Red-Light Triggered H-Abstraction Photoinitiators for the Efficient Oxygen-Independent Therapy of Hypoxic Tumors.

The clinical application of photodynamic therapy (PDT) is limited by oxygen-dependence and side effects caused by photosensitizer residues. Photoinitiators based on the H-abstraction reaction can address these challenges because they can generate alkyl radical-killing cells independently of oxygen and undergo rapid bleaching following H-abstraction. Nonetheless, the development of photoinitiators for PDT has been impeded by the absence of effective design strategies. Herein, we have developed aryl-ketone substituted cyanine (ACy-R), the first red-light triggered H-abstraction photoinitiators for hypoxic cancer therapy. These ACy-R molecules inherited the near-infrared absorption of cyanine dye, and aryl-ketone modification imparted H-abstraction capability. Experimental and quantum calculations revealed that modifying the electron-withdrawing groups of the aryl (e.g., ACy-5F) improved the contribution of the O atom to the photon excitation process promoting intersystem crossing and H-abstraction ability. Particularly, ACy-5F rapidly penetrated cells and enriched in the endoplasmic reticulum. Even under severe hypoxia, ACy-5F initiated red-light induced H-abstraction with intracellular biomolecules, inducing necroptosis and ferroptosis. Moreover, ACy-5F was degraded after H-abstraction, thus avoiding the side effects of long-term phototoxicity after therapy. This study not only provides a crucial molecular tool for hypoxic tumors therapy, but also presents a promising strategy for the development of multifunctional photosensitizers and photoinitiators.

Clearly fluorescent delineating ER+ breast tumor incisal edge and identifying tiny metastatic tumor foci at high resolution.

Fluorescence-image guided surgery (FGS) can intraoperatively provide real-time visualization of a tumor incisal edge and high-resolution identification of tumor foci to improve treatment outcomes. In this contribution, we report a fluorescent probe NB-TAM based on intramolecularly folded photoinduced electron transfer (PET), which displayed a prominent turn-on response in the near-infrared (NIR) window upon specific interaction with the estrogen receptor (ER). Significantly, NB-TAM could delineate a clear tumor incisal edge (tumor-to-normal tissue ratio > 5) in a 70-min time window, and was successfully used to guide the facile and precise resection of ER+ breast tumors in mice. To our surprise, NB-TAM was found to be capable of identifying very tiny lung metastatic ER+ breast tumor foci (0.4 × 0.3 mm), and this ultrahigh resolution was essential to effectively promote tumor resection precision and early diagnosis of tiny tumors. These results clearly elucidate the promising application of NB-TAM as a diagnostic agent for intraoperative fluorescence imaging of ER+ breast cancer.

Charge-reversal polymeric nanomodulators for ferroptosis-enhanced photodynamic therapy.

The clinical application of photodynamic therapy (PDT) has some limitations including poor tumor targeting properties, a high reductive tumor microenvironment, and inefficient activation of single cell death machinery. We herein report pH-sensitive polymeric nanomodulators (NBS-PDMC NPs) for ferroptosis-enhanced photodynamic therapy. NBS-PDMC NPs were constructed using a positively charged type-I photosensitizer (NBS) coordinated with a demethylcantharidin (DMC)-decorated block copolymer via electrostatic interactions. NBS-PDMC NPs had a negative surface charge, which ensures their high stability in bloodstream circulation, while exposure to lysosomal acidic environments reverses their surface charge to positive for tumor penetration and the release of DMC and NBS. Under NIR light irradiation, NBS generated ROS to induce cell damage; in the meantime, DMC inhibited the expression of the GPX4 protein in tumor cells and promoted ferroptosis of tumor cells. This polymer design concept provides some novel insights into smart drug delivery and combinational action to amplify the antitumor effect.

Harnessing a simple ratiometric fluorescent probe for albumin recognition and beyond.

A commercially available naphthalene fluorophore serves as a ratiometric indicator for albumin, showcasing its applications in albumin-based supramolecular recognition.

NIR-II Light-Driven Genetically Engineered Exosome Nanocatalysts for Efficient Phototherapy against Glioblastoma.

Glioblastoma (GBM) poses a significant therapeutic challenge due to its invasive nature and limited drug penetration through the blood-brain barrier (BBB). In response, here we present an innovative biomimetic approach involving the development of genetically engineered exosome nanocatalysts (Mn@Bi2Se3@RGE-Exos) for efficient GBM therapy via improving the BBB penetration and enzyme-like catalytic activities. Interestingly, a photothermally activatable multiple enzyme-like reactivity is observed in such a nanosystem. Upon NIR-II light irradiation, Mn@Bi2Se3@RGE-Exos are capable of converting hydrogen peroxide into hydroxyl radicals, oxygen, and superoxide radicals, providing a peroxidase (POD), oxidase (OXD), and catalase (CAT)-like nanocatalytic cascade. This consequently leads to strong oxidative stresses to damage GBM cells. In vitro, in vivo, and proteomic analysis further reveal the potential of Mn@Bi2Se3@RGE-Exos for the disruption of cellular homeostasis, enhancement of immunological response, and the induction of cancer cell ferroptosis, showcasing a great promise in anticancer efficacy against GBM with a favorable biosafety profile. Overall, the success of this study provides a feasible strategy for future design and clinical study of stimuli-responsive nanocatalytic medicine, especially in the context of challenging brain cancers like GBM.

Activating Iterative Revolutions of the Cancer-Immunity Cycle in Hypoxic Tumors with a Smart Nano-Regulator.

The activation of sequential events in the cancer-immunity cycle (CIC) is crucial for achieving effective antitumor immunity. However, formidable challenges, such as innate and adaptive immune resistance, along with the off-target adverse effects of nonselective immunomodulators, persist. In this study, a tumor-selective nano-regulator named PNBJQ has been presented, focusing on targeting two nonredundant immune nodes: inducing immunogenic cancer cell death and abrogating immune resistance to fully activate endogenous tumor immunity. PNBJQ is obtained by encapsulating the immunomodulating agent JQ1 within a self-assembling system formed by linking a Type-I photosensitizer to polyethylene glycol through a hypoxia-sensitive azo bond. Benefiting from the Type-I photosensitive mechanism, PNBJQ triggers the immunogenic cell death of hypoxic tumors under near-infrared (NIR) light irradiation. This process resolves innate immune resistance by stimulating sufficient cytotoxic T-lymphocytes. Simultaneously, PNBJQ smartly responds to the hypoxic tumor microenvironment for precise drug delivery, adeptly addressing adaptive immune resistance by using JQ1 to downregulate programmed death ligand 1 (PD-L1) and sustaining the response of cytotoxic T lymphocytes. The activatable synergic photoimmunotherapy promotes an immune-promoting tumor microenvironment by activating an iterative revolution of the CIC, which remarkably eradicates established hypoxic tumors and suppresses distal lesions under low light dose irradiation.

Ratiometric determination of etomidate based on an albumin-based indicator displacement assay (IDA).

The first fluorescent sensor based on the indicator displacement assay (IDA) for on-site determination of etomidate.

Light-Driven Mitochondrion-to-Nucleus DNA Cascade Fluorescence Imaging and Enhanced Cancer Cell Photoablation.

Nucleic acids are mainly found in the mitochondria and nuclei of cells. Detecting nucleic acids in the mitochondrion and nucleus in cascade mode is crucial for understanding diverse biological processes. This study introduces a novel nucleic acid-based fluorescent styrene dye (SPP) that exhibits light-driven cascade migration from the mitochondrion to the nucleus. By introducing N-arylpyridine on one side of the styrene dye skeleton and a bis(2-ethylsulfanyl-ethy)-amino unit on the other side, we found that SPP exhibits excellent DNA specificity (16-fold, FDNA/Ffree) and a stronger binding force to nuclear DNA (-5.09 kcal/mol) than to mitochondrial DNA (-2.59 kcal/mol). SPP initially accumulates in the mitochondrion and then migrates to the nucleus within 10 s under light irradiation. By tracking the damage to nucleic acids in apoptotic cells, SPP allows the successful visualization of the differences between apoptosis and ferroptosis. Finally, a triphenylamine segment with photodynamic effects was incorporated into SPP to form a photosensitizer (MTPA-SPP), which targets the mitochondria for photosensitization and then migrates to the nucleus under light irradiation for enhanced photodynamic cancer cell treatment. This innovative nucleic acid-based fluorescent molecule with light-triggered mitochondrion-to-nucleus migration ability provides a feasible approach for the in situ identification of nucleic acids, monitoring of subcellular physiological events, and efficient photodynamic therapy.

Gram-negative bacteria recognition and photodynamic elimination by Zn-DPA based sensitizers.

The abuse and overuse of antibiotics let drug-resistant bacteria emerges. Antibacterial photodynamic therapy (APDT) has shown outstanding merits to eliminate the drug-resistant bacteria via cytotoxic reactive oxygen species produced by irradiating photosensitizer. However, most of photosensitizers are not effective for Gram-negative bacteria elimination. Herein conjugates of NBS, a photosensitizer, linked with one (NBS-DPA-Zn) or two (NBS-2DPA-Zn) equivalents of zinc-dipicolylamine (Zn-DPA) have been designed to achieve the functional recognition of different bacteria. Due to the cationic character of NBS and metal transfer channel effect of Zn-DPA, NBS-DPA-Zn exhibited the first regent to distinguish P. aeruginosa from other Gram-negative bacteria. Whereas NBS-2DPA-Zn showed broad-spectrum antibacterial effect because the two arm of double Zn-DPA enhanced interactions with anionic membranes of bacteria, led the bacteria aggregation and thus provided the efficacy of APDT to bacteria and corresponding biofilm. In combination with a hydrogel of Pluronic, NBS-2DPA-Zn@gel shows promising clinical application in mixed bacterial diabetic mouse model infection. This might propose a new method that can realize functional identification and elimination of bacteria through intelligent regulation of Zn-DPA, and shows excellent potential for antibacterial application.

Dysregulated Ribosome Biogenesis Is a Targetable Vulnerability in Triple-Negative Breast Cancer: MRPS27 as a Key Mediator of the Stemness-inhibitory Effect of Lovastatin.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with limited effective therapeutic options readily available. We have previously demonstrated that lovastatin, an FDA-approved lipid-lowering drug, selectively inhibits the stemness properties of TNBC. However, the intracellular targets of lovastatin in TNBC remain largely unknown. Here, we unexpectedly uncovered ribosome biogenesis as the predominant pathway targeted by lovastatin in TNBC. Lovastatin induced the translocation of ribosome biogenesis-related proteins including nucleophosmin (NPM), nucleolar and coiled-body phosphoprotein 1 (NOLC1), and the ribosomal protein RPL3. Lovastatin also suppressed the transcript levels of rRNAs and increased the nuclear protein level and transcriptional activity of p53, a master mediator of nucleolar stress. A prognostic model generated from 10 ribosome biogenesis-related genes showed outstanding performance in predicting the survival of TNBC patients. Mitochondrial ribosomal protein S27 (MRPS27), the top-ranked risky model gene, was highly expressed and correlated with tumor stage and lymph node involvement in TNBC. Mechanistically, MRPS27 knockdown inhibited the stemness properties and the malignant phenotypes of TNBC. Overexpression of MRPS27 attenuated the stemness-inhibitory effect of lovastatin in TNBC cells. Our findings reveal that dysregulated ribosome biogenesis is a targetable vulnerability and targeting MRPS27 could be a novel therapeutic strategy for TNBC patients.

Lutetium texaphyrin: A photocatalyst that triggers pyroptosis via biomolecular photoredox catalysis.

Photon-controlled pyroptosis activation (PhotoPyro) is a promising technique for cancer immunotherapy due to its noninvasive nature, precise control, and ease of operation. Here, we report that biomolecular photoredox catalysis in cells might be an important mechanism underlying PhotoPyro. Our findings reveal that the photocatalyst lutetium texaphyrin (MLu) facilitates rapid and direct photoredox oxidation of nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and various amino acids, thereby triggering pyroptosis through the caspase 3/GSDME pathway. This mechanism is distinct from the well-established role of MLu as a photodynamic therapy sensitizer in cells. Two analogs of MLu, bearing different coordinated central metal cations, were also explored as controls. The first control, gadolinium texaphyrin (MGd), is a weak photocatalyst but generates reactive oxygen species (ROS) efficiently. The second control, manganese texaphyrin (MMn), is ineffective as both a photocatalyst and a ROS generator. Neither MGd nor MMn was found to trigger pyroptosis under the conditions where MLu was active. Even in the presence of a ROS scavenger, treating MDA-MB-231 cells with MLu at concentrations as low as 50 nM still allows for pyroptosis photo-activation. The present findings highlight how biomolecular photoredox catalysis could contribute to pyroptosis activation by mechanisms largely independent of ROS.

Wavelength-Tuneable Fluorescent Carbon Dots for Nucleic Acid Imaging.

Nucleic acid is one of the most important substances in organisms, and its dynamic changes are closely related to physiological processes. Nucleic acid labeling is conducive to providing important information for the early diagnosis and treatment of pathophysiological processes. Here, we utilized the transfer mechanism between carbon sources and CDs to synthesize wavelength-adjustable N-CDs for the nucleic acid image. Along with the increased graphite nitrogen (from 10.6 to 30.1%) gradually by the precise design of the nitrogen structure in carbon sources (e.g., primary amines, secondary amines, tertiary amines, and liking graphite-nitrogen), the energy gap of CDs reduced, resulting in adjustable wavelength from visible to near-infrared range (from 461 nm/527 nm to 650 nm/676 nm). Furthermore, N-CDs exhibited a selective affinity for nucleic acids, especially RNA. Therefore, N-CDs support an efficient platform for real-time tracking of RNA dynamic changes in cells.

Theranostic Fluorescent Probes.

The ability to gain spatiotemporal information, and in some cases achieve spatiotemporal control, in the context of drug delivery makes theranostic fluorescent probes an attractive and intensely investigated research topic. This interest is reflected in the steep rise in publications on the topic that have appeared over the past decade. Theranostic fluorescent probes, in their various incarnations, generally comprise a fluorophore linked to a masked drug, in which the drug is released as the result of certain stimuli, with both intrinsic and extrinsic stimuli being reported. This release is then signaled by the emergence of a fluorescent signal. Importantly, the use of appropriate fluorophores has enabled not only this emerging fluorescence as a spatiotemporal marker for drug delivery but also has provided modalities useful in photodynamic, photothermal, and sonodynamic therapeutic applications. In this review we highlight recent work on theranostic fluorescent probes with a particular focus on probes that are activated in tumor microenvironments. We also summarize efforts to develop probes for other applications, such as neurodegenerative diseases and antibacterials. This review celebrates the diversity of designs reported to date, from discrete small-molecule systems to nanomaterials. Our aim is to provide insights into the potential clinical impact of this still-emerging research direction.

A non-peptide-based fluorescent probe capable of sensitively visualizing asparagine endopeptidase.

The non-peptide-based fluorescent probe QMC11 is capable of specifically targeting asparagine endopeptidase (AEP) and imaging cellular endogenous AEP. The motion of the probe can be restricted by AEP to activate fluorescence while keeping a low background signal.

Spatiotemporal Controllable Sono-Nanovaccines Driven by Free-Field Based Whole-Body Ultrasound for Personalized Cancer Therapy.

Therapeutic cancer vaccines fail to produce satisfactory outcomes against solid tumors since vaccine-induced anti-tumor immunity is significantly hampered by immunosuppression. Generating an in situ cancer vaccine targeting immunological cold tumor microenvironment (TME) appears attractive. Here, a type of free-field based whole-body ultrasound (US)-driven nanovaccines are constructed, named G5-CHC-R, by conjugating the sonosensitizer, Chenghai chlorin (CHC) and the immunomodulator, resiquimod (R848) on top of a super small-sized dendrimeric nanoscaffold. Once entering tumors, R848 can be cleaved from a hypoxia-sensitive linker, thus modifying the TME via converting macrophage phenotypes. The animals bearing orthotopic pancreatic cancer with intestinal metastasis and breast cancer with lung metastasis are treated with G5-CHC-R under a free-field based whole-body US system. Benefit from the deep penetration capacity and highly spatiotemporal selectiveness, G5-CHC-R triggered by US represented a superior alternative for noninvasive irradiation of deep-seated tumors and magnification of local immune responses via driving mass release of tumor antigens and "cold-warm-hot" three-state transformation of TME. In addition to irradiating primary tumors, a robust adaptive anti-tumor immunity is potentiated, leading to successful induction of systemic tumor suppression. The sono-nanovaccines with good biocompatibility posed wide applicability to a broad spectrum of tumors, revealing immeasurable potential for translational research in oncology.

A PROTAC Augmenter for Photo-Driven Pyroptosis in Breast Cancer.

Proteolysis targeting chimera (PROTAC) has recently emerged as a promising strategy for inducing post-translational knockdown of target proteins in disease treatment. The degradation of bromodomain-containing protein 4 (BRD4), an essential nuclear protein for gene transcription, induced by PROTAC is proposed as an epigenetic approach to treat breast cancer. However, the poor membrane permeability and indiscriminate distribution of PROTAC in vivo results in low bioavailability, limiting its development and application. Herein, a nano "targeting chimera" (abbreviated as L@NBMZ) consisting of BRD4-PROTAC combined with a photosensitizer, to serve as the first augmenter for photo-driven pyroptosis in breast cancer, is developed. With excellent BRD4 degradation ability, high biosafety, and biocompatibility, L@NBMZ blocks gene transcription by degrading BRD4 through proteasomes in vivo, and surprisingly, induces the cleavage of caspase-3. This type of caspase-3 cleavage is synergistically amplified by light irradiation in the presence of photosensitizers, leading to efficient photo-driven pyroptosis. Both in vitro and in vivo outcomes demonstrate the remarkable anti-cancer efficacy of this augmenter, which significantly inhibits the lung metastasis of breast cancer in vivo. Thus, the photo-PROTAC "targeting chimera" augmenter construction strategy may pave a new way for expanding PROTAC applications within anti-cancer paradigms.

An ER-targeted, Viscosity-sensitive Hemicyanine Dye for the Diagnosis of Nonalcoholic Fatty Liver and Photodynamic Cancer Therapy by Activating Pyroptosis Pathway.

The concept of molecular design, integrating diagnostic and therapeutic functions, aligns with the general trend of modern medical advancement. Herein, we rationally designed the smart molecule ER-ZS for endoplasmic reticulum (ER)-targeted diagnosis and treatment in cell and animal models by combining hemicyanine dyes with ER-targeted functional groups (p-toluenesulfonamide). Owing to its ability to target the ER with a highly specific response to viscosity, ER-ZS demonstrated substantial fluorescence turn-on only after binding to the ER, independent of other physiological environments. In addition, ER-ZS, being a small molecule, allows for the diagnosis of nonalcoholic fatty liver disease (NAFLD) via liver imaging based on high ER stress. Importantly, ER-ZS is a type I photosensitizer, producing O2 ⋅- and ⋅OH under light irradiation. Thus, after irradiating for a certain period, the photodynamic therapy inflicted severe oxidative damage to the ER of tumor cells in hypoxic (2 % O2 ) conditions and activated the unique pyroptosis pathway, demonstrating excellent antitumor capacity in xenograft tumor models. Hence, the proposed strategy will likely shed new light on integrating molecular optics for NAFLD diagnosis and cancer therapy.

Near-Infrared Fluorescence Probe for Monoamine Oxidase A with a Large Stokes Shift for Intraoperative Navigation.

Monoamine oxidase A (MAO-A) is a dimeric flavoprotein that is found in the mitochondrial membrane. Currently, there is a lack of near-infrared fluorescent probes (NIR-FPs) with good specificity and high sensitivity for detecting MAO-A, making it difficult to accurately recognize and image cells in vitro and in vivo. In this study, the NIR-FP DDM-NH2 was designed and synthesized in order to detect MAO-A specifically in live biological systems. The probe comprised two functional components: dicyanoisophosphone as an NIR dye precursor and alanine as a recognition moiety. After identifying MAO-A, the probe exhibited an NIR emission peak at 770 nm with a significant Stokes shift (180 nm), 11-fold response factor, low detection limit of 99.7 nM, and considerably higher affinity toward MAO-A than that toward MAO-B, indicating high sensitivity. In addition, DDM-NH2 was effective when applied to the image-based assessment of MAO-A activity in HeLa cells, zebrafish, and tumor-bearing mice, demonstrating great potential for visualization-based research and MAO-A application in vivo.

Lipid Droplet Targeting Type I Photosensitizer for Ferroptosis via Lipid Peroxidation Accumulation.

As an iron-dependent lipid peroxidation (LPO) mediated cell death pathway, ferroptosis offers promises for anti-tumor treatment. Photodynamic therapy (PDT) is an ideal way to generate reactive oxygen species (ROS) for LPO. However, the conventional PDT normally functions on subcellular organelles, such as endoplasmic reticulum, mitochondria, and lysosome, causing rapid cell death before triggering ferroptosis. Herein, the first lipid droplet (Ld)-targeting type I photosensitizer (PS) with enhanced superoxide anion (O2 -· ) production, termed MNBS, is reported. The newly designed PS selectively localizes at Ld in cells, and causes cellular LPO accumulation by generating sufficient O2 -· upon irradiation, and subsequently induces ferroptosis mediated chronical PDT, achieving high-efficient anti-tumor PDT in hypoxia and normoxia. Theoretical calculations and comprehensive characterizations indicate that the Ld targeting property and enhanced O2 -· generation of MNBS originate from the elevated H-aggregation tendency owing to dispersed molecular electrostatic distribution. Further in vivo studies using MNBS-encapsulated liposomes demonstrate the excellent anti-cancer efficacy as well as anti-metastatic activity. This study offers a paradigm of H-aggregation reinforced type I PS to achieve ferroptosis-mediated PDT.

Aryl-Modified Pentamethyl Cyanine Dyes at the C2' Position: A Tunable Platform for Activatable Photosensitizers.

Pentamethyl cyanine dyes are promising fluorophores for fluorescence sensing and imaging. However, advanced biomedical applications require enhanced control of their excited-state properties. Herein, a synthetic approach for attaching aryl substituents at the C2' position of the thio-pentamethine cyanine (TCy5) dye structure is reported for the first time. C2'-aryl substitution enables the regulation of both the twisted intramolecular charge transfer (TICT) and photoinduced electron transfer (PET) mechanisms to be regulated in the excited state. Modulation of these mechanisms allows the design of a nitroreductase-activatable TCy5 fluorophore for hypoxic tumor photodynamic therapy and fluorescence imaging. These C2'-aryl TCy5 dyes provide a tunable platform for engineering cyanine dyes tailored to sophisticated biological applications, such as photodynamic therapy.