Tag: Spring 2011

Intrinsic fluorescence to guide characterization and purification of stem cells

Friday April 22

Chem. Sci. & Engineering Room 211

10:00 am

Presenter: Dr. Brenda M. Ogle, Assistant Professor Biomedical Engineering University of WisconsinMadison

Abstract: Advances in cell research and cell therapies, such as repair of cardiac tissue following infarction, depend on technologies that accurately and non-invasively assess cell state, both as single cells and as 3D entities, with the potential to sort populations based on this assessment.  Defining intrinsic biomarkers that characterize stem cell state advances this goal by reducing the need for extrinsic labels. Several pieces of evidence suggest that pluripotent cells are metabolically different than differentiated cells.  Therefore, we propose that endogenous fluorophores, which are often involved in key metabolic processes and are noninvasively detectable by advanced optical methods, would exhibit different fluorescent properties in pluripotent cells than in their differentiated counterparts, thereby serving as a unique, intrinsic indicators of differentiation state. Indeed, we have identified changes in the fluorescent properties of stem cells during differentiation, utilizing multiphoton optical analysis, with its ability to probe deep within multicellular aggregates, and Fluorescence Lifetime Imaging.  Using a wavelength to excite nicotinamide adenine dinucleotide (NADH) we found that the fluorescence lifetime of NADH decreases during the initial timecourse of differentiation, in both mouse and human embryonic stem cells.  Furthermore, cardiomyocytes developed from human embryonic stem cells exhibit longer fluorescence lifetimes than non-beating cells. We are currently combining these observations with a modular, stage-mounted multiphoton flow cytometry system that could ultimately sort cellular aggregates, such as embryoid bodies or engineered constructs, based on such endogenous fluorescence signatures.

Ex-Situ Mineral Carbonation at Ambient Conditions with Industrial Waste in a Carbonate Solution

1. Brett Spigarelli,Ph.D. Candidate Chemical Engineering
“Ex-Situ Mineral Carbonation at Ambient Conditions with Industrial Waste in a Carbonate Solution”
2. Kaela Leonard, Ph.D. Candidate Chemical Engineering
“Dielectrophoretic Characterization of Human Erythrocytes within a Microdevice” 10:00 a.m., Chem. Sci. & Engineering, Room 211

Mutant alcohol dehydrogenase leads to improved ethanol tolerance in Clostridium thermocellum

Friday March 25
Chem. Sci. & Engineering Room 211
10:00 am

Presenter: Dr. Steven D. Brown, Oak Ridge National LaboratoryBio Energy Science Center

Abstract: The BioEnergy Science Center (BESC) is focused on the fundamental understanding and elimination of biomass recalcitrance. BESC’s approach to improve accessibility to the sugars within biomass involves 1) designing plant cell walls for rapid deconstruction and 2) developing multitalented microbes for converting plant biomass into biofuels in a single step (consolidated bioprocessing).Fuels from cellulosic biomass are among the leading options to meet sustainability and energy security challenges associated with fossil fuels, and conversion processes featuring biological fermentation are among the leading options for producing cellulosic biofuels. Among fermentation-based conversion processes, use of cellulose-fermenting microorganisms without added enzymes – consolidated bioprocessing or CBP – has strong potential and a variety of microorganisms are under development. Clostridium thermocellum is a model thermophilic bacterium that can rapidly solubilize biomass and utilize cellulose as a carbon and energy source. Wild-type strains produce ethanol as well as organic acids but growth is inhibited by relatively lowethanol concentrations (<10 g/L). Cultures of C. thermocellum have been adapted to tolerate ethanol concentrations as high as 80 g/L, and while greater ethanol production has been reported for tolerant strains the highest concentration of ethanol productionreported for this organism is < 30 g/L. We have developed and characterized C. thermocellum mutant strains that can grow in the presence of up to 50 g/L ethanol. One study utilized a distinctive strategy of alternating between increasingly stringent selections for greater ethanol tolerance and relaxation of selection pressure. By this strategy, the adapted strains retained their ability to grow on either cellobiose or crystalline cellulose, and displayed a higher growth rate and biomass yield than the wild-type strain in the absence of ethanol. Another strain, selected with only increasing doses of ethanol, was more tolerant to ethanol but grewpoorly. Several systems biology studies elucidated key metabolites, genes and proteins that form the foundation of its distinctive physiology and the multifaceted response to ethanol stress for the C. thermocellum wild-type strain and several ethanol tolerant mutant strains. The genomes of three ethanol tolerant mutant strains and a wild-type strain were resequenced, which revealed a mutated bifunctional acetaldehyde-CoA/alcohol dehydrogenase gene (adhE) in each of the mutants. We hypothesized based on structural analysis that cofactor specificity may be impacted, and confirmed this hypothesis using enzyme assays. Biochemicalassays confirm a complete loss of NADH-dependent activity with concomitant acquisition of NADPH-dependent activity, which likely affects electron flow in the mutant strain. The simplicity of the genetic basis for the ethanol-tolerant phenotype observed here informs rational engineering of mutant microbial strains for cellulosic ethanol production.

Fuel Cells, Energy Storage, and Solar Hydrogen: Toward a Safe, Clean, and Sustainable Energy Future

Friday March 18
Chem. Sci. & Engineering Room 211
10:00 am

Presenter: Dr. Yushan Yan, University of CaliforniaDepartment of Chemical and Environmental Engineering

Abstract: The availability of abundant energy has been central to human civilization. Our energy problem today can be summed up in three words: Demand, supply and CO2. Fuel cells coupled with solar hydrogen represent a safe, clean and sustainable energy system that can help significantly alleviate or eliminate the energy supply and CO2 problem. For our fuel cell efforts, we have been focusing on developing catalyst and membrane materials that will help to solve the cost and durability problems, the two most significant commercialization barriers for fuel cells. Our fuel cell work began with the exploration of carbon nanotubes as durable catalyst support. In this presentation, however, I will present our work on platinum nanotubes (PtNT) catalysts that have shown to have significantly improved catalyst durability and activity for oxygen reduction reaction. This catalyst platform has the potential to meet the mass and specific activity targets for vehicle applications specified by the US Department of Energy. I will also present our work on hydroxide exchange membrane fuel cells (HEMFCs) where platinum can be replaced by non-platinum-group-metals such as nickel and silver while the expensive fluorinated Nafion membrane substituted by a hydrocarbon membrane, thus drastically reducing the cost of fuel cells and making them potentially economically viable. The HEMFCs can also expand the fuel source much beyond hydrogen and methanol. Toward the end of this presentation, I will discuss the potential application for HEMs for wind and solar electricity storage and solar hydrogen generation.


Monday February 28
Chem. Sci. & Engineering Room 108
10:00 am

Presenter: Dr. Hamid Ghandehari, University of UtahDepartments of Pharmaceutics & Pharmaceutical Chemistry & Bioengineering

Abstract: One area of active exploration is to exploit advances in nanotechnology for targeted treatment of cancer where efficacy is maximized, adverse effects are minimized and as a consequence quality of life and life expectancy for patients are enhanced. Such approaches often utilize nanoscale polymeric or inorganic constructs to target tumor cells passively (by the enhance permeability and retention effect) or actively by attaching targeting moieties. Advances in nanotechnology and materials science have provided unique opportunities to fabricate drug carriers with a high degree of definition in terms of chemical structure, size, shape, surface properties, etc. The emerging question is whether such high degree of control will enable the design and development of novel drug delivery systems with superior properties compared to existing constructs. To address this question detailed studies at the interface of nano- (materials/characteristics) and biotechnology (whole animal, tissue, cells and subcellular compartments) need to be carried out. Over the past few years we have focused on the design and development of multifunctional nanoconstructs for delivery of bioactive agents to solid tumors. This presentation will be a selected overview of our efforts in the design and development of recombinant polymers for cancer gene therapy [1], evaluating the biodistribution and cellular uptake of inorganic nanoconstructs as a function of geometry, size, charge, and surface properties [2], assessing the influence of generation, concentration, incubation time, and surface properties of poly(amido amine) dendrimers on their cellular transport and toxicity in the context of oral drug delivery [3], and finally design and  development of water-soluble polymer-peptide conjugates for targeted drug delivery to sites of tumor angiogenesis.


Friday February 25
Chem. Sci. & Engineering Room 211
10:00 a.m.

Presenter: Dr. George Antos, National Science FoundationEngineering DirectorateCatalysis and Biocatalysis Program

Abstract: The National Science Foundation, the Departments of Energy and Agriculture and other agencies distribute billions of taxpayer dollars in support of the education, training, and the fundamental and developmental research of scientists and engineers at U.S. universities, national laboratories and companies. This investment enables the continuing delivery of technology to fulfill societal needs and wants.  Some of these needs rise to the level of national needs and challenges, and the popular expectation is that the investments in new technology will deliver progress at addressing them. Energy needs are one of these. The National Science Foundation has a number of energy-focused programs which will be explored in a general overview of some of the NSF Program directions.  To address our national need for renewable transportation energy, agencies have funded research into bio-fuels as an avenue for transportation fuels, petroleum replacement, greenhouse gas control, and environmental benefits. NSF has played a role. How effectively has the overall investment worked to date in the area of biomass-derived fuel replacements for petroleum-derived fuels?  This presentation will provide an overview and some illustrative examples of the technological progress to date, the research gaps remaining, and the opportunities for improved cooperation to achieve the country’s goals for bio-fuel inclusion in the transportation fuel pool.

Coherent Optical Methods for Motion, Flow, and Mechanical Measurement

Friday February 18
Chem. Sci. & Engineering Room 211
10:00 a.m.

Presenter: Dr. Sean Kirkpatrick, Michigan Technological UniversityDepartment of Biomedical Engineering

Abstract: Non-contacting and/or remote sensing of fluid flows, mechanical deformations, and even polymerization reactions is frequently required in a variety of biomedical, industrial and military applications.  Imaging and non-imaging coherent optics provides numerous avenues for making such measurements.  In this presentation, a family of inter-related optical metrology methods that we have developed specifically for biomedical and biomaterials applications will be discussed.  Particular applications that will be presented include assessing tissue mechanics for skin cancer diagnostics, non-invasive blood flow measurements, and monitoring of the polymerization kinetics of rapid-cure dental polymer systems.  The approaches used in these very specific applications are all connected by a common mathematical and physical thread, making the general method readily adaptable to numerous applications both within and outside of biomedicine.

Using Logic Models for Program Planning and Evaluation

Friday February 4
Chem. Sci. & Engineering Room 211
10:00 a.m.

Presenter: Dr. Kedmon Hungwe, Michigan Technological UniversityDepartment of Cognitive & Learning Sciences

Abstract: Developing a logic models is an essential step in program planning and evaluation. The logic model provides a clear representation of the underlying rationale for a project and defines the elements of evaluation. The presentation will discuss approaches that can be applied to the development of logic models. The goal of the presentation is to stimulate thought and encourage adaptations to meet individual needs.