Enhanced photoconversion performance of NdVO4/Au nanocrystals for photothermal/photoacoustic imaging guided and near infrared light-triggered anticancer phototherapy

Although neodymium vanadate (NdVO4) has been investigated and applied in some fields owing to its intensive ultraviolet (UV) light absorption, weak absorption in visible (Vis) and near infrared (NIR) regions constrains its environmental remediation and biomedical applications. Herein, plasmonic precious metal Au as light trapping agent is deposited onto NdVO4 to form metal/semiconductor hybrid nanostructure for improving the Vis/NIR light absorption. NdVO4/Au heterojunction nanocrystals (NCs) were synthesized by NdVO4 nanorods (NRs) and plasmonic Au nanoparticles (NPs), followed by introducing polyvinylpyrrolidone (PVP) to enhance stability and biocompatibility, which exhibit elevated photocatalytic performance for organic dye degradation, photothermal conversion effect as high as 32.15% and cytotoxic reactive oxygen species (ROS) production ability. NdVO4/Au can be internalized efficiently via endocytosis and cause apparent phototoxicity on HeLa cells. In vivo experiments further show that NdVO4/Au can act as a high-efficiency NIR light-triggered anticancer agent with excellent tumor inhibition effect. In addition, based on outstanding light-to-heat conversion performance and thermal expansion effect under NIR irradiation, NdVO4/Au provides photothermal (PT) and photoacoustic (PA) dual-modal imaging platform for precise cancer diagnosis and treatment. Statements of Significance It's the first report on integrating precious metal Au and rare earth orthovanadates semiconductor into NdVO4/Au heterojunction NCs. The as-prepared NdVO4/Au heterojunction NCs exhibits improved absorption in Vis/NIR region and increased generation efficiency of photo-induced electron/hole pairs due to the LSPR effect, which results in enhanced photothermal conversion efficiency and the production ability of cytotoxic center dot O-2(-) and center dot OH in comparison with pristine NdVO4. For further clinical application, NdVO4/Au heterojunction NCs could be served as anticancer therapeutic agent for PA/PT dual-modal imaging guided and NIR-triggered photothermal/photodynamic synergistic anticancer treatment. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.