Gokhale A.A.,Michigan State University |
Lu J.,Technova Corporation |
Lee I.,Michigan State University
Journal of Molecular Catalysis B: Enzymatic | Year: 2013
In this study, we report the preparation of pH tunable, temperature sensitive magnetoresponsive graphene-based nano-bio carriers for cellulase immobilization. We discuss a simple route to overcome the geometric disadvantage imposed by most 2D immobilization supports and make them capable of closely mimicking free enzymes (FE) operating under similar reaction conditions. The supramolecular assembly of oppositely charged quenched polyelectrolytes and maghemite-magnetite nanoparticles on 2D graphene supports followed by covalent immobilization of cellulase shows a marked improvement in the bio-receptivity of graphene supports. The incorporation of magnetic nanoparticles opens up the possibility of recovery and reuse of the enzyme over multiple cycles. The immobilized enzymes retained about 55% of the original specific activity even after four cycles of reuse. Cellulase immobilization is achieved by a combination of annealed polyelectrolyte brushes and zero-length spacer molecules. The swelling behavior of annealed polyelectrolyte brushes is a strong function of the environmental conditions. The degree of polyelectrolyte swelling can be easily tweaked by manipulating the pH and temperature, providing us an effective tool to control the activity of immobilized enzymes. At a pH of 5.1 and a temperature of 50 °C, the immobilized enzymes with the annealed polyelectrolyte brushes displayed close to 1.5-fold improvement in the activity as compared to immobilized enzymes without the brushes. Activity of immobilized cellulase is evaluated using both soluble as well as insoluble substrates like 2% (w/v) CMC and avicel respectively. © 2012 Elsevier B.V. All rights reserved. Source
Agency: Environmental Protection Agency | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 225.00K | Year: 2011
Production of cement (the binder in concrete) is a highly polluting and energy-intensive process, accounting for about 6% of global, anthropogenic C02 emissions and close to 2% of worldwide primary energy use. This project focuses on partial (~20%) replacement of cement in concrete with milled (mixed-color) waste glass to improve the moisture barrier qualities, durability, dimensional stability and other engineering properties of concrete. These beneficial effects would be realized as far as waste glass is milled to micro-scale particle size for accelerating its chemical reactions with cement hydrates. The landfill-bound quantities of glass are adequate to significantly impact the concrete construction practice. Waste glass is generated largely in urban areas, where the bulk of concrete production also takes place. Broad use of milled waste glass in concrete would yield significant environmental, energy, and cost benefits, and also would enable more extensive use of recycled aggregate concrete. The Phase I effort identified desired particle size and dosage of milled (mixed-color) waste glass for beneficial use as partial replacement for cement in concrete. The favorable effects of milled waste glass on the chemical composition, microstructure, and key engineering properties (including stability under potential alkali-silica reactions) of normal and recycled aggregate concrete were identified through laboratory investigations. Theoretical and numerical studies were conducted to rationalize the experimental observations and to assess practical implications of using recycled glass concrete. A successful field study also was implemented in collaboration with concrete and recycling industries. The environmental, energy and (initial and life-cycle cost) benefits associated with partial replacement of cement with milled waste glass were quantified using the outcomes of Phase I effort. The proposed Phase II project will: (i) expand the experimental database on recycled glass concrete to cover broader ranges of concrete materials and engineering properties; (ii) corroborate the statistical significance of the benefits rendered by milled waste glass and verify the statistical control over production of recycled glass concrete; (iii) identify the mechanisms through which milled waste glass benefits the engineering properties of normal and recycled aggregate concrete; (iv) thoroughly assess the gains in service life and life-cycle economy of major concrete-based infrastructure associated with the use of milled waste glass; (v) implement and monitor large-scale field projects to demonstrate the scalability, compatibility with prevalent construction practices, and practical value of recycled glass concrete; and (vi) evaluate the environmental, energy, and cost benefits of recycled glass concrete in different applications and service environments.
Agency: Department of Agriculture | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 460.00K | Year: 2011
The perchlorate generated over decades has impacted our nation's waters; it is environmentally recalcitrant and potentially toxic. Perchlorate has significant effects on irrigated agriculture; it is detected in vegetables and dairy food products. Perchlorate has emerged as a significant threat to public health. Substantial efforts are devoted to perchlorate removal and also to its identification down to the lowest possible limit of detection (LoD). The US Environmental Protection Agency (EPA) has recently (in February 2011) announced its decision to set a first-ever national standard for perchlorate. Standard methods for perchlorate detection using ion chromatography or mass spectrometry are costly and time-consuming, and require professional laboratory operators. There is a strong need and opportunity to develop simple and inexpensive analytical methods for rapid field detection of perchlorate. The focus of this project is on development of an simple, inexpensive and highly sensitive nano-biosensor for rapid detection of perchlorate down to 1 ppb. This biosensor will suit field use, laboratory applications, and on-line monitoring; it facilitates cost-effective and convenient monitoring of perchlorate in groundwater, soil, drinking water, food and beverages. It will make important contributions towards improvement of public health. Three primary market segments have been identified for the technology: water quality testing, food safety evaluation, and remediation. In addition, the nano materials developed and investigated in the project for perchlorate biosensor would serve as a protocol for other species-selective bio-interfaces suiting detection of other environmental contaminates (e.g., nitrate).
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 99.99K | Year: 2010
The main thrust of the proposed research is to develop a new class of high-performance pressure-sensitive adhesives for use with aircraft appliqué films. Our approach merges the conventional pressure-sensitive adhesives technology with recent advances towards development of dry adhesives inspired by the nano-fibrillar structure of gecko-foot. Nano-texturing of pressure-sensitive adhesives is proposed here as a means of producing conformable surfaces which can establish thorough intermolecular contacts with rough substrates under pressure without requiring a liquid-type fluidity. The merger of the two (pressure-induced) adhesion mechanisms would complement the powerful and highly versatile contact mechanics of nano-fibrillar structures with the high adhesion energy and peel resistance of pressure-sensitive adhesives associated with their cavitation/fibrillation during debonding. The conformable nano-textured surfaces would remove a major constraint (the need for liquid-type fluidity) against optimum formulation and processing of pressure-sensitive adhesives with a desirable balance of peel and shear resistance, thermal and chemical stability, and repositionability and removability for use with aircraft applique films. The proposed Phase I research will verify the benefits of nano-texturing to pressure-sensitive adhesives, and will demonstrate the potential to refine the formulations and processing conditions of nano-textured pressure-sensitive adhesives to suit aircraft appliqué film applications.
Lu J.,Technova Corporation
Applied Biochemistry and Biotechnology | Year: 2011
Diminishing fossil fuel reserve and increasing cost of fossil hydrocarbon products have rekindled worldwide effort on conversion of lignocellloloses (plant biomass) to renewable fuel. Inedible plant materials such as grass, agricultural, and logging residues are abundant renewable natural resources that can be converted to biofuel. In an effort to mimic natural cellulolytic- xylanolytic microbial community in bioprocessing of lignocelluloses, we enriched cellulolytic-xylanolytic microorganisms, purified 19 monocultures and evaluated their cellulolytic-xylanolytic potential. Five selected isolates (DB1, DB2, DB7, DB8, and DB13) were used to compose a defined consortium and characterized by 16S ribosomal RNA gene sequence analysis. Nucleotide sequence blast analysis revealed that DB1, DB2, DB7, DB8, and DB13 were respectively similar to Pseudoxanthomonas byssovorax (99%), Microbacterium oxydans (99%), Bacillus sp. (99%), Ochrobactrum anthropi (98%), and Klebsiella trevisanii (99%). The isolates produced an array of cellulolytic-xylanolytic enzymes (filter paper cellulase, β-glucosidase, xylanase, and β-xylosidase), and significant activities were recorded in 30 min. Isolates DB1 and DB2 displayed the highest filter paper cellulase: 27.83 and 31.22 U mg-1, respectively. The highest β-glucosidase activity (18.07 U mg-1) was detected in the culture of isolate DB1. Isolate DB2 produced the highest xylanase activity (103.05 U mg-1), while the highest β-xylosidase activity (7.72 U mg-1) was observed with DB13. Use of microbial consortium in bioprocessing of lignocelluloses could reduce problems such as incomplete synergistic enzymes, end-product inhibition, adsorption, and requirement for high amounts of enzymes in direct use of enzymes. © 2010 Springer Science+Business Media, LLC. Source