A Porous Au@Rh Bimetallic Core–Shell Nanostructure as an H₂O₂‐Driven Oxygenerator to Alleviate Tumor Hypoxia for Simultaneous Bimodal Imaging and Enhanced Photodynamic Therapy

Abstract

In treatment of hypoxic tumors, oxygen‐dependent photodynamic therapy (PDT) is considerably limited. Herein, a new bimetallic and biphasic Rh‐based core–shell nanosystem (Au@Rh‐ICG‐CM) is developed to address tumor hypoxia while achieving high PDT efficacy. Such porous Au@Rh core–shell nanostructures are expected to exhibit catalase‐like activity to efficiently catalyze oxygen generation from endogenous hydrogen peroxide in tumors. Coating Au@Rh nanostructures with tumor cell membrane (CM) enables tumor targeting via homologous binding. As a result of the large pores of Rh shells and the trapping ability of CM, the photosensitizer indocyanine green (ICG) is successfully loaded and retained in the cavity of Au@Rh‐CM. Au@Rh‐ICG‐CM shows good biocompatibility, high tumor accumulation, and superior fluorescence and photoacoustic imaging properties. Both in vitro and in vivo results demonstrate that Au@Rh‐ICG‐CM is able to effectively convert endogenous hydrogen peroxide into oxygen and then elevate the production of tumor‐toxic singlet oxygen to significantly enhance PDT. As noted, the mild photothermal effect of Au@Rh‐ICG‐CM also improves PDT efficacy. By integrating the superiorities of hypoxia regulation function, tumor accumulation capacity, bimodal imaging, and moderate photothermal effect into a single nanosystem, Au@Rh‐ICG‐CM can readily serve as a promising nanoplatform for enhanced cancer PDT.

Recent progress in targeted delivery vectors based on biomimetic nanoparticles

“…Oxygen-dependent photodynamic therapy (PDT) is relatively limited for the therapy of solid tumors with hypoxia 77 . To get over the obstacle, Wang et al 78 proposed a novel nanotherapeutic agent (Au@Rh-ICG-CM) that integrated the advantages of hypoxia regulation, tumor accumulation, bimodal imaging, and mild photothermal effect into one single nanoplatform. Au@Rh dramatically catalyzed oxygen generation from endogenous hydrogen peroxide and indocyanine green (ICG) as PS transforming oxygen to tumor-toxic 1 O 2 .…”

Photodynamic therapy: photosensitizers and nanostructures

“…89 Other PSs such as indocyanine green (ICG) can be electrostatically bonded to gold-bearing nanostructures, for example Au nanorods/MoS 2 nanoagents, 90 or porous Au@Rh nanostructures. The latter constitutes one example of the fourth generation of PSs 91 (Figure 3b). Zn porphyrins can also be electrostatically attached to Au NPs functionalised with amphiphile pyridinium salts by following a similar strategy.…”

The Golden Age: Shining the Light on Theragnostics

“…We also noticed that, due to the presence of nanogold and its photothermal effect, the mild temperature increase under light irradiation was also able to promote cellular uptake of ICG and subsequently enhance 1 O 2 generation. [ 63 ]…”