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Environmental context: Everyone is familiar with the earth odour that comes from digging in the soil. We measured the chemicals comprising this odour and studied how the environment influences how much of these chemicals are released from disturbed soils. Understanding what conditions affect emission of these compounds from soils could provide new technologies for remotely assessing soil health and what people are doing to soils. Rationale: Earth scent is the odour emitted from soils. This scent, primarily comprising the alcohols geosmin and 2-methylisoborneol (MIB), has not been fully characterised, but offers high potential for use as an environmental interrogation tool. Methodology: We utilised our field-based, solid-phase microextraction fibre method to test the hypothesis that soil activity and soil property variation can be detected in situ by comparing biogenic volatile emissions. Results: We eliminated sources of error utilising field-based sampling with these fibres, concluding that room temperature storage for up to 7 days is acceptable with minimal loss. Variation in individual fibre affinity for both compounds was higher than expected but no measured concentrations were observed to constitute outliers. Disturbance of minor soil volumes led to significantly higher emission of both compounds over background levels. Soil texture and soil cover had a significant effect on the emission of both compounds. Simulated rainfall, producing the characteristic odour known as petrichor, initiates elevated emission of geosmin. Background (undisturbed soil) concentrations of MIB were occasionally detectable during some sampling events, but geosmin concentrations in the air were always below detection limits without soil disturbance. Virtually all background and disturbed soil samples contained much higher concentrations of MIB compared to geosmin, but geosmin variation between replicates and experimental units was much lower. Discussion: Soil disturbance and soil property variation can be remotely detected using emission of volatile compounds. Correlating emission from the soil with respect to disturbance events and environmental properties could yield a powerful new tool for acquiring soil information. Mechanical disturbance increases emission of two biogenic alcohols from soils. Mechanical disturbance increases emission of two biogenic alcohols from soils. Environmental context. Everyone is familiar with the earth odour that comes from digging in the soil. We measured the chemicals comprising this odour and studied how the environment influences how much of these chemicals are released from disturbed soils. Understanding what conditions affect emission of these compounds from soils could provide new technologies for remotely assessing soil health and what people are doing to soils. [ABSTRACT FROM AUTHOR]

A small synthetic peptide with nanomolar affinity for cardiac troponin I (TnI), previously identified from a polyvalent phage displayed library, has been immobilized on a gold surface for TnI detection. The binding affinity of gold-immobilized peptides for TnI was studied and compared with that of phage-immobilized peptides. Quartz crystal microbalance (QCM), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) were used to monitor both the immobilization and target binding processes. All three techniques show that the binding is specific for TnI as compared to a streptavidin (SA) control. The response curves obtained at TnI concentrations ranging from 0 to 10 [micro]g/mL, using both QCM and EIS, were also compared. For the EIS measurements, the sensitivity was 0.30 [+ or -] 0.030 normalized impedance/ ([micro]g/ mL) and the limit of detection (LOD) was 0.34 [micro]g/mL Using the QCM, a sensitivity of 18 [+ or -] 1 Hz/([micro]g/mL) was obtained, corresponding to an LOD of 0.11 [micro]g/mL Although the QCM demonstrated a lower LOD as compared to EIS, the latter technique exhibited a larger linear dynamic range than QCM. In a relevant tissue culture milieu, Minimum Essential Media (MEM), the sensitivity of the EIS measurement was greater than that obtained in a phosphate buffer system (PBS). The kinetics of target binding using QCM were analyzed by two independent methods, and the dissociation constants ([K.sub.D]) = 66 [+ or -] 4 nM and 17 [+ or -] 8 nM) were an order of magnitude higher than that calculated for the polyvalent phage particles ([K.sub.D]) = 2.5 [+ or -] 0.1 nM). Even though the affinity of the immobilized peptides for TnI was somewhat reduced, overall, these results demonstrate that peptides obtained from the biopanning of phage display libraries can be readily used as sensing probes in biosensor development. 10.1021/ac101657h

A microchip capillary electrophoresis (MCE) system has been developed for the determination of perchlorate in drinking water. The United States Environmental Protection Agency (USEPA) recently proposed a health advisory limit for perchlorate in drinking water of 15 parts per billion (ppb), a level requiring large, sophisticated instrumentation, such as ion chromatography coupled with mass spectrometry (IC-MS), for detection. An inexpensive, portable system is desired for routine online monitoring applications of perchlorate in drinking water. Here, we present an MCE method using contact conductivity detection for perchlorate determination. The method has several advantages, including reduced analysis times relative to IC, inherent portability, high selectivity, and minimal sample pretreatment. Resolution of perchlorate from more abundant ions was achieved using zwitterionic, sulfobetaine surfactants, N-hexadecyl-N,N-dimethyl-3-ammonio-1-propane sulfonate (HDAPS) and N-tetradecylN,N-dimethyl-3-ammonio-1-propane sulfonate (TDAPS). The system performance and the optimization of the separation chemistry, including the use of these surfactants to resolve perchlorate from other anions, are discussed in this work. The system is capable of detection limits of 3.4 [+ or -] 1.8 ppb (n = 6) in standards and 5.6 [+ or -] 1.7 ppb (n = 6) in drinking water. 10.1021/ac9029086

The superoxide radical anion (SO) is a critical biomarker for monitoring cellular stress responses. Electrochemical SO biosensors are frequently constructed through the covalent immobilization of cytochrome c (Cyt c) onto self-assembled monolayers (SAMs); however, a detailed comparison of these systems as well as configuration influence on SO detection is needed to enable robust applications. Two reaction pathways, oxidation of SO by the SAM-modified gold electrode or electron transfer through a protein and monolayer relay, may be involved during the electrochemical detection of SO with Cyt c, depending on the SAM that is used. Although electrodes with SAMs alone can exhibit a high sensitivity and low limit of detection (LOD) for the SO, they can suffer from a strong response to the presence of interferents such as hydrogen peroxide and ascorbic acid. Electrodes with immobilized Cyt c show decreased sensitivity, but exhibit better selectivity and resistance to fouling in complex media. Considering the trade-offs between sensitivity, selectivity, and LOD for SO detection, a bioelectrode made with Cyt c immobilized on dithiobis(succinimidyl)propionate (DTSP) appears to be the most suitable configuration. In phosphate buffer, the DTSP/Cyt c electrode has a sensitivity of 410 nA [micro][M.sup.-1] [cm.sup.-2] and an LOD for SO of 73 nM. Results are also presented for the detection of SO in a complex tissue culture media (MEM) with and without serum, and the sensitivity of the DTSP/Cyt c in MEM in the absence of serum increased to 640 nA [micro][M.sup.-1] [cm.sup.-2]. By measuring SO with a DTSP/Cyt c electrode before and after the addition of a bolus of the superoxide dismutase (SOD) enzyme, the specificity of the SOD enzyme can be combined with the sensitivity of Cyt c system.

Here, we report a catalytic beacon sensor for uranyl (U[O.sup.2+.sub.2]) based on an in vitro-selected U[O.sup.2+.sub.2]-specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3' quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5' and 3' ends, respectively. The presence of U[O.sup.2+.sub.2] causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM, and selectivity of > 1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of [approximately equal to] 230 [micro]M. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium. DNA | DNAzyme | fluorescence | deoxyribozyme | catalytic DNA

A Pb(II)-specific DNAzyme fuorescent sensor has been modified with a thiol moiety in order to immobilize it on a Au surface. Self-assembly of the DNAzyme is accomplished by first adsorbing the single-thiolated enzyme strand (HS-17E-Dy) followed by adsorption of mercaptohexanol, which serves to displace any Au-N interactions and ensure that DNA is bound only through the S-headgroup. The preformed self-assembled monolayer is then hybridized with the complementary fluorophore-containing substrate strand (17DS-FI). Upon reaction with Pb(II), the substrate strand is cleaved, releasing a fluorescent fragment for detection. Fluorescence intensity may be correlated with original Pb(II) concentration, and a linear calibration was obtained over nearly four decades: 10 [micro]M [greater than or equal to] [Pb(II)] [greater than or equal to] 1 nM. The immobilized DNAzyme is a robust system; it may be regenerated after cleavage, allowing multiple sensing cycles. In addition, drying of fully assembled DNAzyme before reaction with Pb(II) does not significantly affect analytical performance. These results demonstrate that, in comparison with solution-based schemes, immobilization of the DNAzyme sensor onto a Au surface lowers the detection limit (from 10 to 1 nM), maintains activity and specificity, and allows sensor regeneration and long-term storage. Realization of Pb(II) detection through an immobilized DNAzyme is the first important step toward creation of a stand-alone, portable Pb(II) detection device such as those immobilizing DNAzyme recognition motifs in the nanofluidic pores of a microfluidic-nanofluidic hybrid multilayer device.

Numerous natural surfaces have micro/nanostructures that result in extraordinary functionality, such as superhydrophobicity, self‐cleaning, antifogging, and antimicrobial properties. One such example is the cicada wing, where differences in nanopillar geometry and composition among species can impact and influence the degree of exhibited properties. To understand the relationships between surface topography and chemical composition with multifunctionality, the wing properties of Neotibicen pruinosus (superhydrophobic) and Magicicada cassinii (hydrophobic) cicadas are investigated at time points after microwave‐assisted extraction of surface molecules to characterize the chemical contribution to nanopillar functionality. Electron microscopy of the wings throughout the extraction process illustrates nanoscale topographical changes, while concomitant changes in hydrophobicity, bacterial fouling, and bactericidal properties are also measured. Extract analysis reveals the major components of the nanostructures to be fatty acids and saturated hydrocarbons ranging from C17 to C44. Effects on the antimicrobial character of a wing surface with respect to the extracted chemicals suggest that the molecular composition of the nanopillars plays both a direct and an indirect role in concert with nanopillar geometry. The data presented not only correlates the nanopillar molecular organization to macroscale functional properties, but it also presents design guidelines to consider during the replication of natural nanostructures onto engineered substrates to induce desired properties. [ABSTRACT FROM AUTHOR]

An in vitro Forster resonance energy transfer (FRET)-based method was employed to study the conformational behavior of an repeats in toxin (RTX) domain from the Bordetella pertussis adenylate cyclase consisting of nine repeat units. The FRET-based method as a useful tool complemented other low-resolution techniques and revealed that entropic stabilization of RTX could be achieved through removal of the sequences flanking the repeat domain that prevented folding and the conformational behavior could be restored by replacing them with fluorescent proteins.

This paper describes the development of an autonomous chemical-sensing aerial robotic system for environmental monitoring in urban and suburban areas. The robot is equipped with a high-performance chemical sensor that identifies and quantifies chemical agents, enabling applications, such as chemical mapping, source localization, and estimation. To enable collision-free monitoring in areas with obstacles, such as in urban and suburban environments where buildings, trees, and other structures pose a challenge, a potential-field algorithm that incorporates past actions is used. A custom-designed ground station for controlling the robot, and planning and visualizing environmental data in real time is described. An empirical method is used to maximize the robot's flight time for improved effective operating range and to provide a safe operating standoff distance. Finally, two outdoor chemical dispersion experiments are conducted to demonstrate the capabilities of the autonomous airborne chemical-sensing system, where results show effective mapping of a propane gas leak. [ABSTRACT FROM AUTHOR]

Laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS) is an emerging bioanalytical tool for direct imaging and analysis of biological tissues. Performing ionization in an ambient environment, this technique requires little sample preparation and no additional matrix, and can be performed on natural, uneven surfaces. When combined with optical microscopy, the investigation of biological samples by LAESI allows for spatially resolved compositional analysis. We demonstrate here the applicability of LAESI-IMS for the chemical analysis of thin, desiccated biological samples, specifically Neotibicen pruinosus cicada wings. Positive-ion LAESI-IMS accurate ion-map data was acquired from several wing cells and superimposed onto optical images allowing for compositional comparisons across areas of the wing. Various putative chemical identifications were made indicating the presence of hydrocarbons, lipids/esters, amines/amides, and sulfonated/phosphorylated compounds. With the spatial resolution capability, surprising chemical distribution patterns were observed across the cicada wing, which may assist in correlating trends in surface properties with chemical distribution. Observed ions were either (1) equally dispersed across the wing, (2) more concentrated closer to the body of the insect (proximal end), or (3) more concentrated toward the tip of the wing (distal end). These findings demonstrate LAESI-IMS as a tool for the acquisition of spatially resolved chemical information from fragile, dried insect wings. This LAESI-IMS technique has important implications for the study of functional biomaterials, where understanding the correlation between chemical composition, physical structure, and biological function is critical.Positive-ion laser-ablation electrospray ionization mass spectrometry coupled with optical imaging provides a powerful tool for the spatially resolved chemical analysis of cicada wings [ABSTRACT FROM AUTHOR]

Endocrine-disrupting compounds (EDCs) can impact the reproductive system by interfering with the hypothalamic-pituitary-gonadal (HPG) axis. Although in vitro testing methods have been developed to screen chemicals for endocrine disruption, extrapolation of in vitro responses to in vivo action shows inconsistent accuracy. The authors describe a tissue coculture of the fathead minnow ( Pimephales promelas) HPG axis and liver (HPG-L) as a tissue explant model that mimics in vivo results. Brain (hypothalamus), pituitary, gonad, and liver tissue explants from adult fish were examined for function both individually and in coculture to determine combinations and conditions that could replicate in vivo behavior. Only cocultures had the ability to respond to an EDC, trenbolone, similarly to in vivo studies, based on estradiol, testosterone, and vitellogenin production trends, where lower exposure doses suppressed hormone production but higher doses increased production, resulting in distinctive U-shaped curves. These data suggest that a coculture system with all components of the HPG-L axis can be used as a link between in vitro and in vivo studies to predict endocrine system disruption in whole organisms. This tissue-based HPG-L system acts as a flexible deconstructed version of the in vivo system for better control and examination of the minute changes in system operation and response on EDC exposure with options to isolate, interrogate, and recombine desired components. Environ Toxicol Chem 2016;35:2530-2541. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America. [ABSTRACT FROM AUTHOR]

[Co(dmgBF2)2(H2O)2] 1 (where dmgBF2 = difluoroboryldimethylglyoximato) was used to synthesize [Co(dmgBF2)2(H2O)(py)]·0.5(CH3)2CO 2 (where py = pyridine) in acetone. The formulation of complex 2 was confirmed by elemental analysis, high resolution MS, and various spectroscopic techniques. The complex [Co(dmgBF2)2(solv)(py)] (where solv = solvent) was readily formed in situ upon the addition of pyridine to complex 1. A spectrophotometric titration involving complex 1 and pyridine proved the formation of such a species, with formation constants, log K = 5.5, 5.1, 5.0, 4.4, and 3.1 in 2-butanone, dichloromethane, acetone, 1,2-difluorobenzene/acetone (4 : 1, v/v), and acetonitrile, respectively, at 20 °C. In strongly coordinating solvents, such as acetonitrile, the lower magnitude of K along with cyclic voltammetry, NMR, and UV-visible spectroscopic measurements indicated extensive dissociation of the axial pyridine. In strongly coordinating solvents, [Co(dmgBF2)2(solv)(py)] can only be distinguished from [Co(dmgBF2)2(solv)2] upon addition of an excess of pyridine, however, in weakly coordinating solvents the distinctions were apparent without the need for excess pyridine. The coordination of pyridine to the cobalt(ii) centre diminished the peak current at the Epc value of the CoI/0 redox couple, which was indicative of the relative position of the reaction equilibrium. Herein we report the first experimental and theoretical 59Co NMR spectroscopic data for the formation of Co(i) species of reduced cobaloximes in the presence and absence of py (and its derivatives) in CD3CN. From spectroelectrochemical studies, it was found that pyridine coordination to a cobalt(i) metal centre is more favourable than coordination to a cobalt(ii) metal centre as evident by the larger formation constant, log K = 4.6 versus 3.1, respectively, in acetonitrile at 20 °C. The electrosynthesis of hydrogen by complexes 1 and 2 in various solvents demonstrated the dramatic effects of the axial ligand and the solvent on the turnover number of the respective catalyst. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterisation of mixed-metal binuclear ruthenium(ii)–vanadium(iv) complexes, which were used as potential photodynamic therapeutic agents for melanoma cell growth inhibition. The novel complexes, [Ru(pbt)2(phen2DTT)](PF6)2·1.5H2O 1 (where phen2DTT = 1,4-bis(1,10-phenanthrolin-5-ylsulfanyl)butane-2,3-diol and pbt = 2-(2′-pyridyl)benzothiazole) and [Ru(pbt)2(tpphz)](PF6)2·3H2O 2 (where tpphz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine) were synthesised and characterised. Compound 1 was reacted with [VO(sal-l-tryp)(H2O)] (where sal-l-tryp = N-salicylidene-l-tryptophanate) to produce [Ru(pbt)2(phen2DTT)VO(sal-l-tryp)](PF6)2·5H2O 4; while [VO(sal-l-tryp)(H2O)] was reacted with compound 2 to produce [Ru(pbt)2(tpphz)VO(sal-l-tryp)](PF6)2·6H2O 3. All complexes were characterised by elemental analysis, HRMS, ESI MS, UV-visible absorption, ESR spectroscopy, and cyclic voltammetry, where appropriate. In vitro cell toxicity studies (with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay) via dark and light reaction conditions were carried out with sodium diaqua-4,4′,4′′,4′′′ tetrasulfophthalocyaninecobaltate(ii) (Na4[Co(tspc)(H2O)2]), [VO(sal-l-tryp)(phen)]·H2O, and the chloride salts of complexes 3 and 4. Such studies involved A431, human epidermoid carcinoma cells; human amelanotic malignant melanoma cells; and HFF, non-cancerous human skin fibroblast cells. Both chloride salts of complexes 3 and 4 were found to be more toxic to melanoma cells than to non-cancerous fibroblast cells, and preferentially led to apoptosis of the melanoma cells over non-cancerous skin cells. The anti-cancer property of the chloride salts of complexes 3 and 4 was further enhanced when treated cells were exposed to light, while no such effect was observed on non-cancerous skin fibroblast cells. ESR and 51V NMR spectroscopic studies were also used to assess the stability of the chloride salts of complexes 3 and 4 in aqueous media at pH 7.19. This research illustrates the potential for using mixed-metal binuclear ruthenium(ii)–vanadium(iv) complexes to fight skin cancer. [ABSTRACT FROM AUTHOR]

There is a consistent demand for new biosensors for the detection of protein targets, and a systematic method for the rapid development of new sensors is needed. Here we present a platform where short unstructured peptides that bind to a desired target are selected using M13 phage display. The selected peptides are then chemically synthesized and immobilized on gold, allowing for detection of the target using electrochemical techniques such as electrochemical impedance spectroscopy (EIS). A quartz crystal microbalance (QCM) is also used as a diagnostic tool during biosensor development. We demonstrate the utility of this approach by creating a novel peptide-based electrochemical biosensor for the enzyme alanine aminotransferase (ALT), a well-known biomarker of hepatotoxicity. Biopanning of the M13 phage display library over immobilized ALT, led to the rapid identification of a new peptide (ALT5-8) with an amino acid sequence of WHWRNPDFWYLK. Phage particles expressing this peptide exhibited nanomolar affinity for immobilized ALT (Kd,app=85±20 nM). The newly identified ALT5-8 peptide was then chemically synthesized with a C-terminal cysteine for gold immobilization. The performance of the gold-immobilized peptides was studied with cyclic voltammetry (CV), QCM, and EIS. Using QCM, the sensitivity for ALT detection was 8.9±0.9 Hz/(μg/mL) and the limit of detection (LOD) was 60 ng/mL. Using EIS measurements, the sensitivity was 142±12 impedance percentage change %/(μg/mL) and the LOD was 92 ng/mL. In both cases, the LOD was below the typical concentration of ALT in human blood. Although both QCM and EIS produced similar LODs, EIS is preferable due to a larger linear dynamic range. Using QCM, the immobilized peptide exhibited a nanomolar dissociation constant for ALT (Kd = 20.1±0.6 nM). These results demonstrate a simple and rapid platform for developing and assessing the performance of sensitive, peptide-based biosensors for new protein targets. [ABSTRACT FROM AUTHOR]

A small synthetic peptide with nanomolar affinity for cardiac troponin I (TnI), previously identified from a polyvalent phage displayed library, has been immobilized on a gold surface for TnI detection. The binding affinity of gold-immobilized peptides for TnI was studied and compared with that of phage-immobilized peptides. Quartz crystal microbalance (QCM), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) were used to monitor both the immobilization and target binding processes. All three techniques show that the binding is specific for TnI as compared to a streptavidin (SA) control. The response curves obtained at TnI concentrations ranging from 0 to 10 g/mL, using both QCM and EIS, were also compared. For the EIS measurements, the sensitivity was 0.30 ± 0.030 normalized impedance/(μg/mL) and the limit of detection (LOD) was 0.34 μg/mL Using the QCM, a sensitivity of 18 ± 1 Hz/(μg/mL) was obtained, corresponding to an LOD of 0.11 μg/mL Although the QCM demonstrated a lower LOD as compared to EIS, the latter technique exhibited a larger linear dynamic range than QCM. In a relevant tissue culture milieu, Minimum Essential Media (MEM), the sensitivity of the EIS measurement was greater than that obtained in a phosphate buffer system (PBS). The kinetics of target binding using QCM were analyzed by two independent methods, and the dissociation constants (KD = 66 ± 4 nM and 17 ± 8 nM) were an order of magnitude higher than that calculated for the polyvalent phage particles (KD = 2.5 ± 0.1 nM). Even though the affinity of the immobilized peptides for TnI was somewhat reduced, overall, these results demonstrate that peptides obtained from the biopanning of phage display libraries can be readily used as sensing probes in biosensor development. [ABSTRACT FROM AUTHOR]

Here, we report a catalytic beacon sensor for uranyl (UO22+) based on an in vitro-selected UO22+-specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3' quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5' and 3' ends, respectively. The presence of UO22+ causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM. and selectivity of >1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of ≈230 μM. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium. [ABSTRACT FROM AUTHOR]

Determines the use of pyrolysis for predicting emission byproducts from the incineration of double-base propellant. Mechanism of Candelillar wax pyrolysis; Incineration process of Army-unique propellant compound; Characterization of the thermal degradation products from pyrolysis.