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results)</h2></header><div class="c-sortpagination"><div class="c-sort"><div class="o-input__droplist1"><label for="c-sort1">Sort By:</label><select name="sort" id="c-sort1" form="facetForm"><option selected="" value="rel">Relevance</option><option value="a-title">A-Z By Title</option><option value="z-title">Z-A By Title</option><option value="a-author">A-Z By Author</option><option value="z-author">Z-A By Author</option><option value="asc">Date Ascending</option><option value="desc">Date Descending</option></select></div><div class="o-input__droplist1 c-sort__page-input"><label for="c-sort2">Show:</label><select name="rows" id="c-sort2" form="facetForm"><option selected="" value="10">10</option><option value="20">20</option></select></div></div><input type="hidden" name="start" form="facetForm" value="0"/><nav class="c-pagination"><ul><li><a href="" aria-label="you are on result set 1" class="c-pagination__item--current">1</a></li><li><a href="" aria-label="go to result set 2" class="c-pagination__item">2</a></li></ul></nav></div><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/1j61h9tq"><div class="c-clientmarkup">Control and Modeling of Imbibition in Paper-Based Microfluidic Devices</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3AModha%2C%20Sidharth">Modha, Sidharth</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2022)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>Access to medical care is a significant challenge facing developing countries. The World Health Organization developed the ASSURED criteria, which specifies requirements for the ideal diagnostic. ASSURED stands for Affordable, Sensitive, Specific, Rapid/Robust, Equipment-free and Deliverable. Traditional microfluidic diagnostics (comprised of glass/PDMS) require expensive fabrication procedures and user-intervention to manipulate fluids on the device. For those reasons, paper shows great promise as a substrate for an ASSURED microfluidic diagnostic. It is affordable and does not require external pumping to move fluids. Initially, microfluidic paper-based analytical devices (μPADs) performed simple, colorimetric assays. However, the field has evolved rapidly. Modern μPADs have been developed for a plethora of applications such as nucleic acid amplification. Wider adaptation of μPADs relies on the incorporation of more complicated assays (i.e. involving multiple fluids), which would allow μPADs to replace more expensive benchtop equipment. This requires more robust fluid control. Typically, fluid control on μPADs has been achieved by slowing fluid down to create delays between different channels. However, adding delays increases overall assay time and creates other complications such as fluid loss due to evaporation. Instead, creating ‘delays’ by accelerating wicking (relative to native paper) is being investigated. Previous approaches include sandwiching the paper between polymer films or creating ‘macro capillaries’ within the paper for the liquid to flow through. Of particular interest is the etching of grooves onto paper channels using either a plotter or a CO2 laser. These grooves create hollow regions in the paper which lead to faster wicking speeds. This study aims to characterize the behavior of grooved channels in paper and assess their performance as ‘delay’ mechanisms for a multi-fluid paper-based sensor. Typically, μPAD designs evolve in a trial-and-error basis, where devices are fabricated, tested and updated. Having accurate models that characterize the imbibition process could streamline development by allowing direct translation of in-silico designs to fully-functioning paper-based tools. Current imbibition models do not adequately describe the complex transport phenomena occurring within the paper matrix. This study also aims to develop an in-silico simulation that can reliably predict imbibition in both native paper and grooved channels. </p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/1j61h9tq"><img src="/cms-assets/1788345f432a01c5a53d33b2f3e95ecc5b31c315355274d96c71f583a7976d43" alt="Cover page: Control and Modeling of Imbibition in Paper-Based Microfluidic Devices"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/67f3692n"><div class="c-clientmarkup">Imbibition in Paper-Based Microfluidic Devices</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3ACastro%2C%20Carlos">Castro, Carlos</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2016)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>Point-of-care technologies provide innovative solutions that improve treatment. Healthcare systems including some low-resource settings have begun implementing these technologies providing the convenience and reduction of large laboratory set-ups. Low-cost is one of the main driving components when it comes to point-of-care diagnostics. Paper-based microfluidics has generated a great amount of interest for the development of low-cost diagnostic and self-contained analytical devices. Satisfying the World Health Organization’s (WHO) recommended ASSURED criteria; Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment free, Deliverable, paper-based microfluidics have made point-of-care testing more accessible. Applications range from healthcare, food safety, and environmental monitoring, among others. What has in part attracted attention is the low-cost, ease-of-use, and adaptability of these paper devices. Compared to conventional microfluidic devices, the paper-based counterparts are able to utilize paper’s inherent wicking property to eliminate the external pumping needed to drive the fluid. Channels are easily formed by either selectively removing sections of the paper substrate or by pattering channel boundaries with a hydrophobic material.</p><p> In spite of the benefits and advantages described above, paper-based microfluidic technologies often lack the necessary sensitivity and sophistication available in conventional microfluidic devices. In order to be a competitive alternative, paper-based microfluidics require improvement and novel development of feasible detection methods. These methods will likely require increasingly complex chemistry and control of reagents. Thus, understanding imbibition as well as obtaining precise, accurate, and consistent fluid handling within the paper device will be crucial.</p><p>Although considerable knowledge exists on techniques to manipulate fluid within the paper channel, what is lacking are studies on how non-laboratory conditions (e.g. relative humidity) influence fluid flow. This presentation aims to address this gap with particular focus on the effects of relative humidity and channel width. A series of controlled imbibition experiments is reported using cellulose papers commonly used in the field of paper-based microfluidics. We show that both the imposed relative humidity and the channel width have critical design considerations in paper-based devices. Additionally, we compare three models, the Lucas-Washburn model, the Fries et al. (2008) model which incorporates evaporation, and a newly developed water saturation model that incorporates evaporation as well as residual water in the paper. We assess their accuracy in representing the experimental data and systematically evaluate the importance of evaporation and water saturation under a wide range of relative humidity conditions. The current study has created a library of paper-specific, imbibition-related properties for commonly used filter and chromatography papers for the first time.</p><p>Lastly, the effort of fluid manipulation is continued. A qualitative investigation on two-dimensional wax-bound channels is covered. The channels encompass the most basic geometry that may be present in complex fluidic designs; sudden expansion, contraction, and a box along the channel. It is found that these simple channel cross-sections can accelerate and decelerate fluid flow, therefore altering the time of fluid delivery. </p><p>Collectively, the success of this research will improve the development of future diagnostic and analytical paper devices producing a user-friendly and cost effective point-of-care alternative.</p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/67f3692n"><img src="/cms-assets/6bf9b6ecdb9f1132c33a48c00c5c5727f2e98af1143023fc669fb83b69eaaa7a" alt="Cover page: Imbibition in Paper-Based Microfluidic Devices"/></a><a href="https://creativecommons.org/licenses/by/4.0/" class="c-scholworks__license"><img class="c-lazyimage" data-src="/images/cc-by-small.svg" alt="Creative Commons 'BY' version 4.0 license"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-article">Article</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/16d654jj"><div class="c-clientmarkup">Using Adhesive Patterning to Construct 3D Paper Microfluidic Devices.</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3AKalish%2C%20Brent">Kalish, Brent</a>; </li><li class="c-authorlist__end"><a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_postprints">UC Riverside Previously Published Works</a> (2016)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup">We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol adhesive through a metal stencil, the overall amount of adhesive used in assembling paper microfluidic devices can be significantly reduced. We show on a simple 4-layer planar paper microfluidic device that the optimal adhesive application technique and device construction style depends heavily on desired performance characteristics. By moderately increasing the overall area of a device, it is possible to dramatically decrease the wicking time and increase device success rates while also reducing the amount of adhesive required to keep the device together. Such adhesive application also causes the adhesive to form semi-permanent bonds instead of permanent bonds between paper layers, enabling single-use devices to be non-destructively disassembled after use. Nonplanar 3D origami devices also benefit from the semi-permanent bonds during folding, as it reduces the likelihood that unrelated faces may accidently stick together. Like planar devices, nonplanar structures see reduced wicking times with patterned adhesive application vs uniformly applied adhesive.</div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/16d654jj"><img src="/cms-assets/9c3a4295b3e8ab984028b15b59452435a6e8afb5bc24439ed73fc0a63a0c3e46" alt="Cover page: Using Adhesive Patterning to Construct 3D Paper Microfluidic Devices."/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/1dw2s6r6"><div class="c-clientmarkup">An Exploration of Aggregation and Fluid Shear Stress in Conventional Spinner Flasks and a Novel Concentric Cylinder Rotating Wall Vessel</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3ALayton%2C%20Carys">Layton, Carys</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2024)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>Fluid mechanics driven bioreactor design has entered a new phase of development in the last 15 years: the scalable expansion and differentiation of human pluripotent stem cells (hPSCs) for translational therapies, drug screening and discovery, developmental biology research, and disease pathology. Demand for hPSC-derived resources is expected to increase due to the evolving global human health initiatives. Bioreactors are a suitable alternative to tissue culture dishes for the purposes of mass production. Stirred spinner flasks are a common bench-scale bioreactor for testing hPSC culture outcomes including the efficient production of undifferentiated cells, intermediate progenitor cells and terminally differentiated end-products. To continuously supply nutrients and oxygen, and homogeneously distribute cellular metabolic waste, culture medium in spinner flasks is stirred; however, this generates heterogenous fluidic shear stress on hPSCs due to the laws of fluid mechanics. As hPSCs are sensitive to physiochemical and bioenergetic cues, this poses a unique challenge. Exposure to shear stress or other forces has been known to kill the cells, or counterproductively direct them to an undesired phenotype. For these reasons, fluidic shear stress is often avoided in bioreactor design and parameterization, but much is unknown about the nuanced effect of fluidic shear on hPSCs. It is unclear if appropriate application of fluidic shear could productively direct lineage specification, maintain pluripotency, or enhance differentiation efficiency or functional maturity. Thus, the development of novel devices and methods capable of integrating refined engineering control of the bulk hydrodynamic conditions and the fluidic microenvironments in which the cells are grown is warranted. This work seeks to uncover the role of fluidic shear in dynamic suspension in bioreactors. This was achieved in part by observing the cellular and molecular expression of hPSC aggregates cultured in stirred spinner flasks compared to monolayer colonies and aggregates grown in static, or stationary, fluid culture medium. Culture outcomes were observed for their cell counts and lineage potentials, and finally assessed with bulk RNAseq. The results of these assays showed that hPSC aggregates exposed to shear in spinner flasks form a gene signature that suggest fluidic agitation may promote de-differentiation to a more naïve-like pluripotency state and promote lineage specification resulting in a dual population. To test these types of shear effects in hPSC cultures in the future, an operating manual for a novel concentric cylinder rotating wall vessel bioreactor (CRWV) is described in this work. The CRWV can impose fluidic shear over a narrow distribution based on circular Couette flow and was shown to support hPSC survival for 24-hrs post-inoculation under certain conditions. </p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/9zs5j2wn"><div class="c-clientmarkup">Paper-Based Microfluidics: DNA Detection via Wicking Distances of Microsphere Aggregates and the Effects of Laser-Etching on Wicking Speeds in Paper Channels</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3AKalish%2C%20Brent">Kalish, Brent</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2019)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>The development of patterning high-resolution microfluidic circuits onto cellulose paper in 2007 initiated widespread research into the use of the paper as a low-cost, easy-to-use alternative substrate over the glass and plastics of traditional microfluidics. Paper, as a porous hydrophilic material, naturally wicks fluid through itself, without the need for external pumps or power sources. The simplest paper-based devices are lateral flow devices, where liquid wicks in one direction along the paper strip. These are suitable for simple detection chemistries; however, for more complex reactions, devices that are more complicated are required, and this frequently entails the sequential delivery of different liquids or reagents to reaction zones. To achieve sequential delivery, one can manually deposit reagents at different times, or deposit them simultaneously and have them arrive at times dictated by their travel paths. Modifying channel lengths and widths is the easiest method, but is constrained by the device's footprint and available sample volume, as longer and wider channels will require larger volumes. Alternatively, one can attempt to modify the speed at which liquid wicks through the paper itself. This is predominantly dictated by the pore size of the paper and is typically modified by adding material to block the pores, slowing flow. Further, one can have the liquid flow outside the paper altogether in some kind of external capillary. This work, on the other hand, investigated the use of a CO2 laser to uniformly etch the surface of the paper. Depending on the degree of etching, this was able to both increase and decrease the wicking speed of water through paper channels. </p><p>The simplest lateral flow devices are typically colorimetric, giving qualitative results. However, getting quantitative data can be quite a bit more difficult. Distance-based devices provide a user-friendly means of obtaining quantitative data without the need for any additional equipment, simply by using an included ruler or calibrated markings. This work details the development of a quantitative DNA detection device that utilizes the aggregation of polystyrene microspheres to affect the distance that microspheres wick through filter paper. The microspheres are conjugated to ssDNA oligomers that are partially complementary to a target strand, and in the presence of the target strand, form a 3-strand complex, resulting in the formation of aggregates. The higher the concentration of the target strand, the larger the aggregate, and the shorter the distance wicked by the microspheres. This behavior was investigated across a wide range of target concentrations and under different incubation times to understand aggregate formation. The device was then used to successfully detect a target strand spiked in extracted plant DNA.</p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/9zs5j2wn"><img src="/cms-assets/68ee44c6117219369aca85d47ea7eed9fcd17360bf5c220aeb406fb58c5ac8c6" alt="Cover page: Paper-Based Microfluidics: DNA Detection via Wicking Distances of Microsphere Aggregates and the Effects of Laser-Etching on Wicking Speeds in Paper Channels"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/31d4m2c1"><div class="c-clientmarkup">Polydiacetylene-Based Colorimetric Sensors for Plant Diagnostics</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3AWen%2C%20Jessica%20Tsai">Wen, Jessica Tsai</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2016)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>The Food and Agriculture Organization of the United Nations (FAO) estimates that 98% of the world’s reported 870 million undernourished people reside in developing countries, where nearly 15% of the population are undernourished. In these regions, smallholder farmers are dominant factors in meeting food demands. Therefore, in order to alleviate recurrent food shortages worldwide, low-cost and robust solutions must be provided to protect and prevent the loss of smallholder crop yield. This research reports on the development of in vitro and in vivo diagnostic devices for in-field crop diagnostics. In particular, we employ chromatic polydiacetylenes in the fabrication of analyte-sensitive strips for plant testing in vitro. Specifically, two sets of strips were developed that exhibited blue to pink/red transitions when incubated in solutions containing plant nutrient, Zn2+, or xylem-limited bacterium, X. fastidiosa respectively. These strips demonstrated one-step, equipment-free detection appropriate for resource-limited settings. Additionally, a poof-of-concept in vivo detection platform was evaluated and subsequently, injectable poydiacetylene liposome sensors were designed for specific colorimetric detection of apoplast-colonizing bacterium P. stewartii. An in vivo detection system would provide continuous monitoring of plant pathogen transmission for early detection of crop diseases. Such a platform would be ideal for disease prevention and management on smallholder farms by eliminating the need for user-initiated testing for disease diagnostics. Both of our in vitro and in vivo detection systems provide great potential to improve in-field plant diagnostics in low-resource settings.</p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/31d4m2c1"><img src="/cms-assets/f587a43ce481c323595495c360cada91881d7e954b13dae5863cb389f3b0727b" alt="Cover page: Polydiacetylene-Based Colorimetric Sensors for Plant Diagnostics"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/3dh0t8f7"><div class="c-clientmarkup">Stirred Suspension Culture for Scalable Production and Differentiation of Human Pluripotent Stem Cells</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3ANampe%2C%20Daniel%20Pareza">Nampe, Daniel Pareza</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2016)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>The success of human pluripotent stem cells (hPSCs) as a source of future cell therapies hinges in part on the availability of a robust scalable culture system that can readily produce clinically relevant number of cells and their derivatives. Stirred suspension culture has been identified as one of such promising platforms due to its ease of use, scalability, and widespread use in the pharmaceutical industry (e.g., CHO cell-based production of therapeutic proteins) among others. However, culture of undifferentiated hPSCs in stirred suspension is a relatively new development in the past several years, and little is known beyond empirically optimized culture parameters. The goal of this study was to elucidate the impact of fluidic agitation on hPSCs in stirred suspension culture. In particular, we systematically investigated various agitation rates to characterize their impact on cell yield, viability, and maintenance of pluripotency. Additionally, we closely examined the distribution of cell aggregates and how the observed culture outcomes are attributed to their size distribution. Our results showed that moderate agitation maximized the propagation of hPSCs by controlling the cell aggregates below the critical size, beyond which the cells suffer from diffusion limitation, while limiting cell death caused by excessive fluidic forces. Furthermore, we observed that fluidic agitation could regulate not only cell aggregation, but also expression of some key signaling proteins in hPSCs. Upon discovering this mechanosensitive effector enabled a novel approach for linking expansion and cardiac differentiation to generate over 90% cardiomyocytes. In addition, these cardiomyocytes displayed highly organized sarcomere structure which suggests an improved maturation in their morphology. Altogether, results presented in this study indicate the new possibility of guiding stem cell fate determination by fluidic agitation in stirred suspension cultures.</p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/3dh0t8f7"><img src="/cms-assets/fdd0d40346eef9d54793f76e1f1fd108ed60e77c8d3ab2b73c1f8a5fef70ff16" alt="Cover page: Stirred Suspension Culture for Scalable Production and Differentiation of Human Pluripotent Stem Cells"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/0g92c968"><div class="c-clientmarkup">Development of Quick Sample Preparation Protocols and Biosensing Platform Toward Sample-to-Answer Plant Disease Diagnostics in The Field</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3ALiu%2C%20Chia-Wei">Liu, Chia-Wei</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2024)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>Plant epidemics have long threatened crop yields and the global economy, with novel pathogenic variants and disease synergism worsening the issue. These destructive plant diseases cause global crop yield losses of up to 40% for maize, potato, rice, soybean, and wheat, resulting in annual financial losses of $220 billion. The UN's 2024 Global Report on Food Crises indicates that nearly 282 million people across 59 countries are experiencing acute food insecurity, a number that has increased since 2019. Crop loss due to plant pathogens and extreme climate are key drivers of this food crisis, exacerbating environmental and socio-economic conditions in affected regions and disproportionately impacting food-insecure populations. Therefore, being able to easily conduct plant disease diagnosis in the field is of great importance for smallholder farmers to prevent disease outbreaks and accurately adopt control strategies. This research focuses on developing quick sample preparation protocols, aiming for efficiently extracting total nucleic acids that are ready for downstream molecular assays, such as polymerase chain reaction (PCR), directly from plant tissues. As a follow-up, an emerging molecular technique, loop-mediated isothermal amplification (LAMP), was integrated with quick sample preparation protocol to develop a colorimetric sensing strategy for plant disease detection in a greenhouse. Subsequent efforts to design and prototype a “pushing-valve” microfluidic chip, as an easy-to-use platform toward in-field disease detection, were also presented in this research. In general, this whole research aims to allow farmers and growers to prepare ready-to-use nucleic acids straight from plants of interest and carry out subsequent detection in a portable manner. Such a platform would benefit disease prevention and management on smallholder farms by removing the need for processing and analyzing large quantities of field samples by laboratory workers. This holds a great potential to improve in-field plant diagnostics in resource-limited settings.</p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a href="https://creativecommons.org/licenses/by-nc-nd/4.0/" class="c-scholworks__license"><img class="c-lazyimage" data-src="/images/cc-by-nc-nd-small.svg" alt="Creative Commons 'BY-NC-ND' version 4.0 license"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/5c07h72n"><div class="c-clientmarkup">Polydiacetylenes for Colorimetric Sensing</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3ARoper%2C%20Jenna%20Marie">Roper, Jenna Marie</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2024)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>Point-of-care (POC) diagnostics have emerged as a critical tool in modern healthcare and agriculture, offering the potential to revolutionize disease detection and management, particularly in resource-limited settings. By enabling rapid, on-site testing without the need for specialized laboratory equipment, POC diagnostics can significantly improve patient outcomes, reduce healthcare costs, and enhance disease surveillance capabilities. Polydiacetylenes (PDAs) are a unique class of polymers with conjugated backbones that undergo a colorimetric blue-to-red transition in response to various stimuli, making them promising candidates for simple, visual detection systems. This dissertation explores the development and optimization of PDA-based sensors for point-of-use diagnostic applications. A systematic investigation of liposome synthesis parameters is conducted, identifying optimal conditions for uniform and responsive PDA assemblies. The effects of diacetylene monomer structure and lipid doping on sensor performance are examined, revealing that shorter alkyl chains and moderate lipid incorporation enhance sensitivity while maintaining stability. Efforts to develop antibody-functionalized PDA sensors for detecting plant pathogens and model proteins are described, highlighting both the potential and limitations of this approach. To overcome challenges encountered with antibody-based systems, an alternative strategy using small-molecule ligands for protein detection is explored. Throughout the work, emphasis is placed on creating robust, reproducible protocols suitable for point-of-use applications. The insights gained from this research contribute to the broader understanding of PDA-based biosensors and provide a foundation for their future development as accessible diagnostic tools for healthcare and agricultural applications. </p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/5c07h72n"><img src="/cms-assets/d2ea3bc857eba51eae72fe7a755bc3c60d5e76c10410acf99e05b12d3ef8a08e" alt="Cover page: Polydiacetylenes for Colorimetric Sensing"/></a></div></section><section class="c-scholworks"><div class="c-scholworks__main-column"><ul class="c-scholworks__tag-list"><li class="c-scholworks__tag-thesis">Thesis</li><li class="c-scholworks__tag-peer">Peer Reviewed</li></ul><div><h3 class="c-scholworks__heading"><a href="/uc/item/2f66029h"><div class="c-clientmarkup">Nonplanar Three Dimensional Paper Microfluidics And Distance-Based Semi-Quantitative DNA Detection</div></a></h3></div><div class="c-authorlist"><ul class="c-authorlist__list"><li class="c-authorlist__begin"><a href="/search/?q=author%3AKalish%2C%20Brent%20Nathaniel">Kalish, Brent Nathaniel</a> </li><li class="c-authorlist__begin"><span class="c-authorlist__heading">Advisor(s):</span> <a href="/search/?q=author%3ATsutsui%2C%20Hideaki">Tsutsui, Hideaki</a> </li></ul></div><div class="c-scholworks__publication"><a href="/uc/ucr_etd">UC Riverside Electronic Theses and Dissertations</a> (2015)</div><div class="c-scholworks__abstract"><div class="c-clientmarkup"><p>The development of patterning high-resolution microfluidic circuits onto cellulose paper in 2007 initiated widespread research into the use of the paper as a low-cost, easy-to-use alternative substrate over the glass and plastics of traditional microfluidics. Paper, as a porous hydrophilic material, naturally wicks fluid through itself, without the need to external pumps or power sources. The patterning of paper into hydrophobic and hydrophilic regions, now achievable with consumer-grade office printers, allowed the design of new 2D devices, capable of multi-analyte detection. 3D devices, made from multiple stacked layers of paper, offer even more possibilities for complex, multi-fluid routing in smaller overall device footprints. The use of patterned aerosol adhesives are investigated as an improved method of attaching multiple paper layers together rapidly and with minimal interference of interlayer fluid transport. Patterned aerosol adhesives also enable the development of nonplanar 3D devices, which represent a novel platform upon which to develop new microfluidic devices, which would otherwise be impossible to construct or function in a planar device.</p><p>Much of paper microfluidics research is focused on developing more sophisticated detection methods that provide quantitative data, instead of simple colorimetric qualitative yes/no answers. Frequently quantification is obtained by scanning the device and performing a color intensity analysis to relate a color change to concentrations of a target analyte. This technique suffers due to variations in the quality of imaging equipment and the ambient lighting conditions during image acquisition. To address this, some have proposed a distance-based lateral flow device, where the distance traveled by a colored substance is proportional to the target analyte concentration. The use of a microsphere aggregation-based sandwich assay was investigated for semi-quantitatively determining the concentration of a target ssDNA strand.</p></div></div><div class="c-scholworks__media"><ul class="c-medialist"></ul></div></div><div class="c-scholworks__ancillary"><a class="c-scholworks__thumbnail" href="/uc/item/2f66029h"><img src="/cms-assets/986ecf1756fee635569c2badf77654bef0bd0275651ffaccbb99df32a84ab9a9" alt="Cover page: Nonplanar Three Dimensional Paper Microfluidics And Distance-Based Semi-Quantitative DNA Detection"/></a></div></section><nav class="c-pagination"><ul><li><a href="" aria-label="you are on result set 1" class="c-pagination__item--current">1</a></li><li><a href="" aria-label="go to result set 2" class="c-pagination__item">2</a></li></ul></nav></section></main></form></div><div><div class="c-toplink"><a href="javascript:window.scrollTo(0, 0)">Top</a></div><footer class="c-footer"><nav class="c-footer__nav"><ul><li><a href="/">Home</a></li><li><a href="/aboutEschol">About eScholarship</a></li><li><a href="/campuses">Campus Sites</a></li><li><a href="/ucoapolicies">UC Open Access Policy</a></li><li><a href="/publishing">eScholarship Publishing</a></li><li><a href="https://www.cdlib.org/about/accessibility.html">Accessibility</a></li><li><a href="/privacypolicy">Privacy Statement</a></li><li><a href="/policies">Site Policies</a></li><li><a href="/terms">Terms of Use</a></li><li><a href="/login"><strong>Admin Login</strong></a></li><li><a href="https://help.escholarship.org"><strong>Help</strong></a></li></ul></nav><div class="c-footer__logo"><a href="/"><img class="c-lazyimage" data-src="/images/logo_footer-eschol.svg" alt="eScholarship, University of California"/></a></div><div class="c-footer__copyright">Powered by the<br/><a href="http://www.cdlib.org">California Digital Library</a><br/>Copyright © 2017<br/>The Regents of the University of California</div></footer></div></div></div></div> <script src="/js/vendors~app-bundle-2aefc956e545366a5d4e.js"></script> <script src="/js/app-bundle-3c8ebc2ec05dcc3202fd.js"></script> </body> </html>