Hydratable Core-Shell Polymer Networks for Atmospheric Water Harvesting Powered by Sunlight.

The development of technologies to enable fresh water harvesting from atmospheric moisture could help overcome the problem of potable water scarcity. Here, an atmospheric water harvesting (AWH) device is assembled in a core-shell structure, with the core consisting of networks of alginate (Alg) and polyaniline (PANI) and the outer layer consisting of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) modified with sulfonic acid groups (SPNIPAM) to increase the water adsorption at low relative humidity. The resulting hydrogel, modified with lithium chloride (LiCl) for increased water storage capacity (SPNIPAM-Li-PANIAlg), displays a similar lower critical solution temperature to pristine PNIPAM (32 °C) while affording a 15-fold higher water capture ratio, and releases water upon exposure to sunlight at intensities less than 1 kW m-2 . The developed AWH system is capable of harvesting 6.5 L of water per kilogram in a single daily absorption/desorption cycle under sunlight and can operate at relative humidity levels as low as 17% with no additional external energy input. The thermo-responsive hydrogel SPNIPAM-Li-PANIAlg exhibits excellent stability during natural sunlight-driven absorption/desorption cycles for at least 30 days, and allows sustainable harvesting of over 28.3 L kg-1 from a moisture-rich environment by means of multiple absorption/desorption cycles.

A versatile bioelectronic interface programmed for hormone sensing.

Precision medicine requires smart, ultrasensitive, real-time profiling of bio-analytes using interconnected miniaturized devices to achieve individually optimized healthcare. Here, we report a versatile bioelectronic interface (VIBE) that senses signaling-cascade-guided receptor-ligand interactions via an electronic interface. We show that VIBE offers a low detection limit down to sub-nanomolar range characterised by an output current that decreases significantly, leading to precise profiling of these peptide hormones throughout the physiologically relevant concentration ranges. In a proof-of-concept application, we demonstrate that the VIBE platform differentiates insulin and GLP-1 levels in serum samples of wild-type mice from type-1 and type-2 diabetic mice. Evaluation of human serum samples shows that the bioelectronic device can differentiate between samples from different individuals and report differences in their metabolic states. As the target analyte can be changed simply by introducing engineered cells overexpressing the appropriate receptor, the VIBE interface has many potential applications for point-of-care diagnostics and personalized medicine via the internet of things.

An Efficient Ambient-Moisture-Driven Wearable Electrical Power Generator.

Existing devices for generating electrical power from water vapor in ambient air require high levels of relative humidity (RH), cannot operate for prolonged periods, and provide insufficient output for most practical applications. Here a heterogeneous moisture-driven electrical power generator (MODEG) is developed in the form of a free-standing bilayer of polyelectrolyte films, one consisting of a hygroscopic matrix of graphene oxide(GO)/polyaniline(PANI) [(GO)PANI] and the other consisting of poly(diallyldimethylammonium chloride)(PDDA)-modified fluorinated Nafion (F-Nafion (PDDA)). One MODEG unit (1 cm2 ) can deliver a stable open-circuit output of 0.9 V at 8 µA for more than 10 h with a matching external load. The device works over a wide range of temperature (-20 to +50 °C) and relative humidity (30% to 95% RH). It is shown that series and parallel combinations of MODEG units can directly supply sufficient power to drive commercial electronic devices such as light bulbs, supercapacitors, circuit boards, and screen displays. The (GO)PANI:F-Nafion (PDDA) hybrid film is embedded in a mask to harvest the energy from exhaled water vapor in human breath under real-life conditions. The device could consistently generate 450-600 mV during usual breathing, and provides sufficient power to drive medical devices, wearables, and emergency communication.

Blood-Glucose-Powered Metabolic Fuel Cell for Self-Sufficient Bioelectronics.

Currently available bioelectronic devices consume too much power to be continuously operated on rechargeable batteries, and are often powered wirelessly, with attendant issues regarding reliability, convenience, and mobility. Thus, the availability of a robust, self-sufficient, implantable electrical power generator that works under physiological conditions would be transformative for many applications, from driving bioelectronic implants and prostheses to programing cellular behavior and patients' metabolism. Here, capitalizing on a new copper-containing, conductively tuned 3D carbon nanotube composite, an implantable blood-glucose-powered metabolic fuel cell is designed that continuously monitors blood-glucose levels, converts excess glucose into electrical power during hyperglycemia, and produces sufficient energy (0.7 mW cm-2 , 0.9 V, 50 mm glucose) to drive opto- and electro-genetic regulation of vesicular insulin release from engineered beta cells. It is shown that this integration of blood-glucose monitoring with elimination of excessive blood glucose by combined electro-metabolic conversion and insulin-release-mediated cellular consumption enables the metabolic fuel cell to restore blood-glucose homeostasis in an automatic, self-sufficient, and closed-loop manner in an experimental model of type-1 diabetes.

Green Chemistry Based Gold Nanoparticles Synthesis Using the Marine Bacterium Lysinibacillus odysseyi PBCW2 and Their Multitudinous Activities.

Green chemistry has paved an 'avant-garde avenue' in the production and fabrication of eco-friendly stable nanoparticles employing the utilization of biological agents. In the present study we present the first report on the potential of the marine bacterium Lysinibacillus odysseyi PBCW2 for the extracellular production of gold nanoparticles (AuNPs). Utilizing a variety of methods, AuNPs in the cell-free supernatant of L. odysseyi (CFS-LBOE) were identified and their antioxidant, antibacterial, and dye-degrading properties were examined. The visual coloring of the reaction mixture to a ruby red hue showed the production of LBOE-AuNPs; validated by means of XRD, TEM, SEM, XRD, DLS, TGA, and FT-IR analysis. Additionally, the 2,2-diphenyl-1-picrylhydrazyl technique and the well diffusion assay were used to examine their dose-dependent antioxidant and antibacterial activity. These biogenic LBOE-AuNPs showed 91% dye degradation efficiency during catalytic reduction activity on BTB dye, demonstrating their versatility as options for heterogeneous catalysis.

Development of the PANI/MWCNT Nanocomposite-Based Fluorescent Sensor for Selective Detection of Aqueous Ammonia.

The present work reported the polyaniline (PANI) and multiwalled carbon nanotube (MWCNT)-based nanocomposite as a sensing material for the determination of aqueous ammonia by the enhanced fluorescence method. The excitation wavelength-dependent photoluminescence (PL) intensity has shown dual emission peaks at 340 and 380 nm that correspond to two different excitation energy states. The pH-based PL intensity and zeta potential variation were analyzed to optimize the suitable medium for aqueous ammonia sensing. Zeta potential was found to shift from 4 to -21 mV upon changing the pH of the the solution from acidic to alkaline medium. The fluorescence intensity of PANI/MWCNTs was found to increase upon increasing the pH from 3.0 to 6.0 (acidic region) and exhibits a plateau upon further increasing the pH from 7.0 to 12 (basic region). The PANI/MWCNT composite has shown a linear response to aqueous ammonia concentration varying from 25 to 200 µM with a correlation coefficient (R 2) of 0.99 and a limit of detection of 15.19 µM. The presence of relevant interference molecules and physiological ions had no influence on the detection of aqueous ammonia. Field-level study demonstrated that the level of aqueous ammonia can be determined selectively by using the PANI/MWCNT composite for various applications. The mechanism for the selective detection of aqueous ammonia is deliberated in detail.

Glucose oxidase immobilized amine terminated multiwall carbon nanotubes/reduced graphene oxide/polyaniline/gold nanoparticles modified screen-printed carbon electrode for highly sensitive amperometric glucose detection.

A novel amine terminated multiwall carbon nanotubes/polyaniline/reduced graphene oxide/gold nanoparticles modified screen-printed carbon electrode (SPCE) was fabricated. Followed by, glucose oxidase (GOx) was immobilized on SPCE for highly sensitive glucose biosensor. The synthesized nanomaterial and their composites were characterized using scanning electron microscope (SEM) and UV-Visible spectroscopy. The electrochemical analysis has been followed at different stages of glucose oxidase coating on modified SPCE using cyclic voltammetry. The reduction current has enhanced 13.43 times with the lowest working potential by the modified SPCE when compared to bare SPCE. The glucose biosensor exhibited good reproducibility (90.23%, n = 7), high stability (after 30 days 96% at -20 °C storage, 2 week 74.5% at -4 °C storage), wide linear range (1-10 mM), less KMapp value (0.734), lowest detection limit (64 µM) and good sensitivity (246 µ Acm-2 mM-1). The biosensor was validated for the detection of glucose level in human blood serum samples using the amperometric technique. As designed nanocomposite based SPCE has the potential for an efficient glucose sensor, which also enabled the platform for various biochemical sensors.

Highly sensitive amperometric detection of glutamate by glutamic oxidase immobilized Pt nanoparticle decorated multiwalled carbon nanotubes(MWCNTs)/polypyrrole composite.

A highly sensitive and selective glutamate biosensor using glutamate Oxidase (GlUtOx) immobilized platinum nanoparticle (PtNP) decorated multiwall carbon nanotube (MWCNTs)/polypyrrole (PPy) composite on glassy carbon electrodes (GC) is demonstrated. PtNP decorated MWCNTs (Pt-MWCNTs), PPy and Pt-MWCNTs/PPy composite were characterized by Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD) and Raman analysis to confirm the formation of the nanocomposite. The glutamate Oxidase (GlUtOx) was immobilized on a GC/Pt-MWCNTs/PPy and characterized by the cyclic voltammetry (CV) and impedance spectroscopy (EIS) analysis. The fabricated L-glutamate biosensor exhibited high sensitivity (723.08 µA cm-2 mM-1) with less response time (3 s) with a detection limit of 0.88 µM. The dynamic range from 10 to 100 µM with a correlation coefficient (R2) of 0.985 was observed for the L-glutamate biosensor. The analytical recovery of added L-glutamate acid (50 and 100 µM) in human serum soup were 96.1% and 97.5% respectively. The enzyme immobilized GC/Pt-MWCNTs/PPy/GlUtOx bioelectrode lost 12.6% and 23.8% of its initial activity after 30 days when stored at - 20 °C and 4 °C respectively.

Polyaniline Anchored MWCNTs on Fabric for High Performance Wearable Ammonia Sensor.

Polyaniline (PANI) functionalized multiwall carbon nanotubes (MWCNTs) were prepared via in situ chemical polymerization process of aniline, in which MWCNTs were spray coated on the fabric for wearable ammonia sensor. Structural, morphological, thermal properties and wettability were analyzed by scanning electron microscope, X-ray diffraction, Raman analysis and contact angle measurement. No substantial change in base resistance of MWCNTs/PANI fabric sensor was observed for a wide range of bending (from 90° to 270°) shows excellent wearability. The sensors were exposed to 20-100 ppm ammonia vapor at room temperature. It was observed that the sensing response of PANI coated MWCNTs was enhanced than MWCNTs and PANI. The sensor has the capability to detect ammonia with high sensitivity (92% for100 ppm), excellent selectivity quick response (9 s), and recovery time (30 s). The lower detection limit (LOD) for the MWCNTs/PANI fabric sensor was found to be 200 ppb. The influence of humidity on sensing parameters was studied. Sensing response and resistance of sensor have shown excellent stability after one month. We observed that PANI have a dual role in enhancing flexibility as well as improve the sensor performance toward ammonia. The results reveal the potential application of fabric based sensor for monitoring NH3 gas under ambient conditions.

Characterizing the effect of nitrosative stress in Saccharomyces cerevisiae.

Nitrosative stress has various pathophysiological implications. We here present a detailed characterization on the effect of nitrosative stress in Saccharomyces cerevisiae wild-type (Y190) and its isogenic flavohemoglobin mutant (Deltayhb1) strain grown in presence of non fermentable carbon source. On addition of sub-toxic dose of nitrosating agent both the strains showed microbiostatic effect. Cellular respiration was found to be significantly affected in both the strains in presence sodium nitroprusside. Although there was no alteration in mitochondrial permeability potential changes and reactive oxygen species production in both the strains but the cellular redox status is differentially regulated in Deltayhb1 strain both in cytosol and in mitochondria indicating cellular glutathione is the major player in absence of flavohemoglobin. We also found important role(s) of various redox active enzymes like glutathione reductase and catalase in protection against nitrosative stress. This is the first report of its kind where the effect of nitrosative stress has been evaluated in S. cerevisiae cytosol as well as in mitochondria under respiratory proficient conditions.

In vivo protein tyrosine nitration in S. cerevisiae: identification of tyrosine-nitrated proteins in mitochondria.

Protein tyrosine nitration (PTN) is a selective post-translational modification often associated with pathophysiological conditions. Although yeast cells lack of mammalian nitric oxide synthase (NOS) orthologues, still it has been shown that they are capable of producing nitric oxide (NO). Our studies showed that NO or reactive nitrogen species (RNS) produced in flavohemoglobin mutant (Deltayhb1) strain along with the wild type strain (Y190) of Saccharomyces cerevisiae can be visualized using specific probe 4,5-diaminofluorescein diacetate (DAF-2DA). Deltayhb1 strain of S. cerevisiae showed bright fluorescence under confocal microscope that proves NO or RNS accumulation is more in absence of flavohemoglobin. We further investigated PTN profile of both cytosol and mitochondria of Y190 and Deltayhb1 cells of S. cerevisiae using two-dimensional (2D) gel electrophoresis followed by western blot analysis. Surprisingly, we observed many immunopositive spots both in cytosol and in mitochondria from Y190 and Deltayhb1 using monoclonal anti-3-nitrotyrosine antibody indicating a basal level of NO or nitrite or peroxynitrite is produced in yeast system. To identify proteins nitrated in vivo we analyzed mitochondrial proteins from Y190 strains of S. cerevisiae. Among the eight identified proteins, two target mitochondrial proteins are aconitase and isocitrate dehydrogenase that are involved directly in the citric acid cycle. This investigation is the first comprehensive study to identify mitochondrial proteins nitrated in vivo.