Date

2019

Author

Akman, Pelin

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Multifunctional nanoparticles have been widely used as drug carriers to control drug release. However, besides controlling drug release, it is important to track the behavior of the drug in body. For this purpose, functionalizing the drug carriers with luminescent or magnetic materials and using them as bioimaging agents have attracted attention in recent years. In this study, luminescent and magnetic core/shell Gd1-xyCexTbyBO3@SiO2 (x=0.05, y=0.05) nanoparticles were synthesized and used in celecoxib drug delivery system. Celecoxib is a nonsteroidal anti-inflammatory and poorly water soluble, hydrophobic drug. In order to visualize the drug in body, both magnetic and luminescent core was synthesized. This core is composed of Ce and Tb doped Gadolinium borate synthesized by Pechini sol-gel method. Different proportions of Ce and Tb doped GdBO3 were synthesized and their photoluminescence (PL) spectra were compared. After that, Gd0.90Ce0.05Tb0.05BO3 was determined as the best luminescent core. Also, Gadolinium is strongly paramagnetic and widely used as contrast agent in magnetic resonance imaging (MRI). To increase drug loading capacity, mesoporous silica was chosen because of its high surface area, porosity, high biocompatibility and easy synthesis route. Mesoporous silica coating to Gd0.90Ce0.05Tb0.05BO3 core was done by modified Stöber method. The obtained Gd0.90Ce0.05Tb0.05BO3 core particles have a diameter of 60 nm and silica coated Gd0.90Ce0.05Tb0.05BO3@SiO2 core/shell particles have a diameter of 200-400 nm. They have considerably high luminescence intensity. After silica coating, drug loading was done in ethanol and a substantial decrease in photoluminescence intensity was observed for drug loaded sample. This means that during the drug release, luminescence increases, so by comparing the PL intensity, drug amount released from the carrier can be calculated. Drug release profile was obtained in pH 7.4, phosphate buffer solution (PBS) for 24 hours. Celebrex is the commercially available form of Celecoxib. For the characterization of the materials, X-Ray Diffractometry (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Photoluminescence spectroscopy (PL), Thermogravimetric Analysis (TGA), Nitrogen-sorption analysis, and Zetapotential analysis were used. For drug release calculations Ultraviolet–visible spectroscopy (UV-VIS) was used. The cytotoxicity assay was done by using HCT116 human colon cancer cells. The release profile of the prepared Celecoxib loaded carrier and commercial drug, Celebrex were compared according to UV-VIS results and it is understood that the solubility of the drug was enhanced with the drug carrier. All of the results here confirm that Gd0.90Ce0.05Tb0.05BO3@SiO2 nanoparticles are promising as drug carriers and also as bioimaging agents.

Subject Keywords

Chemistry, Inorganic., Keywords: Core/shell, Gadolinium Borate, Magnetic, Bioimaging, Drug Delivery

URI

http://etd.lib.metu.edu.tr/upload/12623363/index.pdf
https://hdl.handle.net/11511/43664

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Graduate School of Natural and Applied Sciences, Thesis