An Activatable Hybrid Organic-Inorganic Nanocomposite as Early Evaluation System of Therapy Effect

Activatable Probes for Ratiometric Imaging of Endogenous Biomarkers In Vivo

Dynamic variations in the concentration and abnormal distribution of endogenous biomarkers are strongly associated with multiple physiological and pathological states. Therefore, it is crucial to design imaging systems capable of real-time detection of dynamic changes in biomarkers for the accurate diagnosis and effective treatment of diseases. Recently, ratiometric imaging has emerged as a widely used technique for sensing and imaging of biomarkers due to its advantage of circumventing the limitations inherent to conventional intensity-dependent signal readout methods while also providing built-in self-calibration for signal correction. Here, the recent progress of ratiometric probes and their applications in sensing and imaging of biomarkers are outlined. Ratiometric probes are classified according to their imaging mechanisms, and ratiometric photoacoustic imaging, ratiometric optical imaging including photoluminescence imaging and self-luminescence imaging, ratiometric magnetic resonance imaging, and dual-modal ratiometric imaging are discussed. The applications of ratiometric probes in the sensing and imaging of biomarkers such as pH, reactive oxygen species (ROS), reactive nitrogen species (RNS), glutathione (GSH), gas molecules, enzymes, metal ions, and hypoxia are discussed in detail. Additionally, this Review presents an overview of challenges faced in this field along with future research directions.

Ratiometric Optical and Photoacoustic Imaging In Vivo in the Second Near-Infrared Window

Optical imaging and photoacoustic (PA) imaging have become essential tools to investigate physiological or pathological processes at the molecular level in vivo. The detection of variations at the molecular level in vivo is particularly important owing to the rapid progression of diseases. However, most studies have mainly focused on plain qualitative molecular imaging and detection, which is characterized by the absence of a reference signal in one-channel responsive imaging. To overcome the limitation and quantitatively detect molecules in situ, this Account reviews the recent contributions of our group to the quantitative imaging field in the form of ratiometric optical and PA imaging in vivo in the second near-infrared window (NIR-II, 950-1700 nm).In this Account, we present recent advances that our group has made in ratiometric imaging probe design and biomedical applications by constructing probes based on ratiometric optical imaging and ratiometric PA imaging. First, we highlight the design strategies of ratiometric optical probes that were based on organic ratiometric molecular probes, radio-activated organic ratiometric probes, and hybrid organic-inorganic assembled ratiometric probes. Subsequently, the design strategies of the ratiometric NIR-II optical nanoprobes with activated bioluminescence resonance energy transfer (BRET), Förster resonance energy transfer (FRET), and nonradiative energy transfer (NRET) effects provide a reliable tool to achieve the ratiometric detection of endogenous signaling molecules and thereby apply it to the monitoring and evaluation of the efficacy of photodynamic therapy, radiotherapy, and immunotherapy to guide the treatment process. In addition, we systematically introduce the functional design principles of ratiometric PA imaging probes based on core-shell nanoprobes, core-satellite nanoprobes, and universal hybrid nanoprobes, where we have established that reference signal and sensing signal can be obtained from the random assortment of plasmonic components and organic semiconducting molecules using a phase separation strategy. On these insights, we discuss the rational and detailed biomedical applications of ratiometric PA imaging probes which include accurate quantitative detection of disease-related molecules in inflammation or tumors in real time. In these champion implementations of ratiometric PA imaging probes, different diagnostic modules have been linked through compound modification with activation characteristics (e.g., pH, redox, enzyme, hypoxia). Finally, we present the challenges and perspectives for ratiometric probes based on optical imaging and PA imaging for multitarget design and future clinical translation. We believe that the upcoming generations of ratiometric imaging probes would have promising potential applications in the precise diagnosis of diseases. Finally, this Account may stimulate innovative studies in the design of ratiometric imaging probes and exploration of their clinical applications.

High-Precision Single-Cell microRNA Therapy by a Functional Nanopipette with Sensitive Photoelectrochemical Feedback

This work proposes the concept of single-cell microRNA (miR) therapy and proof-of-concept by engineering a nanopipette for high-precision miR-21-targeted therapy in a single HeLa cell with sensitive photoelectrochemical (PEC) feedback. Targeting the representative oncogenic miR-21, the as-functionalized nanopipette permits direct intracellular drug administration with precisely controllable dosages, and the corresponding therapeutic effects can be sensitively transduced by a PEC sensing interface that selectively responds to the indicator level of cytosolic caspase-3. The experimental results reveal that injection of ca. 4.4 × 10-20  mol miR-21 inhibitor, i.e., 26488 copies, can cause the obvious therapeutic action in the targeted cell. This work features a solution to obtain the accurate knowledge of how a certain miR-drug with specific dosages treats the cells and thus provides an insight into futuristic high-precision clinical miR therapy using personalized medicine, provided that the prerequisite single-cell experiments are courses of personalized customization.

A Self-Assembled Organic Probe with Activatable Near-Infrared Fluoro-Photoacoustic Signals for In Vivo Evaluation of the Radiotherapy Effect

Early evaluation and prediction of the radiotherapy effect against tumors are crucial for effective radiotherapy management. The clinical approach generally relies on anatomical changes in tumor size, which is unable to promptly reflect clinical outcomes and guide a timely adjustment of therapy regimens. To resolve it, we herein develop a self-assembled organic probe (dCyFFs) with caspase-3 (Casp-3)-activatable near-infrared (NIR) fluoro-photoacoustic signals for early evaluation and prediction of radiotherapy efficacy. The probe contains an NIR dye that is caged with a Casp-3-cleavable substrate and linked to a self-assembly initiating moiety. In the presence of Casp-3, the self-assembled probe can undergo secondary assembly into larger nanoparticles and simultaneously activate NIR fluoro-photoacoustic signals. Such a design endows a superior real-time longitudinal imaging capability of Casp-3 generated by radiotherapy as it facilitates the passive accumulation of the probe into tumors, activated signal output with enhanced optical stability, and retention capacity relative to a nonassembling small molecular control probe (dCy). As a result, the probe enables precise prediction of the radiotherapy effect as early as 3 h posttherapy, which is further evidenced by the changes in tumor size after radiotherapy. Overall, the probe with Casp-3-mediated secondary assembly along with activatable NIR fluoro-photoacoustic signals holds great potential for evaluating and predicting the response of radiotherapy in a timely manner, which can also be explored for utilization in other therapeutic modalities.

Nanoprobe-based molecular imaging for tumor stratification

The responses of patients to tumor therapies vary due to tumor heterogeneity. Tumor stratification has been attracting increasing attention for accurately distinguishing between responders to treatment and non-responders. Nanoprobes with unique physical and chemical properties have great potential for patient stratification. This review begins by describing the features and design principles of nanoprobes that can visualize specific cell types and biomarkers and release inflammatory factors during or before tumor treatment. Then, we focus on the recent advancements in using nanoprobes to stratify various therapeutic modalities, including chemotherapy, radiotherapy (RT), photothermal therapy (PTT), photodynamic therapy (PDT), chemodynamic therapy (CDT), ferroptosis, and immunotherapy. The main challenges and perspectives of nanoprobes in cancer stratification are also discussed to facilitate probe development and clinical applications.

Enzyme-Instructed Aggregation/Dispersion of Fluorophores for Near-Infrared Fluorescence Imaging In Vivo

Near-infrared (NIR) fluorescence is a noninvasive, highly sensitive, and high-resolution modality with great potential for in vivo imaging. Compared with "Always-On" probes, activatable NIR fluorescent probes with "Turn-Off/On" or "Ratiometric" fluorescent signals at target sites exhibit better signal-to-noise ratio (SNR), wherein enzymes are one of the ideal triggers for probe activation, which play vital roles in a variety of biological processes. In this review, we provide an overview of enzyme-activatable NIR fluorescent probes and concentrate on the design strategies and sensing mechanisms. We focus on the aggregation/dispersion state of fluorophores after the interaction of probes and enzymes and finally discuss the current challenges and provide some perspective ideas for the construction of enzyme-activatable NIR fluorescent probes.

Combined Epimedii Folium and Ligustri Lucidi Fructus with dexamethasone alleviate the proliferation of airway smooth muscle cells by regulating apoptosis/autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) theory believes kidney deficiency is the root cause of chronic refractory asthma with pathological changes of airway remodeling. Our previous experiments confirmed that the combination of Epimedii Folium and Ligustri Lucidi Fructus (ELL) with the effect of nourishing Yin and Yang of the kidney could improve the pathological changes of airway remodeling in asthmatic rats, but the specific mechanism remains unclear.

AIM OF THE STUDY

This research was designed to reveal the synergy of ELL and dexamethasone (Dex) in the proliferation, apoptosis, and autophagy of airway smooth muscle cells (ASMCs).

MATERIALS AND METHODS

Primary cultures of ASMCs from rats were prepared and induced with histamine (Hist), Z-DEVD-FMK (ZDF), rapamycin (Rap), or 3-Methyladenine (3-MA) at generation 3-7 for 24 or 48 h. Subsequently, the cells were treated with Dex, ELL, and ELL&Dex for 24 or 48 h. The effect of various concentrations of inducers and drugs on cell viability was detected by Methyl Thiazolyl Tetrazolium (MTT) assay, cell proliferation was tested using immunocytochemistry (ICC) by detecting Ki67 protein, cell apoptosis was measured by Annexin V-FITC/PI assay and Hoechst nuclear staining, cell ultrastructure was observed by transmission electron microscopy (TEM), and immunofluorescence (IF), western blot (WB) combined with quantitative real-time PCR (qPCR) were used for measuring autophagy and apoptosis-related genes including protein 53 (P53), cysteinyl aspartate-specific proteinase (Caspase)-3, microtubule-associated protein 1 light chain 3 (LC3), Beclin-1, mammalian target of rapamycin (mTOR) and p-mTOR.

RESULTS

In ASMCs, Hist and ZDF promoted cell proliferation, significantly decreased Caspase-3 protein expression, and up-regulated Beclin-1 levels; Dex alone and in combination with ELL promoted Beclin-1, Caspase-3, and P53 expression, enhancing autophagy activity and apoptosis in Hist and ZDF-induced AMSCs. In contrast, Rap inhibited cell viability, increased Caspase-3, P53, Beclin-1, and LC3-II/I and decreased the levels of mTOR and p-mTOR with promoting apoptosis and autophagy; ELL or ELL&Dex reduced P53, Beclin-1, and LC3-II/I to down-regulate apoptosis and the excessive autophagic state of ASMCs induced by Rap. In the 3-MA model, cell viability and autophagy were reduced; ELL&Dex significantly upgraded the expression of Beclin-1, P53, and Caspase-3 and promoted apoptosis and autophagy of ASMCs.

CONCLUSIONS

These results suggest that ELL combined with Dex may regulate the proliferation of ASMCs by promoting apoptosis and autophagy and be a potential medicine for the treatment of asthma.

Acidity/carbon dioxide-sensitive triblock polymer-grafted photoactivated vesicles for programmed release of chemotherapeutic drugs against glioblastoma

Controllable release of chemotherapeutic drugs in tumor sites remains a big challenge for precision therapy. Herein, we developed acidity/carbon dioxide (H⁺/CO₂)-sensitive poly (ethylene glycol)-b-poly (2-(diisopropylamino) ethyl methacrylate)-b-polystyrene triblock polymer (PEG-b-PDPA-b-PS) grafted photoactivated vesicles for programmed release of chemotherapeutic drugs against glioblastoma. In brief, gold nanoparticles (GNPs) were firstly tethered with the H⁺/CO₂-sensitive PEG-b-PDPA-b-PS polymer. Next, the CO₂ precursor (ammonium bicarbonate, NH₄HCO₃) and doxorubicin (DOX) were loaded during self-assembly process of PEG-b-PDPA-b-PS-tethered GNPs, thus obtaining the multifunctional gold vesicles (denoted as GVND). The programmed multi-stimuli responsive drug release by GVND was undergone in multiple steps as follows: 1) the vesicular architecture of GVND was first swelled in tumor acidic microenvironment, 2) the GVND were partially broken under near-infrared (NIR) laser irradiation, 3) the mild hyperthermia generated by GV triggered the thermal decomposition of encapsulated NH₄HCO₃, leading to the in situ generation of CO₂, 4) the generated CO₂ reacted with PDPA of PEG-b-PDPA-b-PS, changing the hydrophilicity and hydrophobicity of GVND, thus vastly breaking its vesicular architecture, finally resulting in a "bomb-like" release of DOX in tumor tissues. Such a multi-stimuli responsive programmed drug delivery and mild hyperthermia under NIR laser activation displayed strong antitumor efficacy and completely eradicated U87MG glioblastoma tumor. This work presented a promising strategy to realize precision drug delivery for chemotherapy against glioblastoma. STATEMENT OF SIGNIFICANCE.

An Activatable Polymeric Nanoprobe for Fluorescence and Photoacoustic Imaging of Tumor-Associated Neutrophils in Cancer Immunotherapy

Imaging to evaluate tumor-associated neutrophils (TANs) is imperative for cancer immunotherapy but remains challenging. We herein report an activatable semiconducting polymer nanoprobe (SPCy) for near-infrared fluorescence (NIRF) and photoacoustic (PA) imaging of neutrophil elastase (NE), a biomarker of TANs. SPCy comprises a semiconducting polymer conjugated with a hemicyanine (hemi-Cy) dye caged by a NE-cleavable peptide as the side chain. After systemic administration, SPCy passively targets the tumor and reacts with NE to "uncage" the hemi-Cy, leading to enhanced NIRF and PA signals of the hemi-Cy but unchanged signals of the SP. Such NE-activated ratiometric NIRF and enhanced PA signals of SPCy correlate with the intratumoral population of TANs. Thus, this study not only presents the first TAN-specific PA probe, but also provides a general molecular design strategy for PA imaging of other immune-related biomarkers to facilitate screening of cancer immunotherapeutics.

In Vivo Quantitative Assessment of a Radiation Dose Based on Ratiometric Photoacoustic Imaging of Tumor Apoptosis

Accurately assessing the radiation level of tumors and surrounding tissues is of great significance for the optimization of clinical therapeutic interventions as well as minimizing the radiation-induced side effects. Therefore, the development of noninvasive and sensitive biological dosimeters is vital to achieve quantitative detection of a radiation dose in a living system. Herein, as a proof of concept, we report a tumor-targeted and caspase-3-activatable NIR fluorogenic probe AcDEVD-Cy-RGD consisting of a hemicyanine fluorophore as a signal reporter, a caspase-3 specific Asp-Glu-Val-Asp (DEVD) peptide, and a cyclic Arg-Gly-Asp peptide (cRGD) for tumor targeting. Upon cleavage with activated caspase-3, this probe not only displays the lighted-up NIR fluorescence, but also ratiometric photoacoustic (PA₇₁₀/PA₆₈₀) signals concurrently in a caspase-3 concentration-dependent manner, allowing for sensitive and quantitative detection of caspase-3 activity through both fluorescence and PA imaging, which provides the possibility for real-time monitoring of tumor cell apoptosis in a living system. More notably, we utilized this probe to successfully realize the direct visualization of tumor response to chemo- or radiotherapy and, for the first time, achieve the accurate estimation of radiation doses imparted to the tumors. We thus believe that our current strategy would offer an attractive and valuable means for the precise assessment of locally delivered radiation doses in various clinical settings.