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Materials for the concentration of nitroenergetic and perchlorate targets from groundwater were developed for monitoring applications. Novel molecular imprinting and structure direction techniques were used to obtain the necessary materials. The potential for concentration of targets from ground and surface waters as well as from soil extracts was demonstrated. The functional characteristics of the materials were evaluated in order to determine the constraints on there use in inline preconcentration of targets ahead of IMS and electrochemical sensing techniques. The systems were subsequently developed at the bench level and function was evaluated using commercially available portable sensors. An initial portable prototype was also developed and evaluated under a field scenario.

A program was initiated in June 2009 to evaluate the potential of porous organosilicate sorbents in the capture or neutralization of light gas threats. Of primary interest were targets identified by the TIC/TIM Task Force as priority threats. A number of approaches were taken for increasing binding capacity and reactivity in the sorbent materials: grafting of metalloporphyrins, incorporation of sites for metal coordination, and incorporation of acidic and basic groups. In addition, the impact of morphological considerations, such as pore size and organization, were evaluated. Target capture by the sorbents was evaluated using microbreakthrough testing completed at the Edgewood Chemical Biological Center. Development of relevant sorbent morphologies was also pursued. Overall, the sorbents show promise, with several offering improvements in target capture and retention over state-of-the-art materials., The original document contains color images. Prepared in collaboration with Edgewood Chemical Biological Center, Aberdeen Proving Grounds, MD. Sponsored in part by DTRA.

This report summarizes the results of studies directed at the development of organosilicate sorbents for the capture and preconcentration of nitroenergetics targets and perchlorates from natural water sources. Two distinct types of sorbents were developed. The first, directed at nitroenergetics, utilizes new approaches to target templating and a hierarchical structure. The second, directed at perchlorates, utilizes the hierarchical structure with alkylammonium surface modifications. Both materials provide semiselective target capture and offer advantages over commercially available products. Application of the sorbents in single and mixed target solutions is demonstrated. Nitroenergetic capture from natural water sources is also evaluated., The original document contains color images.

The potential for encapsulating RNA within tunable, semi-permeable structures for storage and transportation purposes offers an interesting approach to the reduction of stringent storage requirements that often hamper the field application of genetic analysis methods. In this study, we assessed the potential for application of functionalized, porous silicate sorbents in maintaining nucleic acid integrity. Mesoporous silica nanoparticles (MSNs) with and without incorporated stabilizing reagents were used to encapsulate triosephosphate isomerase mRNA of Arabidopsis thaliana. The absorption, elution, and the long-term stability of the RNA were monitored by using quantitative real-time RT-PCR. The results indicate that adsorbed RNA can be eluted from the sorbents using simple buffers and employed directly for downstream molecular diagnostic assays without any further processing. RNA integrity can be maintained for extended time periods under refrigeration temperatures in the presence of covalently immobilized stabilizing compounds. This study provides initial evidence of the potential for application of MSNs in transportation and storage. They may also have utility in sample collection and processing in restrictive environments., Published in PLOS One, v7 n11, 30 Nov 2012. The original document contains color images.

A novel porous organosilicate material was evaluated for application as a solid phase extraction sorbent for preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbent in spiked deionized water, groundwater, and surface water was evaluated. Targets considered included 2,4,6-trinitrotouene, 2,4-dinitrotoluene. RDX, HMX, and nitroglycerin. The sorbent was shown to provide improved performance over Sep-Pak RDX. The impact of complex matrices on target preconcentration by the sorbent was also found to be less dramatic than that observed for LiChrolut EN. The impact of changes in pH on target preconcentration was considered., Published in the Journal of Environmental Monitoring, 2011.

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., Published in Sensors, v11 p886-904, 14 Jan 2011. Sponsored in part by DTRA.

Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the semi-selective adsorption of small molecule contaminants. These structures offer high surface areas and large pore volumes within an organized framework. The organic bridging groups in the materials can be altered to provide varied binding characteristics. This effort seeks to utilize the tunable binding selectivity, high surface area, and low materials density of these highly ordered pore networks and to combine them with the unique spectrophotometric properties of porphyrins. In the porphyrin-embedded materials (PEMs), the organosilicate scaffold stabilizes the porphyrin and facilitates optimal orientation of porphyrin and target. The materials can be stored under ambient conditions and offer exceptional shelf-life. Here, we report on the design of PEMs with specificity for organophosphates and compounds of similar structure., Published in Sensors, v10 p2315-2331, 2010. Performed in collaboration with NOVA Research Incorporated, Alexandria, VA. Naval Research Laboratory work unit no. 69-8765. Sponsored in part by the Defense Threat Reduction Agency (DTRA; BA08PRO015) and the Department of Defense Strategic Environmental Research and Development Program (SERDP; ER-1604).

Materials for the concentration of nitroenergetic targets from groundwater are sought for monitoring and remediation applications. For this work, 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 precursors 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 (nitroenergetics and their breakdown products) over targets of similar structure (p-cresol and p-nitrophenol). The impact of variations in precursor ratios and amounts of imprint molecule was evaluated. These results were applied to the development of materials possessing organization on both the meso and macro scales. The incorporation of macropores provides a material with enhanced flow through characteristics, thereby reducing back pressure when used in column formats. Concentration of targets from soil sample extracts using these materials was demonstrated., The original document contains color images. Work unit no. 69-9629-0-8-5