A Unique Multifunctional Nanoenzyme Tailored for Triggering Tumor Microenvironment Activated NIR-II Photoacoustic Imaging and Chemodynamic/Photothermal Combined Therapy

Emerging engineered nanozymes: current status and future perspectives in cancer treatments

Composite nanozymes are composed of enzymes with similar or different catalytic capabilities and have higher catalytic activity than a single enzyme. In recent years, composite nanozymes have emerged as novel nanomaterial platforms for multiple applications in various research fields, where they are used to produce oxygen, consume glutathione, or produce toxic reactive oxygen species (ROS) for cancer therapy. The therapeutic approach using composite nanozymes is known as chemo-dynamic therapy (CDT). Some composite nanozymes also show special photothermal conversion effects, enabling them to be combined with pioneering cancer treatments, such as photodynamic therapy (PDT), photothermal therapy (PTT) and sonodynamic therapy (SDT), and enhance the anti-cancer effects. In this study, the classification and catalytic performances of composite nanozymes are reviewed, along with their advantages and synthesis methods. Furthermore, the applications of composite nanozymes in the treatment of cancers are emphasized, and the prospective challenges in the future are discussed.

PdRu bimetallic nanoalloys with improved photothermal effect for amplified ROS-mediated tumor therapy

An emerging strategy in cancer therapy involves inducing reactive oxygen species (ROS), specifically within tumors using nanozymes. However, existing nanozymes suffer from limitations such as low reactivity, poor biocompatibility, and limited targeting capabilities, hindering their therapeutic efficacy. In response, the PdRu@PEI bimetallic nanoalloys were constructed with well-catalytic activities and effective separation of charges, which can catalyze hydrogen peroxide (H2O2) to toxic hydroxyl radical (·OH) under near-infrared laser stimulation. Through facilitating electron transfer and enhancing active sites, the enhanced peroxidase-like (POD-like) enzymatic activity and glutathione (GSH) depletion abilities of nanozymes are boosted through a simple co-reduction process, leading to promising anti-tumor activity. The electron transfer between Pd and Ru of PdRu@PEI nanoalloys contributes to POD-like activity. Then, by oxidizing endogenous overexpressed GSH, enzymatic cycling prevents GSH from consuming ROS. Furthermore, the surface plasmon resonance effect of near-infrared laser on bimetallic nanoalloys ensures its photothermal performance and its local heating, further promoting POD-like activity. The integrated multi-modal therapeutic approach of PdRu@PEI has demonstrated significant anti-cancer effects in vivo studies. The nanozymes exhibit high catalytic efficiency and excellent biocompatibility, offering valuable insights for the development of nano-catalysts/enzymes for biomedical applications.

Applications of nanotheranostics in the second near-infrared window in bioimaging and cancer treatment

Achieving accurate and efficient tumor imaging is crucial in the field of tumor treatment, as it facilitates early detection and precise localization of tumor tissues, thereby informing therapeutic strategies and surgical interventions. The optical imaging technology within the second near-infrared (NIR-II) window has garnered significant interest for its remarkable benefits, such as enhanced tissue penetration depth, superior signal-to-background ratio (SBR), minimal tissue autofluorescence, reduced photon attenuation, and lower tissue scattering. This review explained the design and optimization strategies of nano-agents responsive to the NIR-II window, such as single-walled carbon nanotubes, quantum dots, lanthanum-based nanomaterials, and noble metal nanomaterials. These nano-agents enable non-invasive, deep-tissue imaging with high spatial resolution in the NIR-II window, and their superior optical properties significantly improve the accuracy, efficiency, and versatility of imaging-guided tumor treatments. And we discussed the characteristics and advantages of fluorescence imaging (FL)/photoacoustic imaging (PA) in NIR-II window, providing a comprehensive overview of the latest research progress of different nano-agents in FL/PA imaging-guided tumor therapy. Furthermore, we exhaustively reviewed the latest applications of multifunctional nano-phototherapy technologies carried out by NIR-II light including photothermal therapy (PTT), photodynamic therapy (PDT), and combined modalities like photothermal-chemodynamic therapy (PTT-CDT), photothermal-chemotherapy (PTT-CT), and photothermal- immunotherapy (PTT-IO). These imaging-guided integrated tumor therapy approaches within the NIR-II window have gradually matured over the past decade and are expected to become a safe and effective non-invasive tumor treatment. Finally, we outlined the prospects and challenges of development and innovation of the NIR-II integrated diagnosis and therapy nanoplatform. This review aims to provide insightful perspectives for future advancements in NIR-II optical tumor diagnosis and integrated treatment platforms.

Valence-engineered catalysis-selectivity regulation of molybdenum oxide nanozyme for acute kidney injury therapy and post-cure assessment

The optimization of the enzyme-like catalytic selectivity of nanozymes for specific reactive oxygen species (ROS)-related applications is significant, and meanwhile the real-time monitoring of ROS is really crucial for tracking the therapeutic process. Herein, we present a mild oxidation valence-engineering strategy to modulate the valence states of Mo in Pluronic F127-coated MoO3-x nanozymes (denoted as MF-x, x: oxidation time) in a controlled manner aiming to improve their specificity of H2O2-associated catalytic reactions for specific therapy and monitoring of ROS-related diseases. Experimentally, MF-0 (Mo average valence 4.64) and MF-10 (Mo average valence 5.68) exhibit exclusively optimal catalase (CAT)- or peroxidase (POD)-like activity, respectively. Density functional theory (DFT) calculations verify the most favorable reaction path for both MF-0- and MF-10-catalyzed reaction processes based on free energy diagram and electronic structure analysis, disclosing the mechanism of the H2O2 activation pathway on the Mo-based nanozymes. Furthermore, MF-0 poses a strong potential in acute kidney injury (AKI) treatment, achieving excellent therapeutic outcomes in vitro and in vivo. Notably, the ROS-responsive photoacoustic imaging (PAI) signal of MF-0 during treatment guarantees real-time monitoring of the therapeutic effect and post-cure assessment in vivo, providing a highly desirable non-invasive diagnostic approach for ROS-related diseases.

Fine-Tuning Electron Transfer for Nanozyme Design

Nanozymes, with their versatile composition and structural adaptability, present distinct advantages over natural enzymes including heightened stability, customizable catalytic activity, cost-effectiveness, and simplified synthesis process, making them as promising alternatives in various applications. Recent advancements in nanozyme research have shifted focus from serendipitous discovery toward a more systematic approach, leveraging machine learning, theoretical calculations, and mechanistic explorations to engineer nanomaterial structures with tailored catalytic functions. Despite its pivotal role, electron transfer, a fundamental process in catalysis, has often been overlooked in previous reviews. This review comprehensively summarizes recent strategies for modulating electron transfer processes to fine-tune the catalytic activity and specificity of nanozymes, including electron-hole separation and carrier transfer. Furthermore, the bioapplications of these engineered nanozymes, including antimicrobial treatments, cancer therapy, and biosensing are also introduced. Ultimately, this review aims to offer invaluable insights for the design and synthesis of nanozymes with enhanced performance, thereby advancing the field of nanozyme research.

Atomic Engineering of Single-Atom Nanozymes for Biomedical Applications

Single-atom nanozymes (SAzymes) showcase not only uniformly dispersed active sites but also meticulously engineered coordination structures. These intricate architectures bestow upon them an exceptional catalytic prowess, thereby captivating numerous minds and heralding a new era of possibilities in the biomedical landscape. Tuning the microstructure of SAzymes on the atomic scale is a key factor in designing targeted SAzymes with desirable functions. This review first discusses and summarizes three strategies for designing SAzymes and their impact on reactivity in biocatalysis. The effects of choices of carrier, different synthesis methods, coordination modulation of first/second shell, and the type and number of metal active centers on the enzyme-like catalytic activity are unraveled. Next, a first attempt is made to summarize the biological applications of SAzymes in tumor therapy, biosensing, antimicrobial, anti-inflammatory, and other biological applications from different mechanisms. Finally, how SAzymes are designed and regulated for further realization of diverse biological applications is reviewed and prospected. It is envisaged that the comprehensive review presented within this exegesis will furnish novel perspectives and profound revelations regarding the biomedical applications of SAzymes.

Ultralow Loading Copper-Intercalated MoO3 Nanobelts with High Activity against Antibiotic-Resistant Bacteria

In recent years, the infection rate of antibiotic resistance has been increasing year by year, and the prevalence of super bacteria has posed a great threat to human health. Therefore, there is an urgent need to find new antibiotic alternatives with long-term inhibitory activity against a broad spectrum of bacteria and microorganisms in order to avoid the proliferation of more multidrug-resistant (MDR) bacteria. The presence of natural van der Waals (vdW) gaps in layered materials allows them to be easily inserted by different guest species, providing an attractive strategy for optimizing their physicochemical properties and applications. Here, we have successfully constructed a copper-intercalated α-MoO3 nanobelt based on nanoenzymes, which is antibacterial through the synergistic effect of multiple enzymes. Compared with α-MoO3, MoO3-x/Cu nanobelts with a copper loading capacity of 2.11% possess enhanced peroxidase (POD) catalytic activity and glutathione (GSH) depletion, indicating that copper intercalation significantly improves the catalytic performance of the nanoenzymes. The MoO3-x/Cu nanobelts are effective in inducing POD and oxidase (OXD) and catalase (CAT) activities in the presence of H2O2 and O2, which resulted in the generation of large amounts of reactive oxygen species (ROS), which were effective in bacterial killing. Interestingly, MoO3-x/Cu nanobelts can serve as glutathione oxidase (GSHOx)-like nanoenzymes, which can deplete GSH in bacteria and thus significantly improve the bactericidal effect. The multienzyme-catalyzed synergistic antimicrobial strategy shows excellent antimicrobial efficiency against β-lactamase-producing Escherichia coli (ESBL-E. coli) and methicillin-resistant Staphylococcus aureus (MRSA). MoO3-x/Cu exhibits excellent spectral bactericidal properties at very low concentrations (20 μg mL-1). Our work highlights the wide range of antibacterial and anti-infective biological applications of copper-intercalated MoO3-x/Cu nanobelt catalysts.

Copper Nanodots-Based Hybrid Hydrogels with Multiple Enzyme Activities for Acute and Infected Wound Repair

Effectively controlling bacterial infection, reducing the inflammation and promoting vascular regeneration are all essential strategies for wound repair. Nanozyme technology has potential applications in the treatment of infections because its non-antibiotic dependent, topical and noninvasive nature. In wound management, copper-based nanozymes have emerged as viable alternatives to antibiotics. In this study, an ultrasmall cupric enzyme with high enzymatic activity is synthesized and added to a nontoxic, self-healing, injectable cationic guar gum (CG) hydrogel network. The nanozyme exhibits remarkable antioxidant properties under neutral conditions, effectively scavenging reactive nitrogen and oxygen species (RNOS). Under acidic conditions, Cu NDs have peroxide (POD) enzyme-like activity, which allows them to eliminate hydrogen peroxides and produce free radicals locally. Antibacterial experiments show that they can kill bacteria and remove biofilms. It reveals that low concentrations of Cu ND/CG decrease the expression of the inflammatory factors in cells and tissues, effectively controlling inflammatory responses. Cu ND/CG hydrogels also inhibit HIF-1α and promote VEGF expression in the wound with the ability to promote vascular regeneration. In vivo safety assessments reveal a favorable biosafety profile. Cu ND/CG hydrogels offer a promising solution for treating acute and infected wounds, highlighting the potential of innovative nanomaterials in wound healing.

Recent Progress on Tumor Microenvironment-Activated NIR-II Phototheranostic Agents with Simultaneous Activation for Diagnosis and Treatment

Malignant tumors seriously threaten human life and well-being. Emerging Near-infrared II (NIR-II, 1000-1700 nm) phototheranostic nanotechnology integrates diagnostic and treatment modalities, offering merits including improved tissue penetration and enhanced spatiotemporal resolution. This remarkable progress has opened promising avenues for advancing tumor theranostic research. The tumor microenvironment (TME) differs from normal tissues, exhibiting distinct attributes such as hypoxia, acidosis, overexpressed hydrogen peroxide, excess glutathione, and other factors. Capitalizing on these attributes, researchers have developed TME-activatable NIR-II phototheranostic agents with diagnostic and therapeutic attributes concurrently. Therefore, developing TME-activatable NIR-II phototheranostic agents with diagnostic and therapeutic activation holds significant research importance. Currently, research on TME-activatable NIR-II phototheranostic agents is still in its preliminary stages. This review examines the recent advances in developing dual-functional NIR-II activatable phototheranostic agents over the past years. It systematically presents NIR-II phototheranostic agents activated by various TME factors such as acidity (pH), hydrogen peroxide (H2 O2 ), glutathione (GSH), hydrogen sulfide (H2 S), enzymes, and their hybrid. This encompasses NIR-II fluorescence and photoacoustic imaging diagnostics, along with therapeutic modalities, including photothermal, photodynamic, chemodynamic, and gas therapies triggered by these TME factors. Lastly, the difficulties and opportunities confronting NIR-II activatable phototheranostic agents in the simultaneous diagnosis and treatment field are highlighted.

Suppressing ACQ of molecular photosensitizers by distorting the conjugated-plane for enhanced tumor photodynamic therapy

Non-AIE-type molecular photosensitizers (PSs) suffer from the aggregation-caused-quenching (ACQ) effect in an aqueous medium due to the strong hydrophobic and π-π interactions of their conjugated planes, which significantly hinders the enhancement of tumor photodynamic therapy (PDT). So far, some ionic PSs have been reported with good water-solubility, though the ACQ effect can still be induced in a biological environment rich in ions, leading to unsatisfactory in vivo delivery and fluorescence imaging performance. Hence, designing molecular PSs with outstanding anti-ACQ properties in water is highly desirable, but it remains a tough challenge for non-AIE-type fluorophores. Herein, we demonstrated a strategy for the design of porphyrin-type molecular PSs with remarkable solubility and anti-ACQ properties in an aqueous medium, which was assisted by quantum chemical simulations. It was found that cationic branched side chains can induce serious plane distortion in diphenyl porphyrin (DPP), which was not observed for tetraphenyl porphyrin (TPP) with the same side chains. Moreover, the hydrophilicity of the chain spacer is also crucial to the plane distortion for attaining the desired anti-ACQ properties. Compared to ACQ porphyrin, anti-ACQ porphyrin displayed type-I ROS generation in hypoxia and much higher tumor accumulation efficacy by blood circulation, leading to highly efficient in vivo PDT for hypoxic tumors. This study demonstrates the power of sidechain chemistry in tuning the configuration and aggregation behaviors of porphyrins in water, offering a new path to boost the performance of PSs to fulfill the increasing clinical demands on cancer theranostics.

Photothermal therapy of copper incorporated nanomaterials for biomedicine

Studies have reported on the significance of copper incorporated nanomaterials (CINMs) in cancer theranostics and tissue regeneration. Given their unique physicochemical properties and tunable nanostructures, CINMs are used in photothermal therapy (PTT) and photothermal-derived combination therapies. They have the potential to overcome the challenges of unsatisfactory efficacy of conventional therapies in an efficient and non-invasive manner. This review summarizes the recent advances in CINMs-based PTT in biomedicine. First, the classification and structure of CINMs are introduced. CINMs-based PTT combination therapy in tumors and PTT guided by multiple imaging modalities are then reviewed. Various representative designs of CINMs-based PTT in bone, skin and other organs are presented. Furthermore, the biosafety of CINMs is discussed. Finally, this analysis delves into the current challenges that researchers face and offers an optimistic outlook on the prospects of clinical translational research in this field. This review aims at elucidating on the applications of CINMs-based PTT and derived combination therapies in biomedicine to encourage future design and clinical translation.

Recent Advances in Polyoxometalate Based Nanoplatforms Mediated Reactive Oxygen Species Cancer Therapy

The potential of reactive oxygen species (ROS) cancer therapy in tumor treatment has been greatly enhanced by the introduction of catalytically superior polyoxometalate (POM)-based nanoplatforms, mainly composed of atomic clusters consisting of pre-transition metals and oxygen. These nanoplatforms have unique advantages, such as Fenton activity at neutral pH, induction of cellular ferroptosis instead of just apoptosis, and sensitivity to external field stimulation. However, there are also inevitable challenges such as neutralization of ROS by the antioxidant system of the tumor microenvironment (TME), hypoxia, and limited hydrogen peroxide concentrations. This review article aims to provide an overview of recent research advancements in POM-based nanoplatforms for ROS therapy from the perspective of chemical reactions and biological processes, addressing endogenous and exogenous factors that affect the antitumor efficacy. Endogenous factors include the mechanism of ROS generation by POM, the impact of pH and antioxidant systems on POM, and the various manners of tumor cell death. Exogenous stimuli mainly include light, heat, X-rays, and electricity. The article analyzes the specific mechanisms of action of each influencing factor in the first two sections, concluding with the limitations of the present study and some possible directions for future research.

Three Strategies in Engineering Nanomedicines for Tumor Microenvironment-Enabled Phototherapy

Canonical phototherapeutics have several limitations, including a lack of tumor selectivity, nondiscriminatory phototoxicity, and tumor hypoxia aggravation. The tumor microenvironment (TME) is characterized by hypoxia, acidic pH, and high levels of H2 O2 , GSH, and proteases. To overcome the shortcomings of canonical phototherapy and achieve optimal theranostic effects with minimal side effects, unique TME characteristics are employed in the development of phototherapeutic nanomedicines. In this review, the effectiveness of three strategies for developing advanced phototherapeutics based on various TME characteristics is examined. The first strategy involves targeted delivery of phototherapeutics to tumors with the assistance of TME-induced nanoparticle disassembly or surface modification. The second strategy involves near-infrared absorption increase-induced phototherapy activation triggered by TME factors. The third strategy involves enhancing therapeutic efficacy by ameliorating TME. The functionalities, working principles, and significance of the three strategies for various applications are highlighted. Finally, possible challenges and future perspectives for further development are discussed.

Supramolecular Nanozyme System Based on Polydopamine and Polyoxometalate for Photothermal-Enhanced Multienzyme Cascade Catalytic Tumor Therapy

The advent of enzyme-facilitated cascade events in which endogenous substrates within the human body are used to generate reactive oxygen species (ROS) has spawned novel cancer treatment possibilities. In this study, a supramolecular cascade catalytic nanozyme system was successfully developed, exhibiting photothermal-enhanced multienzyme cascade catalytic and glutathione (GSH) depletion activities and ultimately triggering the apoptosis-ferroptosis synergistic tumor therapy. The nanozyme system was fabricated using β-cyclodextrin-functionalized polydopamine (PDA) as the substrate, which was then entangled with polyoxometalate (POM) via electrostatic forces and assembled with adamantane-grafted hyaluronic acid and glucose oxidase (GOx) via host-guest supramolecular interaction for tumor targeting and GOx loading. The catalytic function of GOx facilitates the conversion of glucose to H2O2 and gluconic acid. In turn, this process affirms the propitious generation of hydroxyl radical (•OH) through the POM-mediated cascade catalysis. Additionally, the POM species actively deplete the intracellular GSH pool, initiating a cascade catalytic tumor therapy. In addition, the PDA-POM-mediated photothermal hyperthermia boosted the cascade catalytic effect and increased ROS production. This confers considerable promise for photothermal therapy (PTT)/nanocatalytic cancer therapy on supramolecular nanozyme systems. The in vitro and in vivo antitumor efficacy studies demonstrated that the supramolecular cascade catalytic nanozyme system was effective at reducing tumor development while maintaining an acceptable level of biocompatibility. Henceforth, this study is to widen the scope of cascade catalytic nanoenzyme production using supramolecular techniques, as well as endeavor to delineate a prospective pathway for the application of PTT-enhanced nanocatalytic tumor therapy.

Activity Regulating Strategies of Nanozymes for Biomedical Applications

On accounts of the advantages of inherent high stability, ease of preparation and superior catalytic activities, nanozymes have attracted tremendous potential in diverse biomedical applications as alternatives to natural enzymes. Optimizing the activity of nanozymes is significant for widening and boosting the applications into practical level. As the research of the catalytic activity regulation strategies of nanozymes is boosting, it is essential to timely review, summarize, and analyze the advances in structure-activity relationships for further inspiring ingenious research into this prosperous area. Herein, the activity regulation methods of nanozymes in the recent 5 years are systematically summarized, including size and morphology, doping, vacancy, surface modification, and hybridization, followed by a discussion of the latest biomedical applications consisting of biosensing, antibacterial, and tumor therapy. Finally, the challenges and opportunities in this rapidly developing field is presented for inspiring more and more research into this infant yet promising area.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Acoustic-Based Theranostic Probes Activated by Tumor Microenvironment for Accurate Tumor Diagnosis and Assisted Tumor Therapy

Acoustic-based imaging techniques, including ultrasonography and photoacoustic imaging, are powerful noninvasive approaches for tumor imaging owing to sound transmission facilitation, deep tissue penetration, and high spatiotemporal resolution. Usually, imaging modes were classified into "always-on" mode and "activatable" mode. Conventional "always-on" acoustic-based probes often have difficulty distinguishing lesion regions of interest from surrounding healthy tissues due to poor target-to-background signal ratios. As compared, activatable probes have attracted attention with improved sensitivity, which can boost or amplify imaging signals only in response to specific biomolecular recognition or interactions. The tumor microenvironment (TME) exhibits abnormal physiological conditions that can be used to identify tumor sections from normal tissues. Various types of organic dyes and biomaterials can react with TME, leading to obvious changes in their optical properties. The TME also affects the self-assembly or aggregation state of nanoparticles, which can be used to design activatable imaging probes. Moreover, acoustic-based imaging probes and therapeutic agents can be coencapsulated into one nanocarrier to develop nanotheranostic probes, achieving tumor imaging and cooperative therapy. Satisfactorily, ultrasound waves not only accelerate the release of encapsulated therapeutic agents but also activate therapeutic agents to exert or enhance their therapeutic performance. Meanwhile, various photoacoustic probes can convert photon energy into heat under irradiation, achieving photoacoustic imaging and cooperative photothermal therapy. In this review, we focus on the recently developed TME-triggered ultrasound and photoacoustic theranostic probes for precise tumor imaging and targeted tumor therapy.

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.

MOF-coated upconversion nanoconstructs for synergetic photo-chemodynamic/oxygen-elevated photodynamic therapy

Excessive production of intracellular reactive oxygen species (ROS) can induce apoptosis of cancer cells; however, it is often limited by severe triggering conditions and hypoxic microenvironments of solid tumors. To address these issues, herein, we have designed a MOF-coated upconversion nanoconstruct (UCTSCF, referring to UC@Ce6/TFS@mSiO₂@MIL-100(Cu/Fe)) for synergetic photochemodynamic therapy (PCT)/oxygen-elevated photodynamic therapy (PDT). The MOF (MIL-100(Fe)) coating with Cu-doping was designed to catalyze H₂O₂ overexpression in cancer cells to generate the most cytotoxic ˙OH via chemodynamic therapy (CDT). It is noted that UC, representing 808 nm driven upconversion nanoparticles with high tissue penetration depth/low over-heating effects, was designed to provide intense blue light which can relieve the severe triggering conditions of CDT via PCT. Furthermore, the functional layer of the photosensitizer chlorin e6 (Ce6) and O₂-carrying triethoxy(1H,1H,2H,2H-nonafluorohexyl)silane (TFS) co-doped mesoporous silicon (Ce6/TFS@mSiO₂) can cause oxygen-elevated ¹O₂ production upon 671 nm light irradiation. In such a simple ROS generation nanoplatform, we heighten the antitumor effect via oxygen-elevated synergetic tumor PCT/PDT.

Vacancy defect-promoted nanomaterials for efficient phototherapy and phototherapy-based multimodal Synergistic Therapy

Phototherapy and multimodal synergistic phototherapy (including synergistic photothermal and photodynamic therapy as well as combined phototherapy and other therapies) are promising to achieve accurate diagnosis and efficient treatment for tumor, providing a novel opportunity to overcome cancer. Notably, various nanomaterials have made significant contributions to phototherapy through both improving therapeutic efficiency and reducing side effects. The most key factor affecting the performance of phototherapeutic nanomaterials is their microstructure which in principle determines their physicochemical properties and the resulting phototherapeutic efficiency. Vacancy defects ubiquitously existing in phototherapeutic nanomaterials have a great influence on their microstructure, and constructing and regulating vacancy defect in phototherapeutic nanomaterials is an essential and effective strategy for modulating their microstructure and improving their phototherapeutic efficacy. Thus, this inspires growing research interest in vacancy engineering strategies and vacancy-engineered nanomaterials for phototherapy. In this review, we summarize the understanding, construction, and application of vacancy defects in phototherapeutic nanomaterials. Starting from the perspective of defect chemistry and engineering, we also review the types, structural features, and properties of vacancy defects in phototherapeutic nanomaterials. Finally, we focus on the representative vacancy defective nanomaterials recently developed through vacancy engineering for phototherapy, and discuss the significant influence and role of vacancy defects on phototherapy and multimodal synergistic phototherapy. Therefore, we sincerely hope that this review can provide a profound understanding and inspiration for the design of advanced phototherapeutic nanomaterials, and significantly promote the development of the efficient therapies against tumor.

Hybrid Ag nanoparticles/polyoxometalate-polydopamine nano-flowers loaded chitosan/gelatin hydrogel scaffolds with synergistic photothermal/chemodynamic/Ag+ anti-bacterial action for accelerated wound healing

Bacterial infections significantly slow the wound healing process, thus severely threatening human health. Furthermore, traditional antibiotics may promote the development of multidrug-resistant bacteria. Therefore, developing novel bactericides and therapeutic strategies for bacterial infections is important to enhance wound healing. Herein, a three-in-one bactericidal flower-like nanocomposite was assembled using Ag nanoparticles/phosphotungstic acid-polydopamine nano-flowers (AgNPs/POM-PDA). The nanocomposite exhibited photothermal therapy (PTT) when exposed to NIR light via photothermal conversion by PDA. The resultant photothermal effect accelerated and controlled the Ag⁺ released from AgNPs. The chemodynamic therapy (CDT) was obtained via POM catalytic Fenton-like reaction. The combined PTT/CDT/Ag⁺ treatment achieved excellent synergistic anti-bacterial activity against both gram-negative E. coli and gram-positive S. aureus. A multifunctional wound dressing was then obtained by embedding the AgNPs/POM-PDA flower-like nanocomposite into the chitosan (CS)/gelatin (GE) biocomposite hydrogel. The synergy of AgNPs/POM-PDA nanocomposites and CS/GE hydrogel remarkably accelerated wound healing in vivo due to the excellent biocompatibility, hydroabsorptivity, and breathability of the hydrogel. In this study, a multifunctional agent was developed to synergistically combat bacterial infections and accelerate wound healing.

Hollow Mesoporous CeO2-Based Nanoenzymes Fabrication for Effective Synergistic Eradication of Malignant Breast Cancer via Photothermal–Chemodynamic Therapy

CeO₂-based nanoenzymes present a very promising paradigm in cancerous therapy, as H₂O₂ can be effectively decomposed under the electron transmit between Ce³⁺ and Ce⁴⁺. However, the limitations of endogenous H₂O₂ and intracellular low Fenton-like reaction rate lead to single unsatisfied chemodynamic therapy (CDT) efficacy. Other therapeutic modalities combined with chemodynamic therapy are generally used to enhance the tumor eradiation efficacy. Here, we have synthesized a novel hollow pH-sensitive CeO₂ nanoenzyme after a cavity is loaded with indocyanine green (ICG), as well as with surface modification of tumor targeting peptides, Arg-Gly-Asp (denoted as HCeO₂@ICG-RGD), to successfully target tumor cells via α_vβ₃ recognition. Importantly, in comparison with single chemodynamic therapy, a large amount of reactive oxygen species in cytoplasm were induced by enhanced chemodynamic therapy with photothermal therapy (PTT). Furthermore, tumor cells were efficiently killed by a combination of photothermal and chemodynamic therapy, revealing that synergistic therapy was successfully constructed. This is mainly due to the precise delivery of ICG and release after HCeO₂ decomposition in cytoplasm, in which effective hyperthermia generation was found under 808 nm laser irradiation. Meanwhile, our HCeO₂@ICG-RGD can act as a fluorescent imaging contrast agent for an evaluation of tumor tissue targeting capability in vivo. Finally, we found that almost all tumors in HCeO₂@ICG-RGD+laser groups were completely eradicated in breast cancer bearing mice, further proving the effective synergistic effect in vivo. Therefore, our novel CeO₂-based PTT agents provide a proof-of-concept argumentation of tumor-precise multi-mode therapies in preclinical applications.