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3D kanser sferoid modelleri aracılığıyla mikroakışkanlar kullanılarak aprotinin tabanlı yeni bir nano-biyokonjugatın geliştirilmesi
Proteins are promising substances for introducing new drug carriers with efficient blood circulation due to low possibilities of clearance by macrophages. However, such natural biopolymers have highly sophisticated molecular structures, preventing them from being assembled into nano-platforms with manipulable payload release profiles. Here, we announce a novel anti-cancer nano-drug carrier moonlighting protein, Aprotinin, to be used as a newly identified carrier for cytotoxic drugs. The Aprotinin-Dox orubicin (Apr-Dox) nano-bioconjugate was prepared via a single-step microfluidics co-flow mixing technique; a feasible and simple way to synthesize a carrier-based drug design with a double-barreled approach that can release and actuate two therapeutic agents simultaneously i.e., Apr-Dox in 1:11 ratio (aprotinin an anti-metastatic carrier drug and chemotherapeutic drug DOX). With a significant stimuli-sensitive (i.e. pH) drug release ability, this nano-bioconjugate achieves superior bio-performances including high cellular uptake, efficient tumor penetration and accumulation into acidic tumor microenvironment, as well as inhibiting further tumor growth by halting the urokinase plasminogen activator (uPA) involved in metastasis and tumor progression. Distinctly, in healthy human umbilical vein endothelial (HUVEC) cells, drastically lower cellular uptake of nano-bioconjugate has been observed and validated compared to anticancer agent Dox. Our findings demonstrate an enhanced cellular internalization of nano-bioconjugates towards breast cancer, prostate cancer, and lung cancer both in vitro and in physiologically relevant biological 3D-spheroid models. Consequently, the designed nano-bioconjugate shows a high potential for targeted drug delivery via natural and biocompatible moonlighting protein, thus opening a new avenue for proving aprotinin in cancer therapy both as an anti-metastatic and drug-carrying agent.
Yeni 2D malzemelerin sentezinin gerçek zamanlı optik gözlemi ve temel özelliklerinin incelenmesi
Two-dimensional transition metal dichalcogenide (2D TMDC) with superb physical and chemical properties, used as the active material for various devices. The on-going primary focus is their reliable high-throughput synthesis using processes compatible with the current semiconductor technology. At present, among the common approaches, chemical vapor deposition (CVD) has been considered as the most promising method for preparing large-area high-quality 2D materials. However, the lack of in-situ information during the growth in conventional CVD systems, makes it impractical to realize high-temperature phenomena. In this thesis, we developed a novel CVD chamber that allows real time optical observation and control of the crystal growth. Using this new CVD method, which we call real time optical-CVD, RTO-CVD in short, we elaborated the involved mechanisms in salt-assisted synthesis of TMDCs and their vertical/lateral heterostructures. Through direct visualization of WSe2 monolayer growth, we identified that both vapour-solid-solid and vapour-liquid-solid growth routes are in an interplay. Then, we focused our attention to synthesize novel 2D materials such as V2O3 and K-MnO2 nanosheets. We succeeded synthesis route in favor of high-quality single-crystalline V2O3 nanoplates whose 2D characteristic allows us to study their peculiar electrical and physical properties such as metal-insulator transition (MIT) and supercritical state. The electrical properties of both as-grown and transferred V2O3 crystals were investigated with respect to the V2O3 phase-stability diagram. We observed emergence of a novel crystal structure upon electron beam heating in selected area electron diffraction (SAED) experiments and correlated it to the supercritical state by means of high-temperature Raman spectroscopy. Finally, we introduced large-area ultra-thin layered MnO2 crystals, spontaneously intercalated by potassium ions during the synthesis. The charge transport in 2D K-MnO2 devices was shown to be dominated by the in-plane ionic conductivity through the motion of hydrated K ions in the interlayer space. The K-MnO2 crystals exhibited reversible layered-to-spinel phase transition accompanied by an optical contrast change based on the electrical and optical modulation of the potassium and the interlayer water concentration. We used the electric-field driven ionic motion in K-MnO2 devices to demonstrate the memristive properties and elucidated the resistance-switching mechanisms via real-time analyses upon the measurements. K-MnO2 memristors were artificially able to emulate neuromorphic synapse-like behaviors, namely short and long-term potentiation/depression as well as ionic coupling effects.
Akıllı malzemeler entegre edilen mikroakışkan çiplerde biyomoleküllerin ve nadir kanser hücrelerinin yakalanması ve salınması
Prevalent clinical conditions are impacting notably on our daily lives and the global economy. Healthcare system is hence garnering more interest in developing innovative material-based technologies along with accurate surface chemistry and signal generation reactions to measure biomarkers for disease diagnosis. In particular, biomedical studies focus to diagnose complex cases such as cancer. For instance, there are some critical stages in cancer development and metastasis. Moreover, impractical, invasive methods, and the restricted repertoire of targeted therapies are driving factors for researchers to find out new monitoring techniques that anticipate the future journey of cancer cells. On the other hand, the analysis of bodily fluids containing circulating tumor cells (CTCs) and biomarkers allows more insight into detecting/monitoring cancer as early as possible, and it would provide more information than that of any single-site biopsies. Yet, implementing the current technologies focusing on CTC detection and isolation in the clinics have notable challenges, i.e., expensive reagents/assays, complex operation, lengthy processes, bio-compatibility, and the need for specialized personnel. In this thesis, we have designed a microfluidic chip to hurdle these existing challenges, and for this regard, we tuned the surface area of the chip by integrating bio-mimetic smart materials (different shapes of silica particles-coated with poly(N -isopropylacrylamide). Initially, we tested our strategy with model proteins for both capture and release aspects. The smart materials were then modified with anti-EpCAM antibodies to capture human breast cancer cells (MCF-7) as a cancer model. Once the cells were captured in the chip, they were released by simply altering the 3-dimensional structure of smart materials above to lower critical solution temperature. Herein, we have anticipated that the developed platform would resolve cost, bio-compatibility, applicability, complexity, and assay duration-related challenges of current technologies in this realm.
Anti-grafiti uygulamalarda su tutmaz-kir tutmaz yüzeyler ve kaplamalar
Graffiti is the arising phenomenon which affects cultural heritage whole around the world from the begininng of the second half of 20th century. There has been many efforts to avoid graffiti application onto these heritage by using law and scientific methods. During the those times, many removing procedure were applied to get rid of graffiti from the heritage. Graffiti should not be confused with street art. Graffiti was defined as illegal way to affect public properties. From the beginning of the 21th century, due to increased amount to remove graffiti from heritage and protect them from these attacks, especially by the EU, many projects have been conducted which lead new products are now on the market. By this time, some implications have also been developed to proctedt these heritage by coatings. One of these implications are creating superhydrophobic surfaces onto masonry heritage and makes easier to remove graffiti without any effects onto stone surface and avoid penetration of the dye into these structures. For this purpose, four different substrate and eight different dispersion were prepared by using wettability phenomenon which are about lowering surface free energy and creating rough surfaces. Goniometer was used to provide contact angle results to characterize coating with specimen as hydrophobic- superhydrophobic or none of these. Results demonstrate that coatings which were prepared by sol-gel method was able to create hydrophobic surfaces and they made the surface ease to clean due to letting the drops easily slide away.
ITO-cam ve ITO-PET altlıklar üzerine kaplanan ZnO nanotellerin hazırlanması ve karakterizasyonları
The study of nanotechnology involves both understanding the materials as well as controlling the processing conditions of these materials at the nanoscale. In the class of nanostructures, semiconducting nanowires are of high interest because of their extraordinary properties and promising applications. The uniqueness mainly arises from the surface-to-volume ratio being higher than that of most nanostructures. Of all semiconducting materials, zinc oxide exhibits a large excitation binding energy and wide bandgap, making it highly desirable to be used for transistors, photodetectors, and multipurpose piezoelectric nanogenerators. Vertically aligned zinc oxide nanowires can be synthesized using a variety of techniques, the hydrothermal growth method being one of the easiest and most affordable and low operating synthesis techniques. In this thesis, vertically aligned zinc oxide nanowires are synthesized onto indium tin oxide coated PET and glass substrates via the hydrothermal growth technique. The growth conditions were optimized with parameters such as growth temperature, annealing temperature, and solution concentration not changing. Other experimental parameters such as seeding layers and growth durations varied throughout. The morphology and microstructures of the zinc oxide nanowires synthesized are investigated with the use of X-ray diffraction and scanning electron microscopy. Furthermore, the transmission percentages are examined with the use of ultraviolet and visible light spectrometer as well as the surface roughness is measured with the use of atomic force microscopy. Electrical conductivity measurements were taken to assess the quality of the substrates and their possible use in applications. Between the growth conditions and parameters and the growth of the zinc oxide nanowires, this thesis presented a strong correlation in terms of the different results achieved.
Yanma sonrası karbon yakalama için yıkım betonunun değerlendirilmesi
In this thesis, the potential use of demolition concrete was examined as a post-combustion carbon capture material. This study's main objective was to use demolished concrete, which is typically regarded as waste and has an adverse effect on the environment, to adsorb carbon dioxide. This research intends to contribute to the reduction of these emissions by creating sustainable techniques of carbon capture in light of the rising levels of carbon dioxide emissions and their detrimental effects on the environment. Concrete is a cementitious substance with a high calcium and silicate content, making it a great substance for carbon capture. Two leaching techniques, acidic and alkaline, were used to the concrete samples to extract the resultant materials, which were then utilized to investigate the potential of destroyed concrete for carbon capture. The materials were subsequently employed for carbon capture studies at the KTH Royal Institute of Technology in Sweden utilizing thermogravimetric analysis (TGA). The trials' findings illustrate how successful demolition concrete is at absorbing carbon dioxide, with the acidic leached material performing best. Additionally, the material's cation release was assessed, and it was determined to be safe for the aquatic environment. These findings have important ramifications for the creation of ecologically responsible and sustainable carbon capture and storage methods.
Hardness and fracture toughness behaviors of CAD-CAM dental ceramics
The purpose of this research is to study the effect of machining on the CAD/CAM dental materials and to evaluate surface roughness, hardness and fracture toughness for a 4different types of dental materials (Vita Enamic, GC Cerasmart, Celtra Duo and IPS e.max ZirCAD). These dental materials also called as CAD/CAM Dental Ceramics. In dental ceramics, actually there are glass-ceramics, composite materials, oxide based ceramics. All these CAD/CAM dental ceramic materials need cutting and polishing steps during the preparation for individual patient. Cutting and polishing are mechanical processes and usually result with a surface with various surface roughness depends on the equipment and polishing powders used. Surface roughness is an important material characteristic which influence the optical properties and mechanical behaviors of the materials. In the present study; surface roughness's of the dental ceramics were evaluated according to the mesh numbers of the polishing papers (600-1200-2500 mesh). The effect of the surface roughness's on the mechanical properties namely hardness (HV) and fracture toughness (Kıc) were studied by applying Vicker's Indentation technique in all the samplesafter various polishing steps. Hardness and fracture toughness values were evaluated and compared for all the dental materials. As expected that, ZrO2 based ceramic was the hardest and toughest and these values were lover with increasing polymer content in dental materials
Enfeksiyon hastalıklarının yerinde tanısı için Up-dönüşümlünanopartikül tabanlı taşınabilir tarama testi geliştirilmesi
This dissertation is concerned with the development and validation of nanotechnological sensor components and platforms for the diagnosis of A-group beta-hemolytic streptococcus using the lateral flow strip (LFA) method. Streptococcus is a common bacterium found in the human flora, especially in the throat and nose, and is prevalent in rural locations where accurate detection may be challenging. LFA is a rapid, simple, and cost-effective biosensor used for the analysis of various samples at the point of care, making it one of the most common biosensors currently available. The main goal of this thesis is to develop an upconversion nanoparticle-based lateral flow assay (UCNP-LFA) for the rapid detection of A-group beta-hemolytic streptococcus. Surface modification of probes with various polymers and conjugating them with disease-specific antibodies (varying concentration), designing the sensor in which disease-specific antibody traps are imprinted onto a membrane are all necessary steps in the development of Lateral Flow Strip units that is performed in this thesis. In addition, optimization of various buffers that allow flow of disease specific antibody-nanoparticle conjugate through the Nitrocellulose Membrane, and optimization of other strip components such as various types of Nitrocellulose Membrane (with varying pore size), conjugation and sample pads, antibodies dispensing speed were investigated. The developed UCNP-LFA samples were characterized by HR-TEM, SEM, XRD, FTIR, DLS, Zeta potential, Uv-Vis spectroscopy, Fluorescent microscope and PL spectroscopy. The UCNP-LFA tests were evaluated for sensitivity, specificity, accuracy, and achieved a value of 73% , 75%, 74% according to the results, respectively.
Metal-organik kafes/grafen oksit türevli gözenekli karbonların platin bazlı oksijen indirgenme reaksiyonu elektrokatalizörlerinde kullanımı
Fossil fuel-based energy economy is bound to change at some point within the 21st century as fossil fuels are inherently limited sources. Energy conversion and storage devices such as batteries, fuel cells, solar cells and supercapacitors need to advance in terms of efficiency for the fruition of a renewable energy ecosystem. Hierarchically porous materials are utilized as catalyst supports in polymer electrolyte membrane fuel cells (PEMFCs) and batteries to increase mass transfer and active site density in the catalyst. Metal-organic frameworks (MOFs) are tailorable crystalline solids where organic linker units are connected to metal centers. They may form molecular gates, channels and pores within the framework in angstrom to nanometer scale. Porous carbons derived from metal-organic frameworks are promising catalyst supports owing to their high surface area and 3-D network structure. In this thesis, a porous carbon has been produced from pyrolysis of a hybrid material based on Zn based MOF called zeolitic imidazolate framework-8 (ZIF-8) and graphene oxide (GO). As observed by physical and chemical characterization, ZIF-8 were coordinated to GO during the synthesis conditions of ZIF-8 and formed a hybrid structure in contrast with simple mixing. Evolution of macro/mesoporosity have been observed when the hybrid was exposed to pyrolyzing temperatures owing to the exfoliating effect of GO on ZIF-8. Pt nanoparticle (Pt NP) deposition on this porous carbon has resulted in catalyst Cat-1, which has been tested via voltammetric experiments against two reference materials; Pt decorated on pyrolyzed ZIF-8 (Cat-0) and Pt decorated on reduced GO (Pt/rGO). Cat-1 exhibits increased mass and specific activity against Pt/rGO at 0.8 V for oxygen reduction reaction (ORR). The nature of increased activity is proposed to be increased mass transport properties of Cat-1 sample that originates from its hierarchical porosity.
Yüksek çevrim performanslı lityum iyon bataryalarının katot elektroları için dizayn edilmiş nafyon yüzey iyileştirmeli nca katot malzemeleri
Lithium-ion batteries, due to their high energy density and portable dimensions, play a very important role in today's technology. Although scientific research has provided many different areas for high-performance anode materials, cathode electrodes with their lower capacities and higher costs have always been less researched. With the advancement of battery technology, the research community has recently been carrying out various studies both on the yield and the performance of the cathode materials for lithium-ion batteries. One of the three-layer cathode electrode family is nickel, cobalt, and aluminum oxide (NCA) used in the positive electrode of electric cars and portable electronic equipment. The NCA cathode material provides higher capacities, energy and power efficiency, and is widely used in lithium-ion batteries. Besides these specifications, they are found among the most promising positive electrode because of two reasons, lower synthesis costs and promising electrochemical properties. The theoretical capacity of NCA cathode is 279.05 mAh /g. While these cathodes have the advantage of being produced via different synthesis methods, they can cause a decrease in capacity with time and degradation of the battery structure during cyclic tests due to micro and nanoscale cracks in the structures alongside reactions occurring over time. To overcome the main problem of NCA cathode, as established earlier, I focused on the Nafion-coated NCA electrode. It is expected that Nafion coated NCA cathode material may improve ionic and electronic conductivity by covering the surface and prevent the side reactions and thus stabilize the capacity under cycles, which may lead to an increment in the life span of NCA cathode. NCA cathode active material was synthesized by a modified co-precipitation method at 750°C in an air atmosphere. The obtained NCA powder was characterized by X-ray diffraction, scanning electron microscopy and inductively coupled plasma-mass spectrometry. To understand the surface and structure of the electrode, the pristine and nafion-coated electrodes were also structurally characterized with X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry as well as battery tests that were carried out on both electrodes to understand their cell characteristics. The results were comparatively interpreted for nafion supported NCA cathode electrode and pristine NCA cathode.
Eklemeli imalat yöntemiyle kullanılabilecek kompleks formdaki manyetik yapıların elde edilmesi için özgün metod geliştirilmesi
Hard magnetic materials do play a critical role in numerous industrial areas relates with magnetic tapes, hard drive units, speaker drivers, biomedical measurement devices, electric motors, hybrid cars, wind turbines. Since these areas include large scale manufacturing, size and cost of the magnetic material have a direct effect on it. Magnetic energy intensity and availability of magnetic material are the main characteristics that concern size and cost-effectiveness. Today, neodymium iron boron (NdFeB), aluminum nickel cobalt (Alnico), and ferrite are mostly used as magnetic materials. NdFeB is the most significant one among them because of its magnetic energy density. Nowadays, the world is experiencing a rare-earth material crisis. Moreover, because of its fragile nature, it is tough to make custom shaped / CNC milled NdFeB magnets, especially for prototyping. These are the main reasons that industry is in search of new, rare-earth free magnetic materials. A metastable iron nitride phase, Fe16N2 shows promising magnetic properties in literature and become prominent as a possible alternative to NdFeB. In this study, we aimed to propose a solution to aforementioned problems by finding a way to synthesize Fe16N2 particles by using ball-milled iron micro/nanoparticles and trying to utilize it with additive manufacturing method. Furthermore, we expected to increase anisotropy, and the magnetic energy density of printed material by manipulating it with a pulse magnetizer circuit. Considering the time consumption of the configuration and optimization of the oven system, we tried to prepare 3d printing system, pulse magnetizer system simultaneously. Therefore Fe16N2 was not used in these systems, instead, we used ball milled NdFeB and iron flakes to show proof of concept. Prepared Fe16N2 particles are characterized by using XRD and SEM analysis.
Çok katmanlı ferromanyetik kobalt filmlerin yapısal ve manyetik özelliklerinin incelenmesi
Bu tez çalışmasında, spintronik bellek ve devrelerinde bilgi taşıyıcısı olarak kullanılan ferromanyetik malzemelerin performansını belirleyen kritik parametrelerin farklı arayüzeyler ile kontrolü amaçlanmıştır. Bu kapsamda, farklı spin-yörünge etkileşimi özelliklerine sahip üst katmanlarla (Cu, CuIr ve Pt) üretilen Kobalt tabanlı ince filmlerin yapısal, statik ve dinamik manyetik özellikleri; sırasıyla X-ışını Kırınımı, Titreşimli Örnek Manyetometresi ve Ferromanyetik Rezonans teknikleri kullanılarak incelenmiştir. XRD analizleri, Co film kalınlığının artmasıyla birlikte kristal kalitesinin iyileştiğini ve yapının gerilimli yüzey merkezli kübik fazdan, bulk özelliklere yakın altıgen sıkı paket faza doğru evrildiğini göstermiştir. Statik manyetik ölçümler, filmlerin doygunluk manyetizasyonunun literatürle uyumlu olduğunu doğrulamakla birlikte; Co/Cu sisteminde manyetik ölü tabaka gözlenmezken, Co/CuIr arayüzeyinde atomik karışım kaynaklı yaklaşık 0.21 nm kalınlığında manyetik bir ölü tabaka tespit edilmiştir. FMR tekniği ile gerçekleştirilen dinamik analizlerde, manyetik sönümlemenin Gilbert sönümü ve İki Magnon Saçılımı mekanizmaları tarafından kontrol edildiği belirlenmiştir. Gilbert sönümleme parametresinin ters Co kalınlığı ile doğrusal artışı, sistemlerde spin-pompalaması mekanizmasının varlığını deneysel olarak kanıtlamıştır. İnce filmlerin kıyaslamasında; güçlü spin-yörünge etkileşimine sahip Pt üst katmanının ideal bir spin yutucu davranışı sergileyerek en yüksek sönümleme ve anizotropi değerlerini sağladığı, CuIr alaşımının safsızlık saçılması nedeniyle ara bir sönümleme performansı gösterdiği, zayıf spin-yörünge etkileşimine sahip Cu katmanının ise spin akımını sönümlemede en zayıf etkiyi yarattığı gözlemlenmiştir. Bu çalışma, arayüzey malzemesi seçimi ve kalınlık optimizasyonu ile manyetik özelliklerin hassas bir şekilde modifiye edilebileceğini ortaya koymaktadır.