BiVO₄@Bi₂S₃ Heterojunction Nanorods with Enhanced Charge Separation Efficiency for Multimodal Imaging and Synergy Therapy of Tumor

Abstract

Despite malignant tumors being one of the most serious diseases threatening human health and living quality, exploring theranostic agents for highly effective tumor diagnosis and treatment is still full of challenges. Herein, we demonstrate the design and preparation of Tween-20-modified BiVO4@Bi2S3 heterojunction nanorods (HNRs) for multimodal computed tomography (CT)/photoacoustic (PA) imaging and radiotherapy (RT)/radiodynamic therapy (RDT)/photothermal therapy (PTT) synergistic therapy. Benefiting from the high X-ray attenuation coefficient of Bi, BiVO4@Bi2S3 HNRs exhibit a sensitive CT imaging capacity and radiation enhancement effect during RT. Meanwhile, the strong NIR absorption of Bi2S3 endows BiVO4@Bi2S3 HNRs with an excellent PA imaging and photothermal transformation capacity. More importantly, by taking advantage of the type II band alignment between BiVO4 and Bi2S3, an extra internal electric field is established to accelerate the separation of X-ray-induced electrons and holes in BiVO4@Bi2S3 HNRs, resulting in the realization of highly effective X-ray-induced RDT. Because the in vitro and in vivo experiments have verified that the RT/RDT/PTT synergistic therapeutic efficacy is greatly superior to any single treatment, it is believed that our BiVO4@Bi2S3 HNRs can be used as the multifunctional nanotheranostic platform for malignant tumor theranostics.

Z-Scheme heterostructures for glucose oxidase-sensitized radiocatalysis and starvation therapy of tumors

“…The peak at 530.06 eV belongs to O 2− in the Bi-O bond, and the peak at 531.80 eV belongs to O 2− in oleic acid. 23 Bi 3+ 4f peaks shift to the low binding energy after the anion exchange. Moreover, Bi 3+ 4f peaks in BiOI/Bi 2 S 3 NSs can be fitted into two pairs.…”

“…2a shows the • OH generation capacity of BiOI/ Bi 2 S 3 @polydopamine NSs under X-ray radiation by using sodium terephthalate as the probe. [22][23][24] No • OH is generated in deionized water with/without BiOI@polydopamine or BiOI/ Bi 2 S 3 @polydopamine NSs in the absence of X-ray radiation. Under X-ray radiation, pure water shows weak fluorescence due to the ionization of water.…”

“…21 Despite the advances of RCT in tumor treatment, the short carrier lifetime and the low efficiency of charge separation in semiconductor radiosensitizers are the main obstacles to improving the therapeutic efficacy of RCT sufficiently. [21][22][23] Many kinds of semiconductor radiosensitizers with special heterostructures have been prepared to overcome these limitations. [22][23][24][25][26] Through carefully selecting and designing the energy levels of heterostructures, electrons and holes caused by ionizing radiation can be spatially separated, resulting in a longer carrier lifetime to increase the probability of generating ROS.…”

“…[21][22][23] Many kinds of semiconductor radiosensitizers with special heterostructures have been prepared to overcome these limitations. [22][23][24][25][26] Through carefully selecting and designing the energy levels of heterostructures, electrons and holes caused by ionizing radiation can be spatially separated, resulting in a longer carrier lifetime to increase the probability of generating ROS. 27,28 Unfortunately, most of these semiconductor radiosensitizers are type-II heterostructures.…”

“…27,28 Unfortunately, most of these semiconductor radiosensitizers are type-II heterostructures. [22][23][24] Although the charge separation efficiency can be enhanced, the redox ability of radiation-generated electrons and holes is sacrificed simultaneously. 27,28 To take full advantage of radiation-generated electrons and holes for RCT, semiconductor radiosensitizers should possess a high radiation absorption coefficient, a potent redox potential, a long carrier lifetime, and a large charge separation efficiency.…”