A Facile Design of Colourimetric Polyurethane Nanofibrous Sensor Containing Natural Indicator Dye for Detecting Ammonia Vapour

Chemicals and industrial gases endanger both human health and the environment. The inhalation of colourless ammonia gas (NH3) can cause organ damage or even death in humans. Colourimetric materials are becoming more popular in the search for smart textiles for both fashion and specific occupational applications. Colourimetric textile sensors based on indicator dyes could be very useful for detecting strong gaseous conditions and monitoring gas leaks. In this study, black carrot extract (BCE) as a natural indicator dye and polyurethane (PU) polymer were used to develop a colourimetric sensor by electrospinning. The properties of the BCE/PU nanofibrous mats were characterized by the Fourier transform infrared spectrum (FTIR) and a scanning electron microscope (SEM). The BCE caused a change in the morphology of the PU nanofibrous mat. To evaluate the colour shift due to NH3 vapour, the BCE/PU nanofibrous mats were photographed by a camera, and software was used to obtain the quantitative colour data (CIE L*a*b). The BCE/PU nanofibrous exhibited a remarkable colour change from pink–red to green–blue under NH3 vapour conditions with a fast response time (≤30 s). These findings showed that colourimetric nanofibrous textile sensors could be a promising in situ material in protective clothing that changes colour when exposed to harmful gases.

Qualitative and Molecular Screening of Potential Ligninolytic Microbes from Termite (Coptotermes curvignathus) Gut

Ligninolytic microbes have great potential in converting high lignin by-products to more utilisable products by decomposing the lignin-rich agricultural and industrial wastes. Thus, the aim of this study are to screen and identify the potential ligninolytic microbes from the termite (Coptotermes curvignathus) gut. The study was conducted at Universiti Putra Malaysia Bintulu Sarawak Campus, Malaysia. Twenty-seven microbes isolated from termite gut obtained from the Microbiology Laboratory, Faculty of Agricultural Science and Forestry, were used for the ligninolytic activity screening. Media with four different ligninolytic indicator dyes (Azure B, phenol red, methylene blue, and Remazol Brilliant Blue) were streaked with microbial isolates and incubated at 37 °C for 48 h. Out of twenty-seven microbe isolates, only three (CH2, CH5, and CH9) isolates showed decolourisation zone indicating the positive presence of ligninolytic activity. The 16S rRNA gene sequence data indicated the isolates are highly homologous to Bacillus spp.

SEC24A facilitates colocalization and Ca2+ flux between the endoplasmic reticulum and mitochondria

ABSTRACT A genome-wide screen recently identified SEC24A as a novel mediator of thapsigargin-induced cell death in HAP1 cells. Here, we determined the cellular mechanism and specificity of SEC24A-mediated cytotoxicity. Measurement of Ca2+ levels using organelle-specific fluorescent indicator dyes showed that Ca2+ efflux from endoplasmic reticulum (ER) and influx into mitochondria were significantly impaired in SEC24A-knockout cells. Furthermore, SEC24A-knockout cells also showed ∼44% less colocalization of mitochondria and peripheral tubular ER. Knockout of SEC24A, but not its paralogs SEC24B, SEC24C or SEC24D, rescued HAP1 cells from cell death induced by three different inhibitors of sarcoplasmic/endoplasmic reticulum Ca2+ ATPases (SERCA) but not from cell death induced by a topoisomerase inhibitor. Thapsigargin-treated SEC24A-knockout cells showed a ∼2.5-fold increase in autophagic flux and ∼10-fold reduction in apoptosis compared to wild-type cells. Taken together, our findings indicate that SEC24A plays a previously unrecognized role in regulating association and Ca2+ flux between the ER and mitochondria, thereby impacting processes dependent on mitochondrial Ca2+ levels, including autophagy and apoptosis.

Halochromic optical nose for assessment of spoilage of packed seer fish

Purpose The present study aims to describe the development of halochromic thin film sensors using mixed indicator dyes for monitoring the spoilage of packed seer fish. Design/methodology/approach Thin film was prepared using renewable polysaccharide incorporated with mixed indicator dyes. The thin film was characterized using ultraviolet visible and Fourier transform-infrared spectroscopy. The characteristics of the thin film were studied by analyzing the CIELAB and Red Green Blue values and biodegradability. The thin films were evaluated for real-time monitoring of the spoilage of packed seer fish. Findings The thin film sensors were found to exhibit excellent halochromism. The color changes were visible and distinguishable. The sensors responded efficiently for real-time monitoring of spoilage of fish by showing unique color changes. Originality/value This study provides promising mixed indicator that exhibits different colors in the alkaline pH. Also the present study reveals a potential combination of materials for preparation of halochromic sensors that can be used for monitoring the spoilage of packed seer fish in real time.

Conformal Coating of Orthopedic Plates with X-Ray Scintillators and pH Indicators for X-Ray Excited Luminescence Chemical Imaging Through Tissue.

We describe a material that allows for high spatial resolution pH mapping through tissue using X-ray excited luminescence chemical imaging (XELCI). This is especially useful for detecting implant associated infection and elucidating how the local biochemical environment changes during infection and treatment. To acquire one pixel in the image, a focused X-ray beam irradiates a small region of scintillators coated on the implant and the X-ray excited optical luminescence spectrum is modulated by indicator dyes to provide a chemically sensitive measurement with low background. Scanning the X-ray beam across the implant surface generates high spatial resolution chemical measurements. Two associated challenges are 1) to make robust sensors that can be implanted in tissue to measure local chemical concentrations and specifically for metal orthopedic implants, and 2) to conformally coat the implant surface with scintillators and pH indicator dyes in order to make measurements over a large area. Previously, we have physically pressed or glued a pH-sensitive hydrogel sensor to the surface of an implant, but this is impractical for imaging over large irregular device areas such as an orthopedic plate with holes and edges. Herein we describe a chemically sensitive and biocompatible XELI sensor material containing scintillator particles (Gd₂O₂S:Eu) and a pH sensitive hydrogel coating using a roughened epoxy coating. A two-part commercial grade epoxy film was tested and found to make the coating of pH sensitive layer adhere better to the titanium surface. Sugar and salt particles were added to the surface of the epoxy as it cured to create a roughened surface and increase surface area. On this roughened surface, a secondary layer of diacrylated polyethylene glycol (PEG) hydrogel, containing a pH sensitive dye, was polymerized. This layer was found to adhere well to the epoxy-coated implant unlike other previously tested polymer surfaces which delaminated when exposed to water or humidity. The focused X-ray beam enabled 0.5 mm spatial resolution through 1 cm thick tissue. The pH sensor coated orthopedic plate was imaged with XELCI through tissue with different pH to acquire a calibration curve. The plates were also imaged through tissue with low pH region from a Staphylococcus aureus biofilm grown on one section. These studies demonstrate the use of pH sensor coated orthopedic plates for mapping the surface pH through tissue during biofilm formation using XELCI.

Conformal Coating of Orthopedic Plates with X-Ray Scintillators and pH Indicators for X-Ray Excited Luminescence Chemical Imaging Through Tissue.

We describe a material that allows for high spatial resolution pH mapping through tissue using X-ray excited luminescence chemical imaging (XELCI). This is especially useful for detecting implant associated infection and elucidating how the local biochemical environment changes during infection and treatment. To acquire one pixel in the image, a focused X-ray beam irradiates a small region of scintillators coated on the implant and the X-ray excited optical luminescence spectrum is modulated by indicator dyes to provide a chemically sensitive measurement with low background. Scanning the X-ray beam across the implant surface generates high spatial resolution chemical measurements. Two associated challenges are 1) to make robust sensors that can be implanted in tissue to measure local chemical concentrations and specifically for metal orthopedic implants, and 2) to conformally coat the implant surface with scintillators and pH indicator dyes in order to make measurements over a large area. Previously, we have physically pressed or glued a pH-sensitive hydrogel sensor to the surface of an implant, but this is impractical for imaging over large irregular device areas such as an orthopedic plate with holes and edges. Herein we describe a chemically sensitive and biocompatible XELI sensor material containing scintillator particles (Gd₂O₂S:Eu) and a pH sensitive hydrogel coating using a roughened epoxy coating. A two-part commercial grade epoxy film was tested and found to make the coating of pH sensitive layer adhere better to the titanium surface. Sugar and salt particles were added to the surface of the epoxy as it cured to create a roughened surface and increase surface area. On this roughened surface, a secondary layer of diacrylated polyethylene glycol (PEG) hydrogel, containing a pH sensitive dye, was polymerized. This layer was found to adhere well to the epoxy-coated implant unlike other previously tested polymer surfaces which delaminated when exposed to water or humidity. The focused X-ray beam enabled 0.5 mm spatial resolution through 1 cm thick tissue. The pH sensor coated orthopedic plate was imaged with XELCI through tissue with different pH to acquire a calibration curve. The plates were also imaged through tissue with low pH region from a Staphylococcus aureus biofilm grown on one section. These studies demonstrate the use of pH sensor coated orthopedic plates for mapping the surface pH through tissue during biofilm formation using XELCI.