Multifunctional Dendrimer-entrapped Gold Nanoparticles: Synthesis, Characterization And Their Application In Ct Imaging

Functionalized dendrimer-entrapped gold nanoparticles (Au DENPs) are of scientific and technological interest in biomedical applications. In this work, Au DENPs prepared using amine-terminated generation 5 poly(amidoamine) dendrimers as templates were subjected to acetylation in order to neutralize the positive surface charge of the particles. By varying the molar ratio of gold salt/G5 dendrimer, the acetylated Au DENPs with a size range of 2-4 nm can be prepared. Meanwhile, we attempted to add glucose to the dialysis liquid of the acetylated Au DENPs to avoid possible particle aggregation after lyophilization. The Au DENPs and acetylated Au DENPs with different compositions (Au salt/dendrimer molar ratios) were characterized using 'H NMR, transmission electron microscopy, UV-vis spectrometry, and zeta potential measurements. We found that the formed Au DENPs (Au salt/dendrimer molar ratios≤200) are not only stable in water, PBS buffer, and cell culture media, but also at different temperatures (from 4 to 50℃) and different pH conditions (pH 5-8), but when the molar ratio of Au salt/dendrimer is equal or larger than 75, the acetylated Au DENPs have a slight aggregation after lyophilization, and the addition of glucose is able to preserve the colloidal stability of the particles. X-ray absorption measurements show that the attenuation of the Au DENPs and the acetylated Au DENPs is much higher than that of the iodine-based contrast agent at the same molar concentration of the active element (Au versus iodine). In addition, the acetylated Au DENPs enabled X-Ray CT imaging of mice after intravenous injection of the particles. These findings suggest a great potential of using Au DENPs as a promising contrast agents for CT imaging applications.In addition, Au DENPs and G5 PAMAM was modificated by the ligands such as fluoresceine isothiocyanate, folic acid and diatrizoic acid so as to a multi-functional materials. The multifunctional Au DENPs were characterized using 1H NMR, UV-vis spectrometry. The results confirm that the'Au DENPs with multifunctional modification is feasible, while the functionalizetion of the Au DENPs providing a unique nanoplatform for targeting and CT imaging of further cancer research.