An antagonist-based two-photon fluorogenic probe for imaging metabotropic glutamate receptor 5 in neuronal cells.

The expression of metabotropic glutamate receptor 5 (mGluR5) is subject to developmental regulation and undergoes significant changes in neuropsychiatric disorders and diseases. Visualizing mGluR5 by fluorescence imaging is a highly desired innovative technology for biomedical applications. Nevertheless, there are substantial problems with the chemical probes that are presently accessible. In this study, we have successfully developed a two-photon fluorogenic probe, mGlu-5-TP, based on the structure of mGluR5 antagonist 6-methyl-2-(phenylethynyl)pyridine (MPEP). Due to this antagonist-based probe selectively recognizes mGluR5, high expression of mGluR5 on living SH-SY5Y human neuroblastoma cells has been detected during intracellular inflammation triggered by lipopolysaccharides (LPS). Of particular significance, the probe can be employed along with two-photon fluorescence microscopy to enable real-time visualization of the mGluR5 in Aß fiber-treated neuronal cells, thereby establishing a connection to the progression of Alzheimer's disease (AD). These results revealed that the probe can be a valuable imaging tool for studying mGluR5-related diseases in the nervous system.

Cascading Detection of Hydrogen Sulfide and N-Acetyltransferase 2 in Hepatocellular Carcinoma Cells Using a Two-Photon Fluorescent Probe.

Hydrogen sulfide (H2S), a critical gas signaling molecule, and N-acetyltransferase 2 (NAT2), a key enzyme in drug metabolism, are both known active biomarkers for liver function. However, the interactions and effects of H2S and NAT2 in living cells or lesion sites remain unknown due to the lack of imaging tools to achieve simultaneous detection of these two substances, making it challenging to implement real-time imaging and precise tracking. Herein, we report an activity-based two-photon fluorescent probe, TPSP-1, for the cascade detection of H2S and NAT2 in living liver cells. Continuous conversion from TPSP-1 to TPSP-3 was achieved in liver cells and tissues. Significantly, leveraging the outstanding optical properties of this two-photon fluorescent probe, TPSP-1, has been effectively used to identify pathological tissue samples directly from clinical liver cancer patients. This work provides us with this novel sensing and two-photon imaging probe, which can be used as a powerful tool to study the physiological functions of H2S and NAT2 and will help facilitate rapid and accurate diagnosis and therapeutic evaluation of hepatocellular carcinoma.

Activatable Dual-Optical Molecular Probe for Bioimaging Superoxide Anion in Epilepsy.

Superoxide anion (O2•-) plays a pivotal role in the generation of other reactive oxygen species within the body and is closely linked to epilepsy. Despite this connection, achieving precise imaging of O2•- during epilepsy pathology remains a formidable challenge. Herein, we develop an activatable molecular probe, CL-SA, to track the fluctuation of the level of O2•- in epilepsy through simultaneous fluorescence imaging and chemiluminescence sensing. The developed probe CL-SA demonstrated its efficacy in imaging of O2•- in neuronal cells, showcasing its dual optical imaging capability for O2•- in vitro. Furthermore, CL-SA was successfully used to observe aberrantly expressed O2•- in a mouse model of epilepsy. Overall, CL-SA provides us with a valuable tool for chemical and biomedical studies of O2•-, promoting the investigation of O2•- fluctuations in epilepsy, as well as providing a reliable means to explore the diagnosis and therapy of epilepsy.

Novel 1,8-Naphthalimide Derivatives As Antitumor Agents and Potent Demethylase Inhibitors.

Functional 1,8-naphthalimide derivatives are rapidly developing in the field of anticancer research. Herein, we designed and synthesized a series of naphthalimide derivatives with different substituents. Interestingly, 1,8-naphthalimide derivatives 1 and 7 inhibited a human demethylase FTO (the fat mass and obesity-associated protein). Computer simulation studies further indicated that 1 and 7 entered the FTO's structural domain II binding pocket through hydrophobic and hydrogen bonding interactions. Anticancer mechanism studies showed that 1 and 7 induced DNA damage and autophagic cell death in A549 cells. The high antiproliferative activity of 1 and 7 was further confirmed by 3D multicellular A549 tumor spheroid assays. This study focuses on the cytotoxicity and mode of action of naphthalimide derivatives, which not only have potential anticancer activity but also are potent demethylase inhibitors.

Novel Dual-Mode NIR-II/MRI Nanoprobe Targeting PD-L1 Accurately Evaluates the Efficacy of Immunotherapy for Triple-Negative Breast Cancer.

Background: Durable responses to immune-checkpoint blocking therapy (ICT) targeting programmed cell death protein-1/ligand-1 (PD-1/PD-L1) have improved outcomes for patients with triple negative breast cancer (TNBC). Unfortunately, only 19-23% of patients benefit from ICT. Hence, non-invasive strategies evaluating responses to therapy and selecting patients who will benefit from ICT are critical issues for TNBC immunotherapy. Methods: We developed a novel nanoparticle-Atezolizumab (NPs-Ate) consisting of indocyanine green (ICG), gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA), human serum albumin (HSA), and Atezolizumab. The efficiency of Gd-DTPA linking was verified using mass spectrometry, and the size of NPs-Ate was characterized using Nano-flow cytometry. The synthesized NPs-Ate were evaluated for fluorescence stability, penetration depth, and target specificity. TNBC cell lines and tumor-bearing mice models were used to identify the feasibility of this dual-modal second near-infrared/magnetic resonance imaging (NIR-II/MRI) system. Additionally, ICT combination with chemotherapy or radiotherapy in TNBC tumor-bearing mice models were used to assess dynamic changes of PD-L1 and predicted therapeutic responses with NPs-Ate. Results: Atezolizumab, a monoclonal antibody, was successfully labeled with ICG and Gd-DTPA to generate NPs-Ate. This demonstrated strong fluorescence signals in our NIR-II imaging system, and relaxivity (γ1) of 9.77 mM-1 s-1. In tumor-bearing mice, the NIR-II imaging signal background ratio (SBR) reached its peak of 11.51 at 36 hours, while the MRI imaging SBR reached its highest as 1.95 after 12 hours of tracer injection. NPs-Ate specifically targets cells and tumors expressing PD-L1, enabling monitoring of PD-L1 status during immunotherapy. Combining therapies led to inhibited tumor growth, prolonged survival, and increased PD-L1 expression, effectively monitored using the non-invasive NPs-Ate imaging system. Conclusion: The NIR-II/MRI NPs-Ate effectively reflected PD-L1 status during immunotherapy. Real-time and non-invasive immunotherapy and response/prognosis monitoring under NIR-II/MRI imaging guidance in TNBC is a promising and innovative technology with potential for extensive clinical applications in the future.

Macrophage Reprogramming via Targeted ROS Scavenging and COX-2 Downregulation for Alleviating Inflammation.

Inflammation-related diseases affect large populations of people in the world and cause substantial healthcare burdens, which results in significant costs in time, material, and labor. Preventing or relieving uncontrolled inflammation is critical for the treatment of these diseases. Herein, we report a new strategy for alleviating inflammation by macrophage reprogramming via targeted reactive oxygen species (ROS) scavenging and cyclooxygenase-2 (COX-2) downregulation. As a proof of concept, we synthesize a multifunctional compound named MCI containing a mannose-based macrophage targeting moiety, an indomethacin (IMC)-based segment for inhibiting COX-2, and a caffeic acid (CAF)-based section for ROS clearance. As revealed by a series of in vitro experiments, MCI could significantly attenuate the expression of COX-2 and the level of ROS, leading to M1 to M2 macrophage reprogramming, as evidenced by the reduction and the elevation in the levels of pro-inflammatory M1 markers and anti-inflammatory M2 markers, respectively. Furthermore, in vivo experiments show MCI's promising therapeutic effects on rheumatoid arthritis (RA). Our work illustrates the success of targeted macrophage reprogramming for inflammation alleviation, which sheds light on the development of new anti-inflammatory drugs.

Water-Soluble Chemically Precise Fluorinated Molecular Clusters for Interference-Free Multiplex 19F MRI in Living Mice.

Fluorine-19 magnetic resonance imaging (19F MRI) is gaining widespread interest from the fields of biomolecule detection, cell tracking, and diagnosis, benefiting from its negligible background, deep tissue penetration, and multispectral capacity. However, a wide range of 19F MRI probes are in great demand for the development of multispectral 19F MRI due to the limited number of high-performance 19F MRI probes. Herein, we report a type of water-soluble molecular 19F MRI nanoprobe by conjugating fluorine-containing moieties with a polyhedral oligomeric silsesquioxane (POSS) cluster for multispectral color-coded 19F MRI. These chemically precise fluorinated molecular clusters are of excellent aqueous solubility with relatively high 19F contents and of single 19F resonance frequency with suitable longitudinal and transverse relaxation times for high-performance 19F MRI. We construct three POSS-based molecular nanoprobes with distinct 19F chemical shifts at -71.91, -123.23, and -60.18 ppm and achieve interference-free multispectral color-coded 19F MRI of labeled cells in vitro and in vivo. Moreover, in vivo 19F MRI reveals that these molecular nanoprobes could selectively accumulate in tumors and undergo rapid renal clearance afterward, illustrating their favorable in vivo behavior for biomedical applications. This study provides an efficient strategy to expand the 19F probe libraries for multispectral 19F MRI in biomedical research.

Novel Self-Assembled Multifunctional Nanoprobes for Second-Near-Infrared-Fluorescence-Image-Guided Breast Cancer Surgery and Enhanced Radiotherapy Efficacy.

Breast-conserving surgery (BCS) is the predominant treatment approach for initial breast cancer. However, due to a lack of effective methods evaluating BCS margins, local recurrence caused by positive margins remains an issue. Accordingly, radiation therapy (RT) is a common modality in patients with advanced breast cancer. However, while RT also protects normal tissue and enhances tumor bed doses to improve therapeutic effects, current radiosensitizers cannot meet these urgent clinical needs. To address this, a novel self-assembled multifunctional nanoprobe (NP) gadolinium (Gd)-diethylenetriaminepentaacetic acid-human serum albumin (HSA)@indocyanine green-Bevacizumab (NPs-Bev) is synthesized to improve the efficacy of fluorescence-image-guided BCS and RT. Fluorescence image guidance of the second near infrared NP improves complete resection in tumor-bearing mice and accurately discriminates between benign and malignant mammary tissue in transgenic mice. Moreover, targeting tumors with NPs induces more reactive oxygen species under X-ray radiation therapy, which not only increases RT sensitivity, but also reduces tumor progression in mice. Interestingly, self-assembled NPs-Bev using HSA, the magnetic resonance contrast agent and Bevacizumab-targeting vascular growth factor A, which are clinically safe reagents, are safe in vitro and in vivo. Therefore, the novel self-assembled NPs provide a solid precision therapy platform to treat breast cancer.

Multicolor 19F magnetic resonance imaging: A promising medical technique for in vivo visualization of multiple biological targets.

Driven by the needs of precision medicine, current imaging techniques are under continuous development to offer more accurate and comprehensive information beyond traditional macroscopic anatomical images. Multispectral color-coded (multicolor) 19F magnetic resonance imaging (MRI) is receiving increasing attention owing to its capability for visualizing quantitative and multiplexed molecular information during various biological processes. The chemical design and preparation of 19F probes lie at the core of multicolor 19F MRI since their performance dominates the accomplishment of this technique. Herein, the working principles of multicolor 19F MRI are briefly introduced. Recent progress on multicolor 19F MRI probes for simultaneous in vivo visualization of multiple biological targets is summarized. Finally, current challenges and potential solutions in this fast-developing field are discussed.

Bio-orthogonal Metabolic Fluorine Labeling Enables Deep-Tissue Visualization of Tumor Cells In Vivo by 19F Magnetic Resonance Imaging.

The high resolution, deep penetration, and negligible biological background of 19F magnetic resonance imaging (MRI) makes it a potential means for imaging various biological targets in vivo. However, the limited targeting strategies of current 19F MRI probes significantly restrict their applications for in vivo tracking of low-abundance targets and specific biological processes, which greatly stimulates the investigations on new targeting methods for 19F MRI. Herein, we report a strategy, termed as bio-orthogonal metabolic fluorine labeling, for selective cellular 19F labeling, which permits in vivo imaging of tumor cells with high specificity. This strategy exploits the display of azido groups on the cell surface via selective uptake and metabolic engineering of tetra-acetylated N-azidoacetylmannosamine (Ac4ManAz) by cancer cells and subsequent rapid and specific bio-orthogonal ligation between azido and cyclootynyl groups to incorporate 19F-containing moieties on the surface of cancer cells. We validated the feasibility of this method on the cellular level with A549 and HepG2 cells and further illustrated the application of this method for in vivo deep-tissue visualization of cancer cells with A549 tumor-bearing BALB/c mice using hot spot 19F MRI. Our strategy expands the arsenal for targeted 19F MRI and provides a promising method for imaging biological targets in living subjects with high tissue penetration and low biological background.

19 F Barcoding Enables Multiplex Detection of Biomarkers Associated with Organ Injury and Cancer.

Simultaneous detection of multiple biomarkers in complex environments is critical for the in-depth exploration of different biological processes, which is challenging for many current analytical methods due to various limitations. Herein, we report a strategy of 19 F barcoding which takes the advantages of 19 F's high magnetic resonance (MR) sensitivity, prompt signal response to environmental changes, negligible biological background, quantitative signal output, and multiplex capacity. A set of 19 F-barcoded sensors responding to different biomarkers involved in organ injury and cancer are designed, synthesized, and characterized. With these sensors, we accomplish concurrent assessment of different biomarkers in the samples collected from the mice with drug-induced liver/kidney injury or tumor, illustrating the feasibility of this approach for multiplexed detection of different biomarkers in complex environments during various biological processes.

A dual-responsive doxorubicin-indoximod conjugate for programmed chemoimmunotherapy.

Herein we report a dual-responsive doxorubicin-indoximod conjugate (DOXIND) for programmed chemoimmunotherapy. This conjugate is able to release doxorubicin and indoximod upon exposure to appropriate stimuli for synergistic chemotherapy and immunotherapy, respectively. We demonstrate its promoting effects on immune response and inhibiting effects on tumor growth through a series of in vitro and in vivo experiments.

Photoinduced Superhydrophilicity of Gd-Doped TiO2 Ellipsoidal Nanoparticles Boosts T1 Contrast Enhancement for Magnetic Resonance Imaging.

The unsatisfactory performance of current gadolinium chelate based T1 contrast agents (CAs) for magnetic resonance imaging (MRI) stimulates the search for better alternatives. Herein, we report a new strategy to substantially improve the capacity of nanoparticle-based T1 CAs by exploiting the photoinduced superhydrophilic assistance (PISA) effect. As a proof of concept, we synthesized citrate-coated Gd-doped TiO2 ellipsoidal nanoparticles (GdTi-SC NPs), whose r1 increases significantly upon UV irradiation. The reduced water contact angle and the increased number of surface hydroxyl groups substantiate the existence of the PISA effect, which considerably promotes the efficiency of paramagnetic relaxation enhancement (PRE) and thus the imaging performance of GdTi-SC NPs. In vivo MRI of SD rats with GdTi-SC NPs further demonstrates that GdTi-SC NPs could serve as a high-performance CA for sensitive imaging of blood vessels and accurate diagnosis of vascular lesions, indicating the success of our strategy.

Tandem Chemoimmunotherapy by a Cascade-Responsive Molecular Prodrug.

The limited therapeutic effects of immunotherapy for most types of cancer stimulates the pursuit for efficient methods to improve its response rate. Herein we report the design and synthesis of a cascade-responsive molecular prodrug for tandem chemoimmunotherapy. This molecular prodrug first releases doxorubicin (DOX) in the mildly acidic tumor microenvironment (TME) to induce immunogenic cell death (ICD) of tumor cells. Caspase 3/7 released during tumor cell apoptosis liberates NLG919 from the prodrug, which inhibits the activity of indoleamine 2,3-dioxygenase (IDO) and results in relief of TME immunosuppression. Meanwhile, tumor-associated antigens and immune stimulatory cytokines released during ICD activate the immune response against the tumor, leading to synergistic chemoimmunotherapy. The efficacy of this prodrug is validated by in vitro and in vivo experiments, demonstrating the success of this strategy for cancer treatment.

Activatable Multiplexed 19F Magnetic Resonance Imaging Visualizes Reactive Oxygen and Nitrogen Species in Drug-Induced Acute Kidney Injury.

In vivo levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are critical to many physiological and pathological processes. Because of the distinct differences in their biological generation and effects, simultaneously visualizing both of them could help deepen our insights into the mechanistic details of these processes. However, real-time and deep-tissue imaging and differentiation of ROS- and RNS-related molecular events in living subjects still remain a challenge. Here, we report the development of two activatable 19F magnetic resonance imaging (MRI) molecular probes with different 19F chemical shifts and specific responsive behaviors for simultaneous in vivo detection and deep-tissue imaging of O2•- and ONOO-. These probes are capable of real-time visualization and differentiation of O2•- and ONOO- in living mice with drug-induced acute kidney injury by interference-free multiplexed hot-spot 19F MRI, illustrating the potential of this technique for background-free real-time imaging of diverse biological processes, accurate diagnosis of various diseases in deep tissues, and rapid toxicity evaluation of assorted drugs.

Redox-Activated Contrast-Enhanced T1-Weighted Imaging Visualizes Glutathione-Mediated Biotransformation Dynamics in the Liver.

GSH-mediated liver biotransformation is a crucial physiological process demanding efficient research tools. Here, we report a type of amorphous FexMnyO nanoparticles (AFMO-ZDS NPs) as redox-activated probes for in vivo visualization of the dynamics of GSH-mediated biotransformation in liver with T1-weighted magnetic resonance imaging (MRI). This imaging technique reveals the periodic variations in GSH concentration during the degradation of AFMO-ZDS NPs due to the limited transportation capacity of GSH carriers in the course of GSH efflux from hepatocytes to perisinusoidal space, providing direct imaging evidence for this important carrier-mediated process during GSH-mediated biotransformation. Therefore, this technique offers an effective method for in-depth investigations of GSH-related biological processes in liver under various conditions as well as a feasible means for the real-time assessment of liver functions, which is highly desirable for early diagnosis of liver diseases and prompt a toxicity evaluation of pharmaceuticals.

Arsenite-loaded albumin nanoparticles for targeted synergistic chemo-photothermal therapy of HCC.

Arsenic trioxide (ATO, As2O3), an active ingredient of traditional Chinese medicine, has been approved by the U.S. Food and Drug Administration as an effective therapeutic agent for acute promyelocytic leukemia (APL). However, the application of ATO in treating advanced solid tumors like hepatocellular carcinoma (HCC) is still restricted by limited therapeutic efficacy and insufferable side effects. To solve this problem, we reported a general and facile strategy using human serum albumin (HSA) as a template for synthesizing a series of ATO-based nanoparticles with uniform single-albumin size. Then, we prepared a multifunctional drug delivery system (MDDS) based on MnAs/HSA termed MnAs/ICG/HSA-RGD, and tested its efficacy both in vitro and in vivo. Our results revealed that the photothermal effect of MnAs/ICG/HSA-RGD can not only cause irreversible damage to the tumor but also accelerate the discharge of As and Mn2+ ions, enabling responsive chemotherapy and magnetic resonance imaging. Interestingly, the expression of HSP90, vimentin, and MMP-9 in tumor cells was inhibited during the treatment, resulting in less metastasis and recurrence. Moreover, no apparent side effect has been observed during the treatment. Therefore, MnAs/ICG/HSA-RGD can be considered as a promising option for HCC with excellent therapeutic efficacy and minimum side effects.

A camptothecin prodrug induces mitochondria-mediated apoptosis in cancer cells with cascade activations.

Mitochondria are crucial regulators of the intrinsic pathway of apoptosis. Herein, we report a photosensitizer-conjugated camptothecin (CPT)-based prodrug for combinative chemo-photodynamic treatment of solid tumors with cascade activations. Upon light irradiation, our prodrug can effectively target the mitochondria of cancer cells, generate singlet oxygen to increase the level of reactive oxygen species (ROS) and trigger ROS-responsive release of CPT, which synergistically induce mitochondrial damage and cause the apoptosis of cancer cells, therefore achieving high therapeutic efficacy for solid tumors and minimized adverse effects to normal tissues. Our prodrug holds great promise as a potent and inspiring means for cancer treatment.

Hypoxia-Activated Prodrug Enabling Synchronous Chemotherapy and HIF-1α Downregulation for Tumor Treatment.

The overexpression of HIF-1α in solid tumors due to hypoxia is closely related to drug resistance and consequent treatment failure. Herein, we constructed a hypoxia-activated prodrug named as YC-Dox. This prodrug could be activated under hypoxic conditions and undergo self-immolation to release doxorubicin (Dox) and YC-1 hemisuccinate (YCH-1), which could execute chemotherapy and result in HIF-1α downregulation, respectively. This prodrug is capable of specifically releasing Dox and YCH-1 in response to hypoxia, leading to a substantial synergistic potency and a remarkable cytotoxic selectivity (>8-fold) for hypoxic cancer cells over normoxic healthy cells. The in vivo experiments reveal that this prodrug can selectively aim at hypoxic cancer cells and avoid undesired targeting of normal cells, leading to elevated therapeutic efficacy for tumor treatment and minimized adverse effects on normal tissues.