An NIR Fluorescence Turn-on and MRl Bimodal Probe for Concurrent Real-time in vivo Sensing and Labeling of β-Galactosidase

Monitoring ROS Responsive Fe3O4-based Nanoparticle Mediated Ferroptosis and Immunotherapy via 129Xe MRI

The immune checkpoint blockade strategy has improved the survival rate of late-stage lung cancer patients. However, the low immune response rate limits the immunotherapy efficiency. Here, we report a ROS-responsive Fe3O4-based nanoparticle that undergoes charge reversal and disassembly in the tumor microenvironment, enhancing the uptake of Fe3O4 by tumor cells and triggering a more severe ferroptosis. In the tumor microenvironment, the nanoparticle rapidly disassembles and releases the loaded GOx and the immune-activating peptide Tuftsin under overexpressed H2O2. GOx can consume the glucose of tumor cells and generate more H2O2, promoting the disassembly of the nanoparticle and drug release, thereby enhancing the therapeutic effect of ferroptosis. Combined with Tuftsin, it can more effectively reverse the immune-suppressive microenvironment and promote the recruitment of effector T cells in tumor tissues. Ultimately, in combination with α-PD-L1, there is significant inhibition of the growth of lung metastases. Additionally, the hyperpolarized 129Xe method has been used to evaluate the Fe3O4 nanoparticle-mediated immunotherapy, where the ventilation defects in lung metastases have been significantly improved with complete lung structure and function recovered. The ferroptosis-enhanced immunotherapy combined with non-radiation evaluation methodology paves a new way for designing novel theranostic agents for cancer therapy.

Senolytic Therapy Enabled by Senescent Cell-Sensitive Biomimetic Melanin Nano-Senolytics

Cellular senescence is a significant risk factor for aging and age-related diseases (ARD). The canonical senolytics Dasatinib and Quercetin (DQ) have shown promise in clearing senescent cells (SnCs); however, the lack of selectivity poses a challenge in achieving optimal outcomes. Despite the recent occurrence of nanomaterial-based approaches targeting SnCs, limited therapeutic effects, and potential toxicity still remain a major concern. Herein, a "double locks-like" nanoplatform is developed that integrated Galactan coating and mesoporous polydopamine to encase the senolytic drug DQ. By this way, DQ is only released in SnCs that are featured with higher levels of β-galactosidase (β-gal) and low PH. Additionally, the nanoparticles are equipped with 2,2,6,6-Tetramethylpiperidine-1-oxyl (Tempo) to gain enhanced photothermal converting potential. Consequently, the synthesized nanosenolytics demonstrate remarkable specificity and efficacy in eradicating SnCs, and accordingly reverse pulmonary fibrosis in mice without affecting normal tissues. Upon exposure of near-infrared (NIR) light, the nanoparticles demonstrate to efficiently remove senescent tumor cells inducted by chemotherapy, thereby hindering the outgrowth and metastasis or breast cancer. Collectively, the present study develops an "On/Off" switchable nanoplatform in response to SnCs, and produces a more safe, efficient, and feasible way to delay aging or alleviate age-associated diseases.

A Dual-Cascade Activatable Near-Infrared Fluorescent Probe for Precise Intraoperative Imaging of Tumor

Accurate intraoperative tumor delineation is critical to achieving successful surgical outcomes. However, conventional techniques typically suffer from poor specificity and low sensitivity and are time-consuming, which greatly affects intraoperative decision-making. Here, we report a cascade activatable near-infrared fluorescent (NIRF) probe IR780SS@CaP that can sequentially respond to tumor acidity and elevated glutathione levels for accurate intraoperative tumor localization. Compared with nonactivatable and single-factor activatable probes, IR780SS@CaP with a cascade strategy can minimize nonspecific activation and false positive signals in a complicated biological environment, affording a superior tumor-to-normal tissue ratio to facilitate the delineation of abdominal metastases. Small metastatic lesions that were less than 1 mm in diameter can be precisely identified by IR780SS@CaP and completely excised under NIRF imaging guidance. This study could benefit tumor diagnosis and image-guided tumor surgery by providing real-time information and reliable decision support, thus reducing the risk of both recurrence and complications to improve patient outcomes.

Quinone Methide Based Self-Immobilizing Molecular Fluorescent Probes for In Situ Imaging of Enzymes

Enzymes play important roles not only in normal physiological processes but in the development of many diseases. In situ imaging of enzymes with high-resolution in living systems would helpful for clinical diagnosis and treatment. However, many molecular fluorescent probes suffer from the drawback of diffusing away from the reaction site of enzymes even out of the cells, losing the in situ information and resulting in poor imaging resolution. Quinone methide (QM) based self-immobilizing probes allow the fluorescent signal to be immobilized near the target for an extended period without deactivating the target enzymes, ensuring that it will provide amplified signals and in situ information of the target with high resolution. In this review, we summarized the recent progress of QM-based self-immobilizing probes including their design strategies, working mechanisms, classifications and applications in in situ enzyme imaging. This review calls for the development of more activatable QM-based probe with the advantages of high stability in the absence of the target but very high labeling efficiency after activation.

High-fidelity imaging of a tumour-associated lysosomal enzyme with an acceptor engineering-boosted near-infrared fluorescent probe

To facilitate the understanding of the dynamic distribution and activity of lysosomal enzymes, it is highly desirable to develop high-fidelity near-infrared (NIR) activatable fluorescent probes. Here, we propose a general acceptor engineering strategy to construct NIR probes with lysosome-targeting capability. Upon isosteric replacement and additional functionalization, the β-gal-activatable probe OELyso-Gal exhibited excellent lysosome-targeting capability and favorable responsive performance to the enzyme of interest. Notably, the steric hindrance effect from acceptor engineering is modest, which renders the probe unprecedented affinity to enzymes. Upon the introduction of acceptor engineering, the lysosome-targeting probe became more sensitive to β-gal in cells and tissues, boosting the discrimination of high β-gal-expressing ovarian cancer tumours from low β-gal-expressing tissues. Furthermore, the superiority of OELyso-Gal was validated in real-time visualization of ovarian cancer in tumour-bearing mice. This elegant acceptor engineering strategy provides inspirational insights into the development of customized fluorescent probes for monitoring disease-associated biomarkers within subcellular organelles.

A β-Galactosidase-Activated Fluorogenic Reporter for the Detection of Gastric Cancer In Vivo and in Urine

Although gastric cancer (GC) is one of the most frequent malignant tumors in the digestive tract with high morbidity and mortality, it remains a diagnostic dilemma due to its reliance on invasive biopsy or insensitive assays. Herein, we report a fluorescent gastric cancer reporter (FGCR) with activatable near-infrared fluorescence (NIRF) signals and high renal-clearance efficiency for the detection of orthotopic GC in a murine model via real-time imaging and remote urinalysis. In the presence of gastric-tumor-associated β-galactosidase (β-Gal), FGCR can be fluorescently activated for in vivo NIRF imaging. Relying on its high renal-clearance efficiency (∼95% ID), it can be rapidly excreted through kidneys to urine for the ultrasensitive detection of tumors with a diameter down to ∼2.1 mm and for assessing the prognosis of oxaliplatin-based chemotherapy. This study not only provides a new approach for noninvasive auxiliary diagnosis and prognosis of GC but also provides guidelines for the development of fluorescence probes for cancer diagnosis.

β-Galactosidase-Activated and Red Light-Induced RNA Modification Strategy for Prolonged NIR Fluorescence/PET Bimodality Imaging

Improving the retention of small-molecule-based therapeutic agents in tumors is crucial to achieve precise diagnosis and effective therapy of cancer. Herein, we propose a β-galactosidase (β-Gal)-activated and red light-induced RNA modification (GALIRM) strategy for prolonged tumor imaging. A β-Gal-activatable near-infrared (NIR) fluorescence (FL) and positron emission tomography (PET) bimodal probe 68Ga-NOTA-FCG consists of a triaaza triacetic acid chelator NOTA for 68Ga-labeling, a β-Gal-activated photosensitizer CyGal, and a singlet oxygen (1O2)-susceptible furan group for RNA modification. Studies have demonstrated that the probe emits an activated NIR FL signal upon cleavage by endogenous β-Gal overexpressed in the lysosomes, which is combined with the PET imaging signal of 68Ga allowing for highly sensitive imaging of ovarian cancer. Moreover, the capability of 68Ga-NOTA-FCG generating 1O2 under 690 nm illumination could be simultaneously unlocked, which can trigger the covalent cross-linking between furan and nucleotides of cytoplasmic RNAs. The formation of the probe-RNA conjugate can effectively prevent exocytosis and prolong retention of the probe in tumors. We thus believe that this GALIRM strategy may provide entirely new insights into long-term tumor imaging and efficient tumor treatment.