Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, Miami University, 2024, Chemistry and Biochemistry

Detection of environmental pollutants, both inorganic and organic, has been an ongoing area of research for nearly three-quarters of a century. In recent years there has been growing research in the discovery of complementary methods for detection of environmental pollutants that are decentralized, rapid, and can be used onsite. A promising approach is the application of biosensors. Two common sensor classes are DNAzymes and Bacteria-Based Sensors (BB sensors). DNAzyme sensors have been discovered for the detection of many different metals. However, DNAzyme sensors have historically had issues with non-specific activity due to the presence of other metal ions with similar valency as their native metal cofactor. Further, they are limited in multiplex detection of environmental pollutants due to the limited number of orthogonal fluorophores. Moreover, there are limited sources in the literature for the design of DNAzyme sensors for the detection of organic pollutants, e.g., per- and polyfluoroalkyl substances (PFAS). In contrast, BB sensors have been developed to detect a broad range of compounds from metals to organic substances. Although many BB sensors have been developed for the detection of organic pollutants, there have been limited reports in the literature of BB sensors designed for the detection of PFAS. This dissertation aims to leverage the nonspecific activity of DNAzyme sensors by using a pattern-based readout to identify metal pollutants. Towards this goal, we investigated the DNAzyme cross-reactivity on five DNAzymes (17E, GR-5m EtNa, Ag10c, and NaA43) with eight different metals, and analyzed the data through several statistical methods. Through this approach, we were able to correctly identify four validation solutions, of which, one validation solution consisted of 100 μM Zn2+, which is a known interferent for 17E. Following this, the dissertation explored a new DNAzyme reporter architecture, DzNanoporeSeq, where sequencing is used as a signal readou (open full item for complete abstract)

Committee: Kevin Yehl (Advisor); Richard Page (Committee Chair); Jason Boock (Committee Member); Cory Rusinek (Committee Member); Neil Daneilson (Committee Member) Subjects: Analytical Chemistry; Chemistry

MS, University of Cincinnati, 2022, Engineering and Applied Science: Electrical Engineering

Due to their high specificity and selectivity, receptor-based biosensors play an important role in real-time health monitoring. Electrochemical enzyme-based biosensors play a significant role in the field of wearable biosensing due to reduced interference and high chemical specificity. However, maintaining an ideal homeostatic sensor environment while correcting for the physiological variability of biofluids is imperative. Biological media contain an abundance of interfering species which if not addressed, can render the biosensor inoperable. Enzyme-based electrochemical sensors are particularly susceptible to redox active interferences as these increase analyte detection limits, making physiological measurements a challenge. For this reason, extensive research has been applied to developing various strategies to mitigate such interferences. Here we present a novel conductive membrane encapsulation strategy designed to mitigate redox-active interferences while allowing redox-inactive target analyte to pass through unaltered to the sensor surface. On the other side of the conductive membrane, and only in proximity to the sensor surface, does the target analyte interact with the immobilized enzyme sensor to produce our redox-active detection analyte. This is then oxidized by the inner sensor electrode without the influence of additional unwanted redox-active species. The result is a decrease in background current, thereby reducing the detection limit of the biosensor even in the presence of redox-active interferences. This redox-active mitigation strategy is highly generalizable as the potential across the conductive membrane can be easily changed to fit the application. Using a first-generation glucose oxidase sensor as a model interferent-sensitive system, we have shown 61 percent reduction in redox-active interference upon implementation of our conductive membrane strategy.

Committee: Jason Heikenfeld Ph.D. (Committee Member); Andrew Steckl Ph.D. (Committee Member); Tao Li Ph.D. (Committee Member) Subjects: Biomedical Research

MS, University of Cincinnati, 2022, Engineering and Applied Science: Biomedical Engineering

Advancing diagnostic ability is imperative for improving patient outcomes. Wearable sensors, such as smart watches and continuous glucose monitors, have opened the door to continuous biosensing, which can provide critical information to clinical practitioners at minimal inconvenience to the patient. Electrochemical aptamer based (EAB) sensing can provide rapid and precise quantitative results for a broad range of potential sensing targets, making it a promising option for continuous, minimally invasive sensing. Another benefit to EAB sensors is that they can be easily interchanged on the same platform. Therefore, this project focused on surface modification techniques to improve the sensing platform for all EAB sensors, with specific emphasis on sensor longevity. First, acupuncture needles were used as a base to improve mechanical stability and provide easy insertion. Physical vapor deposition was used to deposit 10 nm of titanium and 50 nm of gold before either gold nanoparticles were electrochemically deposited or a 300 nm gold-silver (1:3) alloy was sputtered onto the surface. The needles with the gold-silver alloy were then etched in nitric acid to remove the silver and reveal a porous gold surface. Scanning electron microscopy was used to examine the resulting nanostructures. Mechanical and chemical roughening were employed to improve the adhesion between the stainless steel and the deposited layers. Cyclic voltammetry (CV) was utilized to examine the effects of these methods on surface adhesion. The second electrode base that was modified was 250 μm diameter gold wires. Previous studies have shown the benefits on surface gain of roughened gold wires. Building upon these advances, the effect of thermal annealing on the chemical stability of roughened gold wire was examined. A frequency sweep in combination with a concentration “titration” was used to compare the signal gain of annealed and unannealed roughened wires and to identify the ideal scanning par (open full item for complete abstract)

Committee: Jason Heikenfeld Ph.D. (Committee Member); Stacey Schutte Ph.D. (Committee Member); Jing-Huei Lee Ph.D. (Committee Member) Subjects: Biomedical Engineering

PhD, University of Cincinnati, 2022, Engineering and Applied Science: Biomedical Engineering

There are considerable physiological and financial cost associated with our lack of ability to reliably identify patient-to-patient variations for different diseases and pharmaceutical treatments. There is a growing movement towards personalized medicine to address the varied needs of individuals; however, a lack of available tools to monitor individuals efficiently and effectively throughout their daily lives limits its application. Continuous biosensing, and more specifically continuous molecular monitoring, is one of these tools; however, development beyond the success of continuous glucose monitoring has been elusive. In the early 2000s electrochemical aptamer sensing was first proposed. Aptamer sensors have been developed with the potential to advance upon the success of continuous enzymatic monitoring. With aptamer's capabilities to achieve low limits of detection that are attuned to physiological concentrations, rapid response times, and the versatility to be selected for a vast array of analytes they have already addressed many longstanding barriers that limit enzymatic sensing. However, after nearly 2 decades of development they have not been applied in human biofluids in situ nor has there been significant consideration into building wearable, ambulatory aptamer sensing devices. With multiple successful applications of aptamer sensors in animal models it is time to transition testing onto human subjects to ensure this modality is fit as a tool for personalized medicine and to encourage research addressing challenges that arise when manufacturing wearable devices. To test the viability of aptamer sensors with human subjects this dissertation's objective is to develop a minimally-invasive, wearable device using a generalizable, electrochemical aptamer sensor platform for continuous monitoring of interstitial fluid. When paired with microneedles, aptamer sensors provide pain-free access to ISF's analyte rich reservoir and the ability to collect minutes (open full item for complete abstract)

Committee: Jason Heikenfeld Ph.D. (Committee Member); Stacey Schutte Ph.D. (Committee Member); Ronen Polsky Ph.D. (Committee Member); John Martin Ph.D. (Committee Member) Subjects: Biomedical Research

PhD, University of Cincinnati, 2022, Arts and Sciences: Chemistry

The contents of this dissertation are primarily focused on improving the translatability of electrochemical aptamer-based (E-AB) sensors through surface and redox label modifications. To date, E-AB sensors have seen limited use in non-academic settings, being confined mostly to controlled environments withing academic research labs. This lack of adoption by industry is due, in large part, to the lack of translatability of these sensors. Two major contributors to the lack of translatability are sensor failure in more complex solutions that contain proteins, cells, and other agents that lead to accumulation onto the sensor surface, otherwise known as biofouling, as well as a lack of options for unique and reliable redox labels. Of these two issues, the problems that arise from biofouling have received the most attention and effort with advances like using dual labeled probes for drift correction, modification of passivating monolayers, and physical modifications to the electrode surface, all of which have had limited success. In this work, we report on our attempts to improve E-AB sensor performance in biofouling conditions, more specifically in undiluted fetal bovine serum as well as undiluted whole blood, by coupling aptamers and their inherent specificity to nanoporous gold electrodes. To measure our success, we look at three key figures of merit: percent signal retention, maximum percent signal change, and the observed dissociation constant, KD. From these three figures of merit, we can characterize sensor longevity and the sensors response to target, which are critical to the translatability of this sensing platform. While we did not see the increased stability over long periods of time, our results show that using aptamers in conjunction with nanoporous gold electrodes provides a significant increase in maximum signal change for 9K and 12K NPGL E-AB sensors as compared to planar E-AB sensors. The 12K NPGL E-AB sensors also provide significantly lower a (open full item for complete abstract)

Committee: Ryan White Ph.D. (Committee Member); Hairong Guan Ph.D. (Committee Member); Michael Baldwin Ph.D. (Committee Member) Subjects: Chemistry

PhD, University of Cincinnati, 2022, Arts and Sciences: Chemistry

Electrochemical aptamer-based (E-AB) sensors are a class of biosensors that employ single-stranded DNA or RNA oligonucleotides as recognition elements. Signal transduction for this class of sensor relies on a conformation change of these aptamers in the presence of a target that alters the collisional frequency of a 3'-redox reporter. The E-AB sensor platform employing the tethered modified oligonucleotide affords dynamic measurements of analytes of interest that can be used for innovative, relevant detection of analytes. As such, electrochemical biosensors that employ oligonucleotides as recognition elements, require integration into other sensing platforms like microfluidics to exploit the dynamic, reagentless measurements afforded by this class of sensors, further optimization of the sensor in changing temperatures, and applications of the sensors in a useful way which will allow them to transcend from the lab to point-of-care (POC) or medical diagnostics. This dissertation describes several ways in which the dynamic measurements of these sensors can be used to help them transcend from the lab to POC or medical diagnostics. The integration of this class of sensors into a microfluidic device using 3D printing to make microfluidic molds affords rapid prototyping of different microfluidic architectures, coupled with epoxy-embedded electrodes that use a three-electrode setup, and fabricating E-AB sensors under flow conditions to exploit the dynamic measurements afforded by E-AB sensors. Additionally, E-AB sensor signaling was characterized at different temperatures to better understand how temperature changes affect sensor response. The sensors were interrogated in the absence of and with target analyte within a temperature window of 1°C to 37°C. The chapter looks into how temperature affects sensor signaling, signal polarity, and binding affinity within the chosen temperature range. Finally, the last half of this dissertation demonstrates the capability of a (open full item for complete abstract)

Committee: Ryan White Ph.D. (Committee Member); Ashley Ross Ph.D. (Committee Member); Elke Buschbeck Ph.D. (Committee Member); Noe Alvarez Ph.D. (Committee Member) Subjects: Chemistry

Master of Science, Miami University, 0, Chemistry and Biochemistry

The COVID-19 pandemic has highlighted the importance of diagnostics in detecting and containing infectious diseases. Recently, a class of CRISPR-Cas enzymes, known as Cas12, has been discovered and is being utilized as a biosensor for detecting genetic biomarkers. Cas12 is similar to other CRISPR-Cas proteins, in that it forms an RNA-protein complex with crRNA, which then recognizes and cleaves target DNA determined by the crRNA sequence. Cas12 is unique in that upon activation, it non-specifically cleaves any nearby DNA. This non-specific cleavage property can be leveraged to create molecular biosensors by adding in a fluorescent reporter DNA substrate to the reaction. In our system, Cas12 is programmed to recognize a specific sequence of the SARS-CoV-2 genome. This class of biosensor is useful due to a faster response compared to traditional PCR-based assays. However, CRISPR-Cas biosensors suffer from off-target activity, meaning that similar sequences can activate the biosensor, resulting in false positive signal. The goal of this project is to systematically study factors that affect Cas12 activity. Specifically, we investigated how the role of crRNA concentration, crRNA length, and mutation position affect Cas12 activity. Findings from this research will aid in developing next-generation point-of-care diagnostics for detecting and containing disease outbreaks.

Committee: Kevin Yehl (Advisor); David Tierney (Committee Member); Andrea Kravats (Committee Member); Neil Danielson (Committee Member) Subjects: Biology; Chemistry; Molecular Biology; Molecular Chemistry

PhD, University of Cincinnati, 2022, Engineering and Applied Science: Chemical Engineering

Significant research efforts have been made toward the development of real-time monitoring of human performance biomarkers, however outside of glucose, few have made it outside the research lab and to the commercial market. The transition from an idealized laboratory environment to the in vivo variability of human physiological fluids has been found to be the bottleneck step for existing biosensor technologies. A challenge of biofluid sensing is the abundance of interfering species, which if not addressed, renders the biosensor inoperable. Non-invasive biofluids, such as sweat, are further susceptible to interferences as many analytes besides glucose and alike metabolites exist at dramatically reduced concentrations compared to blood. If the impact of these interferents cannot be diminished, real-time monitoring of human performance biomarkers will remain science fiction. The objective of this dissertation is to develop methods to broadly mitigate the effects of biofluid interferents using membrane-based technologies. This dissertation will encompass two high generalizable mitigation strategies: 1) hydrophobic/hydrophilic selective membranes to block the majority of the interferents from the sensor and 2) an electrically active membrane to deactivate interferents before they reach the sensor. The hydrophobic/hydrophilic selective membrane takes advantage of the hydrophilic nature of most interfering solutes—such as salts, acids, bases, proteins, and most redox-active interferents—by impeding diffusion to the biosensor surface, while also allowing hydrophobic target molecules to pass through for detection. The electrically active membrane functions broadly across all redox-active interferents, regardless of hydrophobicity, by electrochemically deactivating the interferent before reaching the biosensor. Together, the membrane-based mitigation strategies validated in this dissertation will advance biosensor systems toward real-time wearable monitoring of human perfo (open full item for complete abstract)

Committee: Jason Heikenfeld Ph.D. (Committee Member); Yoonjee Park Ph.D. (Committee Member); Aashish Priye Ph.D. (Committee Member); Saber Hussain Ph.D. (Committee Member); Jonathan Nickels Ph.D. (Committee Member); Greg Harris Ph.D. (Committee Member) Subjects: Chemical Engineering

PhD, University of Cincinnati, 2021, Arts and Sciences: Chemistry

Nanoparticles (NPs) are defined as particulate dispersions or solid particles with a size in the range of 10-1000 nm. They have shown tremendous potentials to impact the broad fields, especially analytical field. The properties of new nanomaterials in different composition, size, and shape have greatly attracted the attention of analysts. NPs allow intimate interaction with target chemicals with the extremely small sizes and appropriate surface modifications. An emerging approach for robust real-world applications of sensors relies on NPs with diameters that range from 10 to 100 nm. The sensing mechanism is based on converting target binding events into physical signals that can be amplified and detected. NPs have been widely used for in vitro detection of molecular biomarkers of many diseases (such as cancer, neurodegenerative diseases, and infectious diseases, among others) released into patients' body fluids during disease progression as well as sensing chemicals that can cause variety of diseases. Herein, four projects focused on synthesis and characterization of different NPs for different applications are discussed. First project is a book chapter focused on the upconversion nanoparticles (UCNPs). It describes the various mechanisms of upconversion luminescence, categories of UCNPs, synthesis routes and emerging applications. Second project describes the development of a signal amplifiable detection of Hg2+ by nicking enzyme, Nt.AlWl using UCNPs . It is a highly specific and sensitive isothermal method for mercury detection using DNA-conjugated upconversion nanoparticles. A lower detection limit of 0.14 nM, which is much lower than the US Environmental Protection Agency (EPA) limit of Hg2+ in drinking water was achieved using this detection technique. Third project utilizes a paramagnetic nanoparticle-assisted nuclear relaxation technique to detect Sortase A, a virulence factor responsible for the attachment of surface proteins to Staphylococcus aureus (open full item for complete abstract)

Committee: Peng Zhang Ph.D. (Committee Chair); William Heineman Ph.D. (Committee Member); Pearl Tsang Ph.D. (Committee Member) Subjects: Analytical Chemistry

Doctor of Philosophy, The Ohio State University, 2020, Biomedical Engineering

Matrix metalloproteinases (MMPs) are the primary regulators of matrix degradation and reorganization through which they control key physiological processes such as wound healing and embryogenesis. Aberrant MMP activity contributes to the progression of several disease states, including cancer, in which it has been extensively characterized. To directly measure the activity of MMPs in cancer, researchers have developed MMP-degradable, fluorescent peptide biosensors. However, the peptide sequences used in these biosensors are often characterized in-solution using recombinant or purified enzymes, which are not representative of cell-mediated processes. To overcome this limitation, we have adapted MMP-degradable biosensors to the development of fluorescent peptide zymography. By covalently conjugating the peptide to the polyacrylamide backbone, this technique was able to measure a wider range of MMPs and displayed improved sensitivity compared to traditional zymography. Fluorescent peptide zymography was then used in combination with other MMP-sensing technologies to design a MMP-sensitive hydrogel drug delivery platform targeting liposarcoma, in vitro. Liposarcoma cell lines exhibiting elevated MMP activity stimulated drug release by selectively degrading a stably incorporated peptide-drug conjugate. The drug delivery platform can complement traditional surgical methods for the treatment of locally recurrent liposarcoma. Finally, we adapted a peptide-conjugated poly (ethylene glycol) (PEG) hydrogel to study the effects of dimensionality on drug treatment-induced MMP activity in breast cancer. Culture conditions regulated cellular MMP activity in response to drug treatment, where cells developed a chemoresistant phenotype in three-dimensional culture. This work motivated us to evaluate the feasibility of directly encapsulating tissue samples in the PEG hydrogels to predict patient-specific drug response. Ex vivo breast tissue dissections were >85% viable in PEG hydrogel (open full item for complete abstract)

Committee: Jennifer Leight Ph.D. (Advisor); Keith Gooch Ph.D. (Committee Member); Daniel Stover M.D. (Committee Member) Subjects: Biomedical Engineering

PhD, University of Cincinnati, 2019, Arts and Sciences: Chemistry

This thesis contains work that has been done in order to improve the sensitivity and selectivity of localized surface plasmon resonance sensors, specifically in regards to medical and point-of-care diagnostics. For centuries the vivid optical properties of gold nanoparticles have captured the attention of both artists and scientists. Today, due to the bold colorimetric properties that are highly tunable, plasmonic nanoparticles have been key to their widespread popularity and incorporation into medical diagnostics. As diagnostics become more readily available for self-monitoring of human health, it is imperative that new devices are produced that are highly accurate, precise, and affordable for consumer use. Applying the colorimetric properties of plasmonic nanoparticles, their colorimetric readout helps create a response that is either a simple yes or no, or a quantitative colorimetric readout. The contents of this thesis highlight efforts to enhance the surface chemistry to improve the sensitivity of nanoparticle substrates for improved detection of health relevant biomolecules. In addition, integration of these nanoparticles into extracellular matrix and lipid membrane systems help improve the selectivity of these model schemes. These strategies applied in this thesis are aimed toward improving medical diagnostics to make them affordable for point-of-care scenarios to improve the quality of human health.

Committee: Laura Sagle Ph.D. (Committee Chair); Ruxandra Dima Ph.D. (Committee Member); Patrick Limbach Ph.D. (Committee Member) Subjects: Chemistry

PHD, Kent State University, 2019, College of Arts and Sciences / Department of Chemistry

A biosensor is an analytical device that utilizes recognition element to report specific binding to biological target using a physicochemical transducer element. Biosensors have a very wide range of applications including health care, point of care testing, drug discovery, environmental monitoring, biodefense, bioresearch and many others. In past few decades, biosensors have been developed with high sensitivity, specificity and usability. However, separate arrangement of target recognition and signal transduction in conventional biosensors often compromises real-time response. Moreover, to improve the sensitivity, signals are often increased from numerous molecules accumulated during various amplification processes, which introduce additional steps and increase the cost of biosensors. To address these issues, we combined analyte recognition and signal reporting via mechanochemical coupling in a single-molecule DNA template. We incorporated a DNA hairpin as a signal reporting element while recognition units are placed separately on the DNA template in a tight coupling. With an optically levitated setup in laser-tweezers instrument, DNA hairpin acts as a mechanophore, which undergoes stochastic transitions between folded and unfolded hairpin states to report biosensing events. The sensitivities were demonstrated by detecting 10 pM antibody in a Tris buffer and 100 pM in human serum in 30 minutes by incorporating a pair of antigens in the template. The sensitivities of the single-molecule mechanochemical biosensors were further increased by detecting 1 fM Hg(II) ions in environmental water samples using polyvalent recognition units in 20 minutes. The multiplexing capability of the developed biosensor was tested by detecting several miRNAs in femtomolar detection limits (LOD) in buffer and picomolar LOD in human serum in 25 minutes. We anticipated that these mechanochemical concepts and methods are instrumental for the development of novel bioanalyses and have a great (open full item for complete abstract)

Committee: Hanbin Mao PHD (Advisor) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2019, Biomedical Engineering

Currently, most assays for cancer chemotherapeutic screening and development utilize two dimensional (2D) culturing systems. These 2D systems lack aspects of the in vivo microenvironment creating a poor in vitro representation that significantly affects cellular responses. To recapitulate the in vivo cellular microenvironment more closely, three dimensional (3D) cell culture systems have been developed and utilized. However, 3D cell culture systems are more complex, making analysis of cellular responses more difficult. Therefore, most high throughput (HT) 3D assays have been limited to measurements of cell viability. Yet other cellular functions play critical role in diseases and are promising pharmacological targets. There is a need for a HT 3D culturing system that enables the measurement of cellular functions, other than viability, for drug testing applications. To address this need, we developed, characterized, validated and demonstrated the utility of a HT 3D culturing system to measure matrix metalloproteinase (MMP) and metabolic activity, simultaneously. MMPs are critical regulators of tissue homeostasis and are upregulated in many diseases, such as arthritis and cancer. The developed assay produced edge effect, drift, Z'-factor, %CV, inter-plate, and inter-day fold shifts of the signals that were within the acceptable range for HT applications, designating it suitable for screening applications. Human MMP-1, -2 and -9 resulted in a significant increase in signal intensity. Encapsulation of several cell types, utilizing two different MMP-degradable peptides, produced robust signals above background noise and within the linear range of the assay. Finally, the utility of the system to measure cellular MMP activity in response to chemotherapeutics was demonstrated. Fibrosarcoma cell line (HT1080) was treated with several drugs, known to alter MMP activity, over a range of concentrations. Interestingly, sorafenib (SOR), a small molecule multi-kinase inhibitor uti (open full item for complete abstract)

Committee: Jennifer Leight Ph.D. (Advisor); Jessica Winter Ph.D. (Committee Member); Keith Gooch Ph.D. (Committee Member) Subjects: Biomedical Engineering

MS, University of Cincinnati, 2018, Engineering and Applied Science: Electrical Engineering

The ability to detect single molecule passing through a nano-sized pore holds the potential to serve as a valuable process in the world of nanotechnology. The molecules which translocate or cause a blockade at the pore orifice lead to a sharp change in current, which is shape and size dependent and can be used as the sensing criteria. This phenomenon based on the Coulter-counter principle resulting in resistive spikes can be used for a variety of applications. But to be able to understand the functioning of a nanopore better, it is of utmost important that we understand the electrokinetics that govern the motion of a molecule in the vicinity of the pore. With a comprehensive understanding of the environment that a target molecule exists in and its own surface characteristics, it would be possible to predict the translocation related behavior of the target. In this work, a detailed analysis of the electrokinetic forces that exist in a solid-state pore made in borosilicate glass have been studied. Unlike pores in membrane, which tend to be somewhat cylindrical if not perfect, the current rectification phenomenon is pronounced in conical pores which leads to enhanced field strengths at the tip of the cone. This can be used to great advantage in a variety of applications. We customized our biosensor design with the borosilicate pore sensor for obtaining successful detection with low charge carrying microparticles. This is of great use since the real-world targets such as Nucleic acids have much lower zeta potentials and can't always be electrophoretically propelled. Further, we employed our sensor to detect small miRNA sequences. For which this work discusses the numerical modelling that enabled us to predict the fluid flow behavior under the applied bias. We could see electroosmotic reversal at lower salt concentration in our design and could narrow down our choice of salt concentration. Additionally, we were able to predict the formation of serrated shape signal (open full item for complete abstract)

Committee: Leyla Esfandiari Ph.D. (Committee Chair); Chong Ahn Ph.D. (Committee Member); Rashmi Jha Ph.D. (Committee Member) Subjects: Nanotechnology

PhD, University of Cincinnati, 2017, Engineering and Applied Science: Electrical Engineering

The goal of this project is to a create point-of-care (POC) diagnostic device with several desirable characteristics, combining high sensitivity and semi-quantitative output in a cost effective and disposable package. Another important component of a POC system is power, and in this thesis, several options were explored. The biosensor used in this project is lateral flow immunoassay (LFIA), which is a paper based device. LFIAs have several desirable characteristics such as capillary action for fluid transport and affinity to proteins that makes them ideal candidates for Lab-on- Chip (LOC) applications. The POC described in this paper is a combination of LFIA and organic optoelectronics as the signal detection component. Organic light emitting diodes (OLEDs) and organic photodiodes (OPDs) have been found to be desirable candidates over their inorganic counterparts for POC applications. Organic devices provide the distinct advantages of having planar form factor and large active area in nature which is suitable for the integration with LFIAs. First, phosphorescence-based green OLEDs fabricated on plastic substrates were integrated as excitation light sources for fluorescent quantum dot (QD)-based LFIA devices. A 10× improvement in visual signal intensity was achieved compared to conventional LFIA, resulting in a 7× improvement in the limit-of-detection (LOD) of 3 nM concentration. For power source options, a zero-power (on board) system was designed on a flexible plastic substrate. The system utilized the power provided by near field communication (NFC) antenna to an LED array formed on the same substrate using hybrid manufacturing techniques. Such a system can harvest power from smartphones, which are a ubiquitous presence in this digital century. The NFC LED chip was used to excite the QD-based fluorescent LFA, which demonstrated again a ~10× higher sensitivity compared to conventional commercial devices. The hybrid manufacturing approach u (open full item for complete abstract)

Committee: Andrew Steckl Ph.D. (Committee Chair); Fred Beyette Ph.D. (Committee Member); Leyla Esfandiari Ph.D. (Committee Member); Kenneth James Kozak B.A. (Committee Member); Ian Papautsky Ph.D. (Committee Member) Subjects: Electrical Engineering

Master of Science in Chemistry, Cleveland State University, 2016, College of Sciences and Health Professions

Peroxynitrite (ONOO-) is a strong oxidizing and nitrating agent, and its formation has been correlated with many pathological conditions. It is generated in-vivo through the diffusion-controlled reaction between nitric oxide and superoxide. Peroxynitrite has been linked to nitration of protein and DNA as well as to DNA strand breaks. Accumulation of mutations and/or other kinds of DNA damage represent a carcinogenic risk. The accurate measurement of peroxynitrite concentration has been a challenge since this analyte is very unstable and reacts with many cellular targets. Development of analytical techniques capable of rapid and sensitive detection of this fast-reacting and damaging agent is an important research target to determine the chemical damage by this oxidant both at the tissue and the cellular levels. In this work, we develop DNA films as sensitive sensing platforms to detect and quantify ONOO- DNA damage. We have used two methods for DNA immobilization on the electrodes surfaces: (1) electrochemical grafting and (2) layer-by-layer (LBL) deposition methods. In the first method, we generate carboxylic acid groups on the electrode surface via electrochemical reduction of trans-4cinnamic acid diazonium tetrafluoroborate, followed by coupling of pre-activated carboxylic groups with amino terminated oligonucleotide. In the LBL deposition method, we construct films of alternate layers of posittively charged poly(diallyl dimethyl ammonium) and the target DNA as a negatively charged counterpart on the surface of the graphite electrode. On both platforms (grafted oligos and DNA films), we assess the effect of defined exogenous levels peroxynitrite metabolite on the electrochemical response of the DNA interface. Particularly for the grafted DNA oligonucleotides, we focused on detecting the differential response of complementary strands versus DNA helices with a single base mismatch. We show in the current work that electrodes modified with DNA oligonucleotides show (open full item for complete abstract)

Committee: Mekki Bayachou PhD (Committee Chair); Aimin Zhou PhD (Committee Member); Yana Sandlers PhD (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2016, Chemical Engineering

Since the 1980s, better understanding of protein structure and function has allowed for the design of useful proteins and their subsequent modification. In our laboratory, advances in protein engineering have been harnessed for the development of biosensors and the optimization of bioseparations. This dissertation encompasses work on both of these applications. First, previous work in our laboratory has developed a simple reporter protein in E. coli that can sense hormone-mimicking compounds of human nuclear hormone receptors (NHRs) and report their presence and activity through changes in growth phenotype. This system was extended from our current human targets to incorporate an insect NHR. The nuclear hormone receptor HR96 of both Aedes aegypti and Tribolium castaneum were designed, constructed, and optimized to validate novel bacterial biosensors for the detection of potential insecticides. This cell-based system was then incorporated into a cell-free expression environment to establish a faster colorimetric biosensing assay. Preliminary results show that our bacterial biosensor can be expressed in a cell-free protein synthesis reaction without compromising the sensitivity and selectivity of its response to known ligands. Second, our laboratory seeks to optimize the self-cleaving intein tag as a potential purification platform technology. We have previously shown that the combination of the elastin-like polypeptide (ELP) as a self-aggregating purification tag and the ΔI-CM intein can facilitate the purification of a target protein. This methodology not only eliminates the need of expensive chromatography resins but also eliminates the expenses associated with the use of proteases to recover the native protein after its purification. This promising tool was studied further to determine the optimal ELP tag length required to maximize both expression and purification yields. The shorter ELP tag lengths improved protein expression levels of three model target prot (open full item for complete abstract)

Committee: David Wood (Advisor); James Rathman (Committee Member); Jeffrey Chalmers (Committee Member) Subjects: Chemical Engineering

Master of Science, Miami University, 2015, Physics

This thesis presents the application of an empirical model of total internal reflection (TIR) we recently developed in conjunction with a home-built sensor to detect nanoaggregates in highly scattering opaque polystyrene colloidal suspensions. The nanoaggregates are detected directly without any sample dilution or special sample preparation. Additional results on nanoaggregate detection in gold nanoparticle suspensions are presented. Preliminary tests of our model and sensor in an absorbing dye solution are also presented.

Committee: Samir Bali PhD (Advisor); Lalit Bali PhD (Advisor); Jason Berberich PhD (Advisor); Jon Scaffidi PhD (Advisor); James Clemens PhD (Committee Member); Karthik Vishwanath PhD (Committee Member) Subjects: Analytical Chemistry; Biochemistry; Biomedical Engineering; Biomedical Research; Biophysics; Chemical Engineering; Chemistry; Experiments; Materials Science; Medical Imaging; Molecular Physics; Molecules; Nanoscience; Nanotechnology; Optics; Organic Chemistry; Physics; Polymer Chemistry; Polymers; Scientific Imaging