral infections. Since immunoassays lack adequate sensitivity and selectivity and are unable to identify active state of infection, molecular diagnostics are an effective means to detect ZIKV soon after infection and throughout pregnancy. We report on a highly sensitive reverse transcription-loop mediated, isothermal amplification (RT-LAMP) assay for rapid detection of ZIKV and on the assay implementation in a simple, easy to use, inexpensive, point of care (POC), disposable cassette that carries out all the unit operations from sample introduction to detection. For thermal control of the cassette, we use a chemically-heated cup without a need for any electrical power. Detection is carried out with leuco crystal violet (LCV) dye by eye, thus eliminating the need for any instrumentation. We demonstrated the utility of our POC diagnostic system by detecting ZIKV in oral samples with sensitivity of 5 plaque-forming units (PFU) in less than 40 min. Our system is particularly suitable for resource poor settings, where centralized laboratory facilities, funds, and trained personnel are in short supply, and for use in doctors' offices and at home.

Concepts: Inflammation, Pregnancy, Selectivity, Sensitivity and specificity, Infectious disease, Virus, Disease, Infection

35

Fluorescent antimicrobial peptides are promising structures for in situ, real-time imaging of fungal infection. Here we report a fluorogenic probe to image Aspergillus fumigatus directly in human pulmonary tissue. We have developed a fluorogenic Trp-BODIPY amino acid with a spacer-free C-C linkage between Trp and a BODIPY fluorogen, which shows remarkable fluorescence enhancement in hydrophobic microenvironments. The incorporation of our fluorogenic amino acid in short antimicrobial peptides does not impair their selectivity for fungal cells, and enables rapid and direct fungal imaging without any washing steps. We have optimized the stability of our probes in human samples to perform multi-photon imaging of A. fumigatus in ex vivo human tissue. The incorporation of our unique BODIPY fluorogen in biologically relevant peptides will accelerate the development of novel imaging probes with high sensitivity and specificity.

Concepts: Selectivity, Sensitivity and specificity

28

CdO nanosheet film can be synthesized by electrochemical deposition in an ultra-thin liquid layer by using Cd(NO(3))(2) and HNO(3) as source materials for Cd and oxygen respectively. HNO(3) is also used to adjust the pH of the electrolyte. Studies on the detailed structure indicate that the synthesized CdO nanosheet film has a face-centered cubic structure with (200)-preferred orientation. The response of the CdO nanosheet film to liquefied petroleum gas (LPG) at low temperature has been significantly improved by the novel structure of film. It has exhibited excellent sensitivity and selectivity to LPG at low temperature. A new growth mechanism of electrochemical deposition has been proposed to elaborate the formation of nanosheet in an ultra-thin liquid layer. The self-oscillation of potential in the growth interface and intermediate hydroxide are responsible for the formation of nanosheets.

Concepts: Liquid, Oxygen, Selectivity, Natural gas, Cubic crystal system, Liquefied petroleum gas, Sensitivity and specificity, Gas

27

We demonstrate a novel, rapid and label-free assay for the detection of Ag(+) and biothiols with high sensitivity and selectivity by utilization of Ag nanoparticle-decorated graphene quantum dots.

Concepts: Highly sensitive person, Statistical ratios, Selectivity, Sensitivity and specificity

25

The emergence of nanotechnology suggests new and exciting opportunities for early diagnosis and therapy of cancer. During the recent years, silicon-based nanomaterials featuring unique properties have received great attention, showing high promise for myriad biological and biomedical applications. In this review, we will particularly summarize latest representative achievements on the development of silicon nanostructures as a powerful platform for cancer early diagnosis and therapy. First, we introduce the silicon nanomaterial-based biosensors for detecting cancer markers (e.g., proteins, tumor-suppressor genes and telomerase activity, among others) with high sensitivity and selectivity under molecular level. Then, we summarize in vitro and in vivo applications of silicon nanostructures as efficient nanoagents for cancer therapy. Finally, we discuss the future perspective of silicon nanostructures for cancer diagnosis and therapy.

Concepts: Gene, Selectivity, Nanomaterials, In vivo, In vitro, Sensitivity and specificity, Molecular biology, DNA

24

A larger ratio of conduction-band offset to valence-band offset is the unique character for MgxZn1-xO alloys. For this reason, it is feasible to build a quasi-electric forces, caused by the spatial gradient of the conduction edge, exerting on the electrons. In this paper, a novel graded band gap cubic-MgZnO-based solar-blind photodetector is successfully fabricated from Graded-Band-Gap-Cubic-MgZnO/i-MgO/p-Si heterojunction, via changing stoichiometry spatial gradient. Due to quasi-electric fields in non-uniform MgZnO, the multiple carriers are generated under ultra-low threshold bias voltage. The photodetector showed high performance, namely, high responsivity, quantum efficiency, high sensitivity and selectivity towards the solar-blind spectrum, and fast response times.

Concepts: Scalar field, Condensed matter physics, Semiconductor, Positive predictive value, Selectivity, Responsivity, Sensitivity and specificity, Electronics terms

8

Nitrogen dioxide (NO2) is a gas species that plays an important role in certain industrial, farming and healthcare sectors. However, there are still significant challenges for NO2 sensing at low detection limits, especially in the presence of other interfering gases. The NO2 selectivity of current gas sensing technologies is significantly traded-off with their sensitivity and reversibility as well as fabrication and operating costs. In this work, we present an important progress for selective and reversible NO2 sensing by demonstrating an economical sensing platform based on the charge transfer between physisorbed NO2 gas molecules and two-dimensional (2D) tin disulfide (SnS2) flakes at low operating temperatures. The device shows high sensitivity and superior selectivity to NO2 at operating temperatures of less than 160ºC which are well below those of chemisorptive and ion conductive NO2 sensors with much poorer selectivity. At the same time, excellent reversibility of the sensor is demonstrated which has rarely been observed in other 2D material counterparts. Such impressive features originate from the planar morphology of 2D SnS2 as well as unique physical affinity and favorable electronic band positions of this material that facilitate the NO2 physisorption and charge transfer at parts per billion (ppb) levels. The 2D SnS2 based sensor provides a real solution for low-cost and selective NO2 gas sensing.

Concepts: Solid, Selectivity, Sensitivity and specificity, Oxygen, Oxide, Temperature, Nitrogen, Gas

6

Picky eating is prevalent in childhood. Because pickiness concerns parents and is associated with nutrient deficiency and psychological problems, the antecedents of pickiness need to be identified. We propose an etiological model of picky eating involving child temperament, sensory sensitivity and parent-child interaction.

Concepts: Parent, Human development, Medical statistics, Psychology, Developmental psychology, Selectivity, Child, Sensitivity and specificity

4

Nonlamellar lipid arrangements, including cubosomes, appear in unhealthy cells, e.g., when they are subject to stress, starvation, or viral infection. The bioactivity of cubosomes-nanoscale particles exhibiting bicontinuous cubic structures-versus more common vesicles is an unexplored area due to lack of suitable model systems. Here, glycodendrimercubosomes (GDCs)-sugar-presenting cubosomes assembled from Janus glycodendrimers by simple injection into buffer-are proposed as mimics of biological cubic membranes. The bicontinuous cubic GDC architecture has been demonstrated by electron tomography. The stability of these GDCs in buffer enabled studies on lectin-dependent agglutination, revealing significant differences compared with the vesicular glycodendrimersome (GDS) counterpart. In particular, GDCs showed an increased activity toward concanavalin A, as well as an increased sensitivity and selectivity toward two variants of banana lectins, a wild-type and a genetically modified variant, which is not exhibited by GDSs. These results suggest that cells may adapt under unhealthy conditions by undergoing a transformation from lamellar to cubic membranes as a method of defense.

Concepts: Infection, Model organism, Selectivity, Bacteria, Genetics, Sensitivity and specificity, DNA, Gene