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Tumor‐specific, hypoxia‐activated prodrugs have been developed to alleviate the side effects of chemotherapy drugs. However, the release efficiency of hypoxia‐activated prodrugs is restricted by the degree of tumor hypoxia, which further leads to poor cancer treatment effects. On the other hand, oxygen is consumed gradually in photodynamic therapy (PDT), which aggravates hypoxia at the tumor site. In this study, we combined hypoxia‐activated prodrugs with PDT agents to promote the prodrugs release, thereby improving their bioavailability and therapeutic effects. As a proof of concept, a mitochondria‐targeted molecular prodrug, CS‐P, was designed and synthesized. It can be selectively activated by tumor hypoxia to release chemotherapeutic drugs and photosensitizers, and then further discharge drugs after light irradiation. The design strategy proposed in this paper provides a new idea for enhancing hypoxia‐activated prodrug release and real‐time monitoring prodrug release. [ABSTRACT FROM AUTHOR]

Tumor‐specific, hypoxia‐activated prodrugs have been developed to alleviate the side effects of chemotherapy drugs. However, the release efficiency of hypoxia‐activated prodrugs is restricted by the degree of tumor hypoxia, which further leads to poor cancer treatment effects. On the other hand, oxygen is consumed gradually in photodynamic therapy (PDT), which aggravates hypoxia at the tumor site. In this study, we combined hypoxia‐activated prodrugs with PDT agents to promote the prodrugs release, thereby improving their bioavailability and therapeutic effects. As a proof of concept, a mitochondria‐targeted molecular prodrug, CS‐P, was designed and synthesized. It can be selectively activated by tumor hypoxia to release chemotherapeutic drugs and photosensitizers, and then further discharge drugs after light irradiation. The design strategy proposed in this paper provides a new idea for enhancing hypoxia‐activated prodrug release and real‐time monitoring prodrug release. [ABSTRACT FROM AUTHOR]

In situ monitoring of the location and transportation of bioactive molecules is essential for deciphering diverse biological events in the field of biomedicine. In addition, obtaining the in situ information of lesions will provide a clear perspective for surgeons to perform precise resection in clinical surgery. Notably, delivering drugs or operating photodynamic therapy/photothermal therapy in situ by labeling the lesion regions of interest can improve treatment and reduce side effects in vivo. In various advanced imaging and therapy modalities, optical theranostic agents based on organic small molecules can be conveniently modified as needed and can be easily internalized into cells/lesions in a non-invasive manner, which are prerequisites for in situ bioimaging and precision treatment. In this tutorial review, we first summarize the in situ molecular immobilization strategies to retain small-molecule agents inside cells/lesions to prevent their diffusion in living organisms. Emphasis will be focused on introducing the application of these strategies for in situ imaging of biomolecules and precision treatment, particularly pertaining to why targeting therapy in situ is required. [ABSTRACT FROM AUTHOR]

The in situ and real-time supervision of reactive oxygen species (ROS) generated during photodynamic therapy (PDT) is of great significance for lessening nonspecific damage and guiding personalized therapy. However, photosensitizers frequently fail to deliver successful treatment accompanying the ROS-related imaging signals produced, impeding simple treatment outcome predictions and therapeutic schedule adjustments. Here, we report a two-photon fluorescence self-reporting strategy for the in situ and real-time monitoring of treatment response via a novel black phosphorus-based two-photon nanoprobe (TPBP). TPBP effectively generated singlet oxygen (1O2) under near-infrared laser irradiation for PDT, and 1O2 stimulated a two-photon molecule to emit fluorescence signals for feedback of 1O2 generation, which facilitated the regulation of treatment parameters to achieve precise and personalized medicine in deep tissue. [ABSTRACT FROM AUTHOR]

Hypoxia, as a characteristic feature of solid tumor, can significantly adversely affect the outcomes of cancer radiotherapy (RT), photodynamic therapy, or chemotherapy. In this study, a strategy is developed to overcome tumor hypoxia‐induced radiotherapy tolerance. Specifically, a novel two‐dimensional Pd@Au bimetallic core–shell nanostructure (TPAN) was employed for the sustainable and robust production of O2 in long‐term via the catalysis of endogenous H2O2. Notably, the catalytic activity of TPAN could be enhanced via surface plasmon resonance (SPR) effect triggered by NIR‐II laser irradiation, to enhance the O2 production and thereby relieve tumor hypoxia. Thus, TPAN could enhance radiotherapy outcomes by three aspects: 1) NIR‐II laser triggered SPR enhanced the catalysis of TPAN to produce O2 for relieving tumor hypoxia; 2) high‐Z element effect arising from Au and Pd to capture X‐ray energy within the tumor; and 3) TPAN affording X‐ray, photoacoustic, and NIR‐II laser derived photothermal imaging, for precisely guiding cancer therapy, so as to reduce the side effects from irradiation. [ABSTRACT FROM AUTHOR]

Hypoxia, as a characteristic feature of solid tumor, can significantly adversely affect the outcomes of cancer radiotherapy (RT), photodynamic therapy, or chemotherapy. In this study, a strategy is developed to overcome tumor hypoxia‐induced radiotherapy tolerance. Specifically, a novel two‐dimensional Pd@Au bimetallic core–shell nanostructure (TPAN) was employed for the sustainable and robust production of O2 in long‐term via the catalysis of endogenous H2O2. Notably, the catalytic activity of TPAN could be enhanced via surface plasmon resonance (SPR) effect triggered by NIR‐II laser irradiation, to enhance the O2 production and thereby relieve tumor hypoxia. Thus, TPAN could enhance radiotherapy outcomes by three aspects: 1) NIR‐II laser triggered SPR enhanced the catalysis of TPAN to produce O2 for relieving tumor hypoxia; 2) high‐Z element effect arising from Au and Pd to capture X‐ray energy within the tumor; and 3) TPAN affording X‐ray, photoacoustic, and NIR‐II laser derived photothermal imaging, for precisely guiding cancer therapy, so as to reduce the side effects from irradiation. [ABSTRACT FROM AUTHOR]

Precision diagnosis and effective treatment are the cores of early cancer therapy. Here, for the first time, we report a hybridization chain reaction-based nanoprobe for selective and sensitive cancer cell recognition and amplified photodynamic therapy. [ABSTRACT FROM AUTHOR]

Herein, we developed a strategy to attack the cancer cell defense system against reactive oxygen species to improve photodynamic therapy efficacy with a Ce6@MSN@MTH1 siRNA nanosystem, which was demonstrated to improve cellular sensitivity to reactive oxygen species through suppressing MTH1 protein in cancer cells. [ABSTRACT FROM AUTHOR]

A promising two-photon fluorescent probe MNAH for detecting 1O2 during the PDT process in mitochondria was proposed for the first time. MNAH was successfully applied for two-photon imaging of 1O2 in living cells and tissues during the PDT process with deep-tissue imaging depth. MNAH can be a powerful molecular tool for studying 1O2 generation in mitochondria during the PDT process. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has been applied in cancer treatment by utilizing reactive oxygen species to kill cancer cells. However, a high concentration of glutathione (GSH) is present in cancer cells and can consume reactive oxygen species. To address this problem, we report the development of a photosensitizer-MnO2 nanosystem for highly efficient PDT. In our design, MnO2 nanosheets adsorb photosensitizer chlorin e6 (Ce6), protect it from self-destruction upon light irradiation, and efficiently deliver it into cells. The nanosystem also inhibits extracellular singlet oxygen generation by Ce6, leading to fewer side effects. Once endocytosed, the MnO2 nanosheets are reduced by intracellular GSH. As a result, the nanosystem is disintegrated, simultaneously releasing Ce6 and decreasing the level of GSH for highly efficient PDT. Moreover, fluorescence recovery, accompanied by the dissolution of MnO2 nanosheets, can provide a fluorescence signal for monitoring the efficacy of delivery. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has been applied in cancer treatment by utilizing reactive oxygen species to kill cancer cells. However, a high concentration of glutathione (GSH) is present in cancer cells and can consume reactive oxygen species. To address this problem, we report the development of a photosensitizer-MnO2 nanosystem for highly efficient PDT. In our design, MnO2 nanosheets adsorb photosensitizer chlorin e6 (Ce6), protect it from self-destruction upon light irradiation, and efficiently deliver it into cells. The nanosystem also inhibits extracellular singlet oxygen generation by Ce6, leading to fewer side effects. Once endocytosed, the MnO2 nanosheets are reduced by intracellular GSH. As a result, the nanosystem is disintegrated, simultaneously releasing Ce6 and decreasing the level of GSH for highly efficient PDT. Moreover, fluorescence recovery, accompanied by the dissolution of MnO2 nanosheets, can provide a fluorescence signal for monitoring the efficacy of delivery. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS)‐based cancer therapy, such as photodynamic therapy (PDT), is subject to the hypoxia and overexpressed glutathione (GSH) found in the tumor microenvironment (TME). Herein, a novel strategy is reported to continuously and simultaneously regulate tumor hypoxia and reducibility in order to achieve the desired therapeutic effect. To accomplish this, a biocompatible nanoplatform (MnFe2O4@metal–organic framework (MOF)) is developed by integrating a coating of porphyrin‐based MOF as the photosensitizer and manganese ferrite nanoparticle (MnFe2O4) as the nanoenzyme. The synthetic MnFe2O4@MOF nanoplatform exhibits both catalase‐like and glutathione peroxidase‐like activities. Once internalized in the tumor, the nanoplatform can continuously catalyze H2O2 to produce O2 to overcome the tumor hypoxia by cyclic Fenton reaction. Meanwhile, combined with the Fenton reaction, MnFe2O4@MOF is able to persistently consume GSH in the presence of H2O2, which decreases the depletion of ROS upon laser irradiation during PDT and achieves better therapeutic efficacy in vitro and in vivo. Moreover, the nanoplatform integrates a treatment modality with magnetic resonance imaging, along with persistent regulation of TME, to promote more precise and effective treatment for future clinical application. [ABSTRACT FROM AUTHOR]