Highly efficient capture technologies used to mitigate CO2 emissions have directed the search for alternative methods with low energy consumption rates. There is an estimated 80% increase in energy cost to operate current CO2 capture technologies. In view of that, while most work is aimed at chemical means to reduce this energy cost, we seek to harness solar energy to improve current CO2 capture solvent desorption efficiency. Recently, we reported a new method to release CO2 from solutions using solar energy to drive localized photothermal heating. Photothermal release of CO2, addresses the high-energy costs associated with regenerating capture fluids. By incorporating light absorbing nanoparticles into the capture fluid and irradiating with light, 80% of the incident light energy is used in CO2 release, rather than heating the bulk fluid. In addition to this work, we sought to understand how the mechanism of photothermal release enhances the efficiency of this process. Through covalent modification of the surface, we explore how surface charge and polarity of the nanoparticles influence the photothermal regeneration of a CO2 capture nanofluid through decarboxylation. By incorporating sulfonamides on the surface of CB, we enhanced the photothermal separation of CO2 from monoethanolamine by approximately 70% more than the unmodified CB.

Global climate change is one of the most pressing issues that we currently face. With

atmospheric CO2 level reaching 400 ppm, they are higher now than at any point in the

last 800,000 years. However, the reduction of CO2 emissions remains a signicant challenge. Current CO2 capture technologies are estimated to increase the cost of energy by 80%. As a result, we seek to nd less costly methods of capturing CO2 from point sources by looking at improving current CO2 capture solvent absorption and desorption eciency. CO2 absorption can be made more ecient by looking towards the avian lung. In that system, hierarchically structured capillaries with high specic surface areas enable more ecient mass transport. We have developed mass transport devices that use these principles for ecient capture of CO2 using a sacricial element fabrication technique. CO2 desorption can be enhanced through the use of waste heat and light absorbing nanoparticles. Microstructures could be formed around hot surfaces in order to capture the emitted waste heat. The smaller size scale of the structures enables more ecient use of the waste heat. Carbon black nanoparticles can generate high local heat gradients in the presence of light. The localized photothermal heat generation enable the use of solar energy to drive CO2 desorption in capture uids in order to reduce energy costs.

Nature, while slow to change, has had the benefit of billions of years competitive pressure to hone approaches to interesting problems. In this work, we take advantage of this preexisting work, and make progress towards replicating the benefits found in nature in artificial systems. Taking inspiration from dynamic, living structures such as bone, and muscle, we demonstrate partial synthetic recreations of the conceptual pieces required to mimic such materials. Diffusion controlled etching is used to demonstrate functional optimization of preexisting structures. Incorporating growth into the system allows dynamic, reversible changes in structure to take place. We show the migration of a channel through a solid matrix. We also took inspiration from deep sea fish to develop a device that concentrates gas more efficiently than a simple countercurrent flow separator. Existing methods including hollow fiber membrane contactors, vacuum swing adsorption, and cryogenic distillation represent a significant portion of the worlds energy needs. Countercurrent amplifiers found in the swimbladders of teleost fish, can efficiently concentrate gases at least 15,000 times above the ambient concentrations. Incorporating the architecture found in the swim bladders of deep sea fish with modern CO2 and O2 capture fluids enables a feedback loop of concentration within our artificial device to drive an increase in the release rates of both gases.

The agonists of Toll-like receptors (TLRs) are interesting targets for vaccine adjuvants and other immunotherapies. One particular challenge in their use is their poor pharmacokinetic properties. Targeted covalent inhibitors have been shown to have irreversible binding with the receptors of interest, leading to high selectivity and potency. These properties are very attractive for TLR agonists. In addition, it is currently not known what effect continuous activation of TLRs will have on immune activation. Drawing inspiration from ligand-directed tosyl chemistry, we have synthesized several potential covalent agonists of TLR 7/8 and evaluated them in biological assays. Additionally, we have made progress in determining if these agonists do indeed proceed through covalent modification of the receptor.

The innate control of adaptive immunity has been the target of various therapeutics. By the chemical modification of the chemical patterns recognized by the Toll-like receptors (TLRs) on innate immune cells, we can further control the systemic immune response. Chemical modifications can be used to control the spatial presentation of multiple TLR agonists by covalent conjugation of two TLR agonists which serve as a synthetic mimic of macromolecular pathogens. Additionally, photocaging of TLR agonists is used to control the spatial and temporal presentation of agonists. These strategies would further provide mechanistic insight in TLR synergy as well as therapeutic insight in modulating the immune response.

For the capture of CO2 from mixed gas streams, materials for increased gas exchange are necessary. Efficient gas exchange systems already exist in the form of vascularized lung-tissue. Herein we report a fabrication technique for the synthesis of three-dimensional microvascular gas exchange units capable of removing CO2 from flowing gas created using the recently reported Vaporization of a Sacrificial Component (VaSC) technique. We demonstrate the spatiotemporal pattern of CO2 reactivity in the microvascular gas exchange unit using colorimetric, pH sensitive dyes. Control over three-dimensional placement of channels is shown to increase capture efficiencies. A computational finite element model validates and explains the experimental observations.

The development of vaccines has resulted in a dramatic decrease in the number of cases of diseases, such as measles and smallpox. With the emergence of Ebola and the Zika virus, there is a greater need for the development of more effective and safer vaccines. However, the challenge with designing new immunotherapies is that little is still known about how vaccines work, since most have been empirically determined. Thus, our group is interested in using chemical tools to probe and understand the immune response with the goal of designing more effective vaccines. Dendritic cells, a vital part of the innate immune system, contain Toll-like receptors (TLRs) that are activated by components of pathogens, such as bacterial oligonucleotides and lipopeptides. These molecules are immune agonists that can act as adjuvants, which help elicit or enhance an immune response toward a non-immunogenic protein antigen, and are commonly used in vaccines. Recent studies indicate that vaccines containing multiple TLR agonists enhance the immune response toward a target pathogen compared to the use of a single ligand. A prime example is the Yellow Fever Vaccine, one of the most successful vaccines, which activates the immune system through four different TLRs. Due to this precedence, we hypothesized that activating specific receptors in a precise spatial manner could modulate how the immune system responds by mimicking natural pathogens and therefore control downstream pathways. My research focuses on synthesizing multi-TLR agonist conjugates to study the spatial organization of multiple TLR agonists and how different combinations of agonists affect the immune response, as observed by cellular and antibody responses. To study the effect of multiple TLR agonists on the immune response, we chemically modified whole cell antigens with different TLR agonists as well as covalently conjugated multiple TLR agonists together to present them in a localized manner. As a result of chemical modification and linkage, we observed distinct changes in immune activation, via cytokine production and antibody responses, suggesting implications for downstream immune system signaling. We are applying our findings to more rationally develop safer and more effective vaccine adjuvants and immunotherapies.

Toll-like receptors (TLRs) on innate immune cells are important in the early detection of pathogens and initiation of immune responses. Spatial and temporal aspects of signaling via these receptors are critical in defining unique and effective immune responses. These factors, however, are not well-characterized and there are currently no methods yet to probe them. Herein, I describe approaches developed by the Esser-Kahn lab to address spatial and temporal activation of immune pathways. We have designed photo-labile immunostimulants for controlled activation of cells in space and time. Variants of pyrimido indoles (TLR4 agonist), imidazoquinolines (TLR7 and 8 agonists), and palmitylated-peptides (TLR1, 2, and 6 agonist) were generated with photo-labile protecting groups installed at moieties necessary for productive receptor interaction. We demonstrate controlled activation using light of the NF-κB pathway in RAW macrophages, bone marrow-derived dendritic cells, and TLR-bearing fibroblasts.

We report that photothermal heating of nanoparticles in solution can be achieved via a superheated state of the particles. This state creates nanoscale reaction zones around the particles that reach reaction temperatures far above the bulk solution temperature. These heterogeneous reaction systems improve efficiency in heat driven reactions and the length scale of heating provides new reaction dynamics. To test if these reaction conditions were amenable to traditional organic reactions, we tested if photothermal heating of nanoparticles initiated a radical polymerization. Radical-initiated polymerization of acrylates is a well-studied process initiated heating molecules that decompose into radicals. These radicals, in turn, go on to begin the polymerization process. We report a method where radical polymerization is initiated via photothermal heating of carbon black nanoparticles using a solar simulator. These polymerizations proceed five times faster than polymerizations held at the same measured bulk temperature. Additionally, uniform fibrous morphologies appear at the micron scale when the polymer is examined via SEM. Finally, we report that the photothermal heating acceleration of benzoyl peroxide decomposition results in an order of magnitude increase in reaction rate over bulk heating.