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A Bright NIR-II Fluorescence Probe for Vascular and Tumor Imaging
Published on: March 17, 2023
An APN-activated NIR photosensitizer for cancer photodynamic therapy and fluorescence imaging
Xiao Zhou1, Haidong Li1, Chao Shi1
1State Key Laboratory of Fine Chemicals, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, PR China.
Abstract:
Photodynamic therapy has been developed as a prospective cancer treatment in recent years. Nevertheless, conventional photosensitizers suffer from lacking recognition and specificity to tumors, which causing severe side effects to normal tissues, while the enzyme-activated photosensitizers are capable of solving these conundrums due to high selectivity towards tumors. APN (Aminopeptidase N, APN/CD13), a tumor marker, has become a crucial targeting substance owing to its highly expressed on the cell membrane surface in various tumors, which has become a key point in the research of anti-tumor drug and fluorescence probe. Based on it, herein an APN-activated near-infrared (NIR) photosensitizer (APN-CyI) for tumor imaging and photodynamic therapy has been firstly developed and successfully applied in vitro and in vivo. Studies showed that APN-CyI could be activated by APN in tumor cells, hydrolyzed to fluorescent CyI-OH, which specifically located in mitochondria in cancer cells and exhibited a high singlet oxygen yield under NIR irradiation, and efficiently induced cancer cell apoptosis. Dramatically, the in vivo assays on Balb/c mice showed that APN-CyI could achieve NIR fluorescence imaging (λem = 717 nm) for endogenous APN in tumors and possessed an efficient tumor suppression effect under NIR irradiation.
Insights
A novel enzyme-activated photosensitizer targets tumors by recognizing Aminopeptidase N (APN). This targeted approach enables effective tumor imaging and photodynamic therapy with reduced side effects on healthy tissues.
Area of Science:
- Biomedical Engineering
- Photodynamic Therapy
- Cancer Research
Background:
- Conventional photosensitizers lack tumor specificity, leading to side effects.
- Enzyme-activated photosensitizers offer improved tumor selectivity.
- Aminopeptidase N (APN/CD13) is a tumor marker highly expressed on various cancer cells.
Purpose of the Study:
- To develop a novel APN-activated near-infrared (NIR) photosensitizer for tumor imaging and photodynamic therapy.
- To evaluate the efficacy of the developed photosensitizer in vitro and in vivo.
Main Methods:
- Synthesis of an APN-activated NIR photosensitizer (APN-CyI).
- In vitro studies on cancer cells to assess activation, localization, and apoptosis induction.
- In vivo studies on Balb/c mice for fluorescence imaging and tumor suppression evaluation.
Main Results:
- APN-CyI was successfully activated by APN in tumor cells, yielding fluorescent CyI-OH.
- The activated photosensitizer localized in cancer cell mitochondria and produced high singlet oxygen yield under NIR irradiation.
- In vivo assays demonstrated effective NIR fluorescence imaging of tumors and significant tumor suppression under NIR irradiation.
Conclusions:
- APN-CyI is a promising APN-activated photosensitizer for targeted tumor imaging and photodynamic therapy.
- The developed photosensitizer exhibits high specificity, efficient mitochondrial localization, and potent anti-tumor effects.
- This approach offers a potential strategy for improving cancer treatment outcomes with minimized off-target toxicity.
