This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu). / A role has been proposed for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in central cardiovascular control. This proposa 1 was based on the cardiovascular effects of agents which block or mimic the action of GABA on the post-synaptic membrane. This dissertation reported the cardiovascular effects of 3-mercaptopropionic acid (3-MP), an agent which inhibits GABA biosynthesis in the pre-synaptic nerve terminal in anesthetized guinea pigs. 3-MP interrupts GABAergic transmission by decreasing the amount of GABA in the brain. The effect of 3-MP on mean arterial pressure, heart rate and barorflex-induced bradycardia was determined as well as the mechanism(s) involved in observed changes. The content of GABA in four regions of the brain (hypothalamus, medulla, cerebellum and occipital cortex) was determined at the end of each experiment. In anesthetized guinea pigs, 3-MP (195 mg/kg, i.p.) elicited a biphasic response (Type I) in the majority of animals. This response consisted of sympathetically-mediated hypertension and tachycardia superseded by vagally-mediated bradycardia. The other response (Type II) consisted of only the sympathetically-mediated effects. The Type II response was associated with animals in which the vagus nerves were functionally impaired. In all brain regions measured, the GABA levels of both Types I and II were significantly lower than those of control animals. The sympathetically-mediated effects of 3-MP were reversed by chlordiazepoxide, a GABA-facilitory agent. Therefore, the 3-MP-induced cardiovascular effects appeared to reflect GABAergic activity in the bra in which resulted from a reduction of GABA content. The two phases of the Type I response may have resulted from a reduction of GABA content in specific brain regions. A reduction in hypothalamic GABA levels appeared to be related to the sympathetic activation and a reduction in medullary GABA levels appeared to be related to the vagal activation. In unparalyzed animals, 3-MP elicited convulsive movements as well as the described effects on the cardiovascular system. The centrally acting anticonvulsant phenytoin stopped 3-MP-induced motor manifestations of seizure activity without altering either blood pressure or heart rate. Therefore, the cardiovascular effects of 3-MP appeared to occur independent of the convulsive effect of this agent. These results support the hypothesis of GABAergic involvement in the central control of autonomic outflow to the cardiovascular system. The inability of phenytoin to reverse the cardiovascular effects of 3-MP suggests that these effects were independent of 3-MP-induced seizures.

Magister Scientiae - MSc / Cancer, the second most common cause of death after heart disease, is a complex and multifactorial disease that up to date is still under extensive research. To achieve early detection of cancer disease the discovery of specific, sensitive and reliable biomarkers is required. Telomerase is a ribonucleo-protein complex that has been identified as an important target for cancer diagnostics and cancer therapy, because 85% of more than 950 primary tumours express telomerase activity. The standard method for the detection and quantification of telomerase activity is the polymerase chain reaction (PCR)-based assay known as the telomeric repeat amplification protocol (TRAP) assay. TRAP and other methods developed for telomerase detection have limitations for example its time consuming, requires complicated machinery, expensive equipment and reagents thus there is a need for a more sensitive, reliable and high-throughput method. Electrochemical biosensors are quickly emerging as an alternative for early detection of cancer because they can be designed to detect developing cancer biomarkers and to allow improved monitoring of cancer growth and patient therapy. This research study reported for the first time the successful fabrication and implementation of highly sensitive 3-mercaptopropionic acid indium telluride quantum dots (3MPA-In2Te3 QDs) based genosensor for detection of telomerase biomarker. The colloidal poly-dispersed 3MPA-In2Te3 QDs introduced into the genosensor system were successfully synthesized by a simple, inexpensive and reproducible aqueous method. The as prepared 3MPA-In2Te3 QDs was characterized by Ultraviolet Visible (UV-VIS) spectroscopy, Fluorescence (FL) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy and High Resolution Transmission/Scanning Electron Microscopy (HR TEM/SEM). Electro-analysis of 3MPA-In2Te3 QDs was done by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). HR-TEM studies revealed formation of small sized QDs about 6 nm in diameter while UV-VIS studies showed presence of iv absorption peaks in the ultraviolet region (100-400 nm) which confirmed the formation of these small sized QDs. The good electrochemical, optical, physical and chemical properties of the 3MPA-In2Te3 QDs allowed them to be used as a mediating platform between deoxyribonucleic acid (DNA) and gold electrode (AuE). The successful detection of telomerase was achieved by hybridization process between the probe single stranded deoxyribonucleic acid (ssDNA) drop coated on the 3MPA-In2Te3 QDs/AuE surface and its complementary ssDNA in biological buffer solution (0.10 M tris-ethylenediamine tetraacetic acid (TE) buffer solution, pH 8.00). The response of the 3MPA-In2Te3 QDs based genosensor towards different concentration of complementary ssDNA was studied by CV, square wave voltammetry (SWV) and EIS. It was observed that all three analytical techniques exhibited good linearity since their linear correlation coefficients (R2) corresponded to 0.99. However, it was observed that EIS was the best technique for the detection of telomerase compared to both CV and SWV since it showed a higher sensitivity (2.44 Ω/nM) towards detecting telomerase with a detection limit as low as 0.00014 ng/mL. Control experiments were also carried out by monitoring the hybridization process in the presence and absence of complementary ssDNA and it was determined that the QDs based genosensor was highly selective towards complementary ssDNA. In view of the attractive analytical characteristics and advantages, the ultimate goal of the developed QDs based genosensor is to apply it in real clinical samples of cancer cells or bodily fluids of cancer patients for the detection of telomerase cancer biomarker.

This thesis deals with biosensors based on modified semiconductor core/shell quantum dots (QDs) for diagnosis. The work is divided into four main parts. The first one discusses the theory required for the use of QDs in bioaplications, there are described methods of synthesis, modification, application and bioconjugation of QDs. In the experimental part, CdTe/ZnS QDs with core/shell structure were prepared, in which the core was modified by MPA, GSH and TGA. In the next step, these QDs were further modified using CDI, EDC and NHS as mediators in order to increase affinity to BSA (bovine serum albumine) and IgG (imunoglobuline G). Prepared conjugates were characterized by fluorescence spectroscopy (Infinite M200Pro, Tecan) and capillary electrophoresis (Agilent 7100).

The aim of this work was to synthesise water-soluble QDs using different precursors and stabilizers and to determine the toxicity of the synthesized QDs by in vivo imaging. Experiments were performed on water-soluble QDs (MPA-CdTe, MPA-CdTe/ZnS, MSA-CdTe, MSA-CdTe/ZnS, GSH-CdTe, GSH-CdTe/ZnS, TGA-CdTe, TGA-CdTe/ZnS, GSH-ZnSe and GSH-ZnSe/ZnS ) and toxicity was measured. Synthesized QDs were characterized by high intensity (fluorescence spectroscopy), FWHM and zeta potential (ZS Zetasizer) were selected due to their suitability for this task. The toxicity of QDs was determined by the MTT assay on the cell line HEK 293. The experiments show that a core/shell structure is less toxic than a core structure. The results indicate that the toxicity of our synthesized QDs is the lowest for MPA-CdTe (core structure) and MPA-CdTe/ZnS (core/shell structure).

>Magister Scientiae - MSc / In this study PbSe quantum dots (QDs) were successfully synthesized via the organometallic and aqueous routes. Optical characterization was carried out using photoluminescence (PL) spectroscopy, structural and morphological characterization were carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDS) was used to determine the composition of the QDs. All the synthesized QDs were found to have emissions within the near-infrared region of the spectrum (≥1000 nm) with most of them being less than 5 nm in size. The aqueous synthesized QDs had a perfect Gaussian emission spectrum with a FWHM of ~23 nm indicating pure band gap emission and narrow size distribution respectively. The QDs were determined to have a cubic rock-salt crystal structure consistent with bulk PbSe. The aqueous synthesized QDs were however not stable in solution with the QDs precipitating after approximately 48 h. The organometallic synthesized QDs were transferred into the aqueous phase by exchanging the surface oleic acid ligands with 11-mercaptoundecanoic acid ligands. The ligand exchanged QDs were however stable in solution for over two weeks. The effects of reaction parameters on the optical and structural properties of the organometallic synthesized QDs were investigated by varying the reaction time, temperature, ligand purity, lead and selenium sources. It was observed that larger QDs were formed with longer reaction times, with reactions proceeding faster at higher reaction temperatures than at lower temperatures. Varying the ligand purity was found to have minimal effects on the properties of the synthesized QDs. The lead and selenium sources contributed largely to the properties of the QDs with lead oxide producing spherical QDs which were smaller compared to the cubic QDs produced from lead acetate. TBPSe was seen to produce smaller QDs as compared to TOPSe. The cytotoxity of the synthesized QDs was determined following the WST-1 cell viability assay with the QDs being found to be non-toxic at all the tested concentrations

The aim of this work was to synthesise water-soluble QDs using different precursors and stabilizers and to determine the toxicity of the synthesized QDs by in vivo imaging. Experiments were performed on water-soluble QDs (MPA-CdTe, MPA-CdTe/ZnS, MSA-CdTe, MSA-CdTe/ZnS, GSH-CdTe, GSH-CdTe/ZnS, TGA-CdTe, TGA-CdTe/ZnS, GSH-ZnSe and GSH-ZnSe/ZnS ) and toxicity was measured. Synthesized QDs were characterized by high intensity (fluorescence spectroscopy), FWHM and zeta potential (ZS Zetasizer) were selected due to their suitability for this task. The toxicity of QDs was determined by the MTT assay on the cell line HEK 293. The experiments show that a core/shell structure is less toxic than a core structure. The results indicate that the toxicity of our synthesized QDs is the lowest for MPA-CdTe (core structure) and MPA-CdTe/ZnS (core/shell structure).