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.

Early diagnosis and therapy are clinically crucial in decreasing mortality from breast carcinoma. However, the existing probes have difficulty in accurately identifying the margins and contours of breast carcinoma due to poor sensitivity and specificity. There is an urgent need to develop high-sensitive fluorescent probes for the diagnosis of breast carcinoma and for differentiating tumors from normal tissues during surgery. β-Galactosidase is a significant biomarker, whose overexpression is closely associated with the progression of breast tumors. Herein, we have constructed a β-galactosidase-activated fluorescent probe NIR-βgal-2 through rational design and molecular docking engineering simulations. The probe displayed superior sensitivity (detection limit = 2.0 × 10–3 U/mL), great affinity (K m = 1.84 μM), and catalytic efficiency (k cat/K m = 0.24 μM–1 s–1) for β-galactosidase. Leveraging this probe, we demonstrated the differentiation of cancer cells overexpressing β-galactosidase from normal cells and then applied the probe for intraoperative guided excision of breast tumors. Moreover, we exhibited the application of NIR-βgal-2 for the successful resection of orthotopic breast tumors by “in situ spraying” and monitored a good prognostic recovery. This work may promote the application of enzyme-activated near-infrared fluorescent probes for the development of carcinoma diagnosis and image-guided surgery.

Nonalcoholic fatty liver disease (NAFLD), emerging as one of the most common chronic liver diseases including simple steatosis and non‐alcoholic steatohepatitis (NASH), is likely to progress to liver fibrosis and hepatic carcinoma if not treated in time. Therefore, early diagnosis and treatment of NAFLD are necessary. Currently, liver biopsy, as the gold standard for clinical diagnosis of NAFLD, is not widely accepted by patients due to its invasiveness. However, other non‐invasive methods that had been reported for NAFLD (such as magnetic resonance imaging, positron emission tomography, and ultrasound) still suffer from low resolution and sensitivity, which are available as a guide for liver biopsy sometimes. As a non‐invasive modality with high spatiotemporal resolution and superior sensitivity, optical imaging methods have been widely favored in recent years, mainly including fluorescence imaging, photoacoustic imaging, and bioluminescence imaging. With these optical imaging approaches, a series of optical probes based on optical and molecular‐specific design have been developed for the biomarker diagnosis and research of diseases. In this review, we summarize the existing non‐invasive optical imaging probes for the detection of biomarkers in NAFLD, including microenvironment (viscosity, polarity), ROS, RSS, ions, proteins, and nucleic acids. Design strategies for optical imaging probes and their applications in NAFLD bioimaging are discussed and focused on. We also highlight the potential challenges and prospects of designing new generations of optical imaging probes in NAFLD studies, which will further enhance the diversity, practicality, and clinical feasibility of NAFLD research.

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.