FABRICATION OF GADOLINIUM OXIDE NANOPARTICLES AS T1 MRI CONTRAST AGENT

• Main Author: SOLTIANIE AHAB (NIM : 30212013), ATIKA
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25903
• Institution: Institut Teknologi Bandung

<p align="justify">This thesis addresses the in situ synthesis of pegylated gadolinium oxide (Gd2O3) nanoparticles as T1-weighted magnetic resonance imaging (MRI). Gadolinium based MRI contrast agents have been generally suggested in T1weighted MRI imaging due to their highest paramagnetic properties among magnetic metal which have important role for the contrast enhancement. The gadolinium itself to some extent forms is toxic. When used in medical context it must be transferred into biocompatibility form. In the absence of any coating material, the gadolinium nanoparticles have hydrophobic surfaces and they tend to agglomerate to form large clusters. Coating material provides the effective dispersion ability of the nanoparticles. A variety of experimental procedures have been done to synthesize coated Gd2O3 nanoparticles, including in situ and post synthesis coating. The critical issues involved in coating using the post synthesis method are the time and materials expended in the process (since it requires other treatments after synthesizing the MNPs) and the selective chemical functionality induced by this treatment (resulting in MNPs with selective solubility properties). Three different in situ “green synthesis” routes were explored to produce pegylated Gd2O3 nanoparticles which have dispersibility in water based solvent and biocompatibility properties. Thermal decomposition, solvothermalcalcination, and pulsed laser ablation in liquid medium (PLAL) methods were utilized due to the methods are bottom-up synthesis and using solvent medium to control particles growth. Polyethylene glycol (PEG) was chosen as the liquid environment for gadolinium precursors in the synthesis procedures because PEG serves as a template that governs the morphology of the particles, as a reduction agent, and to functionalize the nanoparticle with other biocompatible materials. Most of all, PEG is much recommended as a solvent for synthesize MNPs for biomedical purposes and range of PEG molecular weights are already approved for internal consumption by Food Drug Administration (FDA). We have successfully prepared nanoparticles pegylated Gd2O3 (Gd2O3@PEG) by facile thermal decomposition, solvothermal-calcination treatment, and pulsed laser ablation in liquid medium (PLAL) methods. Morphology, size distribution, crystallinity, chemical composition, and magnetic properties of the prepared particles were comprehensively validated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM) respectively. In these in situ methods, the partially oxidized molecules of PEG successfully attached to the nanoparticle Gd2O3 surface as carboxyl and carbonyl groups thus transfer its hydrophylic properties to the nanoparticles to become well-dispersed in water based solution. The samples have paramagnetic properties at room temperature which play important role in enhancing MRI contrast image. The performances of the thermal decomposition, solvothermal, and PLAL products were determined by in vitro T1-weighted MRI. Accordingly, the samples have been demonstrated to show T1 enhancing effects as the concentration were increased. Pegylated Gd2O3 nanoparticles prepared by PLAL in 0,01 mM PEG showed highest longitudinal relaxation, r1, at 1,5 T compared to pegylated Gd2O3 nanoparticles synthesized by thermal decomposition and pegylated gadolinium carbonate (Gd2(CO3)3) particles synthesized by solvothermal methods. Moreover, pegylated gadolinium particles and nanoparticles have r1 parameter higher than conventional MRI contrast agents such as Gadovist, Magnevist, Dotarem, and Omniscan at 1,5 T which may create new opportunities of these material products to be developed as T1 MRI contrast agents.<p align="justify"> <br />