Metabolic Engineering

Metabolic engineering involves altering intracellular metabolic pathways and controlling carbon flow through these pathways. The internal regulatory mechanisms used by cells to control carbon flow are complex and may vary with environmental conditions and time. For fermentation engineering, stoichiometric models and neural networks are being used to estimate important physiological-state variables (e.g., specific glucose uptake rate) during fed-batch fermentations. The ability to estimate such variables on-line allows control strategies to target the physiological state of the cells, rather than environmental variables. For investigation of metabolic diseases (e.g., diabetes), differential pathway fluxes for normal and diseased systems are being determined. Knowledge of the underlying metabolic regulation patterns provides insight into the cause and potential treatments.

Multiphase Biocatalysis

Development of biocatalytic processes involving nonpolar reactants often requires a multiphase approach in which a nonpolar phase is dispersed in the continuous aqueous phase. In such cases, interphase mass transfer is often the rate-limiting step. The mass-transfer rate can be increased by using an emulsifier to create and stabilize dispersions having micron-sized droplets or bubbles. However, the stability imparted by the emulsifier hinders efforts to break the dispersions and recover the phases after the reaction step is complete. Novel polymeric emulsifiers are being used to produce dispersions that can be coalesced on demand by a small change in pH. The size distributions, coalescence rates, and mass-transfer properties and of these dispersions are being measured. The emulsifier-stabilized shell surrounding the dispersed phase is being characterized using freeze-fracture electron microscopy and microcalorimetry. Multiphase biocatalytic systems under development include and chiral biotransformations of nonpolar substrates and use of microbubbles in fermentations.

Nanostructured Biomimetic Interfaces

Cell membranes efficiently perform many molecular-scale processes, including catalysis, molecular transport, recognition, signal transduction, and energy generation. These processes can be mimicked in the laboratory using biomimetic interfaces that consist of synthetic lipid bilayers with embedded membrane proteins. For this approach to be commercially exploited, biomimetic interfaces must be developed that are versatile, for use with diverse classes of proteins; customizable, for use in diverse applications; robust, for long lifetime; and mass-producible, for inexpensive fabrication. Multidisciplinary research involving several science and engineering laboratories is underway with the following objectives: (1) Express and purify membrane proteins, including dehydrogenase enzymes, Major Facilitator Subfamily (MFS) transporter proteins, and gated ion channels; (2) Develop functional and nanostructured biomimetic interfaces containing these proteins; (3) Apply physical, electrical, and optical methods to measure, and optimize, performance properties of the biomimetic interfaces; (4) Develop practical devices and processes based on the biomimetic interfaces, including biosensor arrays and biocatalytic systems.

Protein Expression

Proteins needed for research and commercial applications can be produced by cells grown in bioreactors. The MSU Protein Expression Laboratory was established with funding from the Michigan Technology Tri-Corridor as a research and service facility for recombinant protein expression. Research focuses on developing process control schemes that can determine the cells' physiological state during growth and protein expression and control the physiological state so as to optimize protein production levels.

Reviewed Journal Publications

Gao, F.; Sui, D.; Garavito, R. M.; Worden, R. M.; Wang, D. H. "Salt Intake Augments Hypotensive Effects of Transient Receptor Potential Vanilloid 4: Functional Significance and Implication," Hypertension, 53, 228-235 (2009).

Hassler, B. L.; Amundsen, T. J.; Zeikus, J.G.; Lee, I.; Worden, R.M. "Versatile Bioelectronic Interfaces on Flexible Non-conductive Substrates," Biosensors and Bioelectronics 23, 1481-1487, (2008).

Lu, J.; Do, I.; Drzal, L. T.; Worden, R. M.; Lee, I. "Nanometal-Decorated Exfoliated Graphite Nanoplatelet Based Glucose Biosensors with High Sensitivity and Fast Response," ACS Nano 2, 1825-1832, (2008).

Jadhav, S. R.; Sui, D. X.; Garavito, R. M.; Worden, R. M. "Fabrication of highly insulating tethered bilayer lipid membrane using yeast cell membrane fractions for measuring ion channel activity," Journal of Colloid and Interface Science 322(2), 465-472, (2008).

Jadhav, S. R.; Zheng, Y.; Garavito, R. M.; Worden, R. M. "Functional Characterization of PorB class II Porin from Neisseria meningitidis using Tethered Bilayer Lipid Membrane," Biosensors and Bioelectronics, 24(4), 831-835, (2008).

Lu, J.; Drzal, L.T.; Worden, R.M.; Lee, I. "Simple Fabrication of a Highly Sensitive Glucose Biosensor Using Enzymes Immobilized in Exfoliated Graphite Nanoplatelets Nafion Membrane," Chemistry of Materials 19, 6240-6246 (2007).

Kohli, N.; Worden, R.M.; Lee, I. "Direct Transfer of Preformed Patterned Bio-Nanocomposite Films on Polyelectrolyte Multilayer Templates," Macromolecular Bioscience 7, 798-797, (2007).

Hassler, B.; Kohli, N.; Zeikus, J.; Lee, I.; Worden, R.M. "Renewable Dehydrogenase Based Interfaces for Bioelectronic Applications," Langmuir 23, 7127 -7133 (2007).

Kohli, N.; Sivastava, D.; Sun, J.; Richardson, R.J.; Lee, I.; Worden, R.M. "Nanostructured Biosensor for Measuring Neuropathy Target Esterase Activity," Analytical Chemistry 79, 5196-5203, (2007).

Hassler, B. L.; Dennis, M.; Laivenieks, M.; Zeikus, J. G.; Worden, R. M. "Mutation of Tyr-218 to Phe in Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase: Effects on bioelectronic interface performance," Applied Biochemistry and Biotechnology 143(1), 1-15, (2007).

Curtis-Fisk, J.; Preston, C.; Zheng, Z. X.; Worden, R. M.; Weliky, D. P. "Solid-state NMR structural measurements on the membrane-associated influenza fusion protein ectodomain," Journal of the American Chemical Society 129(37), 11320-+, (2007)

Curtis, J. L.; Preston, C.; Weliky, D.; Worden, R. M.; Garavito, R. M. "Structural analysis of membrane-associated influenza fusion protein by solid state NMR," Biophysical Journal, 182A-182A, (2007).

Kohli, N.; Vaidya, S.; Ofoli, R.Y.; Worden, R.M.; Lee, I. "Arrays of Lipid Bilayers on Patterned Polyelectrolyte Templates," Journal of Colloid and Interface Science 301, 461-469, (2006).

Hassler, B.L. and Worden, R.M. "Versatile Bioelectronic Interfaces Based on Heterotrifunctional Linking Molecules," Biosensors & Bioelectronics 21(11), 2146-2154, (2006)

Kohli, N.; Hassler, B.L.; Parthasarathy, L.; Richardson, R.J.; Ofoli, R.Y.; Worden, R.M.; Lee, I. "Tethered Lipid Bilayers on Electrolessly Deposited Gold for Bioelectronic Applications," Biomacromolecules 7, 3327-3335, (2006).

Roush, C. J.; Lastoskie, C. M.; Worden, R. M. "Denitrification and chemotaxis of Pseudomonas stutzeri KC in porous media," Journal of Environmental Science & Health, Part A 41, 1-17, (2006).

Kohli, N.; Worden, R. M.; Lee, I. "Intact Transfer of Layered, Bionanocomposite Arrays by Microcontact Printing," Chemical Communications 3, 316-318, (2005).

Baber, T.; Briedis, D.; R.M. Worden, "The Positive Influence of the College Teaching Certificate Program and other Teaching and Mentoring Opportunities at Michigan State University: A Doctoral Student's Perspective," Chemical Engineering Education 38, 250-253, (2004).

Kohli, N.; Dvornic, P. R.; Kaganove, S. N.; Worden, R. M.; Lee, I. "Nanostructured Cross-linkable Micropatterns via Amphiphilic Dendrimer Stamping," Macromolecular Rapid Communications 25(9), 935-941 (2004).

Worden, R.M.; Briedis, D.; Lira, C.T. "Graduate Bridging and Continuing Education in ChE via the Internet," Chem. Engin. Ed. 35(4), 230, (2001).

Books, Chapters, Monographs

Richardson, R. J.; Worden, R. M.; Makhaeva, G. F. "Biomarkers and biosensors of delayed neuropathic agents," In Handbook of Toxicology of Chemical Warfare Agents; Gupta, R., Ed., Academic Press/Elsevier 859-876, (2009).

Conference Proceedings

Jadhav, S. R.; Worden, R. M. "Interaction of Polyamidoamine (PAMAM) nanoparticles with the glassy carbon supported bilayer lipid membrane," NSTI 2008, Boston, MA, June 1-8, 2008, NSTI, (2008).

Baber, T.; Briedis, D.; Worden, R.M. "Teaching and Mentoring Training Programs at Michigan State University: A Doctoral Student's Perspective," Proc. of the 2005 ASEE Conference and Exposition: Portland, OR, (2005).

Baber, T.; Briedis, D.; R.M. Worden, "Teaching and Mentoring Training Programs: A Doctoral Student's Perspective," Proc. of the 2004 ASEE Conference and Exposition, Salt Lake City, UT, June 20-23, 2004.

Kohli, N.; Vaidya, S.; Ofoli, R.Y.; Worden, R.M.; Lee, I. "3-D Bionanocomposite Surfaces and Interfaces: Fabrication and Characterization," Polymer Preprints 45(1), 124-125, (2004).

Worden, M.R.; Briedis, D. "Institutionalizing the Multidisciplinary Laboratory Experience, "Proc. of the 2003 ASEE Conference and Exposition, Nashville, TN, June 22-25, (2003).

Kohli, N.; Kim, P.; Mason, A.; Lee, I.; Ofoli, R.Y.; Worden, R. M. "Nanoscale Sensing for Biological and Environmental Applications," Proceedings of the Sensors Topical Conference, Annual Meeting of the AIChE, San Francisco, CA, Nov. 16-21, 2003, AIChE:New York, (2003).

Kim, P.; Kohli, N.; Hassler, B.; Dotson, N.; Mason, A.; Worden, R. M.; Ofoli, R. "An Electrochemical Interface for Integrated Biosensors," Proc. IEEE Int. Conf. on Sensors, Toronto, Canada, October (2003).

Kohli, N.; Hassler, B.; Vaidya, S.; Parthasarathy, L.; Ofoli, R.Y.; Lee I.; Worden, R.M. "Biomimetic Interfaces for Integrated Biosensor Arrays," Proceedings of Sensors Topical proceedings of 2003 Annual Meeting of the American Institute of Chemical Engineers."