Thesis (Ph. D.)--Northeastern University, 2008. / Title from title page (viewed Mar. 24, 2009). Graduate School of Arts and Sciences, Dept. of Chemistry and Chemical Biology. Includes bibliographical references (p. 173-176).

Gold nanoparticle (AuNP) is used for the detection of biomolecules and study of the interaction between bio-molecules with the aid of dark field microscopy (DFM). AuNP exhibits unique optical properties and ability to conjugate with different biomolecules either by covalent binding or physical absorption, which allow the AuNP possessing a variety of biological application. We reported a sensitive detection system for measuring DNA–protein interaction at single plasmonic metal nanoparticles level by Localized Scattering Plasmon Resonance (LSPR) spectroscopy. As a proof of concept, DNA molecules were conjugated to gold nanoparticles (AuNPs) through gold–thiol chemistry and the resulted complex was served as single-particle probes of human topoisomerase I (TOPO). By recording the changes in Rayleigh light scattering signal of the individual nanoparticles upon protein binding, DNA–protein interaction was monitored and measured. The .max shifts in LSPR spectrum of individual AuNP was found to be highly correlated with the amount of TOPO that bound onto. We presented an immunosensing platform to detect cancer biomarkers by collecting the LSPR signal of immune-target conjugated gold nanoparticle (AuNP). Prostate specific antigen (PSA), which is a FDA-approved biomarker for prostate cancer, was chosen as an example. Herein, the immunoreaction of PSA, capturing PSA antibody (CHYH1) (Ab1), and detecting PSA antibody (CHYH2) (Ab2) was studied with a spectrometer coupled-dark field microscope. LSPR of immunotarget conjugated AuNP was directly measured. In brief, Ab1 and Ab2 were covalently conjugated with AuNPs separately, followed by addition of PSA for the formation of sandwiched immuno-complex in PBS solution. Then, the complex was immobilized on surface of glass slide for capturing dark-field images and LSPR spectra. Besides, to study the ligand-receptor interaction, we prospect a detection system at single plasmonic metal nanoparticle level by LSPR spectroscopy. Glucocorticoid receptor protein (GR) was chosen as example with two ligands ginsenoside-Rg1 (Rg1) and dexamethasone (DEX). Herein, dsDNA molecules were covalently conjugated with AuNPs and the resulted complex was used as single particle probes of GR. The binding of GR to the dsDNA could be promoted by the agonistic ligands. DNA-GR interaction in the presence of ligands was monitored and measured by recording the changes of LSPR upon protein binding. This technique provides a sensitive and high-throughput platform to screen and monitor accurately the speci.c biomolecular interactions. It is capable of revealing information such as particle–particle variations that might be buried in conventional bulk measurement.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 401-408).

Low molecular weight gelators (LMWGs) have gained much attention over the last few decades, because of their ability to form supramolecular architectures as well as their many potential applications in biomedical research and as advanced materials. Most of the gelators were discovered through serendipity, and their structural requirements are somewhat ambiguous. This is due, in part, to the fact that the supramolecular gelation phenomenon is not yet fully understood, though many structural classes have been found to be excellent organogelators. Carbohydrates are abundant natural resources that are useful in preparing advanced materials. We have previously showed that monosaccharide derivatives can form effective low molecular weight gelators for both organic solvents and aqueous mixtures. In this research, we have studied the gelation capability of several glucosamine derivatives. Several series of 4,6-O-acetal protected glucosamine derivatives were synthesized and screened for their gelation properties in several solvents.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 1996 / The electric field strength and pH gradients generated in isotachophoretic systems may be used for the separation of biomolecules. Poly (2 acrylamido 2-methyl-1-propanesulfonic acid) polymers of a uniform distribution of molecular mass were synthesized and used as spacers in isotachophoresis in order to generate linear electric field strength gradients in which biomolecules could be focused. These novel spacers are designed to operate within sieving media, and hence are useful for the separation of nucleic acids. [Abbreviated Abstract. Open document to view full version]

University of Macau / Institute of Chinese Medical Sciences

Biomolecular interactions are central to all biological functions as the execution of biological function usually depends on the concerted action of biomolecules existing in protein complexes, metabolic or signaling pathways or networks. Therefore, understanding biomolecular interactions, and the temperature dependence of biomolecular interactions is of critical importance for the study of fundamental science, therapeutic drug development, and biomolecule manipulation. Biocalorimetry, a process of measuring the heat involved in biomolecular interactions, has distinct advantages over other biomoelcualr interactions characterization methods as it is solution based, label free, universally applicable, and allows for determination of thermodynamic propoerties. However, the utility of available commercial instruments is limited by complex design, rather large sample consumption, and slow responses. Micro-electro-mechanical systems (MEMS) technology, as an alternative approach, potentially offers solutions to such limitations as it can potentially be fabricated at low cost, operated at high throughput with minimum sample consumption, and available for integration with various functional units. However, existing MEMS calorimeters either do not yet allow proper control of reaction conditions for thermodynamic characterization of biomolecular reaction systems or is not yet suitable for practical applications because of a lack of sensitivity, reliability, and high operating cost. This thesis will build upon our existing knowledge of the MEMS technology in biocalorimetry and develop new generation of polymer MEMS calorimetric devices that are economical, sensitive, and robust for studying biomolecular characterization in practical settings. The development of such devices requires innovations in the fabrication process as the conventional photolithography process is largely incompatible with polymer substrates. To address that, this thesis first presents a novel method of fabricating polymer-based MEMS thermoelectric sensors using a thermally assisted lift-off approach, by which, thick metal or semiconductor films experience controlled breakup due to thermal reflow of the underlying lithographically defined patterns. The thick film MEMS thermoelectric sensors exhibit electric and thermoelectric performances comparable to those made from bulk materials. This allows the sensors to be useful in low-noise, high-efficiency thermoelectric measurements. The polymer-based MEMS sensors fabrication approach is then implemented in making MEMS calorimetric devices for solution-based, quantitative thermodynamic characterization of biomolecular interactions. This thesis presents both polymer-based MEMS differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC) devices that are more robust, and cost lower. The polymer-based MEMS calorimeters eliminate the need for complex, fragile silicon freestanding structures and offer real-time, in-situ temperature control to biomolecules with well-defined miniature volume. Combining with the improved sensitivity, the polymer-based devices also reduce consumption of material and leads to substantially reduced thermal mass of the measurement system for a rapid response time and improved throughput. The interpretation of the DSC, ITC measurement results yielded complete thermodynamic information of several biomolecular interactions of critical scientific and therapeutic interest that include the characterization of the unfolding of protein (lysozyme) for the determination of its thermodynamic properties, and the binding parameters of interactions of 18-Crown-6 and barium chloride in practically applicable reagent concentrations. In addition, PDMS-based microfluidic structures that are used in molecular biological analysis platforms, including MEMS calorimeters are known to be problematic due to its surface adsorption effects and high permeability. To address this, this thesis eliminates the use of PDMS microfluidic structures in MEMS calorimeters entirely by presenting the first demonstration of a miniaturized 3D-printed Lab-on-a-chip (LOC) platform that integrates the polymer-based MEMS calorimeter for quantitative ITC characterization of biomolecular interactions. Exploiting topographical flexibility offered by 3D printing, the platform design features fully isolated cantilever-like calorimetric measurement structures in a differential setup. This design layout improves thermal isolation and reduces overall platform thermal mass, thereby enhancing the measurement sensitivity and reducing the platform response time. The utility of the platform is demonstrated with ITC measurements of the binding of 18-Crown-6 with barium chloride and the binding of ribonuclease A with cytidine 2’-monophosphate in a reusable manner, and with practically relevant reagent concentrations. Finally, some perspectives of how far away the devices are from commercializing are summarized, and future works in suggesting the strategies to achieve this goal are proposed.

Optimization of preparative nonlinear chromatography was carried out for the first time for a biomolecule mixture. Conventional wisdom on optimization, which roots from analytical chromatography, dictates optimizing resolution in an analytical column and obtaining similar separation in a large column for isolation. Such a method of optimization significantly under uses the capacity of the column and consumes large quantities of mobile phase. Hence, in preparative chromatography, the objective function is productivity, a measure of compromise between the amount of feed that can be loaded on to the column and time. Here, we report results from optimization studies carried out on a closely related binary peptide mixture on an analytical reversed-phase column. The goal is to optimize productivity under various chromatographic modes nonlinear isocratic elution, gradient elution, stepwise elution and displacement chromatography. In each mode, feed mixtures at highest possible concentration (limited by solubility), for increasing feed volumes was used. Productivity was monitored for increasing feed volumes, and loading was stopped as it went through a maximum. However, in some cases, solubility limitations from one of the feed components prevented further increase in loading. Even with this constraint, high productivities (5-10 g product/L stationary phase-h) were achieved. Separate experiments were carried out to measure the adsorption isotherms of these peptides over the range permitted by solubility. Separations under nonlinear chromatographic conditions were applied to isolate commercially significant two microcystins (microcystin LR and microcystin LA) from a cyanobacterial process waste. Milligram-level loading of microcystins was obtained on a solid-phase extraction cartridge packed with 0.5 g of C������ stationary phase. The separations were first carried out on an analytical column and then scaled-up to a preparative column. We also report simple and economical process to purify phycocyanins and allophycocyanins from a cyanobactenal process waste stream for two kinds of applications food colorant and biomedical marker. A detailed design for the large-scale production of biliproteins for both applications is also presented. Economic evaluation of the process resulted in comparable costs with the current market price for food-grade product and substantially lower cost for the biomedical grade product. / Graduation date: 2001

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Mary J. Wirth, Dept. of Chemistry and Biochemistry. Includes bibliographical references.

Thesis ( Ph.D.) -- University of Texas at Arlington, 2008.