Plasmonic-Fluorescent Janus Au-PbS Nanoparticles with Bright Near-Infrared-IIb Fluorescence and Photothermal Effect for Computed Tomography Imaging-Guided Combination Cancer Therapy

In recent years, the application of both fluorescence and photothermal systems in one system has received great attention in the biomedical field. Yet, synthesizing a nanomaterial with both fluorescence (radiative decay) and a photothermal effect (nonradiative decay) is rarely reported. Here, we proposed novel plasmonic-fluorescent Janus Au-PbS nanoparticles (NPs) with tunable near-infrared II (NIR-II) fluorescence and photothermal effect to be used as a highly effective nanotheranostic for dual-modal NIR-IIb fluorescence imaging (FI)/computed tomography imaging (CT)-guided photothermal therapy. In addition, we investigated the equilibrium mechanism between the fluorescence and photothermal effects to guide the synthesis of this type of nanomaterial and found that the fluorescent semiconductor PbS quantum dots (QDs) receive electrons from Au NPs in Janus Au-PbS NPs, which could maintain the good fluorescence properties of Janus Au-PbS NPs. In addition, the alteration of electron and hole recombination between PbS QDs and Au NPs in Janus Au-PbS NPs increased nonradiative decay, leading to enhanced photothermal effects of Janus Au-PbS NPs. The electron receiver and electron–hole interactions in Janus Au-PbS NPs offered a fundamentally new means of engineering materials with fluorescence and photothermal properties through tailoring electron redistribution in Janus NPs.