Synthesis of Colloidal Silver, Platinum, and Mixture of Silver-Platinum Nanoparticles Using Pulsed Laser Ablation as a Contrast Agent in Computed Tomography

Introduction: The development of nanoparticles as computed tomography contrast agents has increased significantly. However, few reports have been published on the use of silver and platinum nanoparticles as contrast agents. These nanomaterials are a good candidatefor contrast agents because of their high atomic number and high durability against corrosion. Material and Methods: Experimentally, a Nd:YAG laser (۱۰۶۴ nm, ۴۵ mJ, ۱۰ Hz) was focused on a high-purity metal plate including Ag and Pt plates, which are placed in deionized water medium. Colloidal nanoparticles of Ag and Pt were then mixed to obtain a mixture composition of Ag and Pt with ratios of Ag:Pt of ۷۵:۲۵%, ۵۰:۵۰%, ۲۵:۷۵%, respectively.The Ag, Pt, and Ag-Pt NPs mixture were then examined as contrast agents in CT scan. Results: The imaging results of the quantitative analysiswere measured in the Hounsfield Unit(HU), showing ۱۳.۵, ۱۲.۸, ۱۳.۳, ۱۴.۱, and ۱۷.۳ HU for colloidal ۱۰۰% AgNPs, colloidal Ag and Pt NPs with volume ratios of Ag:Pt of ۷۵:۲۵%, ۵۰:۵۰%, ۲۵:۷۵%, and colloidal ۱۰۰%Pt NPs, respectively. Conclusion: Results reveal the highest absorbent power was found in the colloidal contrast agent of Pt NPs ۱۰۰% is ۱۷.۳ HU, followed by the ۲۵:۷۵% Ag-Pt NPs is ۱۴.۱ HU. The higher HU value for platinum can be attributed to its higher density since the effective energy of ۸۰ kVp is about ۴۲ keV, which is lower than the K-edge of Pt (K-edge ≈ ۷۸ keV), which means that the attenuation of X-ray in Pt is due to Compton scattering dominantly.