Thesis (M.S.)--Rochester Institute of Technology, 1988. / Typescript. Includes bibliographical references (leaves 175-178).

Thesis (M.S.)--Rochester Institute of Technology, 1994. / Typescript. Includes bibliographical references (leaves 134-138).

Thesis (M.S.)--Rochester Institute of Technology, 1995. / Typescript. Includes bibliographical references (leaves 130-131).

Thesis (M.S.)--University of Michigan, 2001. / Includes bibliographical references.

Over the years, colorimetric reagents and immunology have been widely used in screening tests for illicit drugs; however, the test kits are not always convenient for field use and often require the user to mix and develop a specific set of reagents. In our project, we have been working on alternative platforms based on paper microfluidic devices (uPADs) for field testing. These devices utilize wax channels printed on paper to direct the analyte towards a specific set of chemical reagents. Using the procedure, we have developed a six-channel chip that adapts known colorimetric reagents targeting cocaine, opiates, amphetamines and ketamine for multiplex detection. For more sensitive and specific determinations than the colorimetric reagents, we have also developed a paper device that utilizes the interaction between gold nanoparticles and drug specific aptamers. The µPADs using colorimetric reagent are designed as a six-channel multiplexed system. Sequences of different reagents applied to each channel to produce a series of reactions and the color changes appear at the end of each channel. The entire process takes less than five minutes. The adjusted reagents produce specific color changes for seized drugs on the paper microfluidic devices. Procedures have been developed for the detection of cocaine, ketamine, codeine, ephedrine, morphine, amphetamine, methamphetamine, and MDMA. These devices have been tested for sensitivity, specificity and stability against a variety of potential interferences and test conditions. Gold nanoparticles (AuNPs)/ aptamers µPADs were developed to detect cocaine. The presence of cocaine cause the binding with aptamers, and the gold nanoparitcles produced a salt-indicated aggregations and gave a color change of AuNPs from red to black. The absence of cocaine allowed the aptamers freely to bind gold nanoparticles, and no color change occured. The device had a preliminary validation of sensitvity and specificity against a variety of potential interferences. The use of paper microfluidic devices permits the development of rapid, inexpensive and easily operated tests for drug samples in the field. They present a safe and convenient presumptive tool that can be used in the field.

abstract: Proton beam therapy (PBT) is a state-of-the-art radiotherapy treatment approach that uses focused proton beams for tumor ablation. A key advantage of this approach over conventional photon radiotherapy (XRT) is the unique dose deposition characteristics of protons, resulting in superior healthy tissue sparing. This results in fewer unwanted side effects and improved outcomes for patients. Current available dosimeters are intrinsic, complex and expensive; hence cannot be used to determine the dose delivered to the tumor routinely. Here, we report a hydrogel based plasmonic nanosensor for measurements of clinical doses in ranges between 2-4 GyRBE. In this nanosensor, gold ions, encapsulated in a hydrogel, are reduced to gold nanoparticles following irradiation with proton beams. Formation of gold nanoparticles renders a color change to the originally colorless hydrogel. The intensity of the color can be used to calibrate the hydrogel nanosensor in order to quantify different radiation doses employed during treatment. The potential of this nanosensor for clinical translation was demonstrated using an anthropomorphic phantom mimicking a clinical radiotherapy session. The simplicity of fabrication, detection range in the fractionated radiotherapy regime and ease of detection with translational potential makes this a first-in-kind plasmonic colorimetric nanosensor for applications in clinical proton beam therapy. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2017

Made available in DSpace on 2014-10-09T12:25:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:35Z (GMT). No. of bitstreams: 1 06888.pdf: 7154898 bytes, checksum: 2cdf88344fc5d54779947540d009d741 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:97/11079-2

Made available in DSpace on 2014-10-09T12:25:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:35Z (GMT). No. of bitstreams: 1 06888.pdf: 7154898 bytes, checksum: 2cdf88344fc5d54779947540d009d741 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:97/11079-2

Safe drinking water is essential for life, yet at least two billion people around the world consume water contaminated with pathogens among other pollutants. Standard methods like polymerase chain reaction (PCR) and membrane filtration have been developed to detect enteric pathogens in water. However, these methods are limited in their accessibility due to long wait times to obtain results, and the requirements of skilled expertise, electricity, and laboratory equipment. This research has focused on addressing some of these limitations by analyzing the mechanisms of work and optimizing an indirect colorimetric nanosensor developed in previous research. The colorimetric nanosensor investigated herein relies on a competitive binding mechanism. When positively charged gold nanoparticles coated with polyethyleneimine (PEI-AuNPs) are added to a water sample containing negatively charged Escherichia coli (E. coli) and β-galactosidase (β-Gal) enzyme, the PEI-AuNPs will preferably bind to E. coli. This leaves β-Gal free in solution to hydrolyze chlorophenol red β-D-galactopyranoside (CPRG) (a substrate added to the water sample). The hydrolysis reaction of CPRG results in changing the solution color and the magnitude of this color change is a function of the amount of E. coli present in a water sample. It was hypothesized herein that the governing factor for the nanosensor functionality is the surface charge/Coulombic interactions rather than the nanoparticle composition or the type of chemical coating on the nanoparticle surface. To test the research hypotheses, positively charged nanoparticles with different compositions and chemical coatings as well as positively charged polymers were tested herein as potential detection agents for E. coli in water using the competitive binding assay reported in the literature with some modifications. This study produced three main findings that support the research hypotheses. First, gold nanoparticles (AuNPs) were not critical to the nanosensor functionality – other positively charged nanoparticles of silver and iron oxide coated with branched PEI were able to detect E. coli as low as 105 and 107 CFU/mL, respectively. Second, the branched PEI polymer itself (i.e., without a nanomaterial) detected E. coli at 107 CFU/mL. Third, in the absence of E. coli, (1-Hexadecyl) Trimethylammonium Bromide (CTAB), a positively charged polymer, inhibited the hydrolysis of CPRG by β-Gal. This inhibition suggests that other positively charged polymer types have potential applications in colorimetric detection assays that are based on the competitive binding mechanism. The observed behavior with the aforementioned sensing agents indicated that the positive charge was likely responsible for the detection of microbes using this competitive binding detection approach rather than the type of the chemical coating/agent used. These findings open possibilities for more types of recyclable and cost effective nanomaterials and polymers to be developed for detection of E. coli using this competitive binding approach. Furthermore, research is warranted for optimizing the sensing agents tested in this study to lower their detection limit and assess their recyclability.

Advances in our ability to detect biological targets relevant to human health have come from the engineering of biological molecules into assemblies capable of performing target-induced signal generation. Such assemblies, known as biosensors, are composed of a molecular recognition element (MRE) and a signal generating transduction element. One MRE class that has received great attention in recent years is functional nucleic acids, which include DNA aptamers and DNAzymes. Since 1990, a large number of functional nucleic acids have been reported. However, broad commercial use of functional nucleic acids in applications that benefit human health is sparse. The goal of this thesis is to expand the usefulness of functional nucleic acids. The thesis is made of four projects. In the first project I developed a simple colorimetric biosensor for the detection of a toxic metal ion using a reported RNA-cleaving DNAzyme coupled with urease as the signal reporter. This is followed by a project where I developed a highly effective method for the synthesis and purification of the DNA-urease conjugate needed for the biosensor. I then turned my attention to the search for high-affinity DNA aptamers that bind VEGF-165, an important human protein found to be relevant in the progression of cancers. Given that VEGF-165 is a homodimeric protein, in my third project I looked into the suitability of reported DNA aptamers for this protein for the creation of dimeric aptamers with higher binding affinity. I examined multiple factors that may affect the successful engineering of dimeric aptamers and determined that none of the existing aptamers are compatible for creating a productive dimeric aptamer. With this finding, I made an effort to create our own aptamers for this protein target. I was able to isolate a new aptamer that appears to be an excellent candidate for creating a higher affinity DNA aptamer. Overall, my work adds to our increasing appreciation of the functional capability demonstrated by single-stranded DNA molecules. More importantly, I hope the methods I have developed and new functional DNA molecules I have generated in this thesis will continue to drive the development of the functional nucleic acid field and contribute to the health research community’s efforts to increase human longevity. / Thesis / Doctor of Philosophy (PhD)