Triple-Jump Photodynamic Theranostics: MnO2 Combined Upconversion Nanoplatforms Involving a Type-I Photosensitizer with Aggregation-Induced Emission Characteristics for Potent Cancer Treatment

Cyclic catalysis of intratumor Fe3+/2+ initiated by a hollow mesoporous iron sesquioxide nanoparticle for ferroptosis therapy of large tumors

Numerous nanoparticles have been utilized to deliver Fe2+ for tumor ferroptosis therapy, which can be readily converted to Fe3+via Fenton reactions to generate hydroxyl radical (•OH). However, the ferroptosis therapeutic efficacy of large tumors is limited due to the slow conversion of Fe3+ to Fe2+via Fenton reactions. Herein, a strategy of intratumor Fe3+/2+ cyclic catalysis is proposed for ferroptosis therapy of large tumors, which was realized based on our newly developed hollow mesoporous iron sesquioxide nanoparticle (HMISN). Cisplatin (CDDP) and Gd-poly(acrylic acid) macrochelates (GP) were loaded into the hollow core of HMISN, whose surface was modified by laccase (LAC). Fe3+, CDDP, GP, and LAC can be gradually released from CDDP@GP@HMISN@LAC in the acidic tumor microenvironment. The intratumor O2 can be catalyzed into superoxide anion (O2•-) by LAC, and the intratumor NADPH oxidases can be activated by CDDP to generate O2•-. The O2•- can react with Fe3+ to generate Fe2+, and raise H2O2 level via the superoxide dismutase. The generated Fe2+ and H2O2 can be fast converted into Fe3+ and •OH via Fenton reactions. The cyclic catalysis of intratumor Fe3+/2+ initiated by CDDP@GP@HMISN@LAC can be used for ferroptosis therapy of large tumors.

Oxygen-defect bismuth oxychloride nanosheets for ultrasonic cavitation effect enhanced sonodynamic and second near-infrared photo-induced therapy of breast cancer

Sonodynamic therapy (SDT) relies heavily on the presence of oxygen to induce cell death. Its effectiveness is thus diminished in the hypoxic regions of tumor tissue. To address this issue, the exploration of ultrasound-based synergistic treatment modalities has become a significant research focus. Here, we report an ultrasonic cavitation effect enhanced sonodynamic and 1208 nm photo-induced cancer treatment strategy based on thermoelectric/piezoelectric oxygen-defect bismuth oxychloride nanosheets (BNs) to realize the high-performance eradication of tumors. Upon ultrasonic irradiation, the local high temperature and high pressure generated by the ultrasonic cavitation effect combined with the thermoelectric and piezoelectric effects of BNs create a built-in electric field. This facilitates the separation of carriers, increasing their mobility and extending their lifetimes, thereby greatly improving the effectiveness of SDT and NIR-Ⅱ phototherapy on hypoxia. The Tween-20 modified BNs (TBNs) demonstrate ∼88.6 % elimination rate against deep-seated tumor cells under hypoxic conditions. In vivo experiments confirm the excellent antitumor efficacy of TBNs, achieving complete tumor elimination within 10 days with no recurrences. Furthermore, due to the high X-ray attenuation of Bi and excellent NIR-Ⅱ absorption, TBNs enable precise cancer diagnosis through photoacoustic (PA) imaging and computed tomography (CT).

Transition Metal (Molybdenum)-Doped Drug-like Conformational Nanoarchitectonics with Altered Valence States (Mn2+/Mn4+ and Mo5+/Mo6+) for Augmented Cancer Theranostics

Despite the advancements in cancer therapy, delivering active pharmaceutical ingredients (APIs) using nanoparticles remains challenging due to the failed conveyance of the required drug payload, poor targeting ability, and poor biodistribution, hampering their clinical translation. Recently, the appropriate design of materials with intrinsic therapeutic functionalities has garnered enormous interest in the development of various intelligent therapeutic nanoplatforms. In this study, we demonstrate the fabrication of transition metal (molybdenum, Mo)-doped manganese dioxide (MnO2) nanoarchitectures, exhibiting diagnostic (magnetic resonance imaging, MRI) and therapeutic (chemodynamic therapy, CDT) functionalities. The facile hydrothermal approach-assisted Mo-doped MnO2 flower-like nanostructures offered tailorable morphologies in altered dimensions, precise therapeutic effects, exceptional biocompatibility, and biodegradability in the tumor microenvironment. The resultant defects due to doped Mo species exhibited peroxidase and oxidase activities, improving glutathione (GSH) oxidation. The two sets of variable valence metal ion pairs (Mn2+/Mn4+ and Mo5+/Mo6+) and their interplay could substantially improve the Fenton-like reaction and generate toxic hydroxyl radicals (•OH), thus achieving CDT-assisted antitumor effects. As inherent T1-MRI agents, these MnO2 nanoparticles displayed excellent MRI efficacy in vitro. Together, we believe that these conformational Mo-doped MnO2 nanoarchitectures with two pairs of variable valence states could potentiate drugless therapy in pharmaceutics.

Tumor microenvironment-responsive manganese-based nano-modulator activate the cGAS-STING pathway to enhance innate immune system response

BACKGROUND

Manganese ions (Mn2+) combined with adjuvants capable of damaging and lysing tumor cells form an antitumor nano-modulator that enhances the immune efficacy of cancer therapy through the cascade activation of the cyclic GMP-AMP interferon gene synthase-stimulator (cGAS-STING) pathway, which underscores the importance of developing antitumor nano-modulators, which induce DNA damage and augment cGAS-STING activity, as a critical future research direction. METHODS AND RESULTS: We have successfully synthesized an antitumor nano-modulator, which exhibits good dispersibility and biosafety. This nano-modulator is engineered by loading manganese dioxide nanosheets (M-NS) with zebularine (Zeb), known for its immunogenicity-enhancing effects, and conducting targeted surface modification using hyaluronic acid (HA). After systemic circulation to the tumor site, Mn2+, Zeb, and reactive oxygen species (ROS) are catalytically released in the tumor microenvironment by H+ and H2O2. These components can directly or indirectly damage the DNA or mitochondria of tumor cells, thereby inducing programmed cell death. Furthermore, they promote the accumulation of double-stranded DNA (dsDNA) in the cytoplasm, enhancing the activation of the cGAS-STING signalling pathway and boosting the production of type I interferon and the secretion of pro-inflammatory cytokines. Additionally, Zeb@MH-NS enhances the maturation of dendritic cells, the infiltration of cytotoxic T lymphocytes, and the recruitment of natural killer cells at the tumor site.

CONCLUSIONS

This HA-modified manganese-based hybrid nano-regulator can enhance antitumor therapy by boosting innate immune activity and may provide new directions for immunotherapy and clinical translation in cancer.

Designing NIR AIEgens for lysosomes targeting and efficient photodynamic therapy of tumors

Cancer is the most severe health problem facing most people today. Photodynamic therapy (PDT) for tumors has attracted attention because of its non-invasive nature, negligible adverse reactions, and high spatiotemporal selectivity. Developing biocompatible photosensitizers that can target, guide, and efficiently kill cancer cells is desirable in PDT. Here, two amphiphilic organic compounds, PS-I and PSS-II, were synthesized based on the D-π-A structure with a positive charge. The two AIEgens exhibited near-infrared emission, large Stokes shift, high 1O2 and O2-∙ generation efficiency, good biocompatibility, and photostability. They were co-incubated with cancer cells and eventually accumulated to lysosomes by cell imaging experiments. In vitro and in vivo experiments demonstrated that PS-I and PSS-II could effectively kill cancer cells and sufficiently inhibit tumor growth under light irradiation. PS-I had a higher fluorescence quantum yield in the aggregated state, which made it better for bio-imaging in imaging-guided photodynamic therapy. In contrast, PSS-II with a longer conjugated structure had more ROS generation to kill tumor cells under illumination, and the tumor growth inhibition of mice reached 71.95% during the treatment. No observable injury or undesirable outcomes were detected in the vital organs of the mice within the treatment group, suggesting that PSS-II/PS-I had a promising future in efficient imaging-guided PDT for cancer.

Advancements in manganese complex-based MRI agents: Innovations, design strategies, and future directions

This review focuses on the advancements in manganese (Mn) complex-based magnetic resonance imaging (MRI) agents for imaging different diseases. Here we emphasize the unique redox properties of Mn to deliver innovative MRI contrast agents, including small molecules, nanoparticles (NPs), metal-organic frameworks (MOFs), and polymer hybrids. Aspects of their rational design have been discussed, including size dependence, morphology tuning, surface property enhancement, etc., while also discussing the existing challenges and potential solutions. The present work will inspire and motivate scientists to emphasize MRI-guided applications and bring clinical success in the coming years.

Lighting up endogenous H2O2 in the tumor microenvironment using a dual-mode nanoprobe for long afterglow and MR bioimaging

Persistent luminescent nanoparticles (PLNPs) are excellent luminescent materials, and near-infrared PLNPs are efficiently applied for biosensing and bioimaging due to their advantages of no excitation, excellent light stability and long afterglow. However, due to interference from the complex environment within organisms, single-mode imaging methods often face limitations in selectivity, sensitivity, and accuracy. Therefore, it is desirable to construct a dual-mode imaging probe strategy with higher specificity and sensitivity for bioimaging. Magnetic resonance imaging (MRI) has been widely used in the field of bioimaging due to its advantages of high resolution, non-radiation and non-invasiveness. Here, by combining near-infrared PLNPs and manganese dioxide (MnO2) nanosheets, a sensitive and convenient dual-mode "turn on" bioimaging nanoprobe ZGC@MnO2 has been developed for long afterglow imaging and MRI of endogenous hydrogen peroxide (H2O2) in the tumor microenvironment (TME). The monitoring of H2O2 has garnered significant attention due to its crucial role in human pathologies. For the dual-mode "turn on" bioimaging nanoprobe, the near-infrared PLNPs of quasi-spherical ZnGa2O4:Cr (ZGC) nanoparticles were synthesized as luminophores, and MnO2 nanosheets were utilized as a fluorescence quencher, carrier and H2O2 recognizer. H2O2 in the TME could reduce MnO2 nanosheets to Mn2+ for MRI, and ZGC nanoparticles were released for long afterglow imaging. Finally, the ZGC@MnO2 nanoprobe exhibited a rapid response, an excellent signal-to-noise ratio and a limit of detection of 3.67 nM for endogenous H2O2 in the TME. This dual-mode approach enhances the detection sensitivity for endogenous H2O2, thereby facilitating the research of endogenous H2O2-associated diseases and clinical diagnostics.

Advance of Near-Infrared Emissive Carbon Dots in Diagnosis and Therapy: Synthesis, Luminescence, and Application

Carbon dots (CDs) with good optical properties, biocompatibility, easy functionalization, and small size have attracted more and more attention and laid a good foundation for their applications in the biomedicine field. CDs emitted in near-infrared regions (NIR-CDs) can achieve high penetration depth imaging and produce high cytotoxic substance for disease treatment. Therefore, NIR-CDs are promising materials to realize high-quality imaging-guided diagnostic and therapeutic integration. This review first introduces the current mainstream synthesis methods of NIR-CDs by "top-down" and "bottom-up". Second, the luminescence modes of NIR-CDs are introduced, and the luminescence mechanisms based on carbon core state, surface state, molecular state, and crosslinking enhanced emission are summarized. Third, the applications and principles of NIR-CDs in imaging, drug delivery, and non-invasive therapeutics are introduced from a view of diagnosis and therapy. Finally, their prospects and challenges in biomedical and biotechnological applications are outlined.

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.

Study on synergistic mechanism of molybdenum disulfide/sodium carboxymethyl cellulose composite nanofiber mats for photothermal/photodynamic antibacterial treatment

Innovative antibacterial therapies using nanomaterials, such as photothermal (PTT) and photodynamic (PDT) treatments, have been developed for treating wound infections. However, creating secure wound dressings with these therapies faces challenges. The primary focus of this study is to prepare an antibacterial nanofiber dressing that effectively incorporates stable loads of functional nanoparticles and demonstrates an efficient synergistic effect between PTT and PDT. Herein, a composite nanofiber mat was fabricated, integrating spherical molybdenum disulfide (MoS2) nanoparticles. MoS2 was deposited onto polylactic acid (PLA) nanofiber mats using vacuum filtration, which was further stabilized by sodium carboxymethyl cellulose (CMC) adhesion and glutaraldehyde (GA) cross-linking. The composite nanofibers demonstrated synergistic antibacterial effects under NIR light irradiation, and the underlying mechanism was explored. They induce bacterial membrane permeability, protein leakage, and intracellular reactive oxygen species (ROS) elevation, ultimately leading to >95 % antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), which is higher than that of single thermotherapy (almost no antibacterial activity) or ROS therapy (about 80 %). In addition, the composite nanofiber mats exhibited promotion effects on infected wound healing in vivo. This study demonstrates the great prospects of composite nanofiber dressings in clinical treatment of bacterial-infected wounds.

Multi-level Reactive Oxygen Species Amplifier to Enhance Photo-/Chemo-Dynamic/Ca2+ Overload Synergistic Therapy

Reactive oxygen species (ROS)-involved photodynamic therapy (PDT) and chemodynamic therapy (CDT) hold great promise for tumor treatment. However, hypoxia, insufficient H2O2, and overexpressed glutathione (GSH) in the tumor microenvironment (TME) hinder ROS generation significantly. Herein, we reported CaO2@Cu-TCPP/CUR with O2/H2O2/Ca2+ self-supply and GSH depletion for enhanced PDT/CDT and Ca2+ overload synergistic therapy. CaO2 nanospheres were first prepared and used as templates for guiding the coordination between the carboxyl of tetra-(4-carboxyphenyl)porphine (TCPP) and Cu2+ ions as hollow CaO2@Cu-TCPP, which facilitated GSH-activated TCPP-based PDT and Cu+-mediated CDT. The hollow structure was then loaded with curcumin (CUR) to form CaO2@Cu-TCPP/CUR composites. Cu-TCPP prevented degradation of CaO2, while Cu2+ ions reacted with GSH to deplete GSH, produce Cu+ ions, and release TCPP, CaO2, and CUR. CaO2 reacted with H2O to generate O2, H2O2, and Ca2+ to achieve O2/H2O2/Ca2+ self-supply for TCPP-based PDT, Cu+-mediated CDT, and CUR-enhanced Ca2+ overload therapy. Thus, this multilevel ROS amplifier enhances synergistic therapy with fewer side effects and drug resistance.

Precise molecular engineering for the preparation of pyridinium photosensitizers with efficient ROS generation and photothermal conversion

Organic photosensitizers (PSs) with aggregation-induced emission properties have great development potential in the integrated application of multi-mode diagnosis and treatment of photodynamic therapy (PDT) and photothermal therapy (PTT). However, preparing high-quality PSs with both optical and biological properties, high reactive oxygen species (ROS) and photothermal conversion ability are undoubtedly a great challenge. In this work, a series of pyridinium AIE PSs modified with benzophenone have been synthesized. A wide wavelength range of fluorescent materials was obtained by changing the conjugation and donor-acceptor strength. TPAPs5 has a significant advantage over similar compounds, and we have also identified the causes of high ROS generation and high photothermal conversion in terms of natural transition orbitals, excited state energy levels, ground-excited state configuration differences and recombination energy. Interestingly, migration of target sites was also found in biological imaging experiments, which also provided ideas for the design of double-targeted fluorescent probes. Therefore, the present work proposed an effective molecular design strategy for synergistic PDT and PTT therapy.

Ultrathin Clay Nanoparticles-Mediated Mutual Reinforcement of Ferroptosis and Cancer Immunotherapy

Ferroptosis-triggered immunogenic cell death (ICD) is widely adopted to potentiate the body's antitumor immunity by catalyzing the production of toxic reactive oxygen species (ROS). However, the efficacy of ferroptosis and immunotherapy is greatly restricted by intracellular abundant glutathione (GSH) and immunosuppressive tumor microenvironment (TME). Herein, a facile bottom-up method for solvent-free synthesis of ultrathin manganese (Mn)-based layered double hydroxide nanosheets with high loading efficiency for pro-inflammatory cytokine interferon (IFNγ) (IFNγ/uMn-LDHs) is proposed to mutually reinforce the ferroptosis and systemic immunity. The introduction of manganese ions significantly contributes to GSH depletion and hydroxyl radical generation, which can be further enhanced by IFNγ delivery-induced SLC7A11 downregulation. The ICD effect after cell ferroptosis cooperates with the intrinsic immunomodulatory property of IFNγ/uMn-LDHs to facilitate the maturation of dendritic cells (DCs) and the priming of T cells. IFNγ secretion from activated CD8+ T cells in turn involves cascade immunogenic ferroptosis, thus constructing a closed-loop therapy. Remarkably, a potent abscopal effect is observed in the growth inhibition of both primary and distant tumors. Overall, the ultrathin Mn-based clay nanoplatform provides a simple approach for mutual regulation between ferroptosis and antitumor immune response, overcoming the obstacles of current cancer immunotherapy.

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.

The Emerging Landscape for Combating Resistance Associated with Energy-Based Therapies via Nanomedicine

Cancer represents a serious disease with significant implications for public health, imposing substantial economic burden and negative societal consequences. Compared to conventional cancer treatments, such as surgery and chemotherapy, energy-based therapies (ET) based on athermal and thermal ablation provide distinct advantages, including minimally invasive procedures and rapid postoperative recovery. Nevertheless, due to the complex pathophysiology of many solid tumors, the therapeutic effectiveness of ET is often limited. Nanotechnology offers unique opportunities by enabling facile material designs, tunable physicochemical properties, and excellent biocompatibility, thereby further augmenting the outcomes of ET. Numerous nanomaterials have demonstrated the ability to overcome intrinsic therapeutic resistance associated with ET, leading to improved antitumor responses. This comprehensive review systematically summarizes the underlying mechanisms of ET-associated resistance (ETR) and highlights representative applications of nanoplatforms used to mitigate ETR. Overall, this review emphasizes the recent advances in the field and presents a detailed account of novel nanomaterial designs in combating ETR, along with efforts aimed at facilitating their clinical translation.

Dual/Multi-Modal Image-Guided Diagnosis and Therapy Based on Luminogens with Aggregation-Induced Emission

The combination of multiple imaging methods has made an indelible contribution to the diagnosis, surgical navigation, treatment, and prognostic evaluation of various diseases. Due to the unique advantages of luminogens with aggregation-induced emission (AIE), their progress has been significant in the field of organic fluorescent contrast agents. Herein, this manuscript summarizes the recent advancements in AIE molecules as contrast agents for optical image-based dual/multi-modal imaging. We particularly focus on the exceptional properties of each material and the corresponding application in the diagnosis and treatment of diseases.

An AIE Metal Iridium Complex: Photophysical Properties and Singlet Oxygen Generation Capacity

Photodynamic therapy (PDT) has garnered significant attention in the fields of cancer treatment and drug-resistant bacteria eradication due to its non-invasive nature and spatiotemporal controllability. Iridium complexes have captivated researchers owing to their tunable structure, exceptional optical properties, and substantial Stokes displacement. However, most of these complexes suffer from aggregation-induced quenching, leading to diminished luminous efficiency. In contrast to conventional photosensitizers, photosensitizers exhibiting aggregation-induced luminescence (AIE) properties retain the ability to generate a large number of reactive oxygen species when aggregated. To overcome these limitations, we designed and synthesized a novel iridium complex named Ir-TPA in this study. It incorporates quinoline triphenylamine cyclomethylated ligands that confer AIE characteristics for Ir-TPA. We systematically investigated the photophysical properties, AIE behavior, spectral features, and reactive oxygen generation capacity of Ir-TPA. The results demonstrate that Ir-TPA exhibits excellent optical properties with pronounced AIE phenomenon and robust capability for producing singlet oxygen species. This work not only introduces a new class of metal iridium complex photosensitizer with AIE attributes but also holds promise for achieving remarkable photodynamic therapeutic effects in future cellular experiments and biological studies.

Augmenting Immunotherapy via Bioinspired MOF-Based ROS Homeostasis Disruptor with Nanozyme-Cascade Reaction

Despite its remarkable clinical breakthroughs, immune checkpoint blockade (ICB) therapy remains limited by the insufficient immune response in the "cold" tumor. Nanozyme-based antitumor catalysis is associated with precise immune activation in the tumor microenvironment (TME). In this study, a cascade-augmented nanoimmunomodulator (CMZM) with multienzyme-like activities, which includes superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione oxidase (GSHOx), that dissociates under an acidic and abundant GSH TME, is proposed for multimodal imaging-guided chemodynamic therapy (CDT)/photodynamic therapy (PDT) enhanced immunotherapy. Vigorous multienzyme-like activities can not only produce O2 to alleviate hypoxia and promote the polarization of M2 to M1 macrophages, but also generate ROS (•OH and 1 O2 ) and deplete GSH in the TME to expose necrotic cell fragments and reverse immunosuppressive TME by eliciting the maturation of dendritic cells and infiltration of cytotoxic T lymphocytes (CTLs) in tumors. Therefore, inhibitory effects on both primary and distant tumors are achieved through synergy with an α-PD-L1 blocking antibody. This cascade multienzyme-based nanoplatform provides a smart strategy for highly efficient ICB immunotherapy against "cold" tumors by revising immunosuppressive TME.

Composite Nanomaterials of Conjugated Polymers and Upconversion Nanoparticles for NIR-Triggered Photodynamic/Photothermal Synergistic Cancer Therapy

Phototherapies such as photodynamic therapy (PDT) and photothermal therapy (PTT) have attracted great attention in the field of cancer treatment. However, the individual PDT or PTT makes it difficult to achieve optimal antitumor effects compared to the PDT/PTT combined therapy. Also, the effect of PDT is usually limited by the penetration depth of the UV-vis light source. Herein, we designed and synthesized novel composite nanoparticles UCNPs-CPs, which are constructed from two conjugated polymers and upconversion nanoparticles β-NaYF4:Yb,Tm (UCNPs) via a coordination reaction. By virtue of the excellent spectral overlap between absorption of conjugated polymers and emission of UCNPs, the UCNPs can absorb NIR light and effectively excite conjugated polymers by energy transfer to produce massive reactive oxygen species under 980 nm excitation and heat energy under 808 nm laser irradiation, achieving photodynamic/photothermal synergistic therapy. The in vitro cellular investigation proves that the dual modal phototherapy exhibits enhanced antitumor ability compared to single PDT or PTT. Furthermore, UCNPs-CPs inhibit tumor growth 100% in a 4T1 breast tumor mice model with both NIR laser irradiation, indicating that UCNPs-CPs is an excellent platform for synergistic PDT/PTT treatment. Thus, this study provides a promising strategy for NIR-triggered dual modal phototherapy.

Bioparameter-directed nanoformulations as MRI CAs enable the specific visualization of hypoxic tumour

A malignant tumour has hypoxic cells of varying degrees. The more severe the hypoxic degree, the more difficult the prognosis of the tumour and the higher the recurrence rate. Therefore, tumour hypoxia imaging is crucial. Magnetic resonance imaging (MRI) shows its strength in high resolution, depth of penetration and noninvasiveness. However, it needs more excellent contrast agents (CAs) to combat the complex tumour microenvironment (TME) and increased targeting of tumours to enhance clinical safety. Many research studies have focused on developing hypoxia-responsive MRI CAs that take advantage of the unique characteristics of hypoxic tumours. The low oxygen pressure, acidic TME, and up-regulated redox molecule levels found in hypoxic tumours serve as biological stimuli for nanoformulations that can accurately image the hypoxic region. This review highlights the importance of developing bioparameter-directed nanoformulations as MRI CAs for accurate tumour diagnosis. The design strategies and mechanisms of tumour-hypoxia imaging with nanoformulations are exemplified, with a focus on pH-responsiveness, redox-responsiveness, and p(O2)-responsiveness. The promising future of bioparameter-responsive nanoformulations for accurate tumour diagnosis and personalised cancer treatment is discussed.

Photothermal-Triggered Sulfur Oxide Gas Therapy Augments Type I Photodynamic Therapy for Potentiating Cancer Stem Cell Ablation and Inhibiting Radioresistant Tumor Recurrence

Despite advances in cancer therapy, the existence of self-renewing cancer stem cells (CSC) can lead to tumor recurrence and radiation resistance, resulting in treatment failure and high mortality in patients. To address this issue, a near-infrared (NIR) laser-induced synergistic therapeutic platform has been developed by incorporating aggregation-induced emission (AIE)-active phototheranostic agents and sulfur dioxide (SO2 ) prodrug into a biocompatible hydrogel, namely TBH, to suppress malignant CSC growth. Outstanding hydroxyl radical (·OH) generation and photothermal effect of the AIE phototheranostic agent actualizes Type I photodynamic therapy (PDT) and photothermal therapy through 660 nm NIR laser irradiation. Meanwhile, a large amount of SO2 is released from the SO2 prodrug in thermo-sensitive TBH gel, which depletes upregulated glutathione in CSC and consequentially promotes ·OH generation for PDT enhancement. Thus, the resulting TBH hydrogel can diminish CSC under 660 nm laser irradiation and finally restrain tumor recurrence after radiotherapy (RT). In comparison, the tumor in the mice that were only treated with RT relapsed rapidly. These findings reveal a double-boosting ·OH generation protocol, and the synergistic combination of AIE-mediated PDT and gas therapy provides a novel strategy for inhibiting CSC growth and cancer recurrence after RT, which presents great potential for clinical treatment.

Cancer cell membrane-coated upconversion nanoparticles/ZnxMn1-xS core-shell nanoparticles for targeted photodynamic and chemodynamic therapy of pancreatic cancer

Oxidative stress induced by reactive oxygen species (ROS) is promising treatment approach for pancreatic ductal adenocarcinoma (PDAC), which is typically insensitive to conventional chemotherapy. In this study, BxPC-3 pancreatic cancer cell membrane-coated upconversion nanoparticles/ZnxMn1-xS core-shell nanoparticles (abbreviated as BUC@ZMS) were developed for tumor-targeted cancer therapy via synergistically oxidative stress and overcoming glutathione (GSH) overexpression. Using a combination of photodynamic therapy (PDT) and chemodynamic therapy (CDT), the BUC@ZMS core-shell nanoparticles were able to elicit the death of pancreatic cancer cells through the high production of ROS. Additionally, the BUC@ZMS core-shell nanoparticles could deplete intracellular GSH and increase the sensitivity of tumor cells to oxidative stress. The in vivo results indicated that BUC@ZMS nanoparticles can accumulate specifically in tumor locations and suppress PDAC without generating obvious toxicity. Thus, it was determined that the as-prepared core-shell nanoparticles would be a viable treatment option for solid malignancies.

Effective Modulation of Inflammation and Oxidative Stress for Enhanced Regeneration of Intervertebral Discs Using 3D Porous Hybrid Protein Nanoscaffold

Degeneration of fibrocartilaginous tissues is often associated with complex pro-inflammatory factors. These include reactive oxygen species (ROS), cell-free nucleic acids (cf-NAs), and epigenetic changes in immune cells. To effectively control this complex inflammatory signaling, it developed an all-in-one nanoscaffold-based 3D porous hybrid protein (3D-PHP) self-therapeutic strategy for treating intervertebral disc (IVD) degeneration. The 3D-PHP nanoscaffold is synthesized by introducing a novel nanomaterial-templated protein assembly (NTPA) strategy. 3D-PHP nanoscaffolds that avoid covalent modification of proteins demonstrate inflammatory stimuli-responsive drug release, disc-mimetic stiffness, and excellent biodegradability. Enzyme-like 2D nanosheets incorporated into nanoscaffolds further enabled robust scavenging of ROS and cf-NAs, reducing inflammation and enhancing the survival of disc cells under inflammatory stress in vitro. Implantation of 3D-PHP nanoscaffolds loaded with bromodomain extraterminal inhibitor (BETi) into a rat nucleotomy disc injury model effectively suppressed inflammation in vivo, thus promoting restoration of the extracellular matrix (ECM). The resulting regeneration of disc tissue facilitated long-term pain reduction. Therefore, self-therapeutic and epigenetic modulator-encapsulated hybrid protein nanoscaffold shows great promise as a novel approach to restore dysregulated inflammatory signaling and treat degenerative fibrocartilaginous diseases, including disc injuries, providing hope and relief to patients worldwide.

Dual-Pronged Attack: pH-Driven Membrane-Anchored NIR Dual-Type Nano-Photosensitizer Excites Immunogenic Pyroptosis and Sequester Immune Checkpoint for Enhanced Prostate Cancer Photo-Immunotherapy

Prostate cancer (PCa) is a frustrating immunogenic "cold" tumor and generally receives unsatisfied immunotherapy outcomes in the clinic. Pyroptosis is an excellent immunogenic cell death form that can effectively activate the antitumor immune response, promote cytotoxic T-lymphocyte infiltration, and convert tumors from "cold" to "hot." However, the in vivo application of pyroptosis drugs is seriously limited, and the upregulation of tumor PD-L1 caused by photo-immunotherapy further promotes immune escape. Herein, a new nano-photosensitizer (YBS-BMS NPs-RKC) with pH-response integrating immunogenic pyroptosis induction and immune checkpoint blockade is developed. The pH-responsive polymer equipped with the cell membrane anchoring peptide RKC is used as the carrier and further encapsulated with the near-infrared-activated semiconductor polymer photosensitizer YBS and a PD-1/PD-L1 complex small molecule inhibitor BMS-202. The pH-driven membrane-anchoring and pyroptosis activation of YBS-BMS NPs-RKC is clearly demonstrated. In vitro and in vivo studies have shown that this dual-pronged therapy stimulates a powerful antitumor immune response to suppress primary tumor progression and evokes long-term immune memory to inhibit tumor relapse and metastasis. This work provides an effective self-synergistic platform for PCa immunotherapy and a new idea for developing more biocompatible photo-controlled pyroptosis inducers.

Recent theranostic applications of hydrogen peroxide-responsive nanomaterials for multiple diseases

It is well established that hydrogen peroxide (H2O2) is associated with the initiation and progression of many diseases. With the rapid development of nanotechnology, the diagnosis and treatment of those diseases could be realized through a variety of H2O2-responsive nanomaterials. In order to broaden the application prospects of H2O2-responsive nanomaterials and promote their development, understanding and summarizing the design and application fields of such materials has attracted much attention. This review provides a comprehensive summary of the types of H2O2-responsive nanomaterials including organic, inorganic and organic-inorganic hybrids in recent years, and focused on their specific design and applications. Based on the type of disease, such as tumors, bacteria, dental diseases, inflammation, cardiovascular diseases, bone injury and so on, key examples for above disease imaging diagnosis and therapy strategies are introduced. In addition, current challenges and the outlook of H2O2-responsive nanomaterials are also discussed. This review aims to stimulate the potential of H2O2-responsive nanomaterials and provide new application ideas for various functional nanomaterials related to H2O2.

A Photo-Activated Thermoelectric Catalyst for Ferroptosis-/Pyroptosis-Boosted Tumor Nanotherapy

Phototherapy including photothermal therapy (PTT) and photodynamic therapy (PDT) has gradually come into the limelight for oncological treatment due to its noninvasiveness, high specificity, and low side effects. However, upregulated heat-shock proteins (HSPs) and reactive oxygen species (ROS)-defensing system such as glutathione (GSH) or MutT homolog 1 (MTH1) protein in tumor microenvironment counteract the efficiency of single-modality therapy either PTT or PDT. Herein, the well-defined bismuth telluride nanoplates (Bi2 Te3 NPs) are engineered with a high-performance photo-thermo-electro-catalytic effect for tumor-synergistic treatment. Upon near-infrared light illumination, Bi2 Te3 NPs induce a significant temperature elevation for PTT, which effectively inhibits MTH1 expression. Especially, heating and cooling alteration caused temperature variations result in electron-hole separation for ROS generation, which not only damages HSPs to reduce the thermotolerance for enhance PTT, but also arouses tumor cell pyroptosis. Additionally, Bi2 Te3 NPs conspicuously reduce GSH, further improving ROS level and leading to decrease glutathione peroxidase 4 (GPX4) activity, which triggers tumor cell ferroptosis. Due to the photo-thermo-electro-catalytic synergistic therapy, Bi2 Te3 NPs are gifted with impressive tumor suppression on both ectopic and orthotopic ocular tumor models. This work highlights a high-performance multifunctional energy-conversion nanoplatform for reshaping tumor microenvironment to boost the tumor-therapeutic efficacy of phototherapy.

Nanoparticle-Based Photothermal Therapy for Breast Cancer Noninvasive Treatment

Rapid advancements in materials science and nanotechnology, intertwined with oncology, have positioned photothermal therapy (PTT) as a promising noninvasive treatment strategy for cancer. The breast's superficial anatomical location and aesthetic significance render breast cancer a particularly pertinent candidate for the clinical application of PTT following melanoma. This review comprehensively explores the research conducted on the various types of nanoparticles employed in PTT for breast cancer and elaborates on their specific roles and mechanisms of action. The integration of PTT with existing clinical therapies for breast cancer is scrutinized, underscoring its potential for synergistic outcomes. Additionally, the mechanisms underlying PTT and consequential modifications to the tumor microenvironment after treatment are elaborated from a medical perspective. Future research directions are suggested, with an emphasis on the development of integrative platforms that combine multiple therapeutic approaches and the optimization of nanoparticle synthesis for enhanced treatment efficacy. The goal is to push the boundaries of PTT toward a comprehensive, clinically applicable treatment for breast cancer.

Selenium-Containing Type-I Organic Photosensitizers with Dual Reactive Oxygen Species of Superoxide and Hydroxyl Radicals as Switch-Hitter for Photodynamic Therapy

Organic type-I photosensitizers (PSs) which produce aggressive reactive oxygen species (ROS) with less oxygen-dependent exhibit attractive curative effect for photodynamic therapy (PDT), as they adapt better to hypoxia microenvironment in tumors. However, the reported type-I PSs are limited and its exacted mechanism of oxygen dependence is still unclear. Herein, new selenium-containing type-I PSs of Se6 and Se5 with benzoselenadiazole acceptor has been designed and possessed aggregation-induced emission characteristic. Benefited from double heavy-atom-effect of selenium and bromine, Se6 shows a smaller energy gap (ΔEST ) of 0.03 eV and improves ROS efficiency. Interestingly, type-I radicals of both long-lived superoxide anion (O2 •‾ ) and short-lived hydroxyl (• OH) are generated from them upon irradiation. This may provide a switch-hitter of dual-radical with complementary lifetimes for PDT. More importantly, simultaneous processes to produce • OH are revealed, including disproportionation of O2 •‾ and reaction between excited PS and water. Actually, Se6 displays superior in-vitro PDT performance to commercial chlorin e6 (Ce6), under normoxia or hypoxia. After intravenous injection, a significantly in-vivo PDT performance is demonstrated on Se6, where tumor growth inhibition rates of 99% is higher than Ce6. These findings offer new insights about both molecular design and mechanism study of type-I PSs.

A hybrid nanopharmaceutical for specific-amplifying oxidative stress to initiate a cascade of catalytic therapy for pancreatic cancer

BACKGROUND

Oxidative stress (OS) induced by an imbalance of oxidants and antioxidants is an important aspect in anticancer therapy, however, as an adaptive response, excessive glutathione (GSH) in the tumor microenvironment (TME) acts as an antioxidant against high reactive oxygen species (ROS) levels and prevents OS damage to maintain redox homoeostasis, suppressing the clinical efficacy of OS-induced anticancer therapies.

RESULTS

A naturally occurring ROS-activating drug, galangin (GAL), is introduced into a Fenton-like catalyst (SiO₂@MnO₂) to form a TME stimulus-responsive hybrid nanopharmaceutical (SiO₂-GAL@MnO₂, denoted SG@M) for enhancing oxidative stress. Once exposed to TME, as MnO₂ responds and consumes GSH, the released Mn²⁺ converts endogenous hydrogen peroxide (H₂O₂) into hydroxyl radicals (·OH), which together with the subsequent release of GAL from SiO₂ increases ROS. The "overwhelming" ROS cause OS-mediated mitochondrial malfunction with a decrease in mitochondrial membrane potential (MMP), which releases cytochrome c from mitochondria, activates the Caspase 9/Caspase 3 apoptotic cascade pathway. Downregulation of JAK2 and STAT3 phosphorylation levels blocks the JAK2/STAT3 cell proliferation pathway, whereas downregulation of Cyclin B1 protein levels arrest the cell cycle in the G2/M phase. During 18 days of in vivo treatment observation, tumor growth inhibition was found to be 62.7%, inhibiting the progression of pancreatic cancer. Additionally, the O₂ and Mn²⁺ released during this cascade catalytic effect improve ultrasound imaging (USI) and magnetic resonance imaging (MRI), respectively.

CONCLUSION

This hybrid nanopharmaceutical based on oxidative stress amplification provides a strategy for multifunctional integrated therapy of malignant tumors and image-visualized pharmaceutical delivery.

Tumor-targeted nanoflowers regulate glutamine metabolism and amplify oxidative stress for synergistic therapy

We designed and synthesized tumor-targeted nanoflowers to inhibit glutamine metabolism and amplify oxidative stress, which could synergistically suppress tumor growth.

Visible-light-induced strong oxidation capacity of metal-free carbon nanodots through photo-induced surface reduction for photocatalytic antibacterial and tumor therapy

Biocompatible metal-free carbon dots (CDs) with good photo-induced strong oxidation capacity in aqueous solutions are scarce for high-performance photocatalytic antibacterial and tumor therapy. In this work, we achieved effective visible light-induced cell death and antibacterial performance based on biocompatible metal-free CDs. The visible-light-induced reducing ability of the surface electron-withdrawing structure of the CDs allowed for the remaining photo-induced holes with high oxidation capacity to oxidize water molecules and generate hydroxyl radicals. Antibiotic-resistant bacteria were effectively inhibited by the CDs under xenon lamp irradiation with 450 nm long pass filter. Moreover, CD-based tumor photocatalytic therapy in mice was achieved using a xenon lamp with 450 nm long pass filter (0.3 W cm^-2).

A hypochlorite-activated strategy for realizing fluorescence turn-on, type I and type II ROS-combined photodynamic tumor ablation

The combination of cancer cell-activated fluorescence and the advantages of both type I and type II photodynamic therapy (PDT) capabilities to achieve a synergistic therapeutic effect in a complex tumor environment is highly desirable. Herein, we report an approach by means of tumor intracellular hypochlorite (ClO^-) to turn on fluorescence integrated with type I and II ROS generation for imaging-guided PDT. The resultant PTZSPy functions as a type II photosensitizer with mitochondria-targeting capability. In the presence of ClO^-, PTZSPy is transformed into its oxidized counterpart SPTZSPy, turns on an orange-red fluorescence and triggers the type I ROS generation ability. Biological studies revealed that PTZSPy can accurately distinguishes tumor cells from normal cells, dynamically monitors the cell ablation process and be utilized for theranostics in MCF-7 tumor-bearing nude mice in vivo. This work provides an innovative strategy exploiting the highly abundant ClO^- in tumor cells for the type I and II ROS two-pronged and imaging-guided PDT.

Hyaluronic acid-covered piezoelectric nanocomposites as tumor microenvironment modulators for piezoelectric catalytic therapy of melanoma

Increasing the formation of reactive oxygen species (ROS) and reducing the elimination of ROS are the two main objectives in the development of novel inorganic sonosensitizers for use in sonodynamic therapy (SDT). Therefore, BTO-Pd-MnO₂-HA nanocomplexes with targeted tumor cells and degradable oxygen-producing shells were designed as piezoelectric sonosensitizers for enhancing SDT. The deposition of palladium particles (Pd NPs) leads to the formation of Schottky junctions, promoting the separation of electron-hole pairs and thereby increasing the efficiency of toxic ROS generation in SDT. The tumor microenvironment (TME) triggers the degradation of MnO₂, and the released Mn²⁺ ions catalyze the generation of hydroxyl radicals (•OH) from H₂O₂ through a Fenton-like reaction. BTO-Pd-MnO₂-HA can continuously consume glutathione (GSH) and generate O₂, thereby improving the efficiency of SDT and chemodynamic therapy (CDT). A multistep enhanced SDT process mediated by the piezoelectric sonosensitizers BTO-Pd-MnO₂-HA was designed, targeted by hyaluronic acid (HA), activated by decomposition in TME, and amplified by deposition of Pd. This procedure not only presents a new alternative for the improvement of sonosensitizers but also widens the application of piezoelectric nanomaterials in biomedicine.

Recent advances in 2D material-based phototherapy

Phototherapy, which generally refers to photothermal therapy (PTT) and photodynamic therapy (PDT), has received significant attention over the past few years since it is non-invasive, has effective selectivity, and has few side effects. As a result, it has become a promising alternative to traditional clinical treatments. At present, two-dimensional materials (2D materials) have proven to be at the forefront of the development of advanced nanomaterials due to their ultrathin structures and fascinating optical properties. As a result, much work has been put into developing phototherapy platforms based on 2D materials. This review summarizes the current developments in 2D materials beyond graphene for phototherapy, focusing on the novel approaches of PTT and PDT. New methods are being developed to go above and beyond conventional treatment to fully use the potential of 2D materials. Additionally, the efficacy of cutting-edge phototherapy is assessed, and the existing difficulties and future prospects of 2D materials for phototherapy are covered.

Mn3 O4 Nanoshell Coated Metal-Organic Frameworks with Microenvironment-Driven O2 Production and GSH Exhaustion Ability for Enhanced Chemodynamic and Photodynamic Cancer Therapies

Nanomedicine exhibits emerging potentials to deliver advanced therapeutic strategies in the fight against triple-negative breast cancer (TNBC). Nevertheless, it is still difficult to develop a precise codelivery system that integrates highly effective photosensitizers, low toxicity, and hydrophobicity. In this study, PCN-224 is selected as the carrier to enable effective cancer therapy through light-activated reactive oxygen species (ROS) formation, and the PCN-224@Mn₃ O₄ @HA is created in a simple one-step process by coating Mn₃ O₄ nanoshells on the PCN-224 template, which can then be used as an "ROS activator" to exert catalase- and glutathione peroxidase-like activities to alleviate tumor hypoxia while reducing tumor reducibility, leading to improved photodynamic therapeutic (PDT) effect of PCN-224. Meanwhile, Mn²⁺ produced cytotoxic hydroxyl radicals (∙OH) via the Fenton-like reaction, thus producing a promising spontaneous chemodynamic therapeutic (CDT) effect. Importantly, by remodeling the tumor microenvironment (TME), Mn₃ O₄ nanoshells downregulated hypoxia-inducible factor 1α expression, inhibiting tumor growth and preventing tumor revival. Thus, the developed nanoshells, via light-controlled ROS formation and multimodality imaging abilities, can effectively inhibit tumor proliferation through synergistic PDT/CDT, and prevent tumor resurgence by remodeling TME.

Engineering a polymer-encapsulated manganese dioxide/upconversion nanoprobe for FRET-based hydrogen peroxide detection

Hydrogen peroxide (H₂O₂) is considered a significant biomarker in various diseases and could induce deleterious health problems at irregular physiological concentrations. Therefore, developing a simple, efficient biocompatible nanoprobe for trace amount H₂O₂ detection with high sensitivity and specificity is of great help for early diagnosis and therapeutics. Herein, we designed amphiphilic poly(styrene-co-maleic anhydride) (PMSA)-encapsulated nanoclusters composed of upconversion nanoparticles (UCNPs) and manganese dioxide nanoparticles (MnO₂ NPs) at a specific ratio to produce a near-infrared (NIR) excited luminescent nanoprobe for H₂O₂ detection. Our results revealed that the MnO₂ NPs tended to experience catalytic decomposition when exposed to H₂O₂, while the UCNPs were retained inside the PSMA encapsulation, causing recovery of the UCNP emission band at 470 nm in accordance with H₂O₂ concentration. This luminescence recovery was linearly dependent on H₂O₂ concentrations, yielding a limit of detection (LOD) of 20 nM. The easy-to-interpret H₂O₂ nanoprobe also proved high selectivity in the presence of other interfering substances, and biocompatibility and water-dispersibility, making it an ideal candidate for real-time detection of disease-related H₂O₂ in living organisms.

Aggregation Effect on Multiperformance Improvement in Aryl-Armed Phenazine-Based Emitters

The concept of aggregate science was proposed to explain changes in materials performance that accompany the generation of aggregates, but aggregation-triggered multifunction improvements in a class of materials have rarely been reported. Herein, we present the first report of a new class of multifunctional aggregation-induced emission (AIE) luminogens (AIEgens) based on 5,10-diarylphenazine (DPZ) derivates with full-wavelength emission. Intriguingly, multiple properties, such as fluorescence intensity and free radical and type I reactive oxygen species (ROS) efficiencies, could be simultaneously activated from the unimolecular level to the aggregate state. The mechanisms of this multiple performance improvement are discussed in detail based on sufficient performance characterization, and some of the newly prepared AIEgens exhibited toxicity to cancer cells during photodynamic therapy. This work systematically demonstrates the positive effect of aggregation on improving multiple functions of materials, which is expected to promote the development of aggregate science theory for the design of multifunctional materials.

Alkaline Phosphatase-Mediated Bioetching of CoOOH/BiVO4 for Signal-On Organic Photoelectrochemical Transistor Bioanalysis

Organic photoelectrochemical transistor (OPECT) bioanalytics has recently appeared as a promising route for biological measurements, which has major implications in both next-generation photoelectrochemical (PEC) bioanalysis and futuristic biorelated implementations. Via biological dissociation of materials, bioetching is a useful technique for bio-manufacturing and bioanalysis. The intersection of these two domains is expected to be a possible way to achieve innovative OPECT bioanalytics. Herein, we validate such a possibility, which is exemplified by alkaline phosphatase (ALP)-mediated bioetching of a CoOOH/BiVO₄ gate for a signal-on OPECT immunoassay of human immunoglobulin G (HIgG) as the model target. Specifically, target-dependent bioetching of the upper CoOOH layer could result into an enhanced electrolyte contact and light accessibility to BiVO₄, leading to the modulated response of the polymeric poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) channel that could be monitored by the channel current. The introduced biosensor achieves sensitive detection of HIgG with high selectivity and sensitivity. This work features bioetching-enabled high-efficacy OPECT bioanalysis and is anticipated to serve as a generic protocol, considering the diverse bioetching routes.

Innovative strategies for photodynamic therapy against hypoxic tumor

Photodynamic therapy (PDT) is applied as a robust therapeutic option for tumor, which exhibits some advantages of unique selectivity and irreversible damage to tumor cells. Among which, photosensitizer (PS), appropriate laser irradiation and oxygen (O₂) are three essential components for PDT, but the hypoxic tumor microenvironment (TME) restricts the O₂ supply in tumor tissues. Even worse, tumor metastasis and drug resistance frequently happen under hypoxic condition, which further deteriorate the antitumor effect of PDT. To enhance the PDT efficiency, critical attention has been received by relieving tumor hypoxia, and innovative strategies on this topic continue to emerge. Traditionally, the O₂ supplement strategy is considered as a direct and effective strategy to relieve TME, whereas it is confronted with great challenges for continuous O₂ supply. Recently, O₂-independent PDT provides a brand new strategy to enhance the antitumor efficiency, which can avoid the influence of TME. In addition, PDT can synergize with other antitumor strategies, such as chemotherapy, immunotherapy, photothermal therapy (PTT) and starvation therapy, to remedy the inadequate PDT effect under hypoxia conditions. In this paper, we summarized the latest progresses in the development of innovative strategies to improve PDT efficacy against hypoxic tumor, which were classified into O₂-dependent PDT, O₂-independent PDT and synergistic therapy. Furthermore, the advantages and deficiencies of various strategies were also discussed to envisage the prospects and challenges in future study.

Recent Progress in Type I Aggregation-Induced Emission Photosensitizers for Photodynamic Therapy

In modern medicine, precision diagnosis and treatment using optical materials, such as fluorescence/photoacoustic imaging-guided photodynamic therapy (PDT), are becoming increasingly popular. Photosensitizers (PSs) are the most important component of PDT. Different from conventional PSs with planar molecular structures, which are susceptible to quenching effects caused by aggregation, the distinct advantages of AIE fluorogens open up new avenues for the development of image-guided PDT with improved treatment accuracy and efficacy in practical applications. It is critical that as much of the energy absorbed by optical materials is dissipated into the pathways required to maximize biomedical applications as possible. Intersystem crossing (ISC) represents a key step during the energy conversion process that determines many fundamental optical properties, such as increasing the efficiency of reactive oxygen species (ROS) production from PSs, thus enhancing PDT efficacy. Although some review articles have summarized the accomplishments of various optical materials in imaging and therapeutics, few of them have focused on how to improve the phototherapeutic applications, especially PDT, by adjusting the ISC process of organic optics materials. In this review, we emphasize the latest advances in the reasonable design of AIE-active PSs with type I photochemical mechanism for anticancer or antibacterial applications based on ISC modulation, as well as discuss the future prospects and challenges of them. In order to maximize the anticancer or antibacterial effects of type I AIE PSs, it is the aim of this review to offer advice for their design with the best energy conversion.

Synergistically Enhancing Tumor Chemotherapy Using an Aggregation-Induced Emission Photosensitizer on Covalently Conjugated Molecularly Imprinted Polymer Nanoparticles

Due to the polygenic and heterogeneous nature of the tumorigenesis process, traditional chemotherapy is far from desirable. Fabricating multifunctional nanoplatforms integrating photodynamic effect can synergistically enhance chemotherapy because they can make the cancer cells much sensitive to chemotherapeutics. However, how to assemble different units in nanoplatforms and minimize side effects caused by chemodrugs and photosensitizers (PSs) still needs to be explored. Herein, a nanoplatform CPP/PS-MIP@DOX is developed using a simultaneously covalently conjugated new aggregation-induced emission (AIE) PS and a cell-penetrating peptide (CPP) on the surface of silica-based molecularly imprinted polymer (MIP) nanoparticles, prepared with doxorubicin (DOX) as the template in the water system via a sol-gel technique. CPP/PS-MIP@DOX has good biocompatibility, high DOX-loading ability, promoted cellular uptake, and sustained and pH-sensitive drug release capability. Furthermore, it can efficiently penetrate into tumor tissue, accurately home to, and accumulate at the tumor site. As a result, a better efficacy with lower cytotoxicity is achieved with a smaller dosage of DOX by utilizing either the photodynamic effect or unique characteristics of the MIP. It is the first nanoplatform fabricated by chemically conjugating AIE PSs directly on the surface of the scaffold via the surface-decorated strategy and successfully applied in cancer therapy. This work provides an effective strategy by constructing AIE PS-based cancer nanomedicines with MIPs as scaffolds.

Synthesis of dual-stimuli responsive metal organic framework-coated iridium oxide nanocomposite functionalized with tumor targeting albumin-folate for synergistic photodynamic/photothermal cancer therapy

The synergistic effects of photothermal therapy (PTT) and photodynamic therapy (PDT) has attracted considerable attention in the field of cancer therapy because of its excellent anti-tumor effect. This work provides a novel pH/NIR responsive therapeutic nanoplatform, IrO₂@ZIF-8/BSA-FA (Ce6), producing a synergistic effect of PTT-PDT in the treatment of osteosarcoma. Iridium dioxide nanoparticles (IrO₂ NPs) with exceptional catalase-like activity and PTT effects were synthesized by a hydrolysis method and decorated with zeolitic imidazolate framework-8 (ZIF-8) shell layer to promote the physical absorption of Chlorin e6 (Ce6), and further functionalized with bovine serum albumin-folate acid (BSA-FA) for targeting tumor cells. The IrO₂@ZIF-8/BSA-FA nanocomposite indicated an outstanding photothermal heating conversion efficiency of 62.1% upon laser irradiation. In addition, the Ce6 loading endows nanoplatform with the capability to induce cell apoptosis under 660 nm near-infrared (NIR) laser irradiation through a reactive oxygen species (ROS)-mediated mechanism. It was further testified that IrO₂@ZIF-8/BSA-FA can function as a catalase and convert the endogenous hydrogen peroxide (H₂O₂) into oxygen (O₂) to improve the local oxygen pressure under the acidic tumor microenvironment (TME), which could subsequently amplified PDT-mediated ROS cell-killing performance via relieving hypoxia microenvironment of tumor. Both in vitro and in vivo experimental results indicated that the nanomaterials were good biocompatibility, and could remarkably achieve tumor-specific and enhanced combination therapy outcomes as compared with the corresponding PTT or PDT monotherapy. Taken together, this work holds great potential to design an intelligent multifunctional therapeutic nanoplatform for cancer therapy.

Biomedical engineered nanomaterials to alleviate tumor hypoxia for enhanced photodynamic therapy

Photodynamic therapy (PDT), as a highly selective, widely applicable, and non-invasive therapeutic modality that is an alternative to radiotherapy and chemotherapy, is extensively applied to cancer therapy. Practically, the efficiency of PDT is severely hindered by the existence of hypoxia in tumor tissue. Hypoxia is a typical hallmark of malignant solid tumors, which remains an essential impediment to many current treatments, thereby leading to poor clinical prognosis after therapy. To address this issue, studies have been focused on modulating tumor hypoxia to augment the therapeutic efficacy. Although nanomaterials to relieve tumor hypoxia for enhanced PDT have been demonstrated in many research articles, a systematical summary of the role of nanomaterials in alleviating tumor hypoxia is scarce. In this review, we introduced the mechanism of PDT, and the involved therapeutic modality of PDT for ablation of tumor cells was specifically summarized. Moreover, current advances in nanomaterials-mediated tumor oxygenation via oxygen-carrying or oxygen-generation tactics to alleviate tumor hypoxia are emphasized. Based on these considerable summaries and analyses, we proposed some feasible perspectives on nanoparticle-based tumor oxygenation to ameliorate the therapeutic outcomes, which may provide some detailed information in designing new oxygenation nanomaterials in this burgeneous field.

Ir(III) Complexes with AIE Characteristics for Biological Applications

Both biological process detection and disease diagnosis on the basis of luminescence technology can provide comprehensive insights into the mechanisms of life and disease pathogenesis and also accurately guide therapeutics. As a family of prominent luminescent materials, Ir(III) complexes with aggregation-induced emission (AIE) tendency have been recently explored at a tremendous pace for biological applications, by virtue of their various distinct advantages, such as great stability in biological media, excellent fluorescence properties and distinctive photosensitizing features. Significant breakthroughs of AIE-active Ir(III) complexes have been achieved in the past few years and great progress has been witnessed in the construction of novel AIE-active Ir(III) complexes and their applications in organelle-specific targeting imaging, multiphoton imaging, biomarker-responsive bioimaging, as well as theranostics. This review systematically summarizes the basic concepts, seminal studies, recent trends and perspectives in this area.

Platelet-Covered Nanocarriers for Targeted Delivery of Hirudin to Eliminate Thrombotic Complication in Tumor Therapy

Most patients are at high risk of thrombosis during cancer treatment. However, the major discrepancy in the therapeutic mechanisms and microenvironment between tumors and thrombosis makes it challenging for a panacea to treat cancer while being able to eliminate the risk of thrombosis. Herein, we developed a biomimetic MnOx/Ag₂S nanoflower platform with platelet membrane modification (MnOx@Ag₂S@hirudin@platelet membrane: MAHP) for the long-term release of anticoagulant drugs to treat thrombosis together with tumor therapy. This MAHP platform could achieve the targeted delivery of hirudin to the thrombus site and perform the controlled release under the irradiation of near-infrared light, demonstrating effective removal of the thrombus. Moreover, MAHP could inhibit tumor progression and prolong the survival time of mice with thromboembolic complications.

A Microneedle Patch with Self-Oxygenation and Glutathione Depletion for Repeatable Photodynamic Therapy

Photodynamic therapy (PDT) has attained extensive attention as a noninvasive tumor treatment modality. However, the hypoxia in solid tumors, skin phototoxicity of "always on" photosensitizers (PSs), and abundant supply of glutathione (GSH) in cancer cells severely hampered the clinical applications of PDT. Herein, a self-oxygenation nanoplatform (denoted as CZCH) with GSH depletion ability was encapsulated into the hyaluronic acid microneedle patch (MN-CZCH) to simultaneously improve the biosafety and therapeutic efficacy of PDT. The Cu²⁺-doped porous zeolitic imidazolate framework incorporated with catalase (CAT) is capable of efficiently loading PS 2-(1-hexyloxyethyl)-2-divinylpyropheophorbic-a (HPPH). The CZCH intermingled MN patch (MN-CZCH) could effectively penetrate the stratum corneum, topically transport HPPH to the target tumor site, achieve a long tumor retention time, and enhance the efficacy of PDT via the simultaneously synergistic effect of CAT-catalyzed self-supplying O₂ and Cu²⁺-mediated GSH depletion. Using traceable fluorescence (FL) imaging of the released HPPH from CZCH, the FL imaging-guided repeatable PDT can be achieved for enhanced antitumor efficacy. As a result, the MN-CZCH patch exhibited excellent therapeutic efficacy against melanoma with minimal toxicity, which has promising potential for cancer theranostics.

Type I Photosensitizers Based on Aggregation-Induced Emission: A Rising Star in Photodynamic Therapy

Photodynamic therapy (PDT), emerging as a minimally invasive therapeutic modality with precise controllability and high spatiotemporal accuracy, has earned significant advancements in the field of cancer and other non-cancerous diseases treatment. Thereinto, type I PDT represents an irreplaceable and meritorious part in contributing to these delightful achievements since its distinctive hypoxia tolerance can perfectly compensate for the high oxygen-dependent type II PDT, particularly in hypoxic tissues. Regarding the diverse type I photosensitizers (PSs) that light up type I PDT, aggregation-induced emission (AIE)-active type I PSs are currently arousing great research interest owing to their distinguished AIE and aggregation-induced generation of reactive oxygen species (AIE-ROS) features. In this review, we offer a comprehensive overview of the cutting-edge advances of novel AIE-active type I PSs by delineating the photophysical and photochemical mechanisms of the type I pathway, summarizing the current molecular design strategies for promoting the type I process, and showcasing current bioapplications, in succession. Notably, the strategies to construct highly efficient type I AIE PSs were elucidated in detail from the two aspects of introducing high electron affinity groups, and enhancing intramolecular charge transfer (ICT) intensity. Lastly, we present a brief conclusion, and a discussion on the current limitations and proposed opportunities.

AIE-active iridium(III) complex integrated with upconversion nanoparticles for NIR-irradiated photodynamic therapy

The integration of an aggregation induced emission (AIE)-active Ir(III) complex and upconversion nanoparticles (UCNPs) has achieved a NIR-irradiated photosensitizer (PS), UCNPs@Ir-2-N. This PS has satisfactory biocompatibility, excellent phototoxicity, good accumulation in cells and high ¹O₂ generation ability, thereby effectively killing 4T1 mouse cancer cells in vitro. This work has potential for future photodynamic therapy (PDT) applications.