Gold nanoparticles as contrast agents in X-Ray imaging

• Κύριος συγγραφέας: Κάιτατζη, Χριστίνα Συμίνα
• Άλλοι συγγραφείς: Καγκάδης, Γεώργιος
• Μορφή: Thesis
• Γλώσσα: English
• Έκδοση: 2020
• Θέματα: Contrast-agent; Nanoparticles; Gold; Imaging; Σκιαγραφικό; Νανοσωματίδια; Χρυσός; Απεικόνιση

The goal of this study is to demonstrate in an analytical and complete way the theory, applications, limitations and broad potential, of gold nanoparticles (AuNPs) in diagnostic imaging with X-Rays, both on a theory and experimental approach. The x-ray attenuation of a contrast agent is dependent on the atomic number, bulk density, x-ray source energy spectrum and presence of x-ray absorption edges. Gold nanoparticles (AuNPs) have gained attention as an x-ray contrast agent because gold has a high density and a high atomic number. Generally, gold nanoparticles exhibiting a high x-ray attenuation, nontoxicity, biocompatibility, and facile synthesis and surface functionalization for colloidal stability and targeted drug delivery due to their physicochemical and optical properties. This study summarizes the current state of knowledge for AuNP x-ray contrast agents at preclinical level. Four experiments are presented here with commercial and experimental samples of gold nanoparticles, for quantification and for in vivo verification of the obtained results. A combination of computed tomography (CT), (X-CUBE™ Molecubes BE), and a prototype benchtop system for planar X-ray imaging is used. Commercial GNPs (AuroVist™ 15 nm Nanoprobes) of different concentrations (0.01-200 mg GNPs/ml) were studied and compared to standard iodine solutions at the preclinical level (30-80 kVp). The image contrast was quantified through Contrast to Noise Ratio (CNR) for planar imaging and through Hounsfield Units for CT imaging. It was found that CNR slightly increased with higher energies with the best contrast at 40 kVp, thus confirming the optimal energy for x-ray imaging of GNPs at preclinical energies. The quantification study with experimental GNPs was performed on CT with the aim to test their suitability for contrast induction in in vivo studies. The results confirmed that these candidate NPs induced an efficient CT contrast and appropriate dosages were established. The in vivo imaging study was performed on, computed tomography (CT) XCUBE™ system (Molecubes BE) and the images were quantified to provide the contrast-induced by the NPs in Hounsfield Units (HUs). Appropriate dosages were confirmed in vivo for both experimental and commercial GNPs. To sum up, this study demonstrates that gold nanoparticles can be used as an excellent X-ray contrast agent because of their properties that overcome some significant limitations of other contrast agents used at the clinical level. The cost remains a serious limitation for clinical use but the advantages of gold are many. In addition to conventional medical applications such as contrast enhancement, various novel research areas have been developed and are expected to be further developed through AuNP-based -technologies such as cancer therapy, sensing, and drug delivery.