Laser ablation in liquids for the assembly of Se@Au chain-oligomers with long-term stability for photothermal inhibition of tumor cells

Abstract

For the potential use of Au nanoparticles (NPs) in photothermal therapy, it is important and effective to achieve the uniaxial assembly of Au NPs to allow enhanced absorption in the near infrared (NIR) region. Herein, we first presented the construction of amorphous selenium encapsulated gold (Se@Au) chain-oligomers by successive laser ablation of Au and Se targets in sodium chloride solution without other toxic precursors, stabilizers, or templating molecules. Se@Au chain-oligomers showed evidently enhanced NIR absorption and excellent photothermal transduction efficiency (η), which was higher than 47% at 808 nm. After being stored for 1 year, the Se@Au colloids still exhibited outstanding photothermal performance. The cytotoxicity assay demonstrated that there is negligible toxicity of Se@Au chain-oligomers in cells, but cell viability declined to only 1% in phototherapeutic experiments that were implemented in vitro. In intracellular Reactive Oxygen Species (ROS) generation measurements, Se@Au chain-oligomers could trigger a 35.9% increment of ROS upon laser irradiation. The possible synergetic effects between the anticancer function of Se and photothermal behaviors of Se@Au oligomers were intended to increase ROS level in cells. Therefore, such designed Se@Au chain-oligomers of high stability exhibit promising potential for their use as in vivo photothermal therapeutic agents.

Keywords: Au nanoparticle; Bipolar interaction; Chain-oligomer; Directional assembly; Green synthesis; High photothermal transduction efficiency; Laser ablation; Long-term stability; Photothermal therapy; Se nanoparticle.