Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effect of Gold Nanorod Properties on Lspr Response(01. Izmir Institute of Technology, 2023) Kılıç, Şebnem; Bulmuş Zareie, Esma Volga; Tekin, Hüseyin CumhurOptical qualities make gold nanorods (GNRs) excellent for plasmonic biosensors. Localized surface plasmon resonance (LSPR) phenomenon which occurs on GNR surfaces enables the creation of highly sensitive biosensors. The physical properties such as aspect ratio and size are directly related to the LSPR response of GNRs. The aim of this study is to investigate the impact of the aspect ratio (AR) and the interparticle distance on the localized surface plasmon resonance (LSPR) response of GNRs decorated glass sensor chips. For this aim, GNRs were first synthesized using a seed-mediated growth method. The effect of AgNO3 concentration on the AR of GNRs was investigated. It was observed that increasing AgNO3 concentration resulted in GNRs with higher AR and a red shift in the longitudinal plasmon peak wavelength. GNRs with an AR of 4, 6 and 8 were successfully synthesized. Next, the effect of the stabilizer molecule type and molecular weight on the distribution of GNRs on the silanized glass surface was investigated. It was found that the APTES modified glass surfaces cannot be coated with CTAB stabilized GNRs. Using GNRs stabilized with PEG5K resulted in a more homogeneous distribution of GNRs on the glass surface with respect to GNRs stabilized with PEG2K. The interparticle distance between GNRs on the glass surface was successfully controlled by simply concentrating or diluting the GNR solution used for coating the glass surfaces. It was observed that the LSPR peak shifts decreased upon binding of analytes as the interparticle distance between GNRs decreased in the studied range. On the other hand, as the AR decreased, the LSPR response of the GNRs shifted blue. The results presented in this thesis may contribute to future research to improve the potential of LSPR-based biosensors for diverse biomedical and diagnostic applications.Master Thesis Development of an Advanced Lspr-Based Biosensor Chip for Rapid Detection of Border Disease Virus(01. Izmir Institute of Technology, 2023) Alakbarov, Abdullah; Bulmuş Zareie, Esma Volga; Tekin, Hüseyin CumhurThe Border Disease Virus (BDV) is responsible for causing fetal deathly infection, leading to annual occurrences of affected farms. BDV, along with other pestiviruses such as classical swine fever virus (CSFV) and bovine viral diarrhea virus (BVDV), are known to cause major losses in stock farming. These losses can result in reproductive failure, expensive inspections, and other impacts on livestock health. The current detection methods of BDV include various techniques such as RT-PCR, ELISA, VNT, and immunofluorescence assays. These methods, although reliable, may require specialized equipment, time-consuming procedures, and laboratory facilities, making them less suitable for rapid on-site detection. Hence, it is imperative to employ diverse methodologies for detection of BDV. LSPR-based biosensors are a subset of plasmonic biosensors that exhibit numerous advantages for diverse applications. LSPR-based biosensors are particularly well-suited for the production of compact, practical devices for rapid, on-site detection of analytes. The aim of this study is to design and fabricate a biosensor chip utilizing LSPR technology for potential BDV detection. For this aim, glass surfaces were functionalized with gold nanorods modified with a BDV-specific primer sequence, complementary single-strand DNA sequence of 19 bases, and fabricated with PMMA microchannels. Different concentrations of target BDV-DNAsequence ranging from 0.01 pM to 100 nM were exposed to the channels, and the LSPR response was quantified using a Vis-NIR spectrometer. The limit of quantification of the biosensor chips was determined to be 10 pM, while the limit of detection was found to be less than or equal to 1 pM. The sensitivity of the biosensor chips was calculated to be 0.0567 nm/RIU. The dynamic range of the biochips lies between 10 pM to 100 pM.Master Thesis Development of Conductive Oxide Based Thin Film Modified Electrodes and Biosensors Applications(Izmir Institute of Technology, 2021) Yurttaş, Betül; Özyüzer, Lütfi; Erdem Gürsan, Kadriye ArzumFrom the first biosensor produced in 1956 to the present day, biosensors have been highly developed and diversified. In biosensor manufacturing, thin films have become a rapidly emerging field. Depending on the thin film material used, thin films have many advantageous properties for biosensors, such as high surface-to-volume ratio, conductivity, stability, specificity, biocompatibility, and good electrocatalytic activity. Dopamine is a neurotransmitter that has a significant impact on the emergence and treatment of certain diseases such as Alzheimer's and Parkinson's diseases. Dopamine monitoring is important for the prevention of these diseases, and it is a favorable option to use biosensors, which are useful and practical tools, instead of time-consuming and expensive conventional methods. For this purpose, in this thesis, a non-enzymatic electrochemical biosensor based on thin film electrodes was developed for monitoring dopamine levels. The electrodes were developed by deposition of Zn2SnO4 (ZTO) thin film on ITO thin film substrate by DC magnetron sputtering technique. The properties of the electrodes were determined by thickness, optical transmittance, XRD and SEM analysis. Electrochemical analysis, namely CV, EIS and DPV measurements, were performed before and after the electrodes were sonicated and modified with APTES before their application to the voltammetric detection of dopamine. In addition, electrochemical measurements were performed before/after sonication, APTES modification. Dopamine was detected by a voltammetric method using DPV technique. Furthermore, experiments in the presence of interferents such as ascorbic acid (AA), uric acid (UA) etc. showed that the thin film electrodes can be successfully applied for voltammetric determination of dopamine. As a result, the biosensor technology developed in this study has the potential to be wearable in the future, enabling non-invasive monitoring of dopamine levels in body fluids such as saliva, tears and sweat.Master Thesis Design of Localized Surface Plasmon Resonance (lspr) Based Biosensor for Detecting a Potential Cancer Biomarker(Izmir Institute of Technology, 2020) Söylemez, Cansu; Bulmuş Zareie, Esma VolgaConventional methods for detection of cancer are invasive, expensive and not suitable for early diagnosis. Therefore, demand for simple, sensitive and rapid biosensors for detection of cancer have been enormous. Gold nanorods (GNRs) have been ideal materials for utilization in biosensors because of their exceptional optical properties. Localized surface plasmon resonance (LSPR) which is created on GNR surface can be used for the development of label-free and sensitive biosensor systems. LSPR responds to changes in the refractive index of the surroundings and this change can be observed as the shift in the maximum absorption wavelengths. In this thesis, an LSPR based GNR biosensor was developed for sensitive detection of a sialic acid as a potential cancer biomarker. For this purpose, GNRs were synthesized at around 40-50 nm in length. Afterwards, glass surfaces were coated with GNRs and functionalized with self-assembling molecules. Specific monoclonal antibodies(Ab) were conjugated to the surface. The surface modifications were characterized via contact angle, scanning electron microscope, Fourier transform infrared spectroscopy and zeta potential. Ab-functionalized glass surfaces were used to quantitatively detect specific molecular bindings via LSPR. The sensitivity of the biosensor was determined as 281 RIU/nm. The detection limit in PBS was 1 nM, while in serum it was found to be as 10 nM because of the high protein content of serum. Control experiments showed that the developed biosensor chip was selective. The proposed system is promising for early diagnosis of cancer since it can detect a potential cancer biomarker at concentrations as low as nanomolar level.Master Thesis Modification of Graphene Surfaces for Detection of Biomicroparticles(Izmir Institute of Technology, 2019) Yeşiltaş, Gözde; Bulmuş, VolgaPathogens present in the food we consume and the water we drink pose a major threat to human health. Another major health concern is the metastasis of cancer in which cancer cells spread to new areas of the body, often by way of the lymph system or bloodstream. To minimize the burden on health and economy, the detection of biomicroparticles such as pathogens or circulating cancer cells in a highly sensitive and practical manner is higly desirable. This thesis aims to develop a method to create graphene-based biosensor substrate for detection of biomicroparticles such as bacteria, viruses or mammalian cells. For this aim, graphene surface was first functionalized using a linker molecule. The effect of solvent type on functionalization was investigated via Raman spectroscopy and X-Ray spectroscopy (XPS). AntiCD2 antibodies (Ab), as a model antibody, were then conjugated to the functionalized graphene via NHS/EDC chemistry. The Ab conjugation was verified by Raman spectroscopy and XPS analyses. Finally, Jurkat cells, as model biomicroparticles, were recognized and captured by Abconjugated graphene surface, as evidenced by optical microscopy. The temperature, medium, and method for interaction of cells with graphene surfaces as well as the specificity of the Ab- functionalized graphene surface were investigated. The results overall showed the specific and efficient recognition of model cell line by Abconjugated graphene surfaces.Master Thesis A Novel Approach for Fabrication of Free-Standing Conductive Network: Pedot: Pss Based Bendable Chemo and Photoresistor(Izmir Institute of Technology, 2019) Mutlu, Mustafa Umut; Yıldız, Ümit Hakan; Demir, Mustafa MuammerElectrospinning is a simple and versatile technique for the fabrication of polymeric nanofibrous substrate with high surface to volume ratio. Besides high surface to volume ratio, their dimensional stability and flexibility make it a perfect candidate for conductive network for various sensor applications. Free-Standing conductive network can be fabricated by deposition of PEDOT:PSS or MWCNT through bendable nanofibrous substrate. As a simple example for sensor applications, the moving object has been sensed through the electrostatic interactions between fibers and object. The sensing range has been found to be 1-5 cm above the surface of fabric. By the controlled combination of conductive polymers and electrospun polymer nanofibers effective device miniaturization has been provided without loss of performance. The noncontact motion sensor platform has unique flexibility and light weight holding a potential for wearable sensor technology. For another application as a wearable electronics, the controlled combination of conductive network and light-matter interaction provides opportunities to fabricate photo-resistor exhibits broad band response 400 to 1600 nm that holding promises for ultra-thin sensors used in telecommunication. As a final example, we report the effect of gold and iron oxide nanoparticles on the selectivity and sensitivity of MWCNT or PEDOT:PSS based chemiresistor responsive to VOCs. The interplay between conductive layer by gold and iron oxide nanoparticles resulted a significant conductivity improvement that affecting selectivity which is governed by the interaction between electron-donating VOCs and NP doped conductive layer due to variation in charge carrier densities in conductive layer lattice.Master Thesis Design and Construction of Portable Localized Surface Plasmon Resonance Device for Detection of Biological Molecules(Izmir Institute of Technology, 2017) Gül, Aytaç; Bulmuş Zareie, Esma VolgaPoint-of-care devices giving rapid results in non-laboratory settings have become important for biosensor applicattions in a wide range of fields including medical, food, agriculture and pharmaceutical. This work aims to portable device based on localized surface plasmon resonance spectroscopy (LSPR-S) as a potential biosensor platform that can be used in non-laboratory settings for rapid detection of biological molecules at hifh sensivity. The thesis can be divided into two parts: In the first part, the design and consctruction of the device including both the mechanical and electronic parts are presented. The mechanical section includes the integration of the parts to build the device and microchannels designed with the aid of a three-dimensional drawing program Solid Works 2015. The second step of the construction process was the installation of electronic components onto the device. The electronicpart consists of a light source, fiber optic cables, a spectrometer and a temperature sensor. In conclusion, a portable LSPR-S device with an integrated microchannel system has been produced, which potentially allows analysing low volumes of sample without the need to label the molecules. The second part of the thesis covers the studies towards the preparation and application of sensing platforms for the LSPR-S device constructed to enable the rapid detection of biplogical molecules at high sensitivity. These included the preparation of gold nanorods and nanoparticles-based LSPR-S detection of model antibody-antigen and bacteria-bacteriophage interactions, respectively. Studies conducted in this section have led to the conclusion that LSPR-S-based biosensor platforms developed in thisis are promising solutions to overcome current challenges in biosensor applications.Master Thesis Development of Biosensors for Determination of the Total Antioxidant Capacity(Izmir Institute of Technology, 2008) Çoban, Seçil; Bayraktar, OğuzIn this study, an amperometric laccase biosensor was developed for determination of the oleuropein concentration that is the biological active component of olive leaf and contributes dominantly to the total antioxidant capacity. The biosensor was prepared by immobilization of laccase from Trametes versicolor by addition of cross-linking agent, glutaraldehyde, into the carbon paste electrode. Different biosensors were prepared by changing the amount of crosslinking agent and concentration of the enzyme solution. So, effect of these parameters on biosensor performance was investigated. The best biosensor performance was determined for the biosensor having glutaraldehyde amount of 12.03 % vol. of the biosensor bottom part and 5 mg/ml of laccase enzyme. The effect of scan rate and temperature on the biosensor performance was also investigated in this study. The scan rate of 10 mV/s was decided to be the optimum for the amperometric detection of oleuropein considering the fastest response and maximum reduction current. 250C was chosen as an optimum temperature value due to the maximum laccase activity and capability of oleuropein acting as an antioxidant. Extraction of phenolics from olive leaf was also an important part of this study. The extract was divided into fractions varying in their oleuropein amounts such as polar fractions and relatively less polar fractions. Therefore, biosensor performance was investigated for fractions containing different type of phenolics. HPLC analyses of the fractions were also performed in this study. In addition total phenol content and antioxidant capacity of the fractions were determined by conventional methods.