REU: IDEA Incubator in Porous Materials
The Dhar Lab studies molecular interactions at interfaces that occur in pharmaceutical and biological systems. She focuses primarily on the mechanical and morphological changes in lipid-protein mixtures due to interactions with various porous materials, such as toxic materials that lead to bronchial dysfunction in the lungs. The Allgeier Lab studies adsorption phenomena utilizing time-domain nuclear magnetic resonance (NMR) measurements and other techniques. Using biophysical and analytical techniques unique to both labs (such as an interfacial viscosity measurement device coupled to a fluorescence microscopy, high resolution imaging techniques such as AFM, and low-field NMR), students will measure changes in model membrane structures when they interact with porous materials. Projects will study the impact of soft vs. hard porous materials on biological systems, particularly cell membranes, in an effort to access the cytotoxicity of these novel materials.
Students will learn about and personally utilize advanced scientific instrumentation including biophysical tools such as a Langmuir trough, custom designed to be coupled with fluorescence microscopy and a low-field NMR to characterize porous material interactions with biomolecules. Further, they will learn to (a) to interpret data, elucidating the basics of biomolecule / porous particle interactions (b) the significance of health impacts of our studies and (c) fundamentals of both biomedical and chemical engineering fields where concepts learned in their coursework will be applied in a research setting (e.g. thermodynamics, fluid mechanics).
Characterizing Porous Materials
Mentor: Dr. Alan Allgeier
Research Overview: While many porous materials comprise inorganic structures that are resistant to shrinking, many polymeric porous materials lose their porous structure when water is removed from their pores (just like a sponge undergoes shrinking upon evaporation). Such materials are called meta-stable porous materials. They present a challenge for typical characterization techniques, which only interrogate dried solid materials. Dr. Allgeier uses a technique known as low-field nuclear magnetic resonance (LF NMR). He gained this specialized expertise during his prior employment with DuPont Chemical Company. Hydrogels are important examples of meta-stable porous materials and are employed in a number of biomedical applications from contact lenses to drug delivery and wound care. The performance of hydrogels are dependent upon their porosity, e.g. in drug delivery reduced pore sizes can restrict the rate of drug diffusion into the body.
Students will learn how to use various instruments, including the LF-NMR to detect differences in hydrogel porosity and X-ray micro-computed tomography (XµCT). Since XµCT relies on density contrast in imaging and hydrogels have high permeability, the density of the aqueous phase may be increased with added iodide salts. A comparison of XµCT and LF-NMR data from wetted porous media and electron microscopy images of lyophilized (dried) samples will be constructed and considered in light of mechanical and transport (e.g. drug release) properties of hydrogel samples to define the utility of the various analytical methods.
Stabilizing Vaccines with Porous Materials
Mentos: Dr. Mark Shiflett
Research Overview: Vaccines degrade at elevated temperatures because the proteins in the vaccine unfold and lose their functional structure. Vaccine storage and distribution therefore relies on a “cold chain” of continuous refrigeration which is costly and not always effective, as any break in the cold chain can lead to rapid loss of vaccine effectiveness. Dr. Shiflett’s group is developing new techniques to deposit vaccines in the pores of mesoporous silica in order to stabilize the protein from the effects of elevated temperature. The pores constrain the movement of the protein preventing the loss of structure, and subsequently the protein is released back into solution using detergents with the structure and function intact. Dr. Shiflett’s group is currently patenting a material, which is effective for stabilizing a vaccine used to treat Shigellosis.
The REU students working on this project will learn about vaccines and mesoporous silica materials with pore sizes capable of capturing and storing proteins. Students will learn how to characterize the silicas’ surface area, pore size and volume using a Micrometrics ASAP instrument, and how to deposit proteins in silicas using wet impregnation methods. The students will be taught how to measure the amount of protein deposited by measuring the difference in solution using a NanoDrop 2000 UV-vis and how to characterize the secondary protein structure using circular dichroism. They will also learn how to invent new products and how to write patents.
Nano- and microfibers for tunable drug delivery and tissue engineering
Mentor: Dr. Jennifer Robinson
Research Overview: Postmenopausal women experience osteoarthritis (OA) at a higher rate than age-matched men suggesting estrogen deficiency may play a role in the pathogenesis. Hormone replacement therapy with estrogen delivered systemically is the current standard of care but often increases the risk for breast cancer. Thus, targeted release of an estrogen receptor (ER) agonist is hypothesized to promote anabolic effects and reduce detrimental side effects. To address this hypothesis, Dr. Robinson’s group seeks to develop porous fibrous meshes that mimic the fiber structure of native extracellular matrix. By engineering these materials to controllably release ER agonists, they will promote regeneration and provide relief to patients with OA.
Students will create use electrospinning emulsion solutions to create fibrous meshes, and then assess fiber morphology, alignment, and pore architecture. Further, students will determine the release kinetics of a model protein as a function of pore size and interconnectivity.
Porous, soft materials for single-cell capture and gene sequencing
Faculty Mentor: Dr. Brandon DeKosky
Research Overview: Single-cell analysis has the potential to reveal the complex workings of biological systems for addressing a broad range of human health issues, particularly in the area of vaccines and immune responses. However, technologies available for single-cell analysis are often slow, expensive, and limited to a small number of measurements for a single sample. Soft materials have the potential to be applied as massively parallel microreactors for cell capture and gene sequencing, and could permit a tremendous leap in the ability to understand single-cell systems on a comprehensive scale.
To address this gap, REU students in the DeKosky lab will help to advance new soft material technologies for the comprehensive genetic analysis of adaptive immune responses. Students will develop and apply advanced knowledge of materials and biology to achieve single-cell capture and comprehensive gene sequencing using several test experimental systems, permitting the optimization and discovery of new tools for single-cell analysis. This work will enable advanced understanding of human immune responses in the settings of health and disease and provide REU students with a new set of skills in soft materials as applied to biological systems analysis. Students will learn to combine the synthesis and analysis of soft material properties with advanced toolkits in molecular biology, gaining skills in droplet stability and hydrogel chemistry, single-cell isolation and genetic analysis, and fundamental aspects of immune responses as related to vaccination, natural infection, cancer, autoimmunity, and other disease states.
3D Design and microfabrication of biomaterials
Faculty Mentor: Dr. Mei He
Research Overview: Preparation of synthetic, three-dimensional living tissues has the potential of advancing biomedical studies by improving reproducibility and reducing the need for live animal studies. However, to be effective such biomimetic tissue must precisely define the complex three-dimensional changes of cell types in microenvironments that naturally occurs in vivo. To address this technology gap, Dr. He’s group is actively developing peptide hydrogels for use with additive printing technology to create 3D tissue scaffolding. Scaffold pore geometries, interpore distances, and pore connections are some of the variables that influence 3D cell growth. The design of the scaffold building blocks is modeled using 3D computer-aided design and computational fluid dynamics simulations, to ensure the biomimetic tissues will meet the transport requirements of growth factors, nutrients, and waste products.
The REU students will design and determine the porous peptide hydrogel microstructures that can be 3D printed at the microscale level, and predict the influence of scaffold microstructures on cell functional performance. They will gain skills and knowledge in state-of-the-art 3D additive manufacturing for biological systems, learning about various pore shapes and sizes along with biocompatibility, adhesion and sterilizability issues.
Porous materials for the electrocatalytic conversion of H2O into H2 and O2
Faculty Mentor: Dr. Kevin Leonard
Research Overview: Splitting water into hydrogen and oxygen by electrocatalysis plays a vital role in converting solar energy into chemical energy, and it provides a pathway to use water (as opposed to natural gas) as a feedstock for hydrogen production. Traditional electrocatalysts are composed of rare and expensive noble metals (Pt, Ru, Ir). To be environmentally and economically viable, we need to discover robust electrocatalysts that instead use less expensive, earth-abundant materials. Dr. Leonard’s group recently developed a new way to synthesize porous nanoamorphous (Ni, Fe) oxide structures. The technique uses microwaves, and it has recently been shown to result in catalytic activity that can out-perform the traditional synthesis method that creates layered double hydroxide structure.
Students will prepare electrocatalysts using Dr. Leonard’s novel method. They will gain hands-on experience with cyclic voltammetry, gas chromatography, and electron microscopy (SEM and TEM) instruments, learning to interpret data and consider economic/sustainability impacts for commercial viability of new innovations.
Supported Ionic Liquid Phase (SILP) Catalysis
Research Overview: Hazardous acidic or basic catalysts in industrial scale processes need safer alternatives. One such example is the alkylation of isoparaffin to produce high-octane gasoline, which is catalyzed by concentrated hydrofluoric or sulfuric acids, using roughly the same volume of acid as the hydrocarbon. This not only adds cost to the process to make and regenerate the acid; but more importantly, refineries must manage the large quantities of waste acid to avoid serious harm to the environment.
A new system called Supported Ionic Liquid Phase (SILP) catalysis has been proposed as an alternative to these hazardous acids. While SILPs have been applied to a number of different reactions, Dr. Scurto’s group uses a liquid mixture of a non-volatile and molecularly-tunable ionic liquid and soluble catalyst to coat a solid support at the micro-/meso- scale (Figure 7). The IL phase sequesters and influences the reaction and separation for many potential catalysts, while the solid support provides large surface area for increased mass transfer over traditional gas-liquid or liquid-liquid processes. This also reduces the amount of ionic liquid used in the process, improving the economics [59-70].
Students will learn how to synthesize SILPs with different ionic liquids to explore gas phase C4 alkylation. They will learn how to characterize the catalysts with specialized equipment, such as a tapered element oscillating microbalance (TEOM).
Mesoporous solid acid catalysts for alkylation and dehydration reactions
Faculty Mentor: Dr. Bala Subramaniam
Research Overview: Solid acids are used as catalysts for a wide range of industrial chemical processes, such as the alkylation of isobutene with olefins to generate high octane blending stocks for premium gasoline. Zeolites are the most common type of solid acid. However, these materials will not work with bulkier substrates or products since the pore diameter is so small (<2 nm). A mesoporous material, with a pore diameter of 2-50 nm, is needed to facilitate diffusion and conversion of bulkier substrates and products.
Dr. Subramaniam’s group has synthesized new solid acid catalysts by incorporating metals into ordered mesoporous silicas. The REU students will have the chance to explore various applications for these materials, such as the alkylation of 1-butene and isobutane (shale gas derived reactants) to isooctane (a gasoline additive) and the dehydration of biomass-derived glycerol to acrolein (a polymer precursor). Students will learn how to synthesize and evaluate these catalytic materials using GC/FID and HPLC techniques, thermogravimetric analysis, and N2 physisorption. Dr. Subramaniam has expertise in conducting economic and life cycle assessments, and students will learn how understanding such data is critical for effective research and business decision-making.
Catalysts for gas adsorption and reaction
Faculty Mentor: Dr. Juan Bravo-Suarez
Research Overview: Producing fuels and chemicals depends on porous solid catalysts to facilitate reactions. A common reaction for catalysts is dehydrating alcohols to olefins, indeed, this is the key step to making polyethylene from bio-renewable resources for plastics and synthetic fibers. Dr. Bravo-Suarez’s group seeks to synthesize and test various combinations of mixed metal oxides (MMO) as catalysts for this reaction. His group modifies the porosity and surface composition of catalysts and uses advanced analytical techniques for characterization.
Students will learn about catalyst structure using principles of solid-state inorganic chemistry and will also gain experience with cutting-edge analytical methodologies. They will also learn how to use Dr. Bravo-Suarez’s specialized equipment including ultraviolet-visible, Fourier transform infrared, and Raman spectrometers.
Aluminosilicate zeolite catalysts with encapsulated metal or metal oxide nanoparticles
Faculty Mentor: Dr. Franklin Tao
Research Overview: Many hydrocarbon transformations are performed at blazing hot conditions (>600°C), which often leads to coke formation on the catalyst. When this happens, the carbon layers of coke block access of reactants to the catalytic sites, which deactivates the catalyst. Dr. Tao’s group focuses on developing efficient nanocomposite catalytic systems. Here, they seek to prevent catalyst deactivation by developing a zeolite-based catalyst with encapsulated metal or oxide nanoparticles in the lattice of the zeolite using a modified hydrothermal method. The encapsulated catalyst particles should be accessible to reactants through microporous channels.
Students will learn how to synthesize these catalysts, test catalytic performance for methane conversion, and characterize the materials using various techniques, such as ICP, X-ray absorption spectroscopy (XAS), high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffractometer, and NMR.
Bimetallic catalysts for oxidation of sugars
Faculty Mentor: Dr. Raghunath V Chaudhari
Research Overview: Dr. Chaudhari’s group has expertise in developing novel bimetallic catalysts for converting bio-derived sugars into valuable products at mild reaction conditions. His research employs reaction kinetics and reactor engineering to investigate the role of the porous structural supports on catalytic activity and selectivity, exploring diffusion of particles through experimental studies using a trickle bed reactor. Students will learn how to synthesize and characterize bimetallic catalysts and develop correlations between porous structure and catalytic performance for liquid phase oxidation reactions. Furthermore, they will learn how sugars derived from biomass can be used as a renewable feedstock for commodity chemicals, which requires innovative-thinking. Students will also gain experience with lab techniques (e.g., GC and HPLC) and learn about fundamentals concepts like kinetics and reactor modeling.