Yakın kızılötesi bölgesinde ışıyan Ag2X (X: S and Te) kuantum noktacıklarını ve hibrit nanoparçacıklar

Near Infrared Emitting Quantum dots (NIRQDs) has gained great interest recently for biotechnology and energy applications. Silver chalcogenides, especially Ag2S, with low band gap energies offer a great potential for both applications. However, Ag2S NIRQDs are usually synthesized in organic solvents and are hydrophobic in nature which is not suitable for bio-applications. There are few studies in the literature towards their synthesis in water but these are quite complicated synthesis methods. Besides, Quantum yield of Ag2S QDs reported until now are below 3%. Ag2S NIRQDs have been synthesized in a very simple one step aqueous synthetic route with thiolated capping agents. Colloidally stable and highly luminescent Ag2S QDs emitting in the Near infrared window I (NIR-I) have been prepared with 2-mercaptopropionic acid (2-MPA) as a coating. Particles showed near band-edge emission. The emission maximum of these Ag2S-2MPA NIRQDs are tunable between 780-950nm. They have the highest photoluminescence quantum yields (PLQY) in the literature which are 7-39% with respect to LDS 798 NIR dye. An important improvement need of this system is the ability to tune emission in a broader range within NIR-I window with high PLQY for all practical purposes. A second set of Ag2S NIRQDs were synthesized through decomposition of Meso-2,3-dimercapto succinic acid (DMSA) in water. Slow decomposition of DMSA in water allowed better tuning of emission in the 730-920 nm range with PLQYs around 7%. This is not as high as the values obtained from Ag2S-2MPA NIRQDs but the advantage is the fact that particles emitting within this range all has PLQY high enough to be used as optical probes. Potential as optical agents and in vitro cytotoxicity of both 2-MPA and DMSA coated Ag2S-NIRQDs have been determined. They both showed almost no toxicity in MCF-7 and HeLa cancer cell lines and even in more vulnerable NIH/3T3 cells (with quite high doses up to 0.84 mg/ml). In addition, interaction of the NIRQDs with cells and the blood components showed excellent hemocompatibility of these particles. These particles showed internalization by these cell lines and endosomal compartmentalization. These results indicate that both of these Ag2S NIRQDs are highly promising QDs for medical and biotechnology applications satisfying the NIR emission, high quantum yield and excellent cyto and hemocompatibility. Another novel material developed in this work is the hybrid nanoparticle with both optical and super paramagnetic properties. Here, hybrid nanoparticles composed of biocompatible and MRI active super paramagnetic iron oxide nanoparticles (SPIONs) and biocompatible NIR-luminescent Ag2S-2MPA Quantum dots were prepared in a simple a biphasic ligand exchange method. An array of colloidally stable and NIR-I emitting hybrids with magnetic response have been prepared. Magnetic component of hybrids allow magnetic targeting of these particles increasing cellular interaction and uptake as proven by in vitro cell uptake and cytotoxicity experiments. These hybrids were also effectively used in imaging HeLa cancer cells by confocal laser microscopy. These particles demonstrate a great potential for in vivo application of QDs with great cytocompatibility, high luminescence properties and magnetic response. Lastly, in an effort to develope silver chalcogenide QDs with emission tuned in a much broader range within NIR window, alloyed silver sulfides with a lower band gap material, Ag2Te were attempted. In an aqueous synthesis of 2-MPA coated Ag2Te and Ag2TexS1-x NIRQDs, the influence of Te/S, coating/Ag as well as different source of chalcogens and chalcogen addition sequences on particle properties were studied. It was seen that the synthesized Ag2Te-2MPA and Ag2TexS1-x-NIRQDs emit in the NIR-I range between (900-1100 nm) with bimodal emission profile (First peak and second peak were tunable 920-950nm and 1000-1050nm respectively). Origin of such bimodal emission profile has been investigated and discussed yet, further studies are also proposed. These quantum dots were also shown as non-toxic in the in vitro cell studies and showed a great potential as optical labels by the internalization of the QDs to the cytoplasm in HeLa cells. Overall, different silver chalcogenide quantum dots emitting in the 700-900 nm biological window with highest quantum yields in the literature and their hybrids with SPIONs were developed and shown as non-toxic and hemocompatible optical probes in the in vitro studies.