Rational Design of Multifunctional Fe@γ-Fe2 O3 @H-TiO2 Nanocomposites with Enhanced Magnetic and Photoconversion Effects for Wide Applications: From Photocatalysis to Imaging-Guided Photothermal Cancer Therapy

Revolutionizing healthcare: inorganic medicinal nanoarchitectonics for advanced theranostics

Over the last two decades, advancements in nanomaterials and nanoscience have paved the path for the emergence of nano-medical convergence science, significantly impacting healthcare. In our review, we highlight how these advancements are applied in various biomedical technologies such as drug delivery systems, bio-imaging for diagnostic and therapeutic purposes. Recently, novel inorganic nanohybrid drugs have been developed, combining multifunctional inorganic nanomaterials with therapeutic agents (known as inorganic medicinal nanoarchitectonics). These innovative drugs are actively utilized in cutting-edge medical treatments, including targeted anti-cancer therapy, photo and radiation therapy, and immunotherapy. This review provides a detailed overview of the current development status of inorganic medicinal nanoarchitectonics and explores potential future directions in their advancements.

Core-Shell Magnetic Particles: Tailored Synthesis and Applications

Core-shell magnetic particles consisting of magnetic core and functional shells have aroused widespread attention in multidisciplinary fields spanning chemistry, materials science, physics, biomedicine, and bioengineering due to their distinctive magnetic properties, tunable interface features, and elaborately designed compositions. In recent decades, various surface engineering strategies have been developed to endow them desired properties (e.g., surface hydrophilicity, roughness, acidity, target recognition) for efficient applications in catalysis, optical modulation, environmental remediation, biomedicine, etc. Moreover, precise control over the shell structure features like thickness, porosity, crystallinity and compositions including metal oxides, carbon, silica, polymers, and metal-organic frameworks (MOFs) has been developed as the major method to exploit new functional materials. In this review, we highlight the synthesis methods, regulating strategies, interface engineering, and applications of core-shell magnetic particles over the past half-century. The fundamental methodologies for controllable synthesis of core-shell magnetic materials with diverse organic, inorganic, or hybrid compositions, surface morphology, and interface property are thoroughly elucidated and summarized. In addition, the influences of the synthesis conditions on the physicochemical properties (e.g., dispersibility, stability, stimulus-responsiveness, and surface functionality) are also discussed to provide constructive insight and guidelines for designing core-shell magnetic particles in specific applications. The brand-new concept of "core-shell assembly chemistry" holds great application potential in bioimaging, diagnosis, micro/nanorobots, and smart catalysis. Finally, the remaining challenges, future research directions and new applications for the core-shell magnetic particles are predicted and proposed.

Biomimetic CuCoO2 nanosheets reinforced with self-assembling peptide nanofibers for tumor photothermal therapy

The flexible design and unique physical and chemical properties of self-assembled peptides have shown great potential for applications in the fields of materials science, life science, and environmental science. Peptide nanofibers (PNFs), as a kind of bioactive nanomaterials, possess excellent biocompatibility, flexible designability, and multifaceted functionalizability. In this work, we design and describe PNFs that self-assembled by peptide molecules as carriers for bimetallic nanosheets (BMNS), leading to the development of hybrid nanomaterials, BMNS-PNFs, with unique properties. The BMNS-PNFs exhibit a photothermal conversion efficiency (PCE) of up to 31.57%, and can be used as a potential nanoplatform for photothermal therapy (PTT) of lung tumour cells. Through the results, it is shown that the PNFs can reduce the cytotoxicity of BMNS-PNFs and that BMNS-PNFs have excellent cancer cell killing effects, with photothermal killing rates of more than 95% and 90% for lung cancer cells HCC2279 and PC9, respectively. Finally, the comprehensive PTT performance of BMNS-PNFs is analysed by Ranking of Efficiency Performance (REP), and the REP value of BMNS-PNFs is calculated to be 0.741. The peptide sequences used to assemble into PNFs in this study are instructive for functional design and structural modulation of molecular self-assembly, and the constructed bimetallic-biomolecular hybrid materials provide a potential strategy for medical bioengineering.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Mesoporous carbon hemispheres integrated with Fe-Gd nanoparticles for potential MR/PA imaging-guided photothermal therapy

Asymmetric carbon has emerged as an important material to enrich morphologies as well as enhance functions for bioapplications. Here, asymmetric mesoporous carbon hemispheres (CHS) integrated with γ-Fe2O3 and GdPO4 (Fe-Gd) nanoparticles are proposed and prepared for potential imaging-guided photothermal therapy (PTT). Interestingly, Fe-Gd/CHS contributes to an almost 1.5 times enhancement in light harvesting and photothermal conversion efficiency as compared with its corresponding spherical analogue. The possible underlying mechanism is discussed in view of the unique asymmetric structure-featured carbon. Further identification of the inherited photoacoustic (PA) and magnetic resonance (MR) imaging properties leads to the consequent in vivo evaluation of its imaging and PTT performances, which demonstrates its capability as a function-integrated system for potential theranostics.

Iron-Based Nanovehicle Delivering Fin56 for Hyperthermia-Boosted Ferroptosis Therapy Against Osteosarcoma

Background

Although systemic chemotherapy is a standard approach for osteosarcoma (OS) treatment, its efficacy is limited by the inherent or acquired resistance to apoptosis of tumor cells. Ferroptosis is considered as an effective strategy capable of stimulating alternative pathways of cancer cell demise. The purpose of this study is to develop a novel strategy boosting ferroptotic cascade for synergistic cancer therapy.

Methods and Results

A novel nanovehicle composed of arginine-glycine-aspartate (RGD) modified mesoporous silica-coated iron oxide loading Fin56 was rationally prepared (FSR-Fin56). With the RGD-mediated targeting affinity, FSR-Fin56 could achieve selective accumulation and accurate delivery of cargos into cancer cells. Upon exposure to NIR light, the nanovehicle could generate localized hyperthermia and disintegrate to liberate the therapeutic payload. The released Fin56 triggered the degradation of GPX4, while Fe3+ depleted the intracellular GSH pool, producing Fe2+ as a Fenton agent. The local rise in temperature, in conjunction with Fe2+-mediated Fenton reaction, led to a rapid and significant accumulation of ROS, culminating in LPOs and ferroptotic death. The outstanding therapeutic efficacy and safety of the nanovehicle were validated both in vitro and in vivo.

Conclusion

The Fin56-loaded FSR nanovehicle could effectively disturb the redox balance in cancer cells. Coupled with NIR laser irradiation, the cooperative CDT and PTT achieved a boosted ferroptosis-inducing therapy. Taken together, this study offers a compelling strategy for cancer treatment, particularly for ferroptosis-sensitive tumors like osteosarcoma.

Current status of Fe-based MOFs in biomedical applications

Recently nanoparticle-based platforms have gained interest as drug delivery systems and diagnostic agents, especially in cancer therapy. With their ability to provide preferential accumulation at target sites, nanocarrier-constructed antitumor drugs can improve therapeutic efficiency and bioavailability. In contrast, metal-organic frameworks (MOFs) have received increasing academic interest as an outstanding class of coordination polymers that combine porous structures with high drug loading via temperature modulation and ligand interactions, overcoming the drawbacks of conventional drug carriers. FeIII-based MOFs are one of many with high biocompatibility and good drug loading capacity, as well as unique Fenton reactivity and superparamagnetism, making them highly promising in chemodynamic and photothermal therapy, and magnetic resonance imaging. Given this, this article summarizes the applications of FeIII-based MOFs in three significant fields: chemodynamic therapy, photothermal therapy and MRI, suggesting a logical route to new strategies. This article concludes by summarising the primary challenges and development prospects in these promising research areas.

Defect Engineering in Biomedical Sciences

With the promotion of nanochemistry research, large numbers of nanomaterials have been applied in vivo to produce desirable cytotoxic substances in response to endogenous or exogenous stimuli for achieving disease-specific therapy. However, the performance of nanomaterials is a critical issue that is difficult to improve and optimize under biological conditions. Defect-engineered nanoparticles have become the most researched hot materials in biomedical applications recently due to their excellent physicochemical properties, such as optical properties and redox reaction capabilities. Importantly, the properties of nanomaterials can be easily adjusted by regulating the type and concentration of defects in the nanoparticles without requiring other complex designs. Therefore, this tutorial review focuses on biomedical defect engineering and briefly discusses defect classification, introduction strategies, and characterization techniques. Several representative defective nanomaterials are especially discussed in order to reveal the relationship between defects and properties. A series of disease treatment strategies based on defective engineered nanomaterials are summarized. By summarizing the design and application of defective engineered nanomaterials, a simple but effective methodology is provided for researchers to design and improve the therapeutic effects of nanomaterial-based therapeutic platforms from a materials science perspective.

In situ assembled titanium carbide-based heterojunctions for the synergistic enhancement of NIR-II photothermal/photodynamic therapy against breast cancer

The combined use of photothermal therapy (PTT) and photodynamic therapy (PDT) could circumvent the drawbacks of each individual therapeutic strategy, resulting in an enhanced antitumor effect. However, the lack of highly effective photo-agents that are irradiation-safe in the biologically transparent window hinder the advancement of phototherapy clinically. Hence, in this study, a charge separation engineering strategy was adopted to fabricate a nanoplatform with heterojunctions, namely, in situ TiO₂-loaded MXene (Ti₃C₂/TiO₂ heterojunctions). This nanoplatform exhibited reduced bandgap (1.68 eV), enhanced NIR-II photothermal conversion efficiency (44.98%), and extended absorption edge compared to pristine TiO₂ for enhanced photodynamic effect. More importantly, the proliferation of tumor cells could be efficiently inhibited at a 5 mm chicken breast depth after 1064 nm laser irradiation, and the intracellular ROS production significantly increased under 660 nm or even 1064 nm laser irradiation with heterojunctions (HJs) compared with that of TiO₂. Moreover, the in vivo data further confirmed that the as-prepared heterojunctions could efficiently eradicate tumors efficiently via improved photothermal effect with NIR-II laser irradiation and upregulated ROS production. Collectively, the reported HJs strategy provides an opportunity for the success of combinational PTT and PDT therapy in tumor treatment.

Gd2O3/b-TiO2 composite nanoprobes with ultra-high photoconversion efficiency for MR image-guided NIR-II photothermal therapy

Photothermal therapy (PTT), as an important noninvasive and effective tumor treatment method, has been extensively developed into a powerful cancer therapeutic technique. Nevertheless, the low photothermal conversion efficiency and the limited tissue penetration of typical photothermal therapeutic agents in the first near-infrared (NIR-I) region (700-950 nm) are still the major barriers for further clinical application. Here, we proposed an organic/inorganic dual-PTT agent of synergistic property driven by polydopamine-modified black-titanium dioxide (b-TiO2@PDA) with excellent photoconversion efficiency in the second NIR (NIR-II) region (1000-1500 nm). More specifically, the b-TiO2 treated with sodium borohydride produced excessive oxygen vacancies resulting in oxygen vacancy band that narrowed the b-TiO2 band gap, and the small band gap led to NIR-II region wavelength (1064 nm) absorbance. Furthermore, the combination of defect energy level trapping carrier recombination heat generation and conjugate heat generation mechanism, significantly improved the photothermal performance of the PTT agent based on b-TiO2. The photothermal properties characterization indicated that the proposed dual-PTT agent possesses excellent photothermal performance and ultra-high photoconversion efficiency of 64.9% under 1064 nm laser irradiation, which can completely kill esophageal squamous cells. Meanwhile, Gd2O3 nanoparticles, an excellent magnetic resonance imaging (MRI) agent, were introduced into the nanosystem with similar dotted core-shell structure to enable the nanosystem achieve real-time MRI-monitored cancer therapeutic performance. We believe that this integrated nanotherapeutic system can not only solve the application of PTT in the NIR-II region, but also provide certain theoretical guidance for the clinical diagnosis and treatment of esophageal cancer.

Surface Bandgap Engineering of Nanostructured Implants for Rapid Photothermal Ion Therapy of Bone Defects

Bone defects are seriously threatening the health of orthopedics patients and it is difficult for implants to accelerate bone regeneration without using bone growth factors. Herein, a fast photothermal ion therapeutic strategy is developed based on the bandgap engineering of nanostructured TiO₂ through (Si/P)-dual elemental doping by micro-arc oxidation treatment of titanium implants. The (Si/P)-dual doping can tune the surface bandgap structure of TiO₂ by decreasing bandgap and broadening valence band simultaneously, which is confirmed by density functional theory calculations. It not only endows the implants with a mildly photothermal effect under near-infrared (NIR) light irradiation, but also creates an (Si/P) ion-rich microenvironment around the implants. This photothermal ion microenvironment can tune the behaviors of osteoblasts by promoting p38/Smad and ERK signaling pathways of osteoblasts, thus significantly upregulating the expression of osteogenesis genes by the synergistic action of mild photothermal stimulation and increased release of Si/P ions. The in vivo results are also in good agreement with in vitro tests, i.e., under NIR light irradiation, the photothermally responsive TiO₂ enhances the bone formation and osteointegration with implants. Therefore, this kind of photothermal ion strategy is a promising remote and noninvasive therapeutic mode for promoting bone regeneration of Ti implants.

PtBi-β-CD-Ce6 Nanozyme for Combined Trimodal Imaging-Guided Photodynamic Therapy and NIR-II Responsive Photothermal Therapy

Combined photothermal/photodynamic therapy is a promising strategy to achieve an enhanced anticancer effect. However, hypoxia is one of the representative characteristics of the microenvironment of solid tumors, which not only attenuates the therapeutic effects but also promotes tumor invasion and metastasis. Herein, a PtBi-β-CD-Ce6 nanoplatform for the generation of sustained O2 was constructed for more effective tumor therapy. In detail, the catalase (CAT)-like nanozyme, PtBi, which could decompose H2O2 to produce O2, was modified with β-cyclodextrin (β-CD). O2 would be converted into 1O2 by PtBi-β-CD-Ce6 for enhanced photodynamic therapy (PDT) under 650 nm laser irradiation. In addition, by reason of excellent absorption in the near-infrared-II (NIR-II) region, PtBi-β-CD-Ce6 was used for photoacoustic imaging (PA) and photothermal imaging (PT)-guided photothermal therapy (PTT) in the NIR-II biowindow. Furthermore, PtBi-β-CD-Ce6 could be elected to serve as a contrast agent for X-ray computed tomography (CT) imaging due to the apparent X-ray attenuation capability of the Pt and Bi elements themselves. Therefore, by integrating the advantages of overcoming the hypoxia function and photothermal effect into a single nanoplatform, PtBi-β-CD-Ce6 showed an immense possibility in multimodal imaging-guided combined PDT/PTT.

Targeted Phototherapy by Niobium Carbide for Mammalian Tumor Models Similar to Humans

BACKGROUND

In the past few decades, nanomaterial-mediated phototherapy has gained significant attention as an alternative antitumor strategy. However, its antitumor success is majorly limited to the treatment of subcutaneous tumors in nude mice. In fact, no studies have been previously conducted in this area/field on clinically-relevant big animal models. Therefore, there is an urgent need to conduct further investigation in a typical big animal model, which is more closely related to the human body.

RESULTS

In this study, niobium carbide (NbC) was selected as a photoactive substance owing to the presence of outstanding near-infrared (NIR) absorption properties, which are responsible for the generation of NIR-triggered hyperthermia and reactive oxygen species that contribute towards synergetic photothermal and photodynamic effect. Moreover, the present study utilized macrophages as bio-carrier for the targeted delivery of NbC, wherein phagocytosis by macrophages retained the photothermal/photodynamic effect of NbC. Consequently, macrophage-loaded NbC ensured/allowed complete removal of solid tumors both in nude mice and big animal models involving rabbits. Meanwhile, two-dimensional ultrasound, shave wave elastography (SWE), and contrast-enhanced ultrasound (CEUS) were used to monitor physiological evolution in tumor in vivo post-treatment, which clearly revealed the occurrence of the photoablation process in tumor and provided a new strategy for the surveillance of tumor in big animal models.

CONCLUSION

Altogether, the use of a large animal model in this study presented higher clinical significance as compared to previous studies.

Theranostic applications of stimulus-responsive systems based on Fe2O3

According to the interaction of nanoparticles with biological systems, enthusiasm for nanotechnology in biomedical applications has been developed in the past decades. Fe2O3 nanoparticles, as the most stable iron oxide, have special merits that make them useful widely for detecting diseases, therapy, drug delivery, and monitoring the therapeutic process. This review presents the fabrication methods of Fe2O3-based materials and their photocatalytic and magnetic properties. Then, we highlight the application of Fe2O3-based nanoparticles in diagnosis and imaging, different therapy methods, and finally, stimulus-responsive systems, such as pH-responsive, magnetic-responsive, redox-responsive, and enzyme-responsive, with an emphasis on cancer treatment. In addition, the potential of Fe2O3 to combine diagnosis and therapy within a single particle called theranostic agent will be discussed.

Lanthanide-doped bismuth-based nanophosphors for ratiometric upconversion optical thermometry

Nanothermometry could realize stable, efficient, and noninvasive temperature detection at the nanoscale. Unfortunately, most applications of nanothermometers are still limited due to their intricate synthetic process and low-temperature sensitivity. Herein, we reported a kind of novel bismuth-based upconversion nanomaterial with a fast and facile preparation strategy. The bismuth-based upconversion luminophore was synthesized by the co-precipitation method within 1 minute. By optimizing the doping ratio of the sensitizer Yb ion and the activator Er ion and adjusting the synthetic solvent strategy, the crystallinity of the nanomaterials was increased and the upconversion luminescence intensity was improved. Ratiometric upconversion optical measurements of temperature in the range of 278 K to 358 K can be achieved by ratiometric characteristic emission peaks of thermally sensitive Er ion. This method of rapidly constructing nanometer temperature probes provides a feasible strategy for the construction of novel fluorescent temperature probes.

Lanthanide-doped bismuth-based nanospheres can be rapidly synthesized within 1 minute for upconversion luminescence ratiometric temperature detection.

Boosting Chemodynamic Therapy via a Synergy of Hypothermal Ablation and Oxidation Resistance Reduction

Chemodynamic therapy (CDT), deemed as a cutting-edge antineoplastic therapeutic tactics, efficaciously suppresses tumors via catalytically yielding hydroxyl radicals (^•OH) in tumor regions. Nevertheless, its biomedical applications are often restricted by the limited hydrogen peroxide (H₂O₂) level and upregulated antioxidant defense. Herein, a versatile nanoreactor is elaborately designed via integrating Cu_2-xS and MnO₂ for T₁-weighted magnetic resonance (MR) imaging-guided CDT, synergistically enhanced through hypothermal ablation and oxidation resistance reduction, thereby displaying splendid antitumor efficiency as well as suppression on pulmonary metastasis. The as-synthesized Cu_2-xS@MnO₂ nanoreactors afford acid-dependent Cu-based and glutathione (GSH)-activated Mn-based catalytic properties for bimodal CDT. Owing to excellent absorbance at the second near-infrared (NIR-II) window, the Cu_2-xS furnishes hypo-photo-thermal therapy (PTT) against tumor growth and ameliorates the catalytic performance for thermal-enhanced CDT. Additionally, MnO₂ significantly downregulates GSH and glutathione peroxidase 4, which synergistically boosts CDT via promoting oxidative stress, simultaneously generating Mn²⁺ for MR contrast improvement and activatable tumor imaging. Therefore, this study proffers a new attempt centered on the collaborative strategy integrating NIR-II hypothermal PTT and synergistically enhanced CDT for tumor eradication.

Au-Fe3O4 nanoagent coated cell membrane for targeted delivery and enhanced chem/photo therapy

Here, we propose a cancer cell membrane (CM) coated Au-Fe₃O₄ complex (AFTP@CM), loaded with tannic acid and phorbol 12-myristate 13-acetate for targeted drug delivery and enhanced chem/photo therapy.

Building biointegration of Fe2O3-FeOOH coated titanium implant by regulating NIR irradiation in an infected model

Killing bacteria, eliminating biofilm and building soft tissue integration are very important for percutaneous implants which service in a complicated environment. In order to endow Ti implants with above abilities, multifunctional coatings consisted of Fe₂O₃–FeOOH nanograins as an outer layer and Zn doped microporous TiO₂ as an inner layer were fabricated by micro-arc oxidation, hydrothermal treatment and annealing treatment. The microstructures, physicochemical properties and photothermal response of the coatings were observed; their antibacterial efficiencies and cell response in vitro as well as biofilm elimination and soft tissue integration in vivo were evaluated. The results show that with the increased annealing temperature, coating morphologies didn't change obviously, but lattices of β-FeOOH gradually disorganized into amorphous state and rearranged to form Fe₂O_3. The coating annealed at 450 °C (MA450) had nanocrystallized Fe₂O₃ and β-FeOOH. With a proper NIR irradiation strategy, MA450 killed adhered bacteria efficiently and increased fibroblast behaviors via up-regulating fibrogenic-related genes in vitro; in an infected model, MA450 eliminated biofilm, reduced inflammatory response and improved biointegration with soft tissue. The good performance of MA450 was due to a synergic effect of photothermal response and released ions (Zn²⁺ and Fe³⁺).

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Nanocrystallized Fe₂O₃–FeOOH layer endows Ti with good photothermal response.

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With NIR irradiation, Fe₂O₃–FeOOH layer improves biointegration in an infected model.

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Photothermal response combined with released ions gives implants good performance.

Enhanced Near-Infrared Photocatalytic Eradication of MRSA Biofilms and Osseointegration Using Oxide Perovskite-Based P-N Heterojunction

Methicillin-resistant Staphylococcus aureus (MRSA) biofilm infections after orthopedic implant increase the risk of failure and potentially cause amputation of limbs or life-threatening sepsis in severe cases. Additionally, satisfactory bone-implant integration is another important indicator of an ideal implant. Here, an antibiotic-free antibacterial nanofilm based on oxide perovskite-type calcium titanate (CTO)/fibrous red phosphorus (RP) on titanium implant surface (Ti-CTO/RP) in which the P-N heterojunction and internal electric field are established at the heterointerface, is designed. Near-infrared light-excited electron-hole pairs are effectively separated and transferred through the synergism of the internal electric field and band offset, which strongly boosts the photocatalytic eradication of MRSA biofilms by reactive oxygen species with an efficacy of 99.42% ± 0.22% in vivo. Additionally, the charge transfer endows the heterostructure with hyperthermia to assist biofilm eradication. Furthermore, CTO/RP nanofilm provides a superior biocompatible and osteoconductive platform that enables the proliferation and osteogenic differentiation of mesenchymal stem cells, thus contributing to the subsequent implant-to-bone osseointegration after eradicating MRSA biofilms.

Upconverted Metal-Organic Framework Janus Architecture for Near-Infrared and Ultrasound Co-Enhanced High Performance Tumor Therapy

Strict conditions such as hypoxia, overexpression of glutathione (GSH), and high concentration of hydrogen peroxide (H₂O₂) in the tumor microenvironment (TME) limit the therapeutic effects of reactive oxygen species (ROS) for photodynamic therapy (PDT), chemodynamic therapy (CDT), and sonodynamic therapy (SDT). Here we fabricated a biocatalytic Janus nanocomposite (denoted as UPFB) for ultrasound (US) driven SDT and 808 nm near-infrared (NIR) light mediated PDT by combining core-shell-shell upconversion nanoparticles (UCNPs, NaYF₄:20%Yb,1%Tm@NaYF₄:10%Yb@NaNdF₄) and a ferric zirconium porphyrin metal organic framework [PCN-224(Fe)]. Our design not only substantially overcomes the inefficient PDT effect arising from the inadequate Förster resonance energy transfer (FRET) process from UCNPs (donor) to MOFs (acceptor) with only NIR laser irradiation, but also promotes the ROS generation via GSH depletion and oxygen supply contributed by Fe³⁺ ions coordinated in UPFB as a catalase-like nanozyme. Additionally, the converted Fe²⁺ from the foregoing process can achieve CDT performance under acidic conditions, such as lysosomes. Meanwhile, UPFB linked with biotin exhibits a good targeting ability to rapidly accumulate in the tumor region, verified by fluorescence imaging and T₂-weighted magnetic resonance imaging (MRI). In a word, it is believed that the synthesis and antitumor detection of UPFB heterostructures render them suitable for application in cancer therapeutics.

The recent progress on metal-organic frameworks for phototherapy

Some infectious or malignant diseases such as cancers are seriously threatening the health of human beings all over the world. The commonly used antibiotic therapy cannot effectively treat these diseases within a short time, and also bring about adverse effects such as drug resistance and immune system damage during long-term systemic treatment. Phototherapy is an emerging antibiotic-free strategy to treat these diseases. Upon light irradiation, phototherapeutic agents can generate cytotoxic reactive oxygen species (ROS) or induce a temperature increase, which leads to the death of targeted cells. These two kinds of killing strategies are referred to as photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. So far, many photo-responsive agents have been developed. Among them, the metal-organic framework (MOF) is becoming one of the most promising photo-responsive materials because its structure and chemical compositions can be easily modulated to achieve specific functions. MOFs can have intrinsic photodynamic or photothermal ability under the rational design of MOF construction, or serve as the carrier of therapeutic agents, owing to its tunable porosity. MOFs also provide feasibility for various combined therapies and targeting methods, which improves the efficiency of phototherapy. In this review, we firstly investigated the principles of phototherapy, and comprehensively summarized recent advances of MOF in PDT, PTT and synergistic therapy, from construction to modification. We expect that our demonstration will shed light on the future development of this field, and bring it one step closer to clinical trials.

Hollow carbon nanospheres dotted with Gd-Fe nanoparticles for magnetic resonance and photoacoustic imaging

Integrating magnetic resonance (MR) and photoacoustic (PA) contrast agents into porous nanomaterials is a favorable way for screening of potential theranostic nanomedicines. Hollow carbon nanospheres (HCSs) dotted with GdPO₄ and γ-Fe₂O₃ (Gd-Fe) nanoparticles are therefore prepared and studied in this work. The resultant Gd-Fe/HCSs possess a size of ∼100 nm with a cavity of ∼80 nm and a shell thickness of ∼10 nm, where the magnetic Gd-Fe nanoparticles are dotted. Owing to the synergistic effects, the Gd-Fe/HCSs give 2.5 times enhanced PA signals as compared with HCSs as well as the inherited MR imaging properties from Gd-Fe nanoparticles. In vivo MR and PA imaging of the liver in mice are consequently evaluated and validated. Furthermore, taking the tunable particle size, hollow cavity, shell thickness, and dotted amounts of nanoparticles into consideration, our studies here provide a useful structural model for the synergistic integration of MR and PA imaging in HCSs.

Emerging contrast agents for multispectral optoacoustic imaging and their biomedical applications

Optoacoustic imaging is a hybrid biomedical imaging modality which collects ultrasound waves generated via photoexciting contrast agents in tissues and produces images of high resolution and penetration depth. As a functional optoacoustic imaging technique, multispectral optoacoustic imaging, which can discriminate optoacoustic signals from different contrast agents by illuminating samples with multi-wavelength lasers and then processing the collected data with specific algorithms, assists in the identification of a specific contrast agent in target tissues and enables simultaneous molecular and physiological imaging. Moreover, multispectral optoacoustic imaging can also generate three-dimensional images for biological tissues/samples with high resolution and thus holds great potential in biomedical applications. Contrast agents play essential roles in optoacoustic imaging, and they have been widely explored and applied as probes and sensors in recent years, leading to the emergence of a variety of new contrast agents. In this review, we aim to summarize the latest advances in emerging contrast agents, especially the activatable ones which can respond to specific biological stimuli, as well as their preclinical and clinical applications. We highlight their design strategies, discuss the challenges and prospects in multispectral optoacoustic imaging, and outline the possibility of applying it in clinical translation and public health services using synthetic contrast agents.

Covalent Organic Framework-Titanium Oxide Nanocomposite for Enhanced Sonodynamic Therapy

Sonodynamic therapy (SDT) has attracted wide attention for its high tissue-penetration depth capacity. However, developing new kinds of sonosensitizers that are capable of generating large amounts of reactive oxygen species (ROS) still remains a challenge. Herein, covalent organic framework-titanium oxide nanoparticles (COF-TiO₂ NPs) were successfully synthesized by using COF as a template. Under ultrasound (US) irradiation, large quantities of ROS can be generated, and compared with pure TiO₂ NPs, the SDT performance of COF-TiO₂ nanoparticles was significantly improved due to the narrower band gap. Both in vitro and in vivo experiments demonstrated the great tumor inhibitory effect via COF-TiO₂-mediated SDT. This work broadens the biomedical applications of COF-based composites.

Cell membrane camouflaged bismuth nanoparticles for targeted photothermal therapy of homotypic tumors

Bi nanoparticles (NPs) have been demonstrated as effective all-in-one type theranostic agent for imaging-guided photothermal therapy, but their applications have been limited by relatively low biocompatibility and target accumulation capacity. To address this issue, we report the camouflage of Bi NPs (size: ~42 ± 2 nm) by using the mouse colon cancer CT26 cells membrane (CT26 CCM). The camouflaging process confers the efficient coating of CCM shell layer with thickness of ~8 ± 2 nm on Bi NPs cores, which can be confirmed by TEM image, zeta potential and protein gel electrophoresis tests. Simultaneously, CCM shell has no side effects on the photoabsorption/photothermal effect. Importantly, Bi@CCM NPs retain significant features of CCM, including good biocompatibility and homologous targeting ability. When Bi@CCM dispersion was intravenously (i.v.) injected into mice, they exhibited higher blood circulation half-life (11.5 h, ~2.9 times) and accumulation amount (4.7 ± 0.56% ID/g, ~2.3 times) in homotypic CT26 tumor compared to those (4.0 h in blood and 2.03 ± 0.60% ID/g in tumor) from uncoated Bi NPs. After 808 nm laser irradiation, CT26 cancer cells could be effectively ablated after the photothermal therapy of high-accumulated Bi@CCM NPs, and then the tumor tends to be eradicated after 12 days. Thus, Bi NPs camouflaged with CT26 CCM have great potential for the targeted photothermal therapy of homotypic tumors.

Black titanium dioxide@manganese dioxide for glutathione-responsive MR imaging and enhanced photothermal therapy

Multifunctional nanoprobes with tumor microenvironment response are playing important roles in highly efficient theranostics of cancers. Herein, a kind of theranostic nanoprobe was synthesized by coating manganese dioxide (MnO₂) on the surface of black commercial P25 titanium dioxide (b-P25). The resultant nanoprobe (b-P25@MnO₂) possessed glutathione (GSH)-responsive magnetic resonance (MR) imaging and enhanced photothermal therapy (PTT). In tumor microenvironments, the excessive GSH was consumed by reacting with MnO₂ to generate Mn²⁺ for GSH-responsive MR imaging, in which the longitudinal relaxation rate of b-P25@MnO₂ was up to 30.44 mM^-1 s^-1, showing excellent cellular and intratumoral MR imaging. Moreover, the prepared b-P25@MnO₂ exhibited stable and strong photothermal conversion capability with a high photothermal conversion efficiency of 30.67%, by which the 4T1 tumors disappeared completely, indicating safe and highly efficient PTT performance. The current work developed GSH-responsive b-P25@MnO₂ nanoprobes, demonstrated for MR imaging and enhanced PTT in cancers.

Highly efficient solar photocatalytic degradation of a textile dye by TiO2/graphene quantum dots nanocomposite

Herein, two sunlight responsive photocatalysts including TiO₂ nanoparticles (NPs) and TiO₂/graphene quantum dots (GQDs) nanocomposite for degrading a textile dye, Reactive Black 5 (RB5), were prepared. The results showed that 100% of 50 ppm RB5 could be degraded by TiO₂ NPs and TiO₂/GQDs within 60 and 30 min sunlight irradiation, respectively. Hence, much better photocatalytic activity in degradation of RB5 was achieved by TiO₂/GQDs under sunlight irradiation compared with pure TiO₂ NPs due to its lower band gap (2.13 eV) and electron/hole recombination rate. The photocatalytic degradation mechanism of RB5 by TiO₂ NPs was elucidated by adding some scavengers to the solution. The main reactive species contributing to RB5 degradation were surface hydroxyl radicals. The first-order solar degradation rate constant of RB5 for TiO₂/GQDs is greater than that of TiO₂ NPs under sunlight illumination.

Exploiting Co Defects in CoFe-Layered Double Hydroxide (CoFe-LDH) Derivatives for Highly Efficient Photothermal Cancer Therapy

Currently, two-dimensional materials are being actively pursued in catalysis and other fields due their abundance of defects, which results in enhanced performance relative to their bulk defect-free counterparts. To date, the exploitation of defects in two-dimensional materials to enhance photothermal therapies has received little attention, motivating a detailed investigation. Herein, we successfully fabricated a series of novel CoFe-based photothermal agents (CoFe-x) by heating CoFe-layered double hydroxide (CoFe-LDH) nanosheets at different temperatures (x) between 200-800 °C under a Ar atmosphere. The CoFe-x products differed in their particle size, cobalt defect concentration, and electronic structure, with the CoFe-500 product containing the highest concentration of Co²⁺ defects and most efficient photothermal performance under near-infrared (NIR, 808 nm) irradiation. Experiments and density functional theory (DFT) calculations revealed that Co²⁺ defects modify the electronic structure of CoFe-x, narrowing the band gap and thus increasing the nonradiative recombination rate, thereby improving the NIR-driven photothermal properties. In vitro and in vivo results demonstrated that CoFe-500 was an efficient agent for photothermal cancer treatment and also near-infrared (NIR) thermal imaging, magnetic resonance (MR) imaging, and photoacoustic (PA) imaging. This work provides valuable new insights about the role of defects in the rational design of nanoagents with optimized structures for improved cancer therapy.

Ultrathin Transition Metal Chalcogenide Nanosheets Synthesized via Topotactic Transformation for Effective Cancer Theranostics

Ultrathin transition metal chalcogenide (TMC) nanosheets with ultrahigh photothermal conversion efficiency (η) and excellent stability are strongly desired in the application of photothermal therapy (PTT). However, the current synthetic methods of ultrathin TMC nanosheets have issues in obtaining uniform morphology, good dispersion, and satisfactory PTT behavior. Herein, ultrathin nanosheets of CoFe-selenide (CFS) with a finely controlled structure were prepared via a topological structural transformation process from an ultrathin CoFe-layered double hydroxide (LDH) precursor, followed by surface modification with poly(ethylene glycol) (PEG). The as-prepared CFS-PEG nanosheets inherit the ultrathin morphology of CoFe-LDH and exhibit an outstanding photothermal performance with a η of 74.5%, which is the first rank level of reported two-dimensional (2D) TMC nanosheet materials. The CFS-PEG nanosheets possess a satisfactory photoacoustic (PA) imaging capability with an ultralow detection limit (5 ppm) and simultaneously superior T₂ magnetic resonance imaging (MRI) performance with a large transverse MR relaxivity value (r₂) of 347.7 mM^-1 s^-1. Moreover, in vitro and in vivo assays verify superior anticancer activity with a dramatic photoinduced cancer cell apoptosis and tumor ablation. Therefore, a successful paradigm is provided for rational design and preparation of ultrathin TMC nanosheets in this work, holding enormous potential in cancer theranostics.

Microwave-Assisted Synthesis of Hollow Microspheres with Multicomponent Nanocores for Heavy-Metal Removal and Magnetic Sensing

The primary advantage of a hollow structure is the likelihood of introducing diverse components in a single particle to achieve multiple missions. Herein, hollow microspheres with multicomponent nanocores (HMMNs) have been prepared based on a template-free strategy via a microwave-assisted hydrothermal treatment of Chlorella. The resulting HMMNs retain the near-spherical hollow morphology and functional groups of the cell wall of Chlorella, obviating the need for templates and chemical modification. The elements (iron, cobalt, calcium, magnesium, chlorine, and phosphorus) naturally present within the Chlorella cells react to form hydroxyapatite/chlorapatite and magnetic nanocores without the need for exogenous chemical reagents. The performances of HMMNs for cadmium ion (Cd²⁺) removal and antibiotic detection are explored. HMMNs exhibit relatively high adsorbance of Cd²⁺ (1035.8 mmol/kg) and can be easily recovered by application of an external magnetic field. Ion exchange with Ca²⁺ and Mg²⁺ is shown to be the main mechanism of Cd²⁺ elimination. In addition, HMMNs are a suitable carrier for the construction of a magnetic immunosensor, as demonstrated by the successful development of such an immunosensor with acceptable analytical performance for the detection of neomycin in milk samples. The versatile applications of HMMNs result from their multicomponent nanocores, hollow structure, and the functional groups on their shell. This work not only offers a simple and eco-friendly strategy for the fabrication of novel HMMNs but also provides a valuable advanced material for contaminant detection and heavy-metal removal.

Rapid Decomposition and Catalytic Cascade Nanoplatforms Based on Enzymes and Mn-Etched Dendritic Mesoporous Silicon for MRI-Guided Synergistic Therapy

The endogenous tumor microenvironment (TME) can signally influence the therapeutic effects of cancer, so it is necessary to explore effective synergistic therapeutic strategies based on changing of the TME. Here, a catalytic cascade nanoplatform based on manganese (Mn)-etched dendritic mesoporous silicon nanoparticles (designated as DMMnSiO₃ NPs) loaded with indocyanine green (ICG) and natural glucose oxidase (GOD) is established (designated as DIG nanocomposites). As the Mn-O bonds in DMMnSiO₃ NPs are susceptive to mildly acidic and reducing environments, the DIG nanocomposites can be rapidly decomposed because of the biodegradation of DMMnSiO₃ NPs once internalized into the tumor by the consumption of glutathione (GSH) in TME to weaken the antioxidant capability of the tumors. The released Mn²⁺ could catalyze endogenous hydrogen peroxide (H₂O₂) to generate oxygen (O₂) to relieve the hypoxia in TME. The generation of O₂ may promote the catalyzed oxidation of glucose by GOD, which will cut off nutrient supplies, accompanied by the regeneration of H₂O₂. The regenerated H₂O₂ could be sequentially catalyzed by Mn²⁺ to compensate for the consumed O₂, and thus, the catalytic cascade process between Mn²⁺ and GOD was set up. As a result, a synergistic therapeutic strategy based on T₁-weighted magnetic resonance imaging (MRI) of Mn²⁺, starvation therapy by O₂-compensation enhanced catalyzing glucose, dual-model (GSH consumption and O₂ compensation) enhanced photodynamic therapy, and effective photothermal therapy of ICG (η = 23.8%) under 808 nm laser irradiation has been successfully established.

Enhancement of Cr(VI) removal efficiency via adsorption/photocatalysis synergy using electrospun chitosan/g-C3N4/TiO2 nanofibers

Chitosan/g-C₃N₄/TiO₂ (CS/CNT) nanofibers were fabricated by electrospinning technique for Cr(VI) removal through the adsorption and photocatalytic processes. The effects of crucial factors in the adsorption process including contact time (0-1440 min), pH (1-7), initial concentration of Cr(VI) (20-800 mg/L) were investigated. The photocatalytic experiment was executed in a photochemical reactor with an 800 W xenon lamp to simulate visible light. In adsorption process, at pH = 2, the adsorption capacities of chitosan (CS) nanofibers, CS/CNT_10:1 (CS : g-C₃N₄/TiO₂ = 10:1) nanofibers and CS/CNT_5:1 nanofibers were 20.8, 165.3 and 68.9 mg/g, respectively, suggesting the addition of g-C₃N₄/TiO₂ (CNT) could notably enhance the acid resistance of CS and widen its practical application. Under visible-light irradiation, the removal efficiency of Cr(VI) using CS/CNT nanofibers was appreciably improved, which was about 50 % higher than that of pure adsorption, indicating that the CS/CNT nanofibers exhibited the effective synergistic effect of adsorption and photocatalysis.

A Dual-Excitation Decoding Strategy Based on NIR Hybrid Nanocomposites for High-Accuracy Thermal Sensing

Optical thermal sensing holds great promise for disease theranostics. However, traditional ratiometric thermometry methods, in which intensity ratio of two nonoverlapping emissions is defined as the thermosensitive parameter, may have a limited accuracy in temperature read-out due to the deleterious interference from wavelength- and temperature-dependent photon attenuation in tissue. To overcome this limitation, a dual-excitation decoding strategy based on NIR hybrid nanocomposites comprising self-assembled quantum dots (QDs) and Nd3+ doped fluoride nanocrystals (NCs) is proposed for thermal sensing. Upon excitation at 808 nm, the intensity ratio of two emissions at identical wavelength (1057 nm) from QDs and NCs, respectively, is defined as the thermometric parameter R. By employing another 830 nm laser beam following the same optical path as 808 nm laser to exclusively excite QDs, the two overlapping emissions can be easily decoded. The acquired R proves to be inert to the detection depth in tissue, with a minimized temperature reading error of ≈2.3 °C at 35 °C (at a depth of ≈1.1 mm), while the traditional thermometry mode based on the nonoverlapping 1025 and 863 nm emissions may exhibit a large error of ≈43.0 °C. The insights provided by this work pave the way toward high-accuracy deep-tissue biosensing.

A novel "hot spring"-mimetic hydrogel with excellent angiogenic properties for chronic wound healing

The treatment of chronic wounds is a major challenge in regenerative medicine, and angiogenesis is known to be critical for chronic wound healing. Hot springs with temperature in the range of 30-45 °C can promote blood circulation, and some hot spring elements including iron and silicon are also known to be active in promoting angiogenesis. Inspired by the hot spring function, we designed a novel bioactive photothermal hydrogel with "hot spring effect" based on fayalite (FA) and N, O-carboxymethyl chitosan (NOCS), which releases bioactive ions and has heating function to create hot ion environment in wound area. The hot spring-mimetic hydrogel showed significant enhancement of angiogenesis and chronic wound healing in vivo due to the in situ heating through photothermal effect combined with the bioactive ions (Fe²⁺ and SiO₄^4-) released from the hydrogel. It is further confirmed that the synergetic effect of the mild heating and bioactive ions on angiogenesis was mainly because of the activation of different angiogenic factors and signaling pathways. Our study suggests that the hot spring-mimetic approach may be an effective strategy to design bioactive materials for promoting angiogenesis and tissue regeneration.

Near-Infrared Upconversion Mesoporous Tin Oxide Bio-Photocatalyst for H2O2-Activatable O2-Generating Magnetic Targeting Synergetic Treatment

Tumor hypoxia compromises the therapeutic efficacy of oxygen (O₂)-dependent treatment methods as the endogenous O₂ levels have an important influence on the production of reaction oxygen species. Herein, a synergistic multifunctional mesoporous Fe@Sn-UCNPs bio-photocatalytic nanoplatform is provided to comprehensively realize endogenous hydrogen peroxide (H₂O₂)-activatable, self-supplied O₂, photothermal performance, and near-infrared-mediated magnetic targeting PDT/PTT simultaneously for relieving tumor hypoxia. Such a nanoplatform is constructed by encapsulating magnetic Fe₃O₄ with lanthanide-ion-doped mesoporous tin oxide upconversion nanoparticles and further modified with phosphorylated serine and poly(ethylene glycol) for enhancing the biocompatibility and solubility. The nanoparticles can be activated by endogenous H₂O₂ and in situ generated O₂ to relieve hypoxia through catalytic reaction. Therefore, H₂O₂-responsive/O₂-evolving nanoparticles can elevate the O₂ level in the tumor site for an apparently enhanced PDT effect in vitro and in vivo. What is more, Fe@Sn-UCNPs demonstrate enhanced photothermal conversion efficiency based on the special nanostructure and much more circuit loops for electron transitions between Fe₃O₄ and Sn-UCNPs, and the electronic structure of Fe@Sn-UCNPs was calculated. In addition, such Fe@Sn-UCNPs also exhibit multimodality imaging performance (including photothermal, magnetic resonance, and computed tomography imaging) for monitoring and tracking the in vivo tumor therapeutic process. This work provides novel insight into the smart Fe@Sn-UCNPs as an "all-in-one" theranostic nanosystem for cancer therapy.

Self-Amplified Apoptosis Targeting Nanoplatform for Synergistic Magnetic-Thermal/Chemo Therapy In Vivo

The low efficiency homing of nanomaterials in tumors remains a major challenge in nanomedicine. Inspired by the apoptosis targeting properties of phosphatidylserine (PS), a self-amplified apoptosis targeting nanoplatform (MNPs-ZnDPA/β-Lap) is fabricated combining Zn_0.4 Co_0.6 Fe₂ O₄ @Zn_0.4 Mn_0.6 Fe₂ O₄ nanoparticles (MNPs) with an excellent magnetic hyperthermia effect, a chemotherapeutic drug of β-lapachone (β-Lap) with the promotion of cell apoptosis, and the good apoptosis targeting moiety of Zn(II)-bis(dipicolylamine) (bis-ZnDPA) for PS. In an apoptotic 4T1 xenograft model, MNPs-ZnDPA/β-Lap can first accumulate in tumors by the EPR effect. The released β-Lap triggers the apoptosis of cancer cells in the tumor and increases the apoptotic target, which results in amplifying their apoptosis targeting properties. This self-amplified apoptosis targeting efficiency of MNPs-ZnDPA/β-Lap almost inhibits the growth of tumors with the synergistic magnetic-thermal/chemo therapy, which can offer a significant promise for targeting cancer theranostics.

Molybdenum-titanium oxo-cluster, an efficient electrochemical catalyst for the facile preparation of black titanium dioxide film

Black-TiO₂ has become increasingly interesting as a promising photoactive material. Most of the preparations for black-TiO₂ involve either high temperature calcination, plasma, lengthy chemical reactions or dealing with dangerous or toxic chemicals. We found, by accident, that Mo-Ti oxo-clusters are efficient catalysts for the hydrogenation of a TiO₂ electrode to black-TiO₂ at room temperature. A series of Mo-Ti oxo-clusters, [Ti₄Mo₄O₁₀(OR)₁₄(X-BA)₂] (BA = benzoate, X = H (1), F (2), Cl (3), and Br (4)), were prepared and were characterized by crystallography. They have a Mo₄Ti₄ structure with Mo(v)-Mo(v) metal-metal interactions. The activated hydrogen (H*) generated by electrochemically catalytic water splitting turns the TiO₂ electrode to black-TiO₂ at room temperature, due to the reduction of Ti(iv) to H⁺Ti(iii). The potentials applied for water reduction must generally be higher than the overpotential at the TiO₂ electrode (-1.0 V vs. RHE). In this work, the onset potential of hydrogen evolution significantly decreased to -0.1 V vs. RHE. Using this blackened 1-TiO₂ electrode, the effective electrochemical catalytic degradation of a dye was examined in comparison with the degradation using the white TiO₂ electrode. This work provides a method for the facile preparation of a black-TiO₂ film, and is a step forward in black-TiO₂ research.

Fusiform-Like Copper(II)-Based Metal-Organic Framework through Relief Hypoxia and GSH-Depletion Co-Enhanced Starvation and Chemodynamic Synergetic Cancer Therapy

The therapeutic effect of traditional chemodynamic therapy (CDT) agents is severely restricted by their weakly acidic pH and glutathione (GSH) overexpression in the tumor microenvironment. Here, fusiform-like copper(II)-based tetrakis(4-carboxy phenyl)porphyrin (TCPP) nanoscale metal-organic frameworks (nMOFs) were designed and constructed for the first time (named PCN-224(Cu)-GOD@MnO₂). The coated MnO₂ layer can not only avoid conjugation of glucose oxidase (GOD) to damage normal cells but also catalyzes the generation of O₂ from H₂O₂ to enhance the oxidation of glucose (Glu) by GOD, which also provides abundant H₂O₂ for the subsequent Cu⁺-based Fenton-like reaction. Meanwhile, the Cu²⁺ chelated to the TCPP ligand is converted to Cu⁺ by the excess GSH in the tumor, which reduces the tumor antioxidant activity to improve the CDT effect. Next, the Cu⁺ reacts with the plentiful H₂O₂ by enzyme catalysis to produce a toxic hydroxyl radical (^•OH), and singlet oxygen (¹O₂) is synchronously generated from combination with Cu⁺, O₂, and H₂O via the Russell mechanism. Furthermore, the nanoplatform can be used for both TCPP-based in vivo fluorescence imaging and Mn²⁺-induced T₁-weighted magnetic resonance imaging. In conclusion, fusiform-like PCN-224(Cu)-GOD@MnO₂ nMOFs facilitate the therapeutic efficiency of chemodynamic and starvation therapy via combination with relief hypoxia and GSH depletion after acting as an accurate imaging guide.

Virus-Like Fe3O4@Bi2S3 Nanozymes with Resistance-Free Apoptotic Hyperthermia-Augmented Nanozymitic Activity for Enhanced Synergetic Cancer Therapy

Nanomaterials with intrinsic peroxidase-like activities are able to catalyze the oxidation of the substrate with the peroxide, which have been widely considered as artificial enzymatic agents in cancer therapy. However, current peroxidase catalytic oxidation treatments generating reactive oxygen species rely highly on hydrogen peroxide and pH, which limit greatly their therapeutic efficiency in the tumor microenvironment. Here, we report a strategy to construct the complex virus-like Fe₃O₄@Bi₂S₃ nanocatalysts (F-BS NCs) by connecting typical peroxidase Fe₃O₄ (MNPs) with a narrow band gap semiconductor Bi₂S₃ (BS) to enhance the enzymatic activity resorting to the limited intratumoral peroxide and efficient external photothermal stimuli. In this formulation, the integrated F-BS NCs induce cancer-cell death through mild photothermal treatment and sequential photothermal-stimulative catalysis of H₂O₂ into highly toxic ^•OH under 808 nm laser, which successfully realize a remarkable synergistic anticancer achievement.

In Situ Tuning of Defects and Phase Transition in Titanium Dioxide by Lithiothermic Reduction

Defects engineering of oxides plays a vital role in tuning their physicochemical and electronic properties and thereby determining their potential applications. However, the safe and controllable production of effective defects in the oxides is still challenging. Here, we report a facile one-pot solid lithiothermic reduction approach to generate graded oxygen defects in TiO₂ nanoparticles. Various levels of lithium reduction are systematically studied, and meanwhile, a distinct phase transition from anatase TiO₂ to cubic Li_xTiO₂ is observed with the increasing lithium ratio. The structure and evolution of surface defects and bulk phase transition are investigated in detail. Afterward, we demonstrate their applications in carbon dioxide photoreduction and photothermal imaging. The slightly reduced TiO₂ with effective oxygen defects affords a highly broadened solar spectrum absorption and yields significantly enhanced visible photocatalytic activity in CO₂ conversion, which is further revealed by theoretical calculations. The highly reduced TiO₂ with obvious phase transition shows enhanced solar absorption and achieves high photo-thermal-conversion efficacy, showing huge potential in photo-thermal-related applications. The lithiothermic reduction is a general and effective approach to produce defects and induce phase transition in oxides, which can be used in multiple applications.