LEE- Nano Bilim ve Nano Mühendislik-Yüksek Lisans

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http://hdl.handle.net/11527/19416

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Konu "aflatoksinler" ile LEE- Nano Bilim ve Nano Mühendislik-Yüksek Lisans'a göz atma
  • Öge
    Synthesis of yellow-emissive carbon dots and observation of their interaction with aflatoxin B1
    (Graduate School, 2022-11-02) Ergüder, Özge ; Ünlü, Caner ; 513201002 ; Nanoscience and Nanoengineering
    The field of nanoscience focuses on topics between 1 and 100 nm in size, while the field of nanotechnology is primarily concerned with the development of useful tools and equipment for this scale. Although the term "nanotechnology" was coined during the last decade, researchers have been hard at work in this field since the 1950s. It is anticipated that this new technology, whose dimensions are measured in nanometers, would significantly advance the state of the art. Nanotechnology has fascinating potential uses in almost every area of study, from physics and materials science to biology and biotechnology to computer engineering and electronics, and even medicine. The word "nanobiotechnology" is an obvious portmanteau of "nanotechnology" and "biology," as it describes the use of nanotools and nanodevices to interact with, monitor, and modify biological functions at the cellular and molecular levels. Electron transport in nanoscale crystals known as quantum dots (QDs) is an engineering feat. These semiconducting nanoparticles can produce a rainbow of colors when exposed to ultraviolet light. QDs are semiconductor nanoparticles, first postulated in the 1970s and first realized in the early 1980s. The phrase "dots" refers to nanocrystals, while the term "quantum" refers to the smallest and most discrete unit of any physical attribute. QDs have the same arrangement of atoms as in the bulk matter, unlike bulk and nanocrystal quantum dots, therefore much more surface atoms are shown on the surface by virtue of three-dimensional truncation. Sizes of QDs are typically between 2 and 10 nm. Optical characteristics and fluorescence are produced by the semiconductor's basic material. In particular, the core material displays impacts of toxicology, photobleaching, and blinking. Because of their unique physicochemical properties, QDs can be used in a wide range of industries and technologies, from medicine and medicine delivery to electronics and solar power. The two main forms of QD manufacturing are core (bare QDs) and core/shell architectures. The shell is primarily composed of inorganic substance in order to stabilize the core, which is primarily derived from semiconductors. The semiconductor core of QDs may or may not be surrounded by a semiconductor shell. QDs range in size from 2-10 nm. The core material of the semiconductor is responsible for optical properties and fluorescence. Specifically, core material exhibits blinking, photobleaching, and toxicological effects. In core/shell arrangement, the core is passivated by the shell (which often has a wider band-gap), which improves optical quality and prevents leaching. Therefore, core/shell structures are preferable to bare QDs for biological purpose. For biological studies, it is important to modify the QDs to make them water-dispersible. Therefore, the surface of QDs can be modified with various bifunctional surface ligands or caps to enhance their solubility in aqueous media. The modification of QDs can improve their quantum yield (QY) and stability, reduce surface oxidation, and limit the release of hazardous ions. Understanding the composition, shape, crystalline structure, bandgap energy, and surface ligand nature of QDs is crucial for exploiting their optoelectric and physicochemical properties. Characterization techniques for these nanoparticles mostly fall into two categories: optical characterization and structural characterization. In order to get optical information on QDs, such as their concentration, size, and photoluminescence quantum, the UV-Vis and fluorescence spectroscopy methods are frequently employed. Structure investigation of QDs by X-ray diffraction (XRD), X ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) reveals information about the semiconductor nanocrystals' size, shape, crystal structure, and chemical composition. Some laboratories also employ Raman spectroscopy, which provides a fast and precise method for monitoring atomic vibrational changes. Although there are more than 20 different types of aflatoxins, Aflatoxin B1 (AFB1) is widely considered to be the most dangerous because it may contaminate a wide variety of crops. One biomolecule, AFB1, can emit a fluorescent signal. In 2004, researchers developed carbon quantum dots (CQDs), also known as carbon dots (CDs), a class of multifunctional fluorescent carbon-based nanomaterials. Water dispersibility, low toxicity, high photoluminescence emission, cell membrane permeability, biocompatibility, and inexpensive manufacture are only a few of the many outstanding properties of carbon quantum dots. These are put to use in analytical imaging, drug delivery, light-emitting devices, and the field of biology. Cell-specific targeting, in-vivo imaging, and live cell labeling are all made possible through the microwave-assisted synthesis of carbon quantum dots. CDs are promising for in-vivo and in-vitro imaging research, but their fluorescence is most intense between 430 nm and 530 nm, which overlaps with the autofluorescence region of many eukaryotic cells. The development of high-quantum-yield yellow-red emissive CDs is thus a topic of interest. In this research, conventional yellow-emissive CDs were improved in two ways that increased their quantum yield. 1) Using simple, fast, and cheap microwave assisted manufacturing procedures, the surface of conventional yellow-emitting CDs was passivated with a biomolecule, urea. 2) Yellow-emitting CDs were powered by the fluorescent biomolecule aflatoxin B1. First approach achieves 51% quantum yield for CDs. Energy was transferred from AFB1 to CDs efficiently (over 40%) in the second approach. Our results demonstrated that simple-rapid microwave aided synthesis methods can be used to produce highly luminous yellow emissive CDs, which are promising candidates for sensing Aflatoxin B1. AFB1 was also found to be an emission booster for CDs, further supporting our findings. This thesis shows that traditional yellow emissive carbon dots can have their quantum yield improved by passivating their surfaces with urea using a microwave-assisted manufacturing process. Carbon dots' steady-state emission properties were unaffected by surface passivation, but the quantum yield and average fluorescence lifetime were greatly enhanced. After coming into contact with AFB1, the yellow emitted carbon dots' emission intensity was significantly increased. This study, found that AFB1 acted as an energy donor for carbon dots, resulting in a significant increase in fluorescence lifespan and quantum yield, which they measured. These results not only proved that yellow emissive carbon dots have a bright future as a chemosensor for AFB1, but they also hinted that AFB1 might be used as a suitable emission-intensity-booster for yellow emissive carbon dots in biomedical applications like in-vivo cell imaging.