Overcoming the Limits of Hypoxia in Photodynamic Therapy: A Carbonic Anhydrase IX-Targeted Approach

Discovery of Diaryl Piperidone-Sulfonamide as a Novel Dual-Target Inhibitor of STAT3/CAIX Inducing Ferroptosis in Triple-Negative Breast Cancer Cells

A series of diaryl piperidone-sulfonamide derivatives were designed as dual inhibitors of STAT3/CAIX and ferroptosis inducers for triple-negative breast cancer (TNBC). The representative compound 7m demonstrated significant antitumor effects against the MDA-MB-231 cell line both in vitro and in vivo. Mechanistically, 7m inhibits the phosphorylation of STAT3, with a binding affinity determined by surface plasmon resonance (SPR) analysis (KD = 60.03 ± 8.13 μM). Additionally, 7m exhibits potent inhibitory activity against CA IX (IC50 = 80.45 ± 39.7 nM) and shows enhanced antitumor activity under hypoxic conditions compared to normoxic conditions. Molecular docking studies suggest a rational binding mode between 7m and the SH2 domain of STAT3, as well as with the CA IX protein. Furthermore, 7m increases the levels of reactive oxygen species (ROS) and lipid peroxides in MDA-MB-231 cells, thereby inducing ferroptosis. These findings provide a novel therapeutic strategy for the treatment of TNBC.

Small molecular fluorescent probes featuring protein-assisted functional amplification for improved biosensing and cancer therapeutics

In recent years, small molecular fluorescent probes have significantly advanced biosensing and cancer therapy, enabling applications such as target detection, cellular imaging, fluorescence-guided surgery, and phototherapy. However, conventional small molecular probes face limitations, including low biocompatibility, poor stability, and weak signal intensity. Protein-coordinated fluorescent probes have emerged as a promising solution, leveraging protein-assisted functional amplification to address these challenges. Mechanisms such as environmental shielding, conformational restriction, charge stabilization, and increased local concentration collectively enhance fluorescence emission and phototherapeutic efficacy. This article reviews recent progress (primarily within the last five years) in protein-coordinated fluorescent probes for biosensing and cancer therapy. It begins with a systematic summary of the interaction strategies between proteins and fluorescent probes and details key mechanisms behind protein-assisted functional amplification. Subsequently, the applications of these probes in biosensing and cancer therapy are comprehensively concluded. Finally, current challenges and future prospects are discussed in depth. This review aims to refine design strategies for protein-coordinated fluorescent probes and inspire innovative approaches in biosensing and cancer therapy.

Dyad System of BOAHY-BODIPY Conjugates as Novel Photoswitchable Photosensitizers for Photodynamic Therapy

Photodynamic therapy (PDT) offers minimally invasive and repeatable cancer treatment options. Despite advancements in photosensitizer (PS) design, the optical control of PS activation remains unexplored. Here, we present the first photoswitchable PS based on a BOAHY-BODIPY dyad system. Inspired by BODIPY multimer structures and BOAHY's photoisomerization properties, we designed mono-(4 series) and bis-BOAHY-BODIPY (5 series) conjugates. These dyads primarily generate reactive oxygen species via a type-I process under white light. Notably, the 4 series compounds demonstrated effective photocytotoxicity and photoswitching properties in vitro. Building on these, we iodinated the monoconjugates to develop the highly efficient photoswitching PS, 6b, which exhibited enhanced intersystem crossing and type-II reactive oxygen species generation due to a reduced singlet-triplet energy gap. As the first demonstration of photoswitchable PDT agents, this strategy introduces a new approach with significant potential for selective cancer treatment and clinical applications.

Mechanosensitive Conjugated Oligoelectrolytes for Visualizing Temporal Changes in Live Cells

Membrane-intercalating conjugated oligoelectrolytes (COEs) are lipid-bilayer-spanning molecules that serve as fluorescent dyes for bioimaging. However, COE emission has thus far only been capable of visualizing dye location and their preferential accumulation in different membrane-bound intracellular compartments. Herein, we report the first example of environmentally sensitive COEs for visualizing temporal changes in live cells, providing information on the physical properties of intracellular lipid bilayer membranes. The new COE-BY series is designed around a BODIPY central unit with a membrane-spanning topology and six cationic pendant groups ensuring solubility in aqueous media. These reporters feature high two-photon absorption cross section, NIR-II excitation capabilities under multiphoton excitation, and high dye brightness; all highly desirable photophysical features for bioimaging. The emission lifetime of the probes was sensitive to changes to both the lipid composition of model vesicle systems and membrane tension within cells, induced by either mechanical or osmotic stress. Using two-photon fluorescence lifetime imaging microscopy, it is possible to use the most efficient emitter, namely, COE-BYPhOC4, to image changes in the mechanical properties of intracellular membranes. We show that these COEs remain stably vesicle-bound within the endolysosomal pathway over extended periods, allowing for long-term monitoring of the associated biophysical changes of these vesicles over time.

Self-healable and pH-responsive spermidine/ferrous ion complexed hydrogel Co-loaded with CA inhibitor and glucose oxidase for combined cancer immunotherapy through triple ferroptosis mechanism

Tumor microenvironment governs various therapeutic tolerability of cancer such as ferroptosis and immunotherapy through rewiring tumor metabolic reprogramming like Warburg metabolism. Highly expressed carbonic anhydrases (CA) in tumor that maintaining the delicate metabolic homeostasis is thus the most potential target to be modulated to resolve the therapeutic tolerability. Hence, in this article, a self-healable and pH-responsive spermidine/ferrous ion hydrogel loaded with CA inhibitor (acetazolamide, ACZ) and glucose oxidase (ACZ/GOx@SPM-HA Gel) was fabricated through the Schiff-base reaction between spermidine-dextran and oxidized hyaluronic acid, along with ferrous coordination. Investigation on cancer cell lines (MOC-1) demonstrated ACZ/GOx@SPM-HA Gel may induce cellular oxidative stress and mitochondrial dysfunction through disrupting the cellular homeostasis. Moreover, with the facilitation of autophagy induced by spermidine, ACZ/GOx@SPM-HA Gel may trigger a positive feedback loop to maximally amplify cellular ferroptosis and promote DAMPs release. The anti-tumor evaluation on xenograft mice models furtherly proved the local injection of such hydrogel formulation could efficiently inhibit the tumor growth and distinctively promote the immunogenicity of tumor bed to provide a more favorable environment for immunotherapy. Overall, ACZ/GOx@SPM-HA Gel, with such feasible physiochemical properties and great biocompatibility, holds great potential in treating solid tumors with acidosis-mediated immunotherapy tolerance.

Near-infrared light-activatable iridium(iii) complexes for synergistic photodynamic and photochemotherapy

Near-infrared (NIR) light-activatable photosensitizers (PSs) have garnered tremendous interest as PSs for photodynamic therapy (PDT) due to the deeper tissue penetration ability and lower toxicity of NIR radiation. However, the low reactive oxygen species (ROS) production, poor tumor accumulation, and residual toxicity of these PSs pose major challenges for further development in this regime. In this regard, we have meticulously designed and synthesized two novel mitochondria-targeting iridium(iii)-dithiocarbamate-cyanine complexes, Ir1@hcy and Ir2@hcy. In particular, Ir2@hcy exhibited both type I and type II PDT with excellent singlet oxygen (1O2) and hydroxyl radical (˙OH) generation ability under 637 nm/808 nm irradiation, even at an ultra-low power intensity (2 mW cm-2). Under higher-power irradiation (100 mW cm-2), the reactive oxygen species (ROS) production by Ir2@hcy was augmented. The elevated levels of ROS caused the disintegration of Ir2@hcy to produce cytotoxic oxindole scaffolds through the dioxetane mechanism. The synergistic production of ROS and cytotoxic species effectively induced mitochondria-mediated cancer cell death in both in vitro and 3D tumor spheroid models, offering a new avenue to develop combinational phototherapy (PDT + PACT) for cancer treatment with spatio-temporal precision.

Hyperbaric Oxygen Regulates Tumor pH to Boost Copper‐Doped Hydroxyethyl Starch Conjugate Nanoparticles Against Cancer Stem Cells

An extracellular acidic environment and an intracellular mildly alkaline environment induced by carbonic anhydrase 9 (CA9) play a critical role in self‐renewal, invasion, migration, and drug resistance of cancer stem cells (CSCs) within hypoxic solid tumors. Here, we report an antitumor strategy leveraging hyperbaric oxygen therapy (HBO) to regulate tumor pH and boost hydroxyethyl starch‐doxorubicin‐copper nanoparticles (HHD‐Cu NPs) against CSCs. HBO overcomes tumor hypoxia, downregulates pH‐regulatory proteins such as CA9, and leads to intracellular accumulation of acidic metabolites. As a result, HBO promotes intracellular acidification of both tumor cells and CSCs, triggering efficient doxorubicin release and the potent copper‐mediated chemical dynamic effect of subsequently administered dual‐acid‐responsive HHD‐Cu NPs. The combination of HBO with HHD‐Cu NPs not only eliminates tumor cells but also inhibits CSCs, altogether leading to potent tumor inhibition. This study explores a new function of clinical‐widely used HBO and establishes a novel combination therapy for treating CSCs abundant hypoxic solid tumors.

The Combination of Active-Targeted Photodynamic Therapy and Photoactivated Chemotherapy for Enhanced Cancer Treatment

Scientists have been actively investigating novel therapies that can effectively eradicate cancer cells with negligible side effects in normal tissues when used alone or in a combinatorial approach. Photodynamic therapy has emerged as a promising non-invasive therapy that integrates photosensitizer, oxygen, and a specific wavelength of light for the treatment of cancer. Despite encouraging outcomes yielded by PDT, conventional PSs are faced with longstanding challenges such as poor water solubility, a short half-life, and off-target toxicity. Development of nanotherapeutics has shown great potential in overcoming this issue. The tumor microenvironment is inherently hypoxic, and this promotes tumor resistance to PDT, as it is oxygen-dependent. Photoactivated chemotherapy, an oxygen-independent light-based therapy, utilizes chemotherapeutic regimens that remain inert until exposed to light, allowing target-specific activation while minimizing off-target toxicity. Integration of these techniques can improve selectivity and yield synergistic cytotoxic effects that could improve cancer treatment.

A Redox-Triggered Polymeric Nanoparticle for Disrupting Redox Homeostasis and Enhanced Ferroptosis

Cancer cells possess an efficient redox system, enabling them to withstand oxidative damage induced by treatments, especially in hypoxia areas and ferroptosis can disrupt redox homeostasis in cancer cell. Herein, GSH-sensitive nanoparticles are constructed that induce ferroptosis by long-lasting GSH depletion and enhanced PDT. Carbonic anhydrase IX inhibitor, protoporphyrin IX (Por) complexed with Fe and epirubicin (EPI) are grafted to hyaluronic acid (HA) via disulfide bonds to obtain HSPFE and loaded xCT inhibitor SAS for fabricating SAS@HSPFE which is actively targeted to deep hypoxic tumor cells, and explosively releasing EPI, Por-Fe complex and SAS due to at high GSH concentration. Specifically, SAS inhibited the GSH biosynthesis, and the generation of ROS by Por and the involvement of Fe2+ in the Fenton reaction jointly facilitates oxidative stress. Besides, Fe2+ reacted with excess H2O2 to produce O2, which continuously fuels PDT. GPX4 and SLC7A11 related to antioxidant defense are down-regulated, while ACSL4 and TFRC promoting lipid peroxidation and ROS accumulation are up-regulated, which enhanced ferroptosis by amplifying oxidative stress and suppressing antioxidant defense. SAS@HSPFE NPs revealed highly efficient antitumor effect in vivo study. This study provides a novel approach to cancer treatment by targeting redox imbalance.

A review on dendrimer-based nanoconjugates and their intracellular trafficking in cancer photodynamic therapy

Nanotechnology-based cancer treatment has received considerable attention, and these treatments generally use drug-loaded nanoparticles (NPs) to target and destroy cancer cells. Nanotechnology combined with photodynamic therapy (PDT) has demonstrated positive outcomes in cancer therapy. Combining nanotechnology and PDT is effective in targeting metastatic cancer cells. Nanotechnology can also increase the effectiveness of PDT by targeting cells at a molecular level. Dendrimer-based nanoconjugates (DBNs) are highly stable and biocompatible, making them suitable for drug delivery applications. Moreover, the hyperbranched structures in DBNs have the capacity to load hydrophobic compounds, such as photosensitizers (PSs) and chemotherapy drugs, and deliver them efficiently to tumour cells. This review primarily focuses on DBNs and their potential applications in cancer treatment. We discuss the chemical design, mechanism of action, and targeting efficiency of DBNs in tumour metastasis, intracellular trafficking in cancer treatment, and DBNs' biocompatibility, biodegradability and clearance properties. Overall, this study will provide the most recent insights into the application of DBNs and PDT in cancer therapy.

Organelle-Specific Smart Supramolecular Materials for Bioimaging and Theranostics Application

In cellular environments, certain synthetic molecules can form nanostructures via self-assembly, impacting molecular imaging, and biomedical applications. Control over the formation of these self-assembled nanostructures in subcellular organelle is challenging. By the action of stimuli, either present in the cellular environment or applied externally, in situ generation of molecular precursors can lead to accumulation and supramolecular nanostructure formation, resulting in efficient bioimaging. Here, we summarize smart fluorophore-based ordered nanostructure preparation at specific organelles for efficient bioimaging and therapeutic application towards cancer theranostics. We also present challenges and an outlook regarding intercellular self-assembly for theranostics application. Altogether, smart nanostructured materials with fluorescence read-outs at specific subcellular compartments would be beneficial in synthetic biology and precision therapeutics.

Recent progress of porphyrin metal-organic frameworks for combined photodynamic therapy and hypoxia-activated chemotherapy

Nanoscale metal-organic frameworks integrated with porphyrins (Por-nMOFs) have emerged as efficient nanoplatforms for photodynamic therapy (PDT), which relies on the conversion of molecular oxygen into cytotoxic singlet oxygen. However, the hypoxic microenvironment within tumors significantly limits the efficacy of PDT. To address this challenge, researchers have explored various strategies to either alter or exploit the hypoxic conditions in tumors. One such strategy involves leveraging the porous structure of Por-nMOFs to load hypoxia-activated prodrugs (HAPs) like tirapazamine (TPZ), thereby utilizing the tumor's intrinsic hypoxic environment to trigger a chemotherapeutic effect that synergizes with PDT. Advances in nanoscience have enabled the development of porphyrin-based nMOFs capable of simultaneously loading both porphyrin photosensitizers and TPZ, ensuring effective release within cancer cells under high-phosphate conditions. The subsequent activation of co-loaded TPZ, by the tumor's own hypoxic microenvironment, and that created during PDT, facilitates a combined PDT and chemotherapy approach. This method not only enhances the suppression of cancer cell proliferation but also improves control over tumor metastasis while mitigating the negative impact of hypoxia on singular Por-nMOFs in PDT. This review summarizes recent advances in Por-nMOFs research, focusing on the design strategies for enhancing water dispersibility, circulatory stability, and targeting specificity through post-synthetic modifications. Additionally, this review highlights the bioapplication of Por-nMOFs by integrating TPZ chemotherapy and other therapeutic modalities to combat hypoxic and metastatic malignancies. We anticipate that this review will inspire further research into Por-nMOFs and advance their application in biomedicine.

Oxygen Concentration Effect in Photosensitized Generation of 1O2 from Normoxia to Hypoxia

Photodynamic therapy (PDT) has gained widespread acceptance as a clinical cancer treatment modality and has been attracting intensive attention on developing novel PDT strategies. However, the hypoxic environment in tumors is considered as a significant challenge for efficient type II PDT, based on the inference of the highly oxygen-concentration-related 1O2 generation. Contrary to this conventional understanding, our research demonstrates oxygen concentration independence in the photosensitized generation of 1O2, as evidenced through steady-state and transient spectroscopy for chlorin e6 and methylene blue from normoxic to hypoxic conditions. We propose an oxygen-concentration-independent kinetic model, suggesting that efficient 1O2 generation can take place as long as the triplet-state lifetime ratio of the photosensitizer (τh/τn) is in a similar range to pO2n/pO2h. Our findings provide insights into PDT mechanisms and indicate that the oxygen concentration reduction concerns may not be critical for effective PDT in hypoxic tumor environments.

Albumin-based co-loaded sonosensitizer and STING agonist nanodelivery system for enhanced sonodynamic and immune combination antitumor therapy

STING agonists can activate natural and adaptive immune responses, and are expected to become a new type of immunotherapy drug for tumor therapy. However, how to target deliver STING agonists to tumor tissues is a key factor affecting the efficacy of tumor treatment. Sonodynamic therapy (SDT) has become a research hotspot in the field of cancer treatment due to its non-invasive, spatiotemporally controllable, and high tissue penetration capabilities. Therefore, how to choose the appropriate drug delivery strategy, build a suitable drug delivery system to co-deliver photosensitizers and STING agonists, is a challenge faced in the tumor treatment. In this study, we developed an albumin-based nanodelivery system named FA-ICG&MnOx@HSA that co-loaded the sonosensitizers indocyanine green (ICG) and manganese oxide (MnOx). This approach achieved folate receptor-targeting mediated tumor delivery and tumor microenvironment (TME)-responsive release facilitated by high levels of glutathione (GSH) and hydrogen peroxide (H2O2), which catalyze oxygen generation to potentiate SDT efficacy in killing tumors and inducing immunogenic cell death (ICD). Simultaneously, the released Mn2+ acted as a STING agonist promoting dendritic cell maturation, IFN-β production, and proliferation of T cells. Ultimately, this albumin based co-loaded sonosensitizer and STING agonist demonstrated promising potential for advancing tumor treatment.

Light-Enhanced Tandem-Responsive Nano Delivery Platform for Amplified Anti-tumor Efficiency

Designing nanomedicines with low toxicity, high targeting, excellent therapeutic effects, and precise release is always the major challenges in clinical cancer treatment. Here, we report a light-enhanced tandem-responsive nano delivery platform COF-B@X-03 for amplified anti-tumor efficiency. Biotin-loaded COF-B@X-03 could precisely target tumor cells, and the azo and hydrazone bonds in it would be depolymerized by the overexpressed azoreductase and acidic microenvironment in hypoxic tumors. In vitro experimental results indicate mitochondrial and endoplasmic reticulum stress caused by COF-B@X-03 under light is the direct cause of tumor cell death. In vivo experimental data prove COF-B@X-03 achieves low oxygen dependent phototherapy, and the maintenance of intratumoral hypoxia provides the possibility for the continuous degradation of COF-B@X-03 to generate more reactive oxygen species for tumor photodynamic therapy by released X-03. In the end, COF-B@X-03 phototherapy group achieves higher tumor inhibition rate than X-03 phototherapy group, which is 81.37 %. Meanwhile, COF-B@X-03 significantly eliminates the risk of tumor metastasis. In summary, the construction of this tandem-responsive nano delivery platform provides a new direction for achieving efficient removal of solid tumors in clinical practice.

Synthesis and Photodynamic Activities of Pyridine- or Pyridinium-Substituted Aza-BODIPY Photosensitizers

In this work, various novel pyridinyl- and pyridinium-modified Aza-BODIPY PSs were designed and constructed based on monoiodo Aza-BODIPY PSs (BDP-4 and BDP-15) in an attempt to construct "structure-inherent organelles-targeted" PSs to endow potential organelle-targeting ability. Pyridinyl PSs displayed potent photodynamic efficacy, and monorigidified PSs were very effective. The monorigidified PS 20 with meta-pyridinyl moiety displayed the most potent photoactivity and negligible dark toxicity with a favorable dark/phototoxicity ratio (>4800). To our surprise, monorigidified PS with meta-pyridinyl moiety (e.g., 20) was lipid droplet-targeted. 20 showed good cellular uptake and intracellular ROS generation compared with BDP-15. The preliminary cell death process exploration indicated that 20 resulted in lipid peroxidation and induced cell death through an iron-independent ferroptosis-like cell death pathway. In vivo antitumor efficacy experiments manifested that 20 significantly inhibited tumor growth and outperformed BDP-15 and Ce6 even under a single low-dose light irradiation (30 J/cm2).

Tuning singlet oxygen generation with caged organic photosensitizers

Controlling the succession of chemical processes with high specificity in complex systems is advantageous for widespread applications, from biomedical research to drug manufacturing. Despite synthetic advances in bioorthogonal and photochemical methodologies, there is a need for generic chemical approaches that can universally modulate photodynamic reactivity in organic photosensitizers. Herein we present a strategy to fine-tune the production of singlet oxygen in multiple photosensitive scaffolds under the activation of bioresponsive and bioorthogonal stimuli. We demonstrate that the photocatalytic activity of nitrobenzoselenadiazoles can be fully blocked by site-selective incorporation of electron-withdrawing carbamate moieties and restored on demand upon uncaging with a wide range of molecular triggers, including abiotic transition-metal catalysts. We also prove that this strategy can be expanded to most photosensitizers, including diverse structures and spectral properties. Finally, we show that such advanced control of singlet oxygen generation can be broadly applied to the photodynamic ablation of human cells as well as to regulate the release of singlet oxygen in the semi-synthesis of natural product drugs.

Development of carbonic anhydrase IX-targeting molecular-targeted photodynamic therapy

The efficacy of molecular-targeted photodynamic therapy (MT-PDT) targeting carbonic anhydrase (CA) IX, a cancer-specific molecule, was demonstrated. CA ligand-directed photosensitizers 1-3 were evaluated for their ability to deactivate CAIX protein in cells. Compounds 2 and 3 selectively deactivated CAIX protein under 540 nm light without affecting internal standard proteins. Mechanistic studies revealed that compound 3 not only induced CAIX-selective light inactivation via singlet oxygen but also induced cell membrane damage, resulting in an anti-tumor effect. In vivo studies of CAIX-targeting MT-PDT revealed that treatment with compound 3 followed by light irradiation exhibited remarkable anti-tumor activity, leading to tumor degeneration and necrosis.

Self-assembly-integrated tumor targeting and electron transfer programming towards boosting tumor type I photodynamic therapy

Type I photodynamic therapy (PDT) is attracting increasing interest as an effective solution to the poor prognosis of patients with hypoxic tumors. The development of functional type I photosensitizers is limited by a lack of feasible strategies to systematically modulate electron transfer (ET) in photosensitization. Herein, we present an easily accessible approach for the preparation of nanophotosensitizers with self-assembly-integrated tumor-targeting and ET programming towards boosting tumor type I PDT. Specifically, a dual functional amphiphile PS-02 was designed with a ligand (6-NS) that had the ability to not only target tumor cell marker carbonic anhydrase IX (CAIX) but also regulate the ET process for type I PDT. The amphiphile PS-02 tended to self-assemble into PS-02 nanoparticles (NPs), which exhibited a local "ET-cage effect" due to the electron-deficient nature of 6-NS. It is noteworthy that when PS-02 NPs selectively targeted the tumor cells, the CAIX binding enabled the uncaging of the inhibited ET process owing to the electron-rich characteristic of CAIX. Therefore, PS-02 NPs integrated tumor targeting and CAIX activation towards boosting type I PDT. As a proof of concept, the improved PDT performance of PS-02 NPs was demonstrated with tumor cells under hypoxic conditions and solid tumor tissue in mouse in vivo experiments. This work provides a practical paradigm to develop versatile type I PDT nano-photosensitizers by simply manipulating ET and easy self-assembling.

Lutetium Texaphyrin-Celecoxib Conjugate as a Potential Immuno-Photodynamic Therapy Agent

Immuno-photodynamic therapy (IPDT) has emerged as a new modality for cancer treatment. Novel photosensitizers can help achieve the promise inherent in IPDT, namely, the complete eradication of a tumor without recurrence. We report here a small molecule photosensitizer conjugate, LuCXB. This IPDT agent integrates a celecoxib (cyclooxygenase-2 inhibitor) moiety with a near-infrared absorbing lutetium texaphyrin photocatalytic core. In aqueous environments, the two components of LuCXB are self-associated through inferred donor-acceptor interactions. A consequence of this intramolecular association is that upon photoirradiation with 730 nm light, LuCXB produces superoxide radicals (O2-•) via a type I photodynamic pathway; this provides a first line of defense against the tumor while promoting IPDT. For in vivo therapeutic applications, we prepared a CD133-targeting, aptamer-functionalized exosome-based nanophotosensitizer (Ex-apt@LuCXB) designed to target cancer stem cells. Ex-apt@LuCXB was found to display good photosensitivity, acceptable biocompatibility, and robust tumor targetability. Under conditions of photoirradiation, Ex-apt@LuCXB acts to amplify IPDT while exerting a significant antitumor effect in both liver and breast cancer mouse models. The observed therapeutic effects are attributed to a synergistic mechanism that combines antiangiogenesis and photoinduced cancer immunotherapy.

Membrane-anchoring selenophene viologens for antibacterial photodynamic therapy against periodontitis via restoring subgingival flora and alleviating inflammation

Antibacterial photodynamic therapy (aPDT) has emerged as a promising strategy for treating periodontitis. However, the weak binding of most photosensitizers to bacteria and the hypoxic environment of periodontal pockets severely hamper the therapeutic efficacy. Herein, two novel oxygen-independent photosensitizers are developed by introducing selenophene into viologens and modifying with hexane chains (HASeV) or quaternary ammonium chains (QASeV), which improve the adsorption to bacteria through anchoring to the negatively charged cell membrane. Notably, QASeV binds only to the bacterial surface of Porphyromonas gingivalis and Fusobacterium nucleatum due to electrostatic binding, but HASeV can insert into their membrane by strong hydrophobic interactions. Therefore, HASeV exhibits superior antimicrobial activity and more pronounced plaque biofilm disruption than QASeV when combined with light irradiation (MVL-210 photoreactor, 350-600 nm, 50 mW/cm2), and a better effect on reducing the diversity and restoring the structure of subgingival flora in periodontitis rat model was found through 16S rRNA gene sequencing analysis. The histological and Micro-CT analyses reveal that HASeV-based aPDT has a better therapeutic effect in reducing periodontal tissue inflammation and alveolar bone resorption. This work provides a new strategy for the development of viologen-based photosensitizers, which may be a favorable candidate for the aPDT against periodontitis.

Charge Transfer-Promoted Excited State of a Heavy-Atom-Free Photosensitizer for Efficient Application of Mitochondria-Targeted Fluorescence Imaging and Hypoxia Photodynamic Therapy

Conventional photosensitizers (PSs) used in photodynamic therapy (PDT) have shown preliminary success; however, they are often associated with several limitations including potential dark toxicity in healthy tissues, limited efficacy under acidic and hypoxic conditions, suboptimal fluorescence imaging capabilities, and nonspecific targeting during treatment. In response to these challenges, we developed a heavy-atom-free PS, denoted as Cz-SB, by incorporating ethyl carbazole into a thiophene-fused BODIPY core. A comprehensive investigation into the photophysical properties of Cz-SB was conducted through a synergistic approach involving experimental and computational investigations. The enhancement of intersystem crossing (kISC) and fluorescence emission (kfl) rate constants was achieved through a donor-acceptor pair-mediated charge transfer mechanism. Consequently, Cz-SB demonstrated remarkable efficiency in generating reactive oxygen species (ROS) under acidic and low-oxygen conditions, making it particularly effective for hypoxic cancer PDT. Furthermore, Cz-SB exhibited good biocompatibility, fluorescence imaging capabilities, and a high degree of localization within the mitochondria of living cells. We posit that Cz-SB holds substantial prospects as a versatile PS with innovative molecular design, representing a potential "one-for-all" solution in the realm of cancer phototheranostics.

Photodynamic Therapy with Targeted Release of Boron-Dipyrromethene Dye from Cobalt(III) Prodrugs in Red Light

Boron-dipyrromethene (BODIPY) dyes are promising photosensitizers for cellular imaging and photodynamic therapy (PDT) owing to their excellent photophysical properties and the synthetically tunable core. Metalation provides a convenient way to overcome the drawbacks arising from their low aqueous solubility. New photo-/redox-responsive Co(III) prodrug chaperones are developed as anticancer PDT agents for efficient cellular delivery of red-light-active BODIPY dyes. The photobiological activity of heteroleptic Co(III) complexes derived from tris(2-pyridylmethyl)amine (TPA) and acetylacetone-conjugated PEGylated distyryl BODIPY (HL1) or its dibromo analogue (HL2), [CoIII(TPA)(L1/L2)](ClO4)2 (1 and 2), are investigated. The Co(III)/Co(II) redox potential is tuned using the Co(III)-TPA scaffold. Complex 1 displays the in vitro release of BODIPY on red light irradiation. Complex 2, having good singlet oxygen quantum yield (ΦΔ ∼ 0.28 in DMSO), demonstrates submicromolar photocytotoxicity to HeLa cancer cells (IC50 ≈ 0.23 μM) while being less toxic to HPL1D normal cells in red light. Cellular imaging using the emissive complex 1 shows mitochondrial localization and significant penetration into the HeLa tumor spheroids. Complex 2 shows supercoiled DNA photocleavage activity and apoptotic cell death through phototriggered generation of reactive oxygen species. The Co(III)-BODIPY prodrug conjugates exemplify new type of phototherapeutic agents with better efficacy than the organic dyes alone in the phototherapeutic window.

Unsymmetrical Benzothieno-Fused BODIPYs as Efficient NIR Heavy-Atom-Free Photosensitizers

Heavy-atom-free photosensitizers are potentially suitable for use in photodynamic therapy (PDT). In this contribution, a new family of unsymmetrical benzothieno-fused BODIPYs with reactive oxygen efficiency up to 50% in air-saturated toluene was reported. Their efficient intersystem crossing (ISC) resulted in the generation of both 1O2 and O2-• under irradiation. More importantly, the PDT efficacy of a respective 4-methoxystyryl-modified benzothieno-fused BODIPY in living cells exhibited an extremely high phototoxicity with an ultralow IC50 value of 2.78 nM. The results revealed that the incorporation of an electron-donating group at the α-position of the unsymmetrical benzothieno-fused BODIPY platform might be an effective approach for developing long-wavelength absorbing heavy-atom-free photosensitizers for precision cancer therapy.

Engineering tumor-oxygenated nanomaterials: advancing photodynamic therapy for cancer treatment

Photodynamic therapy (PDT), a promising treatment modality, employs photosensitizers to generate cytotoxic reactive oxygen species (ROS) within localized tumor regions. This technique involves administering a photosensitizer followed by light activation in the presence of oxygen (O2), resulting in cytotoxic ROS production. PDT's spatiotemporal selectivity, minimally invasive nature, and compatibility with other treatment modalities make it a compelling therapeutic approach. However, hypoxic tumor microenvironment (TME) poses a significant challenge to conventional PDT. To overcome this hurdle, various strategies have been devised, including in-situ O2 generation, targeted O2 delivery, tumor vasculature normalization, modulation of mitochondrial respiration, and photocatalytic O2 generation. This review aims to provide a comprehensive overview of recent developments in designing tumor-oxygenated nanomaterials to enhance PDT efficacy. Furthermore, we delineate ongoing challenges and propose strategies to improve PDT's clinical impact in cancer treatment.

Functional Upgrading of an Organo-Ir(III) Complex to an Organo-Ir(III) Prodrug as a DNA Damage-Responsive Autophagic Inducer for Hypoxic Lung Cancer Therapy

The efficiency of nitrogen mustards (NMs), among the first chemotherapeutic agents against cancer, is limited by their monotonous mechanism of action (MoA). And tumor hypoxia is a significant obstacle in the attenuation of the chemotherapeutic efficacy. To repurpose the drug and combat hypoxia, herein, we constructed an organo-Ir(III) prodrug, IrCpNM, with the composition of a reactive oxygen species (ROS)-inducing moiety (Ir-arene fragment)-a hypoxic responsive moiety (azo linker)-a DNA-alkylating moiety (nitrogen mustard), and realized DNA damage response (DDR)-mediated autophagy for hypoxic lung cancer therapy for the first time. Prodrug IrCpNM could upregulate the level of catalase (CAT) to catalyze the decomposition of excessive H2O2 to O2 and downregulate the expression of the hypoxia-inducible factor (HIF-1α) to relieve hypoxia. Subsequently, IrCpNM initiates the quadruple synergetic actions under hypoxia, as simultaneous ROS promotion and glutathione (GSH) depletion to enhance the redox disbalance and severe oxidative and cross-linking DNA damages to trigger the occurrence of DDR-mediated autophagy via the ATM/Chk2 cascade and the PIK3CA/PI3K-AKT1-mTOR-RPS6KB1 signaling pathway. In vitro and in vivo experiments have confirmed the greatly antiproliferative capacity of IrCpNM against the hypoxic solid tumor. This work demonstrated the effectiveness of the DNA damage-responsive organometallic prodrug strategy with the microenvironment targeting system and the rebirth of traditional chemotherapeutic agents with a new anticancer mechanism.

Tumor acidification and GSH depletion by bimetallic composite nanoparticles for enhanced chemodynamic therapy of TNBC

Chemodynamic therapy (CDT) based on intracellular Fenton reaction to produce highly cytotoxic reactive oxygen species (ROS) has played an essential role in tumor therapy. However, this therapy still needs to be improved by weakly acidic pH and over-expression of glutathione (GSH) in tumor microenvironment (TEM), which hinders its future application. Herein, we reported a multifunctional bimetallic composite nanoparticle MnO2@GA-Fe@CAI based on a metal polyphenol network (MPN) structure, which could reduce intracellular pH and endogenous GSH by remodeling tumor microenvironment to improve Fenton activity. MnO2 nanoparticles were prepared first and MnO2@GA-Fe nanoparticles with Fe3+ as central ion and gallic acid (GA) as surface ligands were prepared by the chelation reaction. Then, carbonic anhydrase inhibitor (CAI) was coupled with GA to form MnO2@GA-Fe@CAI. The properties of the bimetallic composite nanoparticles were studied, and the results showed that CAI could reduce intracellular pH. At the same time, MnO2 could deplete intracellular GSH and produce Mn2+ via redox reactions, which re-established the TME with low pH and GSH. In addition, GA reduced Fe3+ to Fe2+. Mn2+ and Fe2+ catalyzed the endogenous H2O2 to produce high-lever ROS to kill tumor cells. Compared with MnO2, MnO2@GA-Fe@CAI could reduce the tumor weight and volume for the xenograft MDA-MB-231 tumor-bearing mice and the final tumor inhibition rate of 58.09 ± 5.77%, showing the improved therapeutic effect as well as the biological safety. Therefore, this study achieved the high-efficiency CDT effect catalyzed by bimetallic through reshaping the tumor microenvironment.

A carbonic anhydrase-targeted NIR-II fluorescent cisplatin theranostic nanoparticle for combined therapy of pancreatic tumors

Optically active organic nanoparticles capable of emitting strong near-infrared II (NIR-II) fluorescence and eliciting tumor hyperthermia are promising for tumor imaging and photothermal therapy (PTT). However, their applications for the treatment of pancreatic tumors via mere PTT are challenging as both the nanoparticles and light are hard to enter the deeply located pancreatic tumors. Here, we report a NIR-II light excitable, carbonic anhydrase (CA)-targeting cisplatin prodrug-decorated nanoparticle (IRNPs-SBA/PtIV) for NIR-II fluorescence imaging (FLI)-guided combination PTT and chemotherapy of pancreatic tumors. IRNPs-SBA/PtIV is designed to hold a high photothermal conversion efficiency (PCE ≈ 65.17 %) under 1064 nm laser excitation, a strong affinity toward CA (Kd = 14.40 ± 5.49 nM), and a prominent cisplatin release profile in response to glutathione (GSH) and 1064 nm laser irradiation. We show that IRNPs-SBA/PtIV can be actively delivered into pancreatic tumors where the CA is upregulated, and emits NIR-II fluorescence to visualize tumors with a high sensitivity and penetration depth under 980 nm laser excitation. Moreover, the tumor-resided IRNPs-SBA/PtIV can efficiently inhibit the CA activity and consequently, relieve the acidic and hypoxic tumor microenvironment, benefiting to intensify chemotherapy. Guided by the NIR-II FLI, IRNPs-SBA/PtIV is capable of efficiently inhibiting pancreatic tumor growth via combinational PTT and chemotherapy with 1064 nm laser excitation under a low-power density (0.5 W cm-2, 10 min). This study demonstrates promise to fabricate NIR-II excitable nanoparticles for FLI-guided precise theranostics of pancreatic tumors.

A Bioorthogonal Antidote Against the Photosensitivity after Photodynamic Therapy

As an effective and non-invasive treatment modality for cancer, photodynamic therapy (PDT) has attracted considerable interest. With the recent advances in the photosensitizing agents, the fiber-optic systems, and other aspects, its application is extended to a wide range of superficial and localized cancers. However, for the few clinically used photosensitizers, most of them suffer from the drawback of causing prolonged photosensitivity after the treatment. As a result, post-PDT management is also a crucial issue. Herein, a facile bioorthogonal approach is reported that can effectively suppress this common side effect of PDT in nude mice. It involves the use of an antidote that contains a black-hole quencher BHQ-3 conjugated with a bicyclo[6.1.0]non-4-yne (BCN) moiety and a tetrazine-substituted boron dipyrromethene-based photosensitizer. By using tumor-bearing nude mice as an animal model, it is demonstrated that after PDT with this photosensitizer, the administration of the antidote can effectively quench the photodynamic activity of the residual photosensitizer by bringing the BHQ-3 quencher close to the photosensitizing unit through a rapid click reaction. It results in substantial reduction in skin damage upon light irradiation. The overall results demonstrate that this simple and facile strategy can provide an effective means for minimizing the photosensitivity after PDT.

Bifunctional drug delivery system with carbonic anhydrase IX targeting and glutathione-responsivity driven by host-guest amphiphiles for effective tumor therapy

It remains a critical issue to deliver anticancer drugs to tumor tissues and reducing the toxic effects on normal tissues. The drug delivery system (DDS) based on self-assembly provides a multi-functional way for drug delivery. In this work, a supramolecular host (L-CD) with targeting function based on a β-cyclodextrin (β-CD) backbone was synthesized with carbonic anhydrase IX (CAIX) overexpressed on tumor cells as a target, and the methotrexate prodrug (MTX-SS-Ad) modified by adamantane and disulfide bond was prepared to be used as the guest. The amphiphilic complex was prepared between L-CD and MTX-SS-Ad through host-guest interactions and could further self-assemble into supramolecular nanoparticles (SNPs) with active targeting and stimulus release functions. The interaction between host and guest was investigated by UV, NMR, IR, XRD and TGA. The characteristic of SNPs was observed by DLS and TEM. Throng the study of molecular docking, in vitro inhibition, cell uptake experiments, and western blotting, SNPs have showed CAIX inhibitory effects both inside and outside the cells. The in vitro release experiments indicated that SNPs can undergo disintegration and release drugs under acidic and GSH conditions. Moreover, SNP can effectively inhibit the proliferation of cancer cells without generating additional toxic side effects on normal cells. So, we provide a strategy of bifunctional drug delivery system with targeting and glutathione-responsivity for effective tumor therapy.

Cascade In Situ Self-Assembly and Bioorthogonal Reaction Enable the Enrichment of Photosensitizers and Carbonic Anhydrase Inhibitors for Pretargeted Cancer Theranostics

We report here a tumor-pretargted theranostic approach for multimodality imaging-guided synergistic cancer PDT by cascade alkaline phosphatase (ALP)-mediated in situ self-assembly and bioorthogonal inverse electron demand Diels-Alder (IEDDA) reaction. Using the enzymatic catalysis of ALP that continuously catalyses the dephosphorylation and self-assembly of trans-cyclooctene (TCO)-bearing P-FFGd-TCO, a high density of fluorescent and magnetic TCO-containing nanoparticles (FMNPs-TCO) can be synthesized and retained on the membrane of tumor cells. They can act as 'artificial antigens' amenable to concurrently capture lately administrated tetrazine (Tz)-decorated PS (775NP-Tz) and carbonic anhydrase (CA) inhibitor (SA-Tz) via the fast IEDDA reaction. This two-step pretargeting process can further induce FMNPs-TCO regrowth into microparticles (FMNPs-775/SA) directly on tumor cell membranes, which is analyzed by bio-SEM and fluorescence imaging. Thus, efficient enrichment of both SA-Tz and 775NP-Tz in tumors can be achieved, allowing to alleviate hypoxia by continuously inhibiting CA activity and improving PDT of tumors. Findings show that subcutaneous HeLa tumors could be completely eradicated and no tumor recurred after irradiation with an 808 nm laser (0.33 W cm-2 , 10 min). This pretargeted approach may be applied to enrich other therapeutic agents in tumors to improve targeted therapy.

Nanoscale Covalent Organic Framework with Staggered Stacking of Phthalocyanines for Mitochondria-Targeted Photodynamic Therapy

Phthalocyanine photosensitizers (PSs) have shown promise in fluorescence imaging and photodynamic therapy (PDT) of malignant tumors, but their practical application is limited by the aggregation-induced quenching (AIQ) and inherent photobleaching of PSs. Herein, we report the synthesis of a two-dimensional nanoscale covalent organic framework (nCOF) with staggered (AB) stacking of zinc-phthalocyanines (ZnPc), ZnPc-PI, for fluorescence imaging and mitochondria-targeted PDT. ZnPc-PI isolates and confines ZnPc PSs in the rigid nCOF to reduce AIQ, improve photostability, enhance cellular uptake, and increase the level of reactive oxygen species (ROS) generation via mitochondrial targeting. ZnPc-PI shows efficient tumor accumulation, which allowed precise tumor imaging and nanoparticle tracking. With high cellular uptake and tumor accumulation, intrinsic mitochondrial targeting, and enhanced ROS generation, ZnPc-PI exhibits potent PDT efficacy with >95% tumor growth inhibition on two murine colon cancer models without causing side effects.

Smart stimuli-responsive strategies for titanium implant functionalization in bone regeneration and therapeutics

With the increasing and aging of global population, there is a dramatic rise in the demand for implants or substitutes to rehabilitate bone-related disorders which can considerably decrease quality of life and even endanger lives. Though titanium and its alloys have been applied as the mainstream material to fabricate implants for load-bearing bone defect restoration or temporary internal fixation devices for bone fractures, it is far from rare to encounter failed cases in clinical practice, particularly with pathological factors involved. In recent years, smart stimuli-responsive (SSR) strategies have been conducted to functionalize titanium implants to improve bone regeneration in pathological conditions, such as bacterial infection, chronic inflammation, tumor and diabetes mellitus, etc. SSR implants can exert on-demand therapeutic and/or pro-regenerative effects in response to externally applied stimuli (such as photostimulation, magnetic field, electrical and ultrasound stimulation) or internal pathology-related microenvironment changes (such as decreased pH value, specific enzyme secreted by bacterial and excessive production of reactive oxygen species). This review summarizes recent progress on the material design and fabrication, responsive mechanisms, and in vitro and in vivo evaluations for versatile clinical applications of SSR titanium implants. In addition, currently existing limitations and challenges and further prospective directions of these strategies are also discussed.

Nanomaterials for Disease Treatment by Modulating the Pyroptosis Pathway

Pyroptosis differs significantly from apoptosis and cell necrosis as an alternative mode of programmed cell death. Its occurrence is mediated by the gasdermin protein, leading to characteristic outcomes including cell swelling, membrane perforation, and release of cell contents. Research underscores the role of pyroptosis in the etiology and progression of many diseases, making it a focus of research intervention as scientists explore ways to regulate pyroptosis pathways in disease management. Despite numerous reviews detailing the relationship between pyroptosis and disease mechanisms, few delve into recent advancements in nanomaterials as a mechanism for modulating the pyroptosis pathway to mitigate disease effects. Therefore, there is an urgent need to fill this gap and elucidate the path for the use of this promising technology in the field of disease treatment. This review article delves into recent developments in nanomaterials for disease management through pyroptosis modulation, details the mechanisms by which drugs interact with pyroptosis pathways, and highlights the promise that nanomaterial research holds in driving forward disease treatment.

A dipyridophenazine Ni(II) dithiolene complex as a dual-acting cancer phototherapy agent activatable within the phototherapeutic window

A combination of photodynamic therapy (PDT) and photothermal therapy (PTT) within the phototherapeutic window (600-900 nm) can lead to significantly enhanced therapeutic outcomes, surpassing the efficacy observed with PDT or PTT alone in cancer phototherapy. Herein, we report a novel small-molecule mixed-ligand Ni(II)-dithiolene complex (Ni-TDD) with a dipyridophenazine ligand, demonstrating potent red-light PDT and significant near-infrared (NIR) light mild-temperature PTT activity against cancer cells and 3D multicellular tumour spheroids (MCTSs). The four-coordinate square planar complex exhibited a moderately intense absorption band (ε ∼ 3700 M-1cm-1) centered around 900 nm and demonstrated excellent dark and photostability in an aqueous phase. Ni-TDD induced a potent red-light (600-720 nm) PDT effect on HeLa cancer cells (IC50 = 1.8 μM, photo irritation factor = 44), triggering apoptotic cell death through efficient singlet oxygen generation. Ni-TDD showed a significant intercalative binding affinity towards double-helical calf thymus DNA, resulting in a binding constant (Kb) ∼ 106 M-1. The complex induced mild hyperthermia and exerted a significant mild-temperature PTT effect on MDA-MB-231 cancer cells upon irradiation with 808 nm NIR light. Simultaneous irradiation of Ni-TDD-treated HeLa MCTSs with red and NIR light led to a remarkable synergistic inhibition of growth, exceeding the effects of individual irradiation, through the generation of singlet oxygen and mild hyperthermia. Ni-TDD displayed minimal toxicity towards non-cancerous HPL1D and L929 cells, even at high micromolar concentrations. This is the first report of a Ni(II) complex demonstrating red-light PDT activity and the first example of a first-row transition metal complex exhibiting combined PDT and PTT effects within the clinically relevant phototherapeutic window. Our findings pave the way for designing and developing metal-dithiolene complexes as dual-acting cancer phototherapy agents using long wavelength light for treating solid tumors.

Semiconducting Polymers for Cancer Immunotherapy

As a monumental breakthrough in cancer treatment, immunotherapy has attracted tremendous attention in recent years. However, one challenge faced by immunotherapy is the low response rate and the immune-related adverse events (irAEs). Therefore, it is important to explore new therapeutic strategies and platforms for boosting therapeutic benefits and decreasing the side effects of immunotherapy. In recent years, semiconducting polymer (SP), a category of organic materials with π-conjugated aromatic backbone, has been attracting considerable attention because of their outstanding characteristics such as excellent photophysical features, good biosafety, adjustable chemical flexibility, easy fabrication, and high stability. With these distinct advantages, SP is extensively explored for bioimaging and photo- or ultrasound-activated tumor therapy. Here, the recent advancements in SP-based nanomedicines are summarized for enhanced tumor immunotherapy. According to the photophysical properties of SPs, the cancer immunotherapies enabled by SPs with the photothermal, photodynamic, or sonodynamic functions are highlighted in detail, with a particular focus on the construction of combination immunotherapy and activatable nanoplatforms to maximize the benefits of cancer immunotherapy. Herein, new guidance and comprehensive insights are provided for the design of SPs with desired photophysical properties to realize maximized effectiveness of required biomedical applications.

Diagnosing Orthotopic Lung Tumor Using a NTR-Activatable Near-Infrared Fluorescent Probe by Tracheal Inhalation

Nitroreductase (NTR) is an enzyme that is upregulated under tumor-depleted oxygen conditions. The majority of studies have been conducted on NTR, but many existing fluorescent imaging tools for monitoring NTR inevitably suffer from weak targeting, low sensitivity, and simple tumor models. Research on diagnosing lung tumors has been very popular in recent years, but targeting assays in orthotopic lung tumors is still of great research value, as such models better mimic the reality of cancer in the organism. Here, we developed a novel near-infrared (NIR) fluorescent probe IR-ABS that jointly targets NTR and carbonic anhydrase IX (CAIX). IR-ABS has excellent sensitivity and selectivity and shows exceptional NTR response in spectroscopic tests. The measurements ensured that this probe has good biosafety in both cells and mice. A better NTR response was found in hypoxic tumor cells at the cellular level, distinguishing tumor cells from normal cells. In vivo experiments demonstrated that IR-ABS achieves a hypoxic response at the zebrafish level and enables rapid and accurate tumor margin distinguishment in different mouse tumor models. More importantly, we successfully applied IR-ABS for NTR detection in orthotopic lung tumor models, further combined with tracheal inhalation drug delivery to improve targeting. To the best of our knowledge, we present for the first time a near-infrared imaging method for targeting lung cancerous tumor in situ via tracheal inhalation drug delivery, in contrast to the reported literature. This NIR fluorescence diagnostic strategy for targeting orthotopic lung cancer holds exciting potential for clinical aid in cancer diagnosis.

Carbonic anhydrase inhibitor-decorated semiconducting oligomer nanoparticles for active-targeting NIR-II fluorescence tumor imaging

Second near-infrared window (NIR-II) fluorescence imaging has shown great potential in the field of bioimaging. To achieve a better imaging effect, variety of NIR-II fluorescence probes have been designed and developed. Among them, semiconducting oligomers (SOs) have shown unique advantages including high photostability and quantum yield, making them promise in NIR-II fluorescence imaging. Herein, we design a SO nanoparticle (ASONi) for NIR-II fluorescence imaging of tumor. ASONi is composed of an azido-functionalized semiconducting oligomer as the NIR-II fluorescence emitter, and a benzene sulfonamide-ended DSPE-PEG (DSPE-PEG-CAi) as the stabilizer. Owing to the benzene sulfonamide groups on the surface, ASONi has the capability of targeting the carbonic anhydrase IX (CA IX) of MDA-MB-231 breast cancer cell. Compared with ASON without benzene sulfonamide groups on the surface, ASONi has a 1.4-fold higher uptake for MDA-MB-231 cells and 1.5-fold higher breast tumor accumulation after i.v. injection. The NIR-II fluorescence signal of ASONi can light the tumor up within 4 h, demonstrating its capability of active tumor targeting and NIR-II fluorescence imaging.

Structural basis of antibacterial photodynamic action of curcumin against S. aureus

Antimicrobial photodynamic therapy (aPDT) is an alternative tool to commercial antibiotics for the inactivation of pathogenic bacteria (e.g., S. aureus). However, there is still a lack of understanding of the molecular modeling of the photosensitizers and their mechanism of action through oxidative pathways. Herein, a combined experimental and computational evaluation of curcumin as a photosensitizer against S. aureus was performed. The radical forms of keto-enol tautomers and the energies of curcumin's frontier molecular orbitals were evaluated by density functional theory (DFT) to point out the photodynamic action as well as the photobleaching process. Furthermore, the electronic transitions of curcumin keto-enol tautomers were undertaken to predict the transitions as a photosensitizer during the antibacterial photodynamic process. Moreover, molecular docking was used to evaluate the binding affinity with the S. aureus tyrosyl-tRNA synthetase as the proposed a target for curcumin. In this regard, the molecular orbital energies show that the curcumin enol form has a character of 4.5% more basic than the keto form - the enol form is a more promising electron donor than its tautomer. Curcumin is a strong electrophile, with the enol form being 4.6% more electrophilic than its keto form. In addition, the regions susceptible to nucleophilic attack and photobleaching were evaluated by the Fukui function. Regarding the docking analysis, the model suggested that four hydrogen bonds contribute to the binding energy of curcumin's interaction with the ligand binding site of S. aureus tyrosyl-tRNA synthetase. Finally, residues Tyr36, Asp40, and Asp177 contact curcumin and may contribute to orienting the curcumin in the active area. Moreover, curcumin presented a photoinactivation of 4.5 log unit corroborating the necessity of the combined action of curcumin, light, and O2 to promote the photooxidation damage of S. aureus. These computational and experimental data suggest insights regarding the mechanism of action of curcumin as a photosensitizer to inactivate S. aureus bacteria.

Small diameter expanded polytetrafluoroethylene vascular graft with differentiated inner and outer biomacromolecules for collaborative endothelialization, anti-thrombogenicity and anti-inflammation

Without differentiated inner and outer biological function, expanded polytetrafluoroethylene (ePTFE) small-diameter (<6 mm) artificial blood vessels would fail in vivo due to foreign body rejection, thrombosis, and hyperplasia. In order to synergistically promote endothelialization, anti-thrombogenicity, and anti-inflammatory function, we modified the inner and outer surface of ePTFE, respectively, by grafting functional biomolecules, such as heparin and epigallocatechin gallate (EGCG), into the inner surface and polyethyleneimine and rapamycin into the outer surface via layer-by-layer self-assembly. Fourier-transform infrared spectroscopy showed the successful incorporation of EGCG, heparin, and rapamycin. The collaborative release profile of heparin and rapamycin lasted for 42 days, respectively. The inner surface promoted human umbilical vein endothelial cells (HUVECs) adhesion and growth and that the outer surface inhibited smooth muscle cells growth and proliferation. The modified ePTFE effectively regulated the differentiation behavior of RAW264.7, inhibited the expression of proinflammatory mediator TNF-α, and up-regulated the expression of anti-inflammatory genes Arg1 and Tgfb-1. The ex vivo circulation results indicated that the occlusions and total thrombus weight of modified ePTFE was much lower than that of the thrombus formed on the ePTFE, presenting good anti-thrombogenic properties. Hence, the straightforward yet efficient synergistic surface functionalization approach presented a potential resolution for the prospective clinical application of small-diameter ePTFE blood vessel grafts.

Protoporphyrin IX-loaded albumin nanoparticles reverse cancer chemoresistance by enhancing intracellular reactive oxygen species

Chemoresistance is the main cause of chemotherapy failure in ovarian cancer (OC). The enhanced scavenging of reactive oxygen species (ROS) by the thioredoxin system resulted in insufficient intracellular concentrations of effective ROS, leading to chemoresistance. To induce OC cell apoptosis by enhancing intracellular ROS levels, protoporphyrin IX (PpIX) and albumin-bound PTX nanoparticles (APNP) were utilized to fabricate APNP-PpIX nanoparticles. APNP-PpIX effectively generated ROS and increased the effective ROS concentration in chemoresistant cancer cells. The in vitro and in vivo experiments confirmed the effective inhibition of APNP-PpIX on chemoresistant OC cell proliferation and tumor formation. APNP-PpIX significantly improved the effectiveness of chemotherapy and photodynamic therapy, thus providing a new approach for the clinical treatment of chemoresistant OC.

A Strategy of Fenton Reaction Cycloacceleration for High-Performance Ferroptosis Therapy Initiated by Tumor Microenvironment Remodeling

The emerging tumor ferroptosis therapy confronts impediments of the tumor microenvironment (TME) with weak intrinsic acidity, inadequate endogenous H2 O2 , and a powerful intracellular redox balance system that eliminates toxic reactive oxygen species (ROS). Herein, a strategy of Fenton reaction cycloacceleration initiated by remodeling the TME for magnetic resonance imaging (MRI)-guided high-performance ferroptosis therapy of tumors is proposed. The synthesized nanocomplex exhibits enhanced accumulation at carbonic anhydrase IX (CAIX)-positive tumors based on the CAIX-mediated active targeting, and increased acidification via the inhibition of CAIX by 4-(2-aminoethyl) benzene sulfonamide (ABS) (remodeling TME). This accumulated H+ and abundant glutathione in TME synergistically trigger biodegradation of the nanocomplex to release the loaded cuprous oxide nanodots (CON), β-lapachon (LAP), Fe3+ , and gallic acid-ferric ions coordination networks (GF). The Fenton and Fenton-like reactions are cycloaccelerated via the catalytic loop of Fe-Cu, and the LAP-triggered and nicotinamide adenine dinucleotide phosphate quinone oxidoreductase1-mediated redox cycle, generating robust ROS and plenitudinous lipid peroxides accumulation for ferroptosis of tumor cells. The detached GF network has improved relaxivities in response to the TME. Therefore, the strategy of Fenton reaction cycloacceleration initiated by remodeling the TME is promising for MRI-guided high-performance ferroptosis therapy of tumors.

Are tumour-associated carbonic anhydrases genuine therapeutic targets for photodynamic therapy?

INTRODUCTION

Photodynamic therapy (PDT) is a reactive oxygen species (ROS)-dependent treatment modality which has emerged as an alternative cancer therapy strategy. However, in solid tumors, the therapeutic efficacy of PDT is strongly reduced by hypoxia, a typical feature of many such tumors. The tumor-associated carbonic anhydrases IX (hCA IX) and XII (hCA XII), which are overexpressed under hypoxia are attractive, validated anticancer drug targets in solid tumors. Current challenges in therapeutic design of effective PDT systems aim to overcome the limitation of hypoxia by developing synergistic CA-targeted therapies combining photosensitizers and hCA IX/XII inhibitors.

AREA COVERED

In this review, the current literature on the use of hCA IX/XII inhibitors (CAi) for targeting photosensitizing chemical systems useful for PDT against hypoxic solid tumors is summarized, along with recent progress, challenges, and future prospects.

EXPERT OPINION

hCA IX/XII-focused photosensitizers have recently provided new generation of compounds of considerable potential. Proof of concept of in vivo efficacy studies suggested enhanced efficacy for CAi-PDT hybrid systems. Further research is needed to deepen our understanding of how hCA IX/hCA XII inhibition can enhance PDT and for obtaining more effective such derivatives.

Research development of porphyrin-based metal-organic frameworks: targeting modalities and cancer therapeutic applications

Porphyrins are naturally occurring organic molecules that have attracted widespread attention for their potential in the field of biomedical research. Porphyrin-based metal-organic frameworks (MOFs) that utilize porphyrin molecules as organic ligands have gained attention from researchers due to their excellent results as photosensitizers in tumor photodynamic therapy (PDT). Additionally, MOFs hold significant promise and potential for other tumor therapeutic approaches due to their tunable size and pore size, excellent porosity, and ultra-high specific surface area. Active delivery of nanomaterials via targeted molecules for tumor therapy has demonstrated greater accumulation, lower drug doses, higher therapeutic efficacy, and reduced side effects relative to passive targeting through the enhanced permeation and retention effect (EPR). This paper presents a comprehensive review of the targeting methods employed by porphyrin-based MOFs in tumor targeting therapy over the past few years. It further discusses the applications of porphyrin-based MOFs for targeted cancer therapy through various therapeutic methods. The objective of this paper is to provide a valuable reference and source of ideas for targeted therapy using porphyrin-based MOF materials and to inspire further exploration of their potential in the field of cancer therapy.

Cancer Cell-Specific Fluorescent Prodrug Delivery Platforms

Targeting cancer cells with high specificity is one of the most essential yet challenging goals of tumor therapy. Because different surface receptors, transporters, and integrins are overexpressed specifically on tumor cells, using these tumor cell-specific properties to improve drug targeting efficacy holds particular promise. Targeted fluorescent prodrugs not only improve intracellular accumulation and bioavailability but also report their own localization and activation through real-time changes in fluorescence. In this review, efforts are highlighted to develop innovative targeted fluorescent prodrugs that efficiently accumulate in tumor cells in different organs, including lung cancer, liver cancer, cervical cancer, breast cancer, glioma, and colorectal cancer. The latest progress and advances in chemical design and synthetic considerations in fluorescence prodrug conjugates and how their therapeutic efficacy and fluorescence can be activated by tumor-specific stimuli are reviewed. Additionally, novel perspectives are provided on strategies behind engineered nanoparticle platforms self-assembled from targeted fluorescence prodrugs, and how fluorescence readouts can be used to monitor the position and action of the nanoparticle-mediated delivery of therapeutic agents in preclinical models. Finally, future opportunities for fluorescent prodrug-based strategies and solutions to the challenges of accelerating clinical translation for the treatment of organ-specific tumors are proposed.

Interstitial Photodynamic Therapy of Glioblastomas: A Long-Term Follow-up Analysis of Survival and Volumetric MRI Data

BACKGROUND

The treatment of glioblastomas, the most common primary malignant brain tumors, with a devastating survival perspective, remains a major challenge in medicine. Among the recently explored therapeutic approaches, 5-aminolevulinic acid (5-ALA)-mediated interstitial photodynamic therapy (iPDT) has shown promising results.

METHODS

A total of 16 patients suffering from de novo glioblastomas and undergoing iPDT as their primary treatment were retrospectively analyzed regarding survival and the characteristic tissue regions discernible in the MRI data before treatment and during follow-up. These regions were segmented at different stages and were analyzed, especially regarding their relation to survival.

RESULTS

In comparison to the reference cohorts treated with other therapies, the iPDT cohort showed a significantly prolonged progression-free survival (PFS) and overall survival (OS). A total of 10 of 16 patients experienced prolonged OS (≥ 24 months). The dominant prognosis-affecting factor was the MGMT promoter methylation status (methylated: median PFS of 35.7 months and median OS of 43.9 months) (unmethylated: median PFS of 8.3 months and median OS of 15.0 months) (combined: median PFS of 16.4 months and median OS of 28.0 months). Several parameters with a known prognostic relevance to survival after standard treatment were not found to be relevant to this iPDT cohort, such as the necrosis-tumor ratio, tumor volume, and posttreatment contrast enhancement. After iPDT, a characteristic structure (iPDT remnant) appeared in the MRI data in the former tumor area.

CONCLUSIONS

In this study, iPDT showed its potential as a treatment option for glioblastomas, with a large fraction of patients having prolonged OS. Parameters of prognostic relevance could be derived from the patient characteristics and MRI data, but they may partially need to be interpreted differently compared to the standard of care.

Copper coordination-based conjugated polymer nanoparticles for synergistic photodynamic and chemodynamic therapy

In this work, we presented a copper coordination-based conjugated polymer nanoparticle (PPE-Cu NPs) for synergistic PDT/CDT. Upon irradiation, PPE-Cu NPs exhibited good singlet oxygen generation capability (Φ_Δ = 0.33). Meanwhile, PPE-Cu NPs were able to generate ˙OH in the presence of GSH and H₂O₂. Cellular experiments demonstrated that PPE-Cu NPs can serve as effective agents for synergistic PDT/CDT therapy.

Tumor-targeted redox-regulating and antiangiogenic phototherapeutics nanoassemblies for self-boosting phototherapy

Cancer cells are equipped with abundant antioxidants such as glutathione (GSH) that eliminate reactive oxygen species (ROS) to deteriorate the therapeutic efficacy of photodynamic therapy (PDT). Another challenge in PDT is circumventing PDT-induced hypoxic condition that provokes upregulation of pro-angiogenic factor such as vascular endothelial growth factor (VEGF). It is therefore reasonable to expect that therapeutic outcomes of PDT could be maximized by concurrent delivery of photosensitizers with GSH depleting agents and VEGF suppressors. To achieve cooperative therapeutic actions of PDT with in situ GSH depletion and VEGF suppression, we developed tumor targeted redox-regulating and antiangiogenic phototherapeutic nanoassemblies (tRAPs) composed of self-assembling disulfide-bridged borylbenzyl carbonate (ssBR), photosensitizer (IR780) and tumor targeting gelatin. As a framework of tRAPs, ssBR was rationally designed to form nanoconstructs that serve as photosensitizer carriers with intrinsic GSH depleting- and VEGF suppressing ability. tRAPs effectively depleted intracellular GSH to render cancer cells more vulnerable to ROS and also provoked immunogenic cell death (ICD) of cancer cells upon near infrared (NIR) laser irradiation. In mouse xenograft models, tRAPs preferentially accumulated in tumors and dramatically eradicated tumors with laser irradiation. The design rationale of tRAPs provides a simple and versatile strategy to develop self-boosting phototherapeutic agents with great potential in targeted cancer therapy.