Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Chemical Vapor Deposited Reusable Fluorescent Thin Film Sensor Nanoprobes for the Detection of Heavy Metal Ions(01. Izmir Institute of Technology, 2023) Ebil, Özgenç; Karabıyık, Merve; Ebil, Özgenç; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyHeavy metal pollution has made a serious threat to the environment and human health day by day due to developing science, technology and industrial activities, therefore, the importance of selective detection of heavy metals has increased. Heavy metals gradually accumulate in the human body, especially via water sources. Among heavy metals, cadmium is one of the most carcinogenic ones and has harmful effects even in trace amounts. Despite it, detection studies of cadmium ion are very few. This thesis study focuses on the development of Initiated Chemical Vapor Deposition (iCVD) synthesized polymer thin film based quantum dot-nitroxide radical fluorescence sensor nanoprobe, which has a multi-use property and high durability, unlike sensor probes developed for single use in liquid media, and selective detection of Cd2+ ions in real water sources. By examining the effects of pH, concentration, solvent type and reaction time, the most suitable conditions to improve the interaction between Cd2+ ion and the newly developed sensor nanoprobe were investigated. The results proved that it is possible to detect the target ion easily even in complex environments where other heavy metal ions are present. Cd2+ ion detection limit with this proposed nanoprobe was found as 0.195 μM and high recovery percentage (>90%) obtained in standard addition method. In the multi-use study, it was confirmed that nanoprobe could be used repeatedly for the selective and sensitive detection of Cd2+ ion without being influenced by the content of daily water samples. This thesis is a great guide for new fluorescent sensor applications.Doctoral Thesis Development of a Plasmonic Biosensor for Detection of Exosomes(Izmir Institute of Technology, 2020) Tekin, Hüseyin Cumhur; Bulmuş Zareie, Volga; Bulmuş Zareie, Esma Volga; Tekin, Hüseyin Cumhur; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this work was to develop Localized Surface Plasmon Resonance (LSPR) surfaces for quantitative detection of exosomes from different sources. For this aim, gold nanorods (AuNRs) with a mean diameter of 40 nm with an aspect ratio of 2.9 were first synthesized and characterized. The self-assembly of AuNRs on glass wafers were optimized through several experiments. In parallel, PEGylation of cetrimonium bromide (CTAB) stabilized AuNRs was investigated using PEGs with three different molecular weights via LSPR, zeta potential and XPS techniques. PEGylated AuNRs were further self-assembled on silanized microscope slides as confirmed. Surface functionalization of AuNR patterned slides was performed using alkane thiol molecules having carboxylic acid and hydroxyl functional groups and confirmed via XPS, FTIR and zeta potential. Specific antibodies (Ab) were conjugated to the surface following two different methods, i.e. click and NHS/EDC chemistry. To perform click chemistry strategy, ImmuneLink® molecules were conjugated with Abs and the final conjugate was used to functionalize surfaces prepared beforehand using azide bearing molecules. The functionalization procedure was confirmed via XPS FTIR and LSPR spectroscopy. The orientation of the antibodies on the AuNRs patterned surfaces was investigated with LSPR in comparison with conventional EDC/NHS chemistry. The click-chemistry strategy proved to provide conjugation of antibodies through their Fc regions exposing Fab regions better for antigen recognition. Finally, surfaces functionalized with a variety of antibodies were used to detect first a pregnancy-associated protein, PLAP, and then exosomes obtained from human semen samples with pre-determined exosome concentrations. The LoD of the biosensor surfaces was found to be between 103-104 exosomes/mL and 5 ng/mL (0.3 pM) PLAP. Human breast cancer cell culture samples having an unknown concentration of exosomes were further analyzed using the newly developed LSPR biochips and the exosome concentration was determined as 108 exosomes/mL for MCF-7 cell line and 107 exosomes/mL for MDA-MB-231 cell line.