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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 29, 2009) Includes bibliographical references.

SPIONs have unique material properties: ultra-small size and high magnetic susceptibility. These properties give SPIONs advantages to be used in a wide range of applications such as NMR/MRI contrast agents, cancer hyperthermia therapy, and cell- targeted and magnetically-triggered intracellular uptake. However, research has found that it is challenging to develop a SPION system that has controllable colloidal stability. This thesis endeavored to develop a SPION surface coating that allowed creation of a SPION system with known surface properties, hence enabling the study of its colloidal stability with a combination of computational and experimental methods. With the knowledge of colloidal behavior of nanoparticles, this thesis further explored the magnetic properties of SPIONs by designing lipid nanoparticles encapsulating (LNPs) that target and isolate a rare type of immune cell.

Cell biophysical properties are a new class of biomarkers that can characterize cells into subgroups that indicate differences in phenotypes that may correlate with disease and cell state. Microfluidic biophysical cell sorters are platforms that utilize these newly developed biomarkers to expand biomedical capabilities for improvements in cell state detection and characterization. Cell biophysical properties are important indicators for cell state and function because they point to differences in cell structures, such as cytoskeletal arrangement and nuclear content. In particular, some diseases, such as cancer and malaria, can cause significant changes in cell biophysical properties. Therefore, cell biophysical properties have the potential to be used for disease diagnostics. Microfluidic systems which can interrogate these biophysical properties and exploit changes in biophysical properties to separate cells into subpopulations will provide important biomedical capabilities. In this combined theoretical and experimental investigation, we explore a new type of cell sorter which utilizes differences in biophysical properties of cells. These biophysical properties that can be utilized to sort cells include size, elasticity and viscosity. We invented a microfluidic system for continuous, label-free cell separation that utilizes variations in cell biophysical properties. A microfluidic channel is decorated by periodic diagonal ridges that are designed to compress flowing cells in rapid succession. The physical compression, in combination with hydrodynamic secondary flows induced by the ridged microfluidic channel, translates each cell perpendicular to the channel axis in proportion to its biophysical properties. Through careful experimental and computational studies, we found that the cell trajectories in the microfluidic cell sorter correlated to these biophysical properties. Furthermore, we examine the effect of channel design parameters under various experimental conditions to derive cell separation models that can be used to qualitatively predict cell sorting outcome. A variety of biophysical measurement tools, including atomic force microscopy and high-speed optical microscopy are used to directly characterize the heterogeneous population of cells before and after separation. Taken together, we describe the physical principles that our microfluidic approach can be effectively used to separate a variety of cell types. The major contribution is the creation and characterization of a novel microfluidic cell- sorting platform that utilizes cell biophysical properties to enrich cells into phenotypic subtypes. This innovative approach opens new ways for conducting rapid and low-cost cell analysis and disease diagnostics through biophysical markers.

Compounds from the marine environment exhibit a wide variety of biological activities, and thus hold much promise as potential drugs. The halichondrins, isolated from the Kaikoura sponge Lissodendoryx sp. are no exception to this, demonstrating potent anticancer activity. Novel cytotoxic compounds have also been isolated from the Chatham Rise sponge Lamellomorpha strongylata. Knowledge of the cellular origins of such compounds is desirable, in order to establish if the sponge or associated micro-organisms are producing the compounds of interest. Siderophores are also important molecules, which are produced on demand by bacteria in order to obtain sufficient iron necessary for their growth. Knowledge of the biosynthesis of these compounds has potential for the control of undesirable bacteria, such as the anthrax-causing pathogen Bacillus anthracis. Cell separation studies have been carried out on Lamellomorpha strongylata, locating a swinholide in sponge-associated filamentous bacteria and theonellapeptolides in sponge-associated unicellular bacteria. A microscopic analysis of dissociated cells from Lissodendoryx sp. was also undertaken. The structures of four new halichondrins (3.13 - 3.16), isolated from Lissodendoryx sp., have been determined from spectral data. All of these compounds are very similar to known B series halichondrins, with differences occurring only beyond carbon 44. As biological activity has been shown to be derived from the portion of the molecule between carbons 1 and 35, they all retain good activity in the P388 assay as expected. A new siderophore, petrobactin sulfonate (4.2), was characterised, along with three cyclic imide siderophore derivatives (4.3 - 4.5). Petrobactin sulfonate is the first marine siderophore containing a sulfonated 3,4-dihydroxy aromatic ring. The structures were elucidated from spectral data, resulting in a revision of the NMR assignments of petrobactin.

CdSe semiconductor nanocrystals (quantum dots--QDs) with diameters ranging between 1.5 and 8 nm exhibit strong, tunable luminescence [1-5]. They have been widely investigated for their size-dependent optoelectronic properties [6], and for their potential use in optical devices [7], biological labels [8] and sensors [9]. Luminescent quantum dots (QDs) show higher photostability and narrower emission peaks compared to organic fluorophores [8]. The objective of my project was to apply QDs magnetic/luminescent nanoparticle as biological labels in cells. Luminescent CdSe QDs emit bright visible light with high quantum yield and sharp emission peak. The CdSe QDs were capped with a ZnS layer. This increased their emission efficiency and photostability due to the larger band gap of ZnS. The QDs were transferred from organic solvent (e.g. chloroform, hexane) to water by exchanging the capping group (Trioctylphosphine Oxide—TOPO) with mercaptoacetic acid. To develop a separation and detection tool for cells, we combined γ-Fe2O3 magnetic particles with CdSe/ZnS QDs in core-shell composite. The composite nanoparticles showed strong fluorescence emission and high water solubility. Different antibodies were attached to the particles through EDAC coupling. The antibody-coated particles were used to successfully separate and detect breast cancer cells in blood cells.

Thesis (M.Sc. (Biochemistry)) -- University of Limpopo, 2012 / Various cytomorphologic and biochemical markers of apoptosis are found in different compartments (plasma membrane, cytoplasm, nucleus, and mitochondria) of target cells. Although the plasma membrane is an easily accessible cellular compartment, relatively little is known about the changes in the expression of plasma membrane glycoproteins during apoptosis, and whether these changes could be used for detection of apoptosis. A critical element of this study was to purify lectins from crude homogenate on glycoprotein-cryogel affinity matrices, and later use the lectins to detect changes on the cell surface of apoptotic cells. Pterocarpus angolensis seed lectin was extracted and fractionated using ammonium sulphate precipitation. The 60 % ammonium sulphate pellet was dissolved in saline azide and purified using Sephadex G-75 affinity chromatography. A 28 kDa lectin was retarded within the column and appeared as a short and broad peak on the chromatogram. Traditionally, Sephadex G-75 column are used predominantly for size exclusion, in this study, the column was used in a non-traditional way for affinity chromatography, as the purified protein is able to bind sugar moieties existing in the structure of Sephadex G-75. A single-step purification of P. angolensis seed lectin was achieved by directly applying unclarified P. angolensis crude extract to the pAAm-cryogel using fetuin as the affinity ligand. Pterocarpus angolensis extract fractionated into 2 peaks, which revealed a highly concentrated band on SDS-PAGE. The results also revealed that an increased binding of the lectin to the fetuin-cryogel matrices was also dependent on the time of incubation. This study suggested very low capacities of the cryogels for the protein due to low coupling sites on the matrix. Taking into account that lectins serve as invaluable tools in diverse area of biomedical research, this study proposed using specific plant lectins to follow the expression of plasma membrane glycoproteins during programmed cell death. Treatment of HL-60 cells with lithium and actinomycin D confirmed a time- and dose-dependent inhibition of proliferation and a decrease in proliferation, which suggest cell death of the treated cells. The observed cell death was further investigated for cellular and biochemical hallmark features of apoptosis, which has shown preferential binding of annexin V-FITC to phosphatidylserine and low molecular DNA ladder. Several FITC labelled lectins were used to detect changes in cell surface glycosylation that accompany apoptosis. This study xvii has shown amongst several FITC-labelled lectins that T. vulgaris lectin could intensively stain the membrane area of apoptotic cells suggesting that the expression of N-acetylglucosamine was significantly increased during actinomycin D induced apoptosis of HL-60 cells. Binding was shown to be specific because it was blocked by the corresponding inhibitory sugar. Thus, the method described in this study could be suitable for the detection of very early stages of apoptosis by recognizing the cell surface carbohydrates of apoptosis.

Pik1p, one of three phosphatidylinositol 4-kinases in the fission yeast, <i>Schizosaccharomyces pombe</i>, was found previously to interact with Cdc4p, a myosin essential light chain that is required for cytokinesis. The involvement of pik1 in cell cycle control was investigated. A fluorescently tagged Pik1p fusion protein was associated with Golgi throughout the cycle, and was found at the medial division plane of the cell during late cytokinesis. This latter distribution has not been reported previously. Gene deletion in diploid cells and tetrad analysis revealed that pik1 is essential for cell viability and is required for spore germination. The terminal phenotype of a temperature-sensitive, loss-of-function allele (pik1-td) indicated that pik1 is involved in cytokinesis: particularly for suppression of secondary septum material deposition, for suppression of initiation of supernumerary septa, and for cell separation. Contractile ring formation was normal in pik1-td cells at the restrictive temperature although the pattern of F-actin patches was disrupted. The F-actin patches were dispersed throughout the cytoplasm. Accumulation of extra inner membranous or vesicle-like structures was observed in these cells. The <i>S. pombe</i> nmt1 promoter and attenuated versions of it were found to be useful for complementation studies in <i>S. cerevisiae</i>. Heterologous expression of <i>S. pombe</i> pik1 complemented the essential functions of a temperature-sensitive allele (pik1﷓101) of its orthologue in <i>Saccharomyces cerevisiae</i> that were lost at the restrictive temperature. A residue required for <i>S. pombe</i> Pik1p lipid kinase activity, D709, was also required for this complementation. A residue, R838, which is required for interactions between Pik1p and Cdc4p was not required for this complementation. The timing and localization of Pik1p to the division plane of the cell late in cytokinesis combined with analysis of the terminal phenotype of a loss-of-function allele, indicate that Pik1p and/or its derived phosphoinositides are required for regulation of septation and cell separation. Pik1p may be involved in the transport, possibly via vesicular transport, of enzymes required for hydrolysis of the primary septum. It may be involved in signaling pathways that lead to the initiation of septation and to the cessation of the deposition of secondary septum material.

Pik1p, one of three phosphatidylinositol 4-kinases in the fission yeast, <i>Schizosaccharomyces pombe</i>, was found previously to interact with Cdc4p, a myosin essential light chain that is required for cytokinesis. The involvement of pik1 in cell cycle control was investigated. A fluorescently tagged Pik1p fusion protein was associated with Golgi throughout the cycle, and was found at the medial division plane of the cell during late cytokinesis. This latter distribution has not been reported previously. Gene deletion in diploid cells and tetrad analysis revealed that pik1 is essential for cell viability and is required for spore germination. The terminal phenotype of a temperature-sensitive, loss-of-function allele (pik1-td) indicated that pik1 is involved in cytokinesis: particularly for suppression of secondary septum material deposition, for suppression of initiation of supernumerary septa, and for cell separation. Contractile ring formation was normal in pik1-td cells at the restrictive temperature although the pattern of F-actin patches was disrupted. The F-actin patches were dispersed throughout the cytoplasm. Accumulation of extra inner membranous or vesicle-like structures was observed in these cells. The <i>S. pombe</i> nmt1 promoter and attenuated versions of it were found to be useful for complementation studies in <i>S. cerevisiae</i>. Heterologous expression of <i>S. pombe</i> pik1 complemented the essential functions of a temperature-sensitive allele (pik1﷓101) of its orthologue in <i>Saccharomyces cerevisiae</i> that were lost at the restrictive temperature. A residue required for <i>S. pombe</i> Pik1p lipid kinase activity, D709, was also required for this complementation. A residue, R838, which is required for interactions between Pik1p and Cdc4p was not required for this complementation. The timing and localization of Pik1p to the division plane of the cell late in cytokinesis combined with analysis of the terminal phenotype of a loss-of-function allele, indicate that Pik1p and/or its derived phosphoinositides are required for regulation of septation and cell separation. Pik1p may be involved in the transport, possibly via vesicular transport, of enzymes required for hydrolysis of the primary septum. It may be involved in signaling pathways that lead to the initiation of septation and to the cessation of the deposition of secondary septum material.

Circulating tumor cells (CTCs) are the cells that are shed from a primary tumor into the vasculature and circulate in the bloodstream. CTCs may trigger cancer metastasis, which leads to most cancer-related deaths. CTCs are widely studied due to their value in cancer diagnosis, prognosis, and oncology studies. The major challenges with CTCs lie in their extremely low concentration in blood, thus requiring an effective enriching system to enable downstream analyses. The immunomagnetic assay has proved to be a promising CTC detection tool with high sensitivity and throughput. Key factors related to the immunomagnetic assay include the capture rate, which indicates the sensitivity, and distributions of target cells after capture, which impact the cell integrity and other biological properties. In this dissertation, we build a sedimentation model, a partial viscosity model, and a cell-tracking model to address the principle of the immunomagnetic cell separation. We examine the channel orientations and determine the favorable inverted condition. In addition, we develop a micromagnet approach to modulate the in-channel magnetic field toward enhanced cell detection and distribution. Through numerical studies, we calculate the magnetic field generated by the thin-film micromagnets, determine its effective ranges, and demonstrate its value in optimizing cell distribution. In the experimental demonstration, we present two types of micromagnets based on e-beam Ni deposition and inkjet printing technology, respectively. In the screening experiments, the Ni micromagnet integrated system achieves over 97% capture rate. It shows a 14% increase in capture rate, and a 14% improvement in distribution uniformity compared with plain slides. We also successfully isolate CTCs from metastatic cancer patients with the micromagnet assay. The inkjet-printed patterns yield a similarly high capture rate of 103%. With the pixel permanent magnet array, the inkjet patterns further increase the distribution uniformity for 20%. The proposed models lay the theoretical foundations for future modification of the immunomagnetic assay, and the micromagnet-integrated system provides a promising tool for translational applications in cancer diagnose and clinical cancer management. / text