The relentless pace of industrialization has significantly exacerbated environmental pollution, with heavy-metal ions (HMIs) emerging as some of the most persistent and toxic pollutants in natural ecosystems. Growing concerns over environmental pollution have created a need for advanced sensing technologies that offer superior sensing sensitivity, selectivity, and reliability. This work reports the development of an electrochemical sensor based on a UiO-66-NH2(Zr) metal-organic framework (MOF)/graphene oxide (GO) nanocomposite for the simultaneous detection of HMIs in aqueous environments. Using one-pot hydrothermal synthesis, MOFs and conductive GO materials were integrated into a single nanostructure via in situ growth of the UiO-66-NH2(Zr) MOF on the GO matrix, resulting in the formation of a stable MOF/GO nanocomposite with enhanced conductivity and increased number of effective reaction sites. The amino groups (-NH2) on UiO-66-NH2(Zr) porous materials serve as adsorption sites to capture HMIs. The morphological, structural, and electrochemical properties of the UiO-66-NH2(Zr)-GO nanocomposite were examined by using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Differential pulse anodic stripping voltammetry (DPASV) was subsequently employed for the detection of heavy-metal ions over nanomolar to micromolar concentration ranges using a UiO-66-NH2(Zr)-GO-modified glassy carbon (GC) electrode. The electrochemical sensor developed in this study was successfully utilized for the selective and concurrent detection of multiple HMIs, namely, copper ion (Cu2+), cadmium ion (Cd2+), and lead ion (Pb2+) in electrolyte solution. The sensor demonstrated achieving high selectivity and sensitivity (1.30 μA μM-1 for Cu2+, 0.50 μA μM-1 for Cd2+, and 12.38 μA μM-1 for Pb2+) with low limit of detection (LOD) (0.59 ng/mL for Cu2+, 0.84 ng/mL for Cd2+, and 2.9 ng/mL for Pb2+), and observed ≥85% reproducibility. The sensor demonstrated excellent long-term stability and operated effectively within a temperature range of 283-313 K, enabling the simultaneous detection of multiple heavy-metal ions from small sample volumes. The developed electrochemical method can equally be employed to detect HMIs at trace (parts-per-billion (ppb)) levels in diverse environmental matrices such as lake, river, tap water, river sediments, and wastewater.

Direct air capture (DAC) of CO 2 is becoming increasingly important for reducing greenhouse gas concentrations in the atmosphere. However, the cost and energy requirements associated with DAC make it less economically feasible than carbon capture from flue gases. While various methods like solid sorbents and gas–liquid absorption have been explored for DAC, membrane processes have only recently been investigated. The objective of this study is to examine the separation performance of a membrane unit for capturing CO 2 from ambient air. The performance of a membrane depends on several factors, including the composition of the feed gas, pressure ratio, material selectivity, and membrane area. The single‐stage separation process with the co‐current flow and constant permeability flux model is evaluated using a commercial module integrated with a process simulator to separate a binary mixture of carbon dioxide and nitrogen to assess the sensitivity of selectivity on purity and recovery of CO 2 in permeate, and power requirement. Additionally, three levels of CO 2 reduction from the feed stream to the retentate stream (25%, 50%, and 75%) are studied. A trade‐off between purity and recovery factor is observed, and achieving high purity in permeate requires high concentration in the retentate.

Harnessing electrochemical energy in an engineered electrical circuit from biochemical substrates in the human body using biofuel cells is gaining increasing research attention in the current decade due to the wide range of biomedical possibilities it creates for electronic devices. In this report, we describe and characterize the construction of just such an enzymatic biofuel cell (EBFC). It is simple, mediator-free, and glucose-powered, employing only biocompatible materials. A novel feature is the two-dimensional mesoporous thermally reduced graphene oxide (rGO) host electrode. An additionally novelty is that we explored the potential of using biocompatible, low-cost filter paper (FP) instead of carbon paper, a conductive polymer, or gold as support for the host electrode. Using glucose (C6H12O6) and molecular oxygen (O2) as the power-generating fuel, the cell consists of a pair of bioelectrodes incorporating immobilized enzymes, the bioanode modified by rGO-glucose oxidase (GOx/rGO), and the biocathode modified by rGO-laccase (Lac/rGO). Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy, and Raman spectroscopy techniques have been employed to investigate the surface morphology, defects, and chemical structure of rGO, GOx/rGO, and Lac/rGO. N2 sorption, SEM/EDX, and powder X-ray diffraction revealed a high Brunauer-Emmett-Teller surface area (179 m2 g-1) mesoporous rGO structure with the high C/O ratio of 80:1 as well. Results from the Fourier transform infrared spectroscopy, UV-visible spectroscopy, and electrochemical impedance spectroscopy studies indicated that GOx remained in its native biochemical functional form upon being embedded onto the rGO matrix. Cyclic voltammetry studies showed that the presence of mesoporous rGO greatly enhanced the direct electrochemistry and electrocatalytic properties of the GOx/rGO and Lac/rGO nanocomposites. The electron transfer rate constant between GOx and rGO was estimated to be 2.14 s-1. The fabricated EBFC (GOx/rGO/FP-Lac/rGO/FP) using a single GOx/rGO/FP bioanode and a single Lac/rGO/FP biocathode provides a maximum power density (Pmax) of 4.0 nW cm-2 with an open-circuit voltage (VOC) of 0.04 V and remains stable for more than 15 days with a power output of ∼9.0 nW cm-2 at a pH of 7.4 under ambient conditions.

Microelectronic devices (MEDs) that utilize functionalized single-walled carbon nanotubes (SWCNTs) for hydrazine (HZ) sensing applications were developed and investigated, demonstrating their selective and sensitive detection of trace level HZ (0.01 ppm) in the presence of high-concentration interfering gases in ambient air at room temperature. These MEDs were fabricated with excellent reproducibility by the site-specific deposition of functionalized SWCNTs using a dielectrophoretic technique. Rigorous gas exposure testing conducted on these MEDs demonstrated a fast response with high sensitivity, selectivity, reproducibility, and reliability for detecting HZ. A dynamic response range was established from a linear relationship between the sensor response and the concentration of HZ (0.01 to 0.33 ppm). Additionally, these MEDs exhibited a linear trend relationship between device resistance and sensor response, which provided tunability in selecting and fabricating devices for improving sensing response. Field-emission scanning electron microscopy images showed the morphology of SWCNTs as a bundle on MEDs. Additional analytic gas exposure tests revealed negligible responses from these MEDs for high concentrations of interfering gases, such as 300 +/- 17 ppm methanol (MeOH), 85 +/- 6 ppm ethanol (EtOH), 145 +/- 12 ppm formaldehyde (CH2O), and 500 ppm ammonia (NH3), compared to that of HZ (<= 0.33 ppm), with HZ to interfering gas concentration ratios of 1:900, 1:250, 1:440, and 1:1500, respectively, demonstrating high sensor selectivity for HZ.

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by both senile plaques composed of amyloid-β (Aβ) peptide and neurofibrillary tangles composed of tau protein. AD is the 6th leading cause of death in the United States, 5.7 million Americans are living with Alzheimer's. By 2050, 14 million Americans and 160 million people globally are projected to develop AD. While there are no available therapies to cure or stall AD, early and accurate diagnosis may delay the severity of the disease and can reduce medical cost up to $7.9 trillion. AD onset can occur decades before the manifestation of the pathological hallmarks. Thus, a panel of biomarkers that can tap into this early window of opportunity will be beneficial in detecting, staging, treating, and monitoring the disease. Toward this goal, ISL has developed an ultrasensitive biosensor array AdnosTM for rapid and early diagnosis of AD. We designed a lab-on-a chip sensor array based on single walled carbon nanotubes (SWNT) deposited on microelectronic devices fabricated on a silicon wafer. An array of capture molecules attached to the SWNTs detect AD biomarker proteins from AD patient's cerebrospinal fluid (CSF). Interaction between the capture molecules and their corresponding proteins are detected using current-voltage (I-V) response curves and monitored using a Keithley source meter. AD protein marker response is compared with the BioPlex 3D suspension array for validation. Amyloid beta 1–42 (Aβ42), total tau (tTau), phosphorylated threonine 181 tau (pTau181) were detected at ≤100 fM level in AD CSF with distinct response in the presence of other biomolecules. When Aβ42 antibody was cross reacted with Creutzfeldt-Jacob disease antigen (14-3-3-γ), minimal cross-reactivity was observed. Our results clearly validate Adnos’ superior sensitivity and specificity. Adnos can be used as a point-of-care assessment tool and for monitoring patients in AD clinical trials and AD drug development due to its ease-of-use and accurate results.

Six new rugged, high-temperature tolerant phosphine oxide-containing poly(4,4′-(p-phenylene)-bis(2,6-diphenylpyridinium)) polymers P-1, P-2, P-3, P-4, P-5, and P-6 are synthesized, characterized, and evaluated. Synthesis results in high yield and purity, as confirmed by elemental, proton (1H), and carbon 13 (13C) nuclear magnetic resonance (NMR) spectra analyses. High glass transition temperatures (Tg > 230 °C) and high char yields (>50% at 700 °C) are determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. These new ionic polymers exhibit excellent processability, thin-film forming, high-temperature resistance, fire-resistance and retardation, coating, adhesion, mechanical and tensile strength, and n-type (electron transport) properties. The incorporation of phosphine oxide and bis(phenylpyridinium) moieties in the polymer backbones leads to high glass transition temperatures and excellent fire retardant properties, as determined by microcalorimetry measurements. The use of organic counterions allows these ionic polymers to be easily processable from several common organic solvents. A large variety of these polymers can be synthesized by utilizing structural variants of the bispyrylium salt, phosphine oxide containing diamine, and the counterion in a combinatorial fashion. These results make them very attractive for a number of applications, including as coating and structural component materials for automobiles, aircrafts, power and propulsion systems, firefighter garments, printed circuit boards, cabinets and housings for electronic and electrical components, construction materials, mattresses, carpets, upholstery and furniture, and paper-thin coatings for protecting important paper documents.

Alzheimer's Disease (AD) is a complex neurodegenerative disorder. In the United States, 5.7 million Americans are living with AD, which is the 6th leading cause of death. While there are no therapeutics currently available to cure or stall AD, early diagnosis may delay the severity of the disease. Research suggests that changes in the brain associated with AD may occur 20 years or more before symptoms appear. Early and accurate diagnosis could save up to $7.9 trillion in medical care. During the early onset of the disease, AD-specific biomarkers are difficult to detect. Toward the goal of ultrasensitive, early detection and screening, we are developing single walled carbon nanotubes (SWNTs) based AD diagnostics. We designed a lab-on-a-chip assay based on SWNTs deposited on microelectronic devices fabricated on a silicon wafer. An array of capture molecules attached to the SWNTs detected AD specific proteins from cerebrospinal fluid. Interaction between the capture molecules and their corresponding proteins was detected with a current-voltage (I-V) curve and monitored using a portable Keysight U2722A sourcemeter unit. Our studies showed that the devices detected AD- specific biomarkers such as amyloid beta 1-42 and its conformational variants, tau and p-tau at ≤100 femtomolar (fM) level with distinct response in the presence of other biomolecules. Based on our results, the sensor chips showed high specificity and fM detection making it ideal for early stage AD detection. Our device can be used for point-of-care AD diagnostics. It can also be used by physicians for monitoring patients involved in clinical trials associated with various AD drug development projects. Additionally, this device can be used by scientists in labs during the research and development stage of AD related studies.

Fluorescence tomography is a non invasive, non ionizing imaging technique able to provide a 3D distribution of fluorescent agents within thick highly scattering mediums, using low cost instrumentation. However, its low spatial resolution due to undetermined and ill-posed nature of its inverse problem has delayed its integration into the clinical settings. In addition, the quality of the fluorescence tomography images is degraded due to the excitation light leakage contaminating the fluorescence measurements. This excitation light leakage results from the excitation photons that cannot be blocked by the fluorescence filters. In this contribution, we present a new method to remove this excitation light leakage noise based on the use of a temperature sensitive fluorescence agents. By performing different sets of measurements using this temperature sensitive agents at multiple temperatures, the excitation light leakage can be estimated and then removed from the measured fluorescence signals. The results obtained using this technique demonstrate its potential for use in in-vivo small animal imaging.

Optical thin film sensors have been developed to detect chloroform in aqueous and nonaqueous solutions. These sensors utilize a modified Fujiwara reaction, one of the only known methods for detecting halogenated hydrocarbons in the visible spectrum. The modified Fujiwara reagents, 2,2'-dipyridyl and tetra-n-butyl ammonium hydroxide (n-Bu4NOH or TBAH), are encapsulated in an ethyl cellulose (EC) or sol-gel film. Upon exposure of the EC sensor film to HCCl3 in petroleum ether, a colored product is produced within the film, which is analyzed spectroscopically, yielding a detection limit of 0.830 ppm (parts per million v/v or μL/L hereinafter) and a quantification limit of 2.77 ppm. When the chloroform concentration in pentane is ≥5 ppm, the color change of the EC sensor is visible to the naked eye. In aqueous chloroform solution, reaction in the sol-gel sensor film turns the sensor from colorless to dark yellow/brown, also visible to the naked eye, with a detection limit of 500 ppm. This is well below the solubility of chloroform in water (ca. 5,800 ppm). To our knowledge, these are the first optical quality thin film sensors using Fujiwara reactions for halogenated hydrocarbon detection.

Fluorescent tomography has been hindered by poor tissue penetration and weak signal which results in poor spatial resolution and quantification accuracy. Recently, it has been reported that activatable temperature responsive fluorescent probes which respond to focused ultrasound heating can improve the resolution and quantification of fluorescent tomography in deep tissue. This has lead to a new imaging modality, "Temperature-modulated fluorescent tomography." This technique relies on activatable thermo-sensitive fluorescent nanocapsules for whose fluorescence quantum efficiency is temperature dependent. Within a 4-5 degrees C temperature range, the fluorescent signal increase more than 10-fold. In this molecular probe, Indocyanine Green (ICG) is encapsulated inside the core of a thermo-reversible pluronic micelle. Here we show the fluorescence response and temperature range of the nanocapsules which have been optimized for a higher temperature range to be used for in vivo animal imaging. We report on the feasibility of these temperature-sensitive reversible nanocapsules for in vivo applications by studying the pharmacokinetics in a subcutaneous mouse tumor model in vivo.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDesign and Synthesis of n-Type Organic−Inorganic Hybrid Material Incorporating CdSe Quantum Dots Nanocrystal Core and Diphenylquinoline Peripheral GroupMaksudul M. Alam*†, Mohammad Mushfiq†, Haesook Han‡, Pradip K. Bhowmik‡, and Kisholoy Goswami†View Author Information Innosense LLC, 2531 West 237th Street, Torrance, California 90505, and Department of Chemistry, University of Nevada Las Vegas, 4505 Maryland Parkway Box 454003, Las Vegas, Nevada 89154-4003* Corresponding author: e-mail [email protected], Tel 1-310-530-2011; Fax 1-310-530-2099.†Innosense LLC.‡University of Nevada Las Vegas.Cite this: Macromolecules 2008, 41, 21, 7790–7793Publication Date (Web):October 10, 2008Publication History Received24 June 2008Revised1 October 2008Published online10 October 2008Published inissue 11 November 2008https://doi.org/10.1021/ma801416xCopyright © 2008 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views717Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (636 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Cadmium selenide,Hybrid materials,Nanocrystals,Quantum dots,Transmission electron microscopy Get e-Alerts

Carbon modified (CM)-n-TiO2 was used as the photoanode in CM-n- TiO2/Pt photoelectrochemical cell (PEC), to split water and an amorphous (a)-Si triple junction solar cell was used to supply an extra photovoltage. Hydrogen production rate in terms of cell photocurrent density in CM-n-TiO2/Pt PEC was measured. Also, the effects of solar cell parameters on the PEC cell photocurrent density were investigated. It was found that under assistance of the photovoltage from the a-Si solar cell, the CM-n-TiO2/Pt PEC generated significantly increased photocurrent density (5.3 mA/cm2) compared to that by undoped n-TiO2/Pt PEC (1.0 mA/cm2). The photoresponse of CM-n-TiO2/Pt PEC was found to be limited due to low short circuit photocurrent density generated at a-Si solar cell even though it supplied needed extra photovoltage for water splitting.

Since the TWA flight 800 accident in July 1996, significant emphasis has been placed on fuel tank safety. The Federal Aviation Administration (FAA) has focused research to support two primary methods of fuel tank protection - ground-based and on-board - both involving fuel tank inerting. Ground-based fuel tank inerting involves some combination of fuel scrubbing and ullage washing with Nitrogen Enriched Air (NEA) while the airplane is on the ground (applicable to all or most operating transport airplanes). On-board fuel tank inerting involves ullage washing with OBIGGS (on-board inert gas generating system), a system that generates NEA during aircraft operations. An OBIGGS generally encompasses an air separation module (ASM) to generate NEA, a compressor, storage tanks, and a distribution system. Essential to the utilization of OBIGGS is an oxygen sensor that can operate inside the aircraft's ullage and assess the effectiveness of the inerting systems. OBIGGS can function economically by precisely knowing when to start and when to stop. Toward achieving these goals, InnoSense LLC is developing an all-optical fuel tank ullage sensor (FTUS) prototype for detecting oxygen in the ullage of an aircraft fuel tank in flight conditions. Data would be presented to show response time and wide dynamic range of the sensor in simulated flight conditions and fuel tank environment.

Single-molecule semiconductor nanomaterials with pi-stacked structures in solution and the solid state are prepared from a polystyrene backbone and densely tethered pi-conjugated polyquinoline side chains (see figure). Highly structured optical absorption spectra and exclusive broad, structureless yellow excimer emission in toluene solutions confirm the pi-stacked structures and collective optical properties of the side-chain conjugated polymers.

An efficient, site-specific and scalable approach has been developed to produce high-quality and individually addressable conducting polymer nanowire electrode junctions (CPNEJs) in a parallel-oriented array. Polypyrrole and PEDOT conducting polymer nanowires (CPNWs) with uniform diameters (ca. 60-150 nm) were introduced into the desired electrode junctions in a precise manner by performing a three-step constant-current electrochemical process at a low current density and a low concentration of monomers. A low scan rate, cyclic voltammetric method was also employed and gave similar results. These CPNEJ arrays function as a miniaturized sensor for the parallel and real-time detection of gas and organic vapour. The electrochemical approaches utilized allow the conducting polymer chains to self-organize in the CPNWs to form novel polycrystalline structures, observed by high resolution TEM. The weak diffraction rings at 4.88 Å and 4.60 Å were observed for PEDOT and polypyrrole CPNWs, respectively.

Photoinduced electron transfer processes between fullerenes (C60) and four phenothiazine derivatives (PTZs) in the absence and presence of hexylviologen dication (HV2+) have been studied by the transient absorption method in the visible and near-IR regions. Electron-transfer takes place from PTZs to the triplet states of fullerenes (3C60*) giving the radical anion of fullerenes (C60·-) and the radical cations of PTZs (PTZ·+). The rate constants and efficiencies of electron transfer are quite high, because of the high electron-donor abilities of PTZs as elucidated by their low oxidation potentials. On addition of HV2+ to the C60 and PTZ systems, the electron-mediating process occurs from C60·- to HV2+, yielding the viologen radical cation (HV·+). In the presence of a sacrificial donor, HV·+ persisted for a long time.