Physical Sciences and Mathematics Commons^™

Binding Interactions Of Biologically Relevant Molecules Studied Using Surface-Modified And Nanostructured Surfaces, Palak Sondhi

Dissertations

This research focuses on the field of surface nanobioscience, wherein different nanosurfaces that will be used as working electrodes in the electrochemical cell are manufactured and surface modified to understand the critical binding interactions between biologically significant molecules like proteins, carbohydrates, small drug molecules, and glycoproteins. This research is essential if we are to determine whether a synthetic molecule can serve as a therapeutic candidate or diagnose a disease in its early stages. In order to fully understand the binding interactions, the study begins with defining some of the fundamental concepts, principles, and analytical tools for biosensing.

Afterwards, we addressed …

Optimizing The Fluorescent Quantum Yield Of Carbon Dots, Megan B. Prado

MSU Graduate Theses

Carbon dots (CDs) are a subclass of carbon nanomaterials that exhibit unique properties of fluorescence, photostability, low toxicity, and biocompatibility. These unique properties have enabled numerous applications including biosensing, heavy-metal detection, and pH-sensing, among others. Their optical properties can be modified via doping to produce increasingly fluorescent CDs after appropriate purification. Herein, doped CDs were synthesized in four bottom-up methods for comparison using sucrose or citric acid as carbon precursors. Varying hetero-atom dopants (N, S, B) were used in differing molar ratios. The pH-dependent fluorescence and fluorescent quantum yield (QY) were measured for each sample. Characterization was conducted using Fourier-Transform …

Total Internal Reflection: Applications In Nonlinear Microscopy And Fluorescence Anisotropy, Brandon Colon

Doctoral Dissertations

As technology advances to harness new energies and to create new cures, the sophistication of analysis grows not only in depth but in efficiency. Total internal reflection (TIR) has been coupled to microscopy leveraging its unique optical phenomenon on a breadth of topics. In this dissertation, the work presented will show how TIR was applied in two different instrumental analyses to evaluate two unique and complex systems. The first project features TIR paired with the transient absorption microscopy (TAM), a nonlinear optical technique, to gauge solvent mixing and diffusion in microreactors. Microreactors gained acclaim for their ability to produce high …

Instrument Development For High Sensitivity Size Characterization Of Lipid Vesicles And Other Biological Macromolecules Via Taylor Dispersion Analysis, Meagan Moser

Doctoral Dissertations

Just as humans communicate with other humans, the cells in our bodies communicate with each other through various, often complex, mechanisms. Cell-to-cell transmission of small molecules, lipids, proteins, peptides, or nucleic acids can be mediated by extracellular lipid vesicles called exosomes. Exosomes have been found to play a role in the delivery of regulatory molecules from one cell to another, serving as a universal communication mechanism. Currently, there is an emerging focus on characterizing exosome communication dynamics. Understanding exosome mechanisms of cell-to-cell communication requires accurate measurements of the spatiotemporal and chemical dynamics of exosome secretion. No current analytical approach offers …

Plasmon Enhanced Single Molecule Fluorescence In Zero Mode Waveguides (Zmws), Abdullah Masud

Theses and Dissertations--Chemistry

Plasmonic nanostructures are an extensive research focus due to their ability to modify the photophysical properties of nearby fluorophores. Surface plasmons (SP), defined as the collective oscillation of delocalized electrons, are the fundamental characteristic primarily responsible for altering those photophysical properties. Studying fluorophores at the single-molecule level has received significant attention since more specific information can be extracted from single molecule-based studies, which otherwise could be obscured in ensemble studies. However, single-molecule studies are inherently challenging because the signal from a single molecule is usually dim, making it difficult to detect. The situation is even worse in a crowded environment …

Functionalized Gold Nanoparticles For Sensing Of Pesticides: A Review, Wei-Bin Tseng, Ming-Mu Hsieh, Che-Hsie Chen, Tai-Chia Chiu, Wei-Lung Tseng

Journal of Food and Drug Analysis

Pesticides are a family of non-biodegradable chemical compounds which widely used in agriculture to control pests and increase yield production. However, overuse or abuse of pesticides and their metabolites may cause potential toxicity for the environment as well as human health and all other living organisms, even at deficient concentrations. Consequently, the development of sensors for monitoring these compounds is significant. Recently, nanoparticles-based sensors have been extensively employed as a potential alternative or complementary analytical tool to conventional detection methods for pesticides. Among them, gold nanoparticles (AuNPs) owing to their unique optical properties have been developed as smart sensors with …

Towards Machine Learning In Chemical Sensing : Milk Differentiation And Quality Control Through Two-Dimensional Nano-Sensor Array, Yu Sheng Chen

Legacy Theses & Dissertations (2009 - 2024)

Herein, we developed a novel artificial tongue using machine learning and 12 nanoassemblies (2D-NAs) to identify and analyzed different kinds of milk beverages for quality control. This biomimetic sensor array was trained to “taste” different milk types as an “artificial tongue” which is the first time we demonstrated that this sensor array can be implemented to complex systems. Two-dimensional nanoparticles (2D-nps) and nine fluorescently labeled single stranded oligonucleotides (ssDNA) with different length and nucleobases were assembled to create 12 2D-NAs. The artificial tongue was deployed to identify and analyze five milk types. All five milk types were discriminated with 95% …

Oleic Acid Vesicles: Formation, Mechanisms Of Reactivity, And Uses In Determination Of Terpene Activity, Laura A. Walther

Theses and Dissertations--Chemistry

This dissertation will focus on the volatile compounds released upon the burning of incense which are numerous and varied. The first part of this dissertation is the gas chromatography-mass spectral (GC-MS) analysis of burning incense collected via solid phase microextraction (SPME) with the aim of developing a library of compounds found in incense as used in the Orthodox church.

The second part of this dissertation has the aim of developing a method for forming oleic acid bilayer vesicle membranes and a fluorescence spectroscopy method by which the reactivities of these vesicles can be analyzed. These reactivities include permeability, fluidity, aggregation, …

Aptamer-Based Assay For Detection Of Ochratoxin A, Amanda Nicole Bartley

FIU Electronic Theses and Dissertations

Ochratoxin A (OTA) is a potent mycotoxin found in a wide range of agricultural products that has been linked to mitochondrial damage and renal disease. The standard methods for OTA analysis currently rely on the use of high-performance liquid chromatography (HPLC) coupled to fluorescence detection or mass spectrometry. Toward a highthroughput analysis of OTA, a single-stranded DNA aptamer, modified with a fluorophore, coupled to a complementary sequence, modified with a FRET-based quencher that dissociates in the presence of the target toxin, is proposed. In order to integrate “target trapping,” aptamer immobilization methods were explored to mediate interference issues. Assays were …

Assessment Of The Viability Of Microwell Plates As Sample Holders For Analytical Excitation-Emission Spectroscopy Of Polyaromatic Hydrocarbons In 75% Ethanol, Lauren M. Ridley-Hoffman

Seton Hall University Dissertations and Theses (ETDs)

Polyaromatic hydrocarbons (PAHs) in the environment are a significant concern as many compounds in this class are potential carcinogens. PAHs resulting from petroleum spills can contaminate natural waters and the products obtain from them (fish and fish products in particular). Previous studies by Pena, et. al. on ethanolic extracts of organs from menhaden captured in the vicinity of the Deepwater Horizon (Macondo oil well) spill have shown that fluorescence excitation spectroscopy is a useful technique for detecting the presence of PAH metabolites and fluorescent vitamins. The study has also concluded that previous methods for analyzing PAHs using fluorescence spectroscopy used …

Development Of A High Performance Liquid Chromatography Method For The Analysis Of Next-Generation Cyanide Antidote, 3-Mercaptopyruvate, In Plasma, Elaf Alzhrani

Electronic Theses and Dissertations

Although the current FDA approved cyanide antidotes (i.e., sodium nitrite, sodium thiosulfate, and hydoxocoboalamine) are effective for treating cyanide poisoning, each individual antidote has major limitations, including large effective dosage, delayed onset of action, or dependence on enzymes generally confined to specific organs. To overcome these current limitations, next-generation cyanide antidotes are being investigated, including 3-mercaptopyruvate (3-MP). Analytical methods capable of detecting 3-MP from plasma are essential for the development of 3-MP as a nextgeneration cyanide antidote. Although 3-MP has been analyzed by LC-MS-MS, this instrument is not widely available. Therefore, a high performance liquid chromatography (HPLC) method with fluorescence …

Using Metastable-State Photoacid For Fluorescence And Ph Modulation, Renan Gongora, Juan Arias, Parth Patel, Karin Chumbimuni-Torres

EGS Content

The transfer of protons lies at the core of numerous biological and chemical processes. Herein we propose a visible-light triggered molecular system that allows to reversibly tailor acidity and, additionally, fluorescence. This robust bi-functional system opens up the doors for novel studies on acid-mediated processes by incorporating fluorescence. The two photosensitive compounds used for this study, a Metastable-state Photoacids (mPAH) and a boron-dipyrromethene (BODIPY) derivative, allow for consistent modulation of both fluorescence and pH over multiple cycles.

Using Metastable-State Photoacid For Fluorescence And Ph Modulation, Renan S. Gongora, Juan Arias, Parth K. Patel, Karin Y. Chumbimuni-Torres

Juan Arias

Quantifying The Interactions Of Nickel With Marine Dissolved Organic Matter Using Fluorescence, Elissa Dow

Theses and Dissertations (Comprehensive)

Nickel (Ni) is a versatile metal with an abundance of applications, namely its role in stainless steel, electronics, and batteries, making it a popular choice in industry. Unfortunately, with increasing demand and production comes higher amounts of Ni pollution. Nickel enters ocean waters - either directly or indirectly - and can have profound effects on marine life. Nickel has been established as a toxicant to a variety of aquatic biota, with the divalent cation (Ni²⁺) thought to be the most bioavailable fraction and thus the most toxic. Having a reliable means of quantifying free Ni ion is pertinent …

Kinetic Decay Of A Polymer/Ink Complex As An O2 Indicator, Becca Hoene

All Master's Theses

Indicator inks are an important part of the continued consumption of packaged goods. This thesis is focused on understanding the kinetics and reaction mechanism for a unique indicator ink that is based upon the oxidation of indigotetrasulfonate (ITS) encapsulated in the polyelectrolyte poly(diallyldimethylammonium chloride) (polyDADMAC). Sodium bisulfite (NaHSO₃) was used as the initial oxygen scavenger and to drive the reduction of the ITS. Studies were predominantly done in solution phase through the dilution of the ink systems. Fluorescence spectroscopy was the primary method used to determine the kinetic decay rates and interaction between the ITS dye molecules and …

Source-Specific Molecular Signatures For Light-Absorbing Organic Aerosols, Amanda Susan Willoughby

Chemistry & Biochemistry Theses & Dissertations

Organic aerosols (OA) are universally regarded as an important component of the atmosphere based on quantitative significance as well as the far-reaching impact they have on global climate forcing and human health. Despite the acknowledged importance, OA amounts and impacts remain the largest uncertainties regarding radiative forcing estimates. Incomplete chemical characterization of aerosol organic matter (OM) and a lack of concrete source apportionment is a major source of this uncertainty. The primary focus of this study is to provide much needed molecular details regarding ambient OA from key emission sources, and establish links between molecular and optical properties.

Complete chemical …

Design And Development Of Bodipy-Based Fluorescent Probes For Sensing And Imaging Of Cyanide, Zn (Ii) Ions, Lysosomal Ph And Cancer Cells, Jingtuo Zhang

Dissertations, Master's Theses and Master's Reports - Open

BODIPY (4,4-Difluoro-3a,4a-diaza-s-indacene) dyes have gained lots of attention in application of fluorescence sensing and imaging in recent years because they possess many distinctive and desirable properties such as high extinction coefficient, narrow absorption and emission bands, high quantum yield and low photobleaching effect. However, most of BODIPY-based fluorescent probes have very poor solubilities in aqueous solution, emit less than 650 nm fluorescence that can cause cell and tissue photodamages compared with bio-desirable near infrared (650-900 nm) light. These undesirable properties extremely limit the applications of BODIPY-based fluorescent probes in sensing and imaging applications. In order to overcome these drawbacks, we …

Development Of Optical Sensors For Chemical Detection, Jonathan Kelly Fong

Doctoral Dissertations

Detection of biodiesel at low and high concentrations in diesel is highly desired in the aviation and fuel industries. Cross contamination of jet fuel with biodiesel may impact the thermal stability and freezing point which can cause deposits in the fuel system or cause the fuel to gel, leading to jet engine operability problems and possible engine flameout. A dye doped optical sensor utilizing the dye Nile Blue Chloride has been developed for quick and direct detection of biodiesel which mainly contains fatty acid methyl esters (FAME). The sensing mechanism relies on the solvatochromatic properties of the dye which undergoes …

Selective Fluorescence Sensing Of Salicylic Acid Using A Simple Pyrene Appended Imidazole Receptor, Md Wasi Ahmad, Bo Yeon Kim, Hong Seok Kim

Dr. Mohammad Wasi Ahmad (Md Wasi Ahmad)

A simple salicylic acid selective fluorescence receptor 1 was designed by combining 1-pyrenecarboxaldehyde and 1-(3-aminopropyl)imidazole. The selective sensing of salicylic acid resulted in a significant increase in monomer emissions due to the p–p interactions between the benzene and pyrene rings. The nature of the interactions between receptor 1 and salicylic acid was investigated further by 1H NMR spectroscopy, and the energy minimised structure of the complex between receptor 1 and salicylic acid was optimised. Receptor 1 showed the highest binding constant with 5-nitrosalicylic acid among all the aromatic carboxylic acids tested. 5-Nitrosalicylic acid formed a complex with receptor 1 at …

Pyrenyl-Appended Imidazolium Receptor For Selective Fluorescence Sensing Of Oxalic Acid, Md Wasi Ahmad, Sung Hong Kim, Hong Seok Kim

Dr. Mohammad Wasi Ahmad (Md Wasi Ahmad)

A new fluorescent imidazolium-based cholestane receptor 4 bearing a pyrene moiety was synthesized. The binding ability of 4 toward various dicarboxylic acids was examined by UV–vis and fluorescence spectroscopy. Receptor 4 showed the highest binding constant for oxalic acid among all the tested dicarboxylic acids. Oxalic acid formed a complex with 4 with a 1:2 ratio in ethanol.

Studies Of Surfactants Effect On Riboflavin Fluorescence And Its Determination In Commercial Food Products And Vitamin Tablets., William Emmanuel Ghann

Electronic Theses and Dissertations

A simple and economical fluorometer using blue LEDs excitation sources and simple PMT detection had been built, assembled, optimized, and employed for measurement of fluorescence from riboflavin (vitamin B₂). Surfactants have been known to enhance the intensity of fluorescence of fluorescent compounds. Fluorescence analysis of riboflavin in the presence of various anionic, cationic, and nonionic surfactants was also conducted to determine if they could improve analysis. However, the surfactants employed did not seem to have any meaningful enhancement; in fact, some actually diminished the fluorescence intensity of riboflavin. The procedure was linear for riboflavin from 0.01 to 2.5 …