Efficient and Rapid Synthesis of Radioactive Gold Nanoparticles by Dielectric Barrier Discharge

A compact bench-top system based on a dielectric barrier plasma discharge (DBD), enables the rapid, automatable, and continuous-flow synthesis of gold nanoparticles (AuNPs) and radioactive gold nanoparticles ((198)AuNPs). AuNPs are used as radiosensitizers in oncology, and 198AuNPs (half-life: 2.7 d) have been suggested as potential cancer brachytherapy sources. Plasma applied at the surface of a liquid containing gold ions (AuCl4- ) and dextran induces the production of AuNPs directly in water. This synthesis is monitored in real time by UV-visible spectrometry: the change of absorbance of the solution provides new insights on the growth dynamics of AuNPs by plasma synthesis. By balancing gold ions and surfactant molecules, particles with a diameter lying in the optimal range for radiosensitizing applications (28 +/- 9 nm) are produced. The method yields a reduction of more than 99% of the gold ions within only 30 min of plasma treatment. A postsynthesis ripening of the AuNPs is revealed, monitored by UV-visible spectrometry, and quantified within the first few hours following plasma treatment. Radioactive 198AuNPs are also produced by DBD synthesis and characterized by electron microscopy and single-photon emission computed tomography imaging. The results confirm the efficiency of DBD reactors for AuNPs synthesis in oncology applications.