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Enzymatic decontamination of organophosphate compounds offers a biofriendly pathway to the neutralization of highly dangerous compounds. Environmental dissemination of enzymes, however, is an ongoing problem considering the costly process of production and chemical modification for stability that can diminish catalytic activity. As a result, there is interest in the potential for enzymatic encapsulation in situ or into nascent bacterial membrane vesicles to improve catalytic stability across various environmental challenges associated with storage and field deployment. In this study, we have engineered bacterial outer membrane vesicles (OMVs) to encapsulate the diisopropyl fluorophosphatase (DFPase), an enzyme originally isolated from squid

Melanin is a ubiquitous natural pigment found in a diverse array of organisms. Allomelanin is a class of nitrogen-free melanin often found in fungi. Herein, we find artificial allomelanin analogues exhibit high intrinsic microporosity and describe an approach for further increasing and tuning that porosity. Notably, the synthetic method involves an oxidative polymerization of 1,8-DHN in water, negating the need for multiple complex templating steps and avoiding expensive or complex chemical precursors. The well-defined morphologies of these nanomaterials were elucidated by a combination of electron microscopy and scattering methods, yielding to high-resolution 3D reconstruction based on small-angle X-ray scattering (SAXS) results. Synthetic allomelanin nanoparticles exhibit high BET areas, up to 860 m2/g, and are capable of ammonia capture up to 17.0 mmol/g at 1 bar. In addition, these nanomaterials can adsorb nerve agent simulants in solution and as a coating on fabrics with high breathability where they prevent breakthrough. We also confirmed that naturally derived fungal melanin can adsorb nerve gas simulants in solution efficiently despite lower porosity than synthetic analogues. Our approach inspires further analysis of yet to be discovered biological materials of this class where melanins with intrinsic microporosity may be linked to evolutionary advantages in relevant organisms and may in turn inspire the design of new high surface area materials.

Commonly known as a skin pigment, melanin has a vital role in UV radiation protection, primarily acting as a radical scavenger. However, a lesser known natural property of melanin, observed in some melanized organisms, is its capacity to adsorb toxins, including metals and organic molecules. Inspired by this, we set out to generate a synthetic porous melanin that would pave the way to enhancing the natural adsorbent properties of melanin and melanin-like materials. Here, we developed a method for the synthesis of porous polydopamine-based melanin utilizing a mesoporous silica (MS) nanoparticle template and characterized its physical properties. Through the oxidative polymerization of dopamine, followed by the etching of silica, we generated synthetic porous melanin (SPM) with the highest measured surface area of any known polydopamine-based material. The prepared SPM was effective for the uptake of various gases and organophosphate toxins, with the material exhibiting high selectivity for CO2 over CH4 and high potential for ammonia capture. Given the demonstrated advantages provided by synthetic porous melanin and melanin's role as an adsorbent in nature, we anticipate the discovery of porous analogues in biological systems.

Broadly nanoporous silicas and their composites comprise an extensive space in the literature with research examining silicas as: adsorbents for separating gases, as well as supports for various materials including catalysts, nanoparticles, sensors, porous materials, enzymes, and drugs. This chapter focuses on gas-phase applications of these materials and is organized into three sections: (1) synthesis steps to produce such materials; (2) isotherms and diffusion in silica materials; and (3) composite materials and associated adsorption behaviors.

This report describes the hardware for a prototype sensor system and a processing algorithm developed for application with time dependent, reflectance color values obtained using that device. The system utilizes paper supported porphyrin and metalloporphyrin indicators for chemical detection. Here, we explain the event identification algorithm, variations for application of the algorithm in real-time, and potential adjustments to improve sensitivity and selectivity in the output. The described algorithm has been developed with a view toward minimizing the processing power necessary to facilitate its application onboard highly miniaturized sensor devices. The goal is to develop devices that can be utilized as part of a highly distributed chemical sensing network.

This study demonstrates the potential of porphyrin modified antimicrobial peptides for indication of bacterial targets on the basis of changes in the spectrophotometric characteristics of the construct. Detection is a result of changes in the structure of the antimicrobial peptide upon target binding. Those constructs comprised of peptides that offer little or no change in conformation upon interaction with bacterial cells demonstrated negligible changes in absorbance and fluorescence when challenged using Escherichia coli or Bacillus cereus. CD analysis confirms the presence/absence of conformational changes in the porphyrin-peptide constructs. Differing spectrophotometric responses were observed for constructs utilizing different peptides. The incorporation of metals into the porphyrin component of the constructs was shown to alter their spectrophotometric characteristics as well as the resulting absorbance and fluorescence changes noted upon interaction with a target. The described constructs offer the potential to enable a new type of biosensing approach in which the porphyrin-peptide indicators offer both target recognition and optical transduction, requiring no additional reagents. Keywords: Antimicrobial peptide, Porphyrin, Bacterial detection, Absorbance, Fluorescence

This review describes an ongoing effort intended to develop wireless sensor networks for real-time monitoring of airborne targets across a broad area. The goal is to apply the spectrophotometric characteristics of porphyrins and metalloporphyrins in a colorimetric array for detection and discrimination of changes in the chemical composition of environmental air samples. The work includes hardware, software, and firmware design as well as development of algorithms for identification of event occurrence and discrimination of targets. Here, we describe the prototype devices and algorithms related to this effort as well as work directed at selection of indicator arrays for use with the system. Finally, we review the field trials completed with the prototype devices and discuss the outlook for further development.

Introduction This effort seeks to develop chemical and biological sensing capabilities suitable for use in long duration, distributed sensing applications. For this type of application, it is desirable to provide inexpensive devices that can detect a range of targets, both known and unknown, with minimal power requirements. Porphyrins and metalloporphyrins are intensely colored, aromatic molecules with spectrophotometric characteristics that are sensitive to interaction with other chemicals. Porphyrins offer diverse chemical interactions that can be changed through alterations to the molecular structure and the coordinated metal. Through selection of a group of porphyrin indicators, it is possible to generate an array for which the relative responses of the indicator materials can provide target discrimination. The indicators selected for this effort provide reversible responses to chemical targets, offering the potential for long duration deployments and ongoing or repeated use of the indicator arrays [1-5]. Method Hardware. The prototype sensing hardware, our Array Based Environmental Air Monitor (ABEAM), is used with the paper supported porphyrin and porphyrin-antimicrobial peptide indicators. This device comprises a custom housing and control board with commercially available color sensors [4]. Communication with the device is via USB or wireless, with power supplied by DC barrel jack or batteries. Device output is as red, green, and blue (RGB) values versus time either stored in onboard flash memory or reported to a control computer via drip-feed [3-5]. Algorithm. An automated algorithm was developed to process ABEAM output for identification of chemical exposures [1, 3]. Processing by the algorithm is based on the angles between slopes in the device reported RGB color data for each of the color sensors. In general, two windows of data are compared for each color on each device: a baseline window populated by 120 data points and an active window populated by 20 points. The active window includes those points collected in the most recent 10 min with the baseline window including the previous 60 min. The use of these two sliding windows accounts for device drift as well as diurnal changes in environmental conditions. Results and Conclusions Initial work with the ABEAM prototype was completed without the housing or fans [2, 4, 6]. This effort largely focused on identification of indicator materials for use in an array that would allow for discrimination of alcohols (ethanol, methanol, and isopropanol) as model targets to be used in environmental evaluations. Under this work, a standard deviation based algorithm for event identification was developed. When the focus of the effort shifted from rapid on/off target exposures to those completed in an enclosure, to more effectively simulate expected environmental exposures, dramatic differences were noted in the performance of the standard deviation algorithm. The responses of the indicator materials did not occur within a short enough time duration to trigger the algorithm. The slope based algorithm (Section II) was developed as a result. This move from screening experiments to environmental exposures also served to identify shortfalls in instrument parameters. With the short on/off exposures, the use of a 5 s sampling interval with a 100 ms integration time produced data sufficient for characterization. For longer duration autonomous deployments, the 5 s sampling interval produced memory overrun in less than three days. The 30 s sampling interval allowed a run time of seven days in the original device and fourteen days in a follow-on iteration of the prototype. It was also necessary to extend the integration time for the devices under environmental exposure (to 400 ms) to provide sufficient signal to noise ratios for discrimination of events by the slope based algorithm [3-4]. We have demonstrated that the ABEAM provides detection of the alcohol targets in either an indoor or outdoor environment. When parameters are optimized and a negative control is included in the array, a specificity of 0.97 with sensitivity 1.0 can be achieved [3]. Here, we also present the results of recent evaluations of a network of six devices used in an outdoor environment for the detection of methyl salicylate. This is the first demonstration of these devices used with ongoing drip-feed data reporting and real-time analysis via wireless communications and using battery power. References 1. J. S. Erickson; A. P. Malanoski; B. J. White; D. A. Stenger; E. R. Tankard, Practical Implementation of Detection Algorithm for Reflectance-Based, Real-Time Sensing, US Naval Research Laboratory, Washington, DC (2018) MR/6930--18-9812. 2. B. J. Johnson; J. S. Erickson; J. Kim; A. P. Malanoski; I. A. Leska; S. M. Monk; D. J. Edwards; T. N. Young; J. Verbarg; C. Bovais; R. D. Russell; D. A. Stenger, Miniaturized reflectance devices for chemical sensing. Meas. Sci. Technol. 25 (2014) 095101 095101. DOI: 10.1088/0957-0233/25/9/095101 3. B. J. Johnson; A. P. Malanoski; J. S. Erickson; R. Liu; A. R. Remenapp; D. A. Stenger; M. H. Moore, Reflectance-based detection for long term environmental monitoring. Heliyon 3 (2017) e00312 DOI: 10.1016/j.heliyon.2017.e00312 4. A. P. Malanoski; B. J. Johnson; J. S. Erickson; D. A. Stenger, Development of a Detection Algorithm for Use with Reflectance-Based, Real-Time Chemical Sensing. Sensors 16 (2016) 1927. DOI: 10.3390/s16111927 5. B. J. White; J. S. Erickson; A. P. Malanoski; M. H. Moore, Reflectance-Based Sensing: Post-Evaluation Analysis of Sensor Responses, US Naval Research Laboratory, Washington, DC (2019) MR/6930--19-9852. 6. B. J. Johnson; R. Liu; R. C. Neblett; A. P. Malanoski; M. Xu; J. S. Erickson; L. Zang; D. A. Stenger; M. H. Moore, Reflectance-based detection of oxidizers in ambient air. Sens. Actuator B-Chem. 227 (2016) 399-402 DOI: 10.1016/j.snb.2015.12.040 Figure 1

Here, we report on the development of a genetic system for Marinobacter sp. strain CP1, previously isolated from the Biocathode MCL community and shown to oxidize iron and grow as a cathodic biofilm. Sequence analysis of the small and large subunits of the 16S rRNA gene of CP1, as well as comparison of select conserved proteins, indicate that it is most closely related to Marinobacter adhaerens HP15 and Marinobacter sp. ES.042. In silico DNA-DNA hybridization using the genome-to-genome distance calculator (GGDC) predicts CP1 to be a new species of Marinobacter described here as Marinobacter atlanticus. CP1 is competent for transformation with plasmid DNA using conjugation with Escherichia coli donor strain WM3064 and constitutive expression of green fluorescent protein (GFP) is stable in the absence of antibiotic selection. Targeted double deletion mutagenesis of homologs for the M. aquaeoli fatty acyl-CoA reductase (acrB) and fatty aldehyde reductase (farA) genes resulted in a loss of production of wax esters; however, single deletion mutants for either gene resulted in an increase in total wax esters recovered. Genetic tools presented here for CP1 will enable further exploration of wax ester synthesis for biotechnological applications, as well as furthering our efforts to understand the role of CP1 within the Biocathode MCL community.

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

This study sought to demonstrate the impact of surface-target interactions in a device bearing geometrical features through evaluations of chemical modification to the surface and alteration of the charge state of both surface and targets. The movement of commercial fluorescent nanoparticles through a field of geometric features was monitored based on the output of the field measured at different points transverse to the direction of flow. Modification of the device surfaces using carboxylate, amine, phenyl, and fluorinated groups was considered. The functional group on the surface was found to significantly impact biased particle movement in the device with amine groups leading to the greatest differences. Other factors, such as flow rate, pH, and initial particle concentration, were also found to have a significant impact on particle concentrations across the feature field.

Biodiesel is produced by transesterification of animal fat, vegetable oil, or waste cooking oil with alcohol. After production costs, the economic viability of biodiesel is dependent on what steps are necessary to remove impurities following synthesis and the effectiveness of quality control analysis. Solid-phase extraction offers a potentially advantageous approach in biodiesel processing applications. Nanoporous scaffolds were investigated for adsorption of glycerol, a side product of biodiesel synthesis that is detrimental to engine combustion when present. Materials were synthesized with varying pore wall composition, including ethane and diethylbenzene bridging groups, and sulfonated to promote hydrogen bonding interactions with glycerol. Materials bearing sulfonate groups throughout the scaffold walls as well as those post-synthetically grafted onto the surfaces show notably superior performance for uptake of glycerol. The sorbents are effective when used in biodiesel mixtures, removing greater than 90% of glycerol from a biodiesel preparation.

Physical protection of nucleic acids from the environment for improved stability through encapsulation or adsorption has been reported using various materials, including liposomes, metal particles, mesoporous silica nanoparticles, and polymers. In an extension of that approach, our previous study demonstrated the potential of mesoporous silica nanoparticles with and without covalently attached stabilizing reagents, such as sugar and bovine serum albumin, for improving the stability of RNA. The goal of the current study is to evaluate the potential of silicate sorbents bearing chemical functionalities for stabilization of nucleic acid targets. Materials offering charged groups, metal chelating sites, and π-bonding sites are considered. Adsorption and elution of RNA, DNA, and single stranded DNA (ssDNA) are evaluated as is subsequent elution of the bound target. A sorbent functionalized with primary amine groups showed promising results for RNA and ssDNA stabilization. The impact of the sorbents on long term viability the targets is also evaluated. Storage of adsorbed targets at room temperature and 37∘C over a period of 200 d indicates the potential for stabilization of RNA and ssDNA using several of the functionalities. None of the sorbents improved the stability of DNA either under room temperature or 37∘C storage.

The adsorption characteristics for paraoxon, diazinon, and structurally related compounds by hierarchical diethylbenzene-bridged organosilicate sorbents are reported here. Adsorption behavior was found to deviate from the expected Langmuir–Freundlich binding isotherm. Instead, capillary phase-separation within the pores of the sorbent structure occurred when presented with these targets in aqueous solution. This behavior has not been widely reported, but it is similar to the pore condensation observed in gas adsorption studies. The behavior is a result of the pore sizes, the availability of interaction sites on the pore walls, and the miscibility of the targets (solutes) with water (solvent). Adsorption of targets from aqueous solution was observed to follow a hybrid Freundlich–BET binding isotherm. Adsorption of the targets from octanol solutions was observed to follow the Langmuir–Freundlich binding isotherm as was adsorption of more soluble targets such as p-nitrophenol. With the increasing numbers of applications described for mesoporous materials, this phenomenon will likely be more frequently encountered. The range of conditions utilized in characterization of sorbents should be considered carefully.

This effort evaluated the potential of two prototype devices for enhanced electrochemical detection of 2,4,6-trinitrotoluene (TNT) and dinitrotoluene (DNT) following preconcentration using an organosilicate sorbent. The bench-scale prototype provides adsorption of the targets from aqueous solution followed by elution in a mixture of methanol and potassium chloride (KCl). Following elution, the eluant is diluted using an aqueous KCl solution to provide sufficient electrolyte for electrochemical analysis. Concentrations of methanol greater than 50% were detrimental to sensor performance and lifetime. Calibration of the electrochemical sensor was completed and results of electrochemical analysis were compared to those of HPLC analysis over a range of concentrations and in varied matrices. TNT detection was found to be consistent and detection limits were improved from 200 ppb to 3 ppb depending on the sample volume utilized. DNT detection showed higher variability and significantly greater false response rates. On the basis of these results, a second, more advanced, prototype was developed and utilized in limited field trials with the intention of moving the technology toward in situ applications.

Summary The ability of enzymes to catalyze reactions and engage in complex syntheses has long made them attractive for use in a multitude of industrial, biotechnological, and research applications. Although this utility grows with each passing year, the exploitation of enzymes in ex vivo formats is still hampered by relatively low rates of turnover, particularly when attached to planar surfaces. However, a growing number of reports suggest that assembling enzymes or their substrates onto nanoparticle (NP) surfaces can accelerate or otherwise improve catalysis when compared to freely diffusing enzyme in bulk solution. Here, we present an in-depth review and discussion of what is currently known about this phenomenon with an emphasis on inorganic NPs. The assembly of enzyme–NP and substrate–NP bioconjugates is first described, emphasizing their heterogeneity and the expected impact on enzymatic activity within the framework of collision theory, biomolecular interactions, and the classic Michaelis–Menten model. We next discuss representative examples from the literature where accelerated enzyme activity has been reported in conjunction with NP materials, the mechanisms that have been proposed to account for the accelerated activity, and the challenges that remain to fully understand and optimize this potentially valuable phenomenon. Finally, approaches to quantitative modeling of NP-associated enzyme activity are discussed, including a kinetic analysis that we suggest can provide insight into the underlying mechanisms that may drive the observed rate enhancements. We conclude with a perspective on the future evolution and broader impact of this growing area of nanoresearch.

With emerging systems and applications accessing features within the nanoregime, whether due to droplet size or feature size, understanding the wetting behaviours of these materials is an area of ongoing interest. Theoretical studies, providing a fundamental understanding of how contact angle behaviour changes at these length scales, are important to further such work. This study provides a comprehensive examination of the application of lattice density functional theory (LDFT) to a pillared surface to confirm the suitability of LDFT for studying more complex surfaces. Incorporation of the correct level of details for the fluid-wall interaction was found to produce all of the qualitative changes that have been observed in off-lattice theories. Though previous reports have provided apparently conflicting results, the more comprehensive examination of feature sizes provided here demonstrates that those behaviours are consistent with one another. The well-studied failure of macroscopic models that results from non-negligible line tension contributions and small droplets to feature size ratios was demonstrated using LDFT. Furthermore, the failure of macroscopic models resulting upon reduction in feature size, which has been considered less often, is clearly demonstrated. A key assumption of the macroscopic models is the consistent interaction between surface and fluid regardless of the flatness or roughness of the surface. The density functional results presented here show that, for the smallest features, this is not the case and demonstrate that macroscopic models do not predict the correct contact angle for droplets of any size on nanorough surfaces.

Sorbent materials were developed utilizing two morphological structures, comprising either hexagonally packed pores (HX) or a disordered pore arrangement (CF). The sorbents were functionalized with combinations of two types of alkylammonium groups. When capture of perchlorate by the sorbents was compared, widely varying performance was noted as a result of differing morphology and/or functional group loading. A material providing improved selectivity for perchlorate over perrhenate was synthesized with a CF material using N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. Materials were applied in batch and column formats. Binding isotherms followed the behavior expected for a system in which univalent ligands of varying affinity compete for immobilized sites. Performance of the sorbents was also compared to that of commercial Purolite materials.

A previous effort demonstrated the utility of porphyrin functionalized organosilicate sorbents in the removal of phosgene. The current study sought to characterize the spectrophotometric response of the sorbents during their application to determine the potential for dual use in both removal of phosgene and reporting on phosgene exposure. The effort is intended as a first step toward using the materials for self-reporting or residual life indication. An ethane bridged silica was functionalized using deuteroporphyrin IX 2,4 bis-ethylene glycol. Several metalloporphyrin variants were generated based on this porphyrin functionalized sorbent, and fluorescence characteristics were evaluated in the prior to and following exposure to phosgene. Reflectance characteristics and changes upon target exposure were also evaluated. Cu, Mg, and Zn sorbents showed the most significant changes upon exposure to phosgene. The reflectance characteristics of these sorbents were evaluated across a range of loading levels for sorbent columns to the point of complete target breakthrough. The results indicate the possibility for reflectance or visual inspection based end-of-life indication for these sorbents.

Here, we describe our efforts focused on development of an algorithm for identification of detection events in a real-time sensing application relying on reporting of color values using commercially available color sensing chips. The effort focuses on the identification of event occurrence, rather than target identification, and utilizes approaches suitable to onboard device incorporation to facilitate portable and autonomous use. The described algorithm first excludes electronic noise generated by the sensor system and determines response thresholds. This automatic adjustment provides the potential for use with device variations as well as accommodating differing indicator behaviors. Multiple signal channels (RGB) as well as multiple indicator array elements are combined for reporting of an event with a minimum of false responses. While the method reported was developed for use with paper-supported porphyrin and metalloporphyrin indicators, it should be equally applicable to other colorimetric indicators. Depending on device configurations, receiver operating characteristic (ROC) sensitivities of 1 could be obtained with specificities of 0.87 (threshold 160 ppb, ethanol).

This study describes the application of porphyrin-embedded porous organosilicate materials to the adsorption of ammonia gas. Organosilicate scaffolds were synthesized through a surfactant-templating process combined with a phase separation technique. The structure offers a macro-textured scaffold to facilitate flow through the sorbent material and provide enhanced access to the available surface area provided by a combination of micro- and mesopores distributed over a range of sizes. The materials were grafted post-synthesis to provide sites for covalent immobilization of porphyrins. These porphyrins were utilized for incorporation of metal sites into the organosilicate materials. The removal of ammonia was evaluated for a number of materials incorporating copper metalloporphyrins of varied structure at varied loading levels. Results have been compared to removal of ammonia by a carbon material. Copper deuteroporphyrin IX bis-ethylene glycol provided the strongest interactions with ammonia. High loading levels of this porphyrin within the sorbent structure showed increasing evidence of stacking and did not improve the performance of the material.

This study sought to characterize the removal of phosgene by functionalized porous organosilicate sorbents. Metalloporphyrin variants were generated based on a Deuteroporphyrin IX 2,4 bis-ethylene glycol functionalized sorbent. The copper(II) variant removed phosgene at rates significantly higher than that of the bare sorbent. It was further demonstrated that the sorbent was reusable and that illumination resulted in additional target removal. The column effluent from the Cu(II) functionalized sorbent was shown to contain chloride; however, the levels were significantly less than would be expected based on a mass balance.

Recent studies show that polyvalent, ligand-modified nanoparticles provide significantly enhanced binding characteristics compared to isolated ligands. Here, we assess the ability of substrate-modified nanoparticles to provide enhanced enzymatic activity. Energy transfer assays allowed quantitative, real-time measurement of proteolytic digestion at polyvalent quantum dot-peptide conjugates. Enzymatic progress curves were analyzed using an integrated Michaelis-Menten (MM) formalism, revealing mechanistic details, including deviations from classic MM-behavior. A "hopping" mode of proteolysis at the nanoparticle was identified, confirming enhanced activity.

Organosilicate materials functionalized through post-synthesis grafting have been evaluated for their potential to remove irritant gases. Organosilicate scaffolds were synthesized through a technique combining surfactant-templating and phase separation to produce a macro-textured scaffold with a combination of micro- and mesopores. This structure facilitates diffusion through the sorbent material providing enhanced access to the available surface area. Post-synthesis grafting was used to incorporate amine and isocyanate groups on the surfaces of the pore walls in an attempt to modify the binding and reactive character of the materials. These modified materials were compared to the unmodified organosilicate scaffold. The removal of irritant gases including ammonia, sulfur dioxide, cyanogen chloride, and octane was evaluated for the materials variants. Results have been compared to the removal of the gases by carbons as well as other materials reported in recent literature.

We examined the adsorption and release of TNT using diethylbenzene-bridged (DEB) periodic mesoporous organosilica sorbents under varying conditions. The sorbents were applied for in-line target pre-concentration in conjunction with an electrochemical flow cell containing a glassy carbon electrode. Square wave voltammetry was employed for TNT detection. TNT sample volumes between 2 and 480 mL at concentrations ranging from 0.5 to 500 ppb were passed through the DEB sorbents (imprinted or not imprinted for TNT) at pH 6 (sodium acetate) or at pH 7.4 (PBS). Release of target was accomplished using solvent mixtures of methanol/water with sodium acetate as electrolyte or acetonitrile/water with PBS components as electrolyte. Under these conditions, the TNT was released in 3000 can be achieved when using large volumes of trace TNT samples. When sample volumes of 2 mL were utilized, the sensing system gave a linear response between 20 and 500 ppb with an estimated limit of detection of 13 ppb. When pre-concentrating 480 mL of sample in either buffered solution or seawater, detection of 0.5 ppb TNT was achieved with a signal to noise ratio of 20.

The development of porphyrin-embedded mesoporous organosilicate materials for application to the detection of volatile hydrocarbon solvents is described. Design of the receptor and optical indicator construct begins with parallel selection of the porphyrin indicator and design of the mesoporous sorbent. For the porphyrin indicator, high binding affinity and strong changes in spectrophotometric character upon target interaction are desired. The sorbent should provide high target binding capacity and rapid binding kinetics. A number of porphyrin/metalloporphyrin variants and organosilicate sorbents were evaluated to determine the characteristics of their interaction with the targets, benzene, toluene, and hexane. The selected porphyrin candidates were covalently immobilized within a benzene-bridged sorbent. This construct was applied to the detection of targets using both fluorescence- and reflectance-based protocols. The use of red, green, and blue (RGB) color values from the constructs in a highly simplified detection scheme is described.

Hierarchical organosilicate sorbents were synthesized which possess structure on two length scales: macropores of approximately 1 μm lined by mesopores (35–45 A). The incorporation of macropores provides enhanced flow-through characteristics over purely mesoporous materials, thereby reducing back pressure when used in column formats. Materials of this type with varied surface groups were applied to the adsorption of 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) in both batch and column formats. The results presented here demonstrate the potential of these materials for application as solid phase extraction materials for the pre-concentration of nitroenergetic targets from aqueous solutions. The structural and binding characteristics of the materials have been evaluated and preliminary data on the impact of complex matrices is provided.

Periodic mesoporous organosilicas (PMOs) with diethylbenzene bridging groups (DEB) in the pore walls are promising adsorbents for harmful compounds including nitroenergetics. The hierarchical macropore–mesopore structures developed here are expected to facilitate diffusion for such applications and to offer the potential for application in column formats. DEB-functionalized PMOs were synthesized with triblock copolymer Pluronic®P123 and the swelling additive mesitylene. Many of the materials were prepared through co-condensation of the DEB precursor bis(trimethoxysilylethyl)benzene with 1,2-bis(trimethoxysilyl)ethane (BTE) to improve mesostructure. Conditions were optimized to form micron-scale macropores by polymerization-induced phase separation. PMOs were also produced using only the DEB precursor. These materials exhibited relatively high surface areas (ca. 400 m 2 /g) and mesopore sizes (ca. 45 A) as well as isolated macropores. As-synthesized materials were fabricated as centimeter-scale monoliths that became powders after multiple solvent refluxes. Soxhlet extraction could be used to preserve monolithic morphology while removing enough P123 to access mesopores. Nitrogen sorption, powder X-ray diffraction, SEM, TEM, and TGA were applied to characterize the PMOs.

The ability of the metal reducer Shewanella oneidensis MR-1 to generate electricity in microbial fuel cells (MFCs) depends on the activity of a predicted type IV prepilin peptidase; PilD. Analysis of an S. oneidensis MR-1 pilD mutant indicated that it was deficient in pili production (Msh and type IV) and type II secretion (T2S). The requirement for T2S in metal reduction has been previously identified, but the role of pili remains largely unexplored. To define the role of type IV or Msh pili in electron transfer, mutants that lack one or both pilus biogenesis systems were generated and analyzed; a mutant that lacked flagella was also constructed and tested. All mutants were able to reduce insoluble Fe(III) and to generate current in MFCs, in contrast to the T2S mutant that is deficient in both processes. Our results show that loss of metal reduction in a PilD mutant is due to a T2S deficiency, and therefore the absence of c cytochromes from the outer surface of MR-1 cells, and not the loss of pili or flagella. Furthermore, MR-1 mutants deficient in type IV pili or flagella generated more current than the wild type, even though extracellular riboflavin levels were similar in all strains. This enhanced current generating ability is in contrast to a mutant that lacks the outer membrane c cytochromes, MtrC and OmcA. This mutant generated significantly less current than the wild type in an MFC and was unable to reduce Fe(III). These results indicated that although nanofilaments and soluble mediators may play a role in electron transfer, surface exposure of outer membrane c cytochromes was the determining factor in extracellular electron transfer in S. oneidensis MR-1.

Periodic mesoporous organosilicas incorporating diethylbenzene bridges in their pore walls were applied for the adsorption of nitroenegetic targets from aqueous solution. The materials were synthesized by co-condensing 1,4-bis(trimethoxysilylethyl)benzene (DEB) with 1,2-bis(trimethoxysilyl)ethane to improve structural characteristics. Molecular imprinting of the pore surfaces was employed through the use of a novel target-like surfactant to further enhance selectivity for targets of interest (tri- and dinitrotoluenes) over targets of similar structure ( p-cresol and p-nitrophenol). The headgroup of the commonly used alkylene oxide surfactant Brij76 was modified by esterification with 3,5-dinitrobenzoyl chloride. This provided a target analogue which was readily miscible with the Brij76 surfactant micelles used to direct material mesopore structures. The impact of variations in precursor ratios and amounts of imprint molecule was evaluated. The use of 12.5% of the modified Brij surfactant with a co-condensate employing 30% DEB was found to provide the best compromise between total capacity and selectivity for nitroenergetic targets.

Proanthocyanidins (PACs), polyphenolic metabolites that are widely distributed in higher plants, have been associated with potential positive health benefits including antibacterial, chemotherapeutic, and antiatherosclerotic activities. In this paper, we analyze the binding of PACs from cranberries, tea, and grapes to lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria and the cause of several human illnesses. We demonstrate that in the case of cranberries, the most potent LPS-binding activity is contained within a PAC fraction composed of polymers with an average degree of polymerization of 21. The PAC fraction modestly inhibits the binding of LPS to the surface of HEK 293 cells expressing the full complement of LPS receptors (TLR4/MD2 and CD14), while it significantly abrogates the endocytosis of LPS. This PAC fraction also inhibits LPS-induced nuclear factor-kappaB activation in a manner that is not readily overcome by excess LPS. Such an effect is mediated through the inhibition of LPS interaction with TLR4/MD2 and the partial abrogation of LPS interaction with CD14. Importantly, PAC concentrations that mediate effective LPS neutralization elicit minimal in vitro cytotoxicity. Our results identify PACs as a new class of LPS-binding compound and suggest that they have potential utility in applications that necessitate either the purification and removal of LPS or the in vivo neutralization of LPS.

The metabolic versatility, tractability and rapid growth potential of the Vibrio spp. have made them increasingly attractive systems for investigating carbon cycling in the marine environment. In this study, an in silico subtractive proteomic strategy was used to identify a novel 101 kDa GH3 family β-glucosidase (LamN) that was found in bioluminescent Vibrio campbellii strains capable of utilizing the algal storage glucan laminarin. A heterologous overexpression system verified the sequence-predicted function of LamN as it enabled the growth of E scherichia coli on laminarin as a sole carbon source. Quantitative reverse transcription PCR analyses revealed that V. campbellii grown on laminarin demonstrated a 4- to 314-fold induction of lamN gene expression when compared to the same strains grown on glucose or glycerol. Corresponding tandem mass spectrometric analyses detected LamN protein expression only in cells grown on laminarin. Heterologous expression, purification and biochemical characterization identified LamN as a heat stable laminarinase with β-1,3, β-1,4 and β-1,6 glucosidase activity. Collectively, these data identify an enzyme that may allow V. campbellii to exploit some of the most abundant polysaccharides associated with deteriorating phytoplankton blooms and provide support for the potential involvement of V. campbellii in the formation of bioluminescent milky seas.

The anti-adhesive effects of cranberry have been attributed to both interactions of its components with the surface of bacterial cells and to inhibition of p-fimbriae expression. Previous reports also suggested that the presence of cranberry juice changed the Gram stain characteristics of Escherichia coli. Here, we show that the morphology of E. coli is changed when grown in the presence of juice or extract from Vaccinium macrocarpon (cranberry). Gene expression analysis indicates the down regulation of flagellar basal body rod and motor proteins. Consistent with this finding and previous reports, the SEM images indicate a decrease in the visible p-fimbriae. The iodine used in Gram-staining protocols was found to interact differently with the bacterial membrane when cells were cultured in spiked media. Slight alterations in the Gram stain protocol demonstrated that culturing in the presence of cranberry juice does not change the Gram stain characteristics contradicting other reports.