Wet/Sono-Chemical Synthesis of Enzymatic Two-Dimensional MnO2 Nanosheets for Synergistic Catalysis-Enhanced Phototheranostics

Bacteria/Nanozyme Composites: New Therapeutics for Disease Treatment

Bacterial therapy is recognized as a cost-effective treatment for several diseases. However, its development is hindered by limited functionality, weak inherent therapeutic effects, and vulnerability to harsh microenvironmental conditions, leading to suboptimal treatment activity. Enhancing bacterial activity and therapeutic outcomes emerges as a pivotal challenge. Nanozymes have garnered significant attention due to their enzyme-mimic activities and high stability. They enable bacteria to mimic the functions of gene-edited bacteria expressing the same functional enzymes, thereby improving bacterial activity and therapeutic efficacy. This review delineates the therapeutic mechanisms of bacteria and nanozymes, followed by a summary of strategies for preparing bacteria/nanozyme composites. Additionally, the synergistic effects of such composites in biomedical applications such as gastrointestinal diseases and tumors are highlighted. Finally, the challenges of bacteria/nanozyme composites are discussed and propose potential solutions. This study aims to provide valuable insights to offer theoretical guidance for the advancement of nanomaterial-assisted bacterial therapy.

Manganese-derived biomaterials for tumor diagnosis and therapy

Manganese (Mn) is widely recognized owing to its low cost, non-toxic nature, and versatile oxidation states, leading to the emergence of various Mn-based nanomaterials with applications across diverse fields, particularly in tumor diagnosis and therapy. Systematic reviews specifically addressing the tumor diagnosis and therapy aspects of Mn-derived biomaterials are lacking. This review comprehensively explores the physicochemical characteristics and synthesis methods of Mn-derived biomaterials, emphasizing their role in tumor diagnostics, including magnetic resonance imaging, photoacoustic and photothermal imaging, ultrasound imaging, multimodal imaging, and biodetection. Moreover, the advantages of Mn-based materials in tumor treatment applications are discussed, including drug delivery, tumor microenvironment regulation, synergistic photothermal, photodynamic, and chemodynamic therapies, tumor immunotherapy, and imaging-guided therapy. The review concludes by providing insights into the current landscape and future directions for Mn-driven advancements in the field, serving as a comprehensive resource for researchers and clinicians.

Targeting starvation therapy for diabetic bacterial infections with endogenous enzyme-triggered hyaluronan-modified nanozymes in the infection microenvironment

The high-glycemic microenvironment of diabetic wounds promotes bacterial proliferation, leading to persistent infections and delayed wound healing. This poses a significant threat to human health, necessitating the development of new nanodrug visualization platforms. In this study, we designed and synthesized cascade nano-systems modified with targeted peptide and hyaluronic acid for diabetic infection therapy. The nano-systems were able to target the site of infection using LL-37, and in the microenvironment of wound infection, the hyaluronic acid shell of the nano-systems was degraded by endogenous hyaluronidase. This precise degradation released a cascade of nano-enzymes on the surface of the bacteria, effectively destroying their cytoskeleton. Additionally, the metals in the nano-enzymes provided a photo-thermal effect, accelerating wound healing. The cascade nano-visualization platform demonstrated excellent bactericidal efficacy in both in vitro antimicrobial assays and in vivo diabetic infection models. In conclusion, this nano-system employs multiple approaches including targeting, enzyme-catalyzed therapy, photothermal therapy, and chemodynamic therapy to kill bacteria and promote healing. The Ag@Pt-Au-LYZ/HA-LL-37 formulation shows great potential for the treatment of diabetic wounds.

Single-atom nanozymes shines diagnostics of gastrointestinal diseases

Various clinical symptoms of digestive system, such as infectious, inflammatory, and malignant disorders, have a profound impact on the quality of life and overall health of patients. Therefore, the chase for more potent medicines is both highly significant and urgent. Nanozymes, a novel class of nanomaterials, amalgamate the biological properties of nanomaterials with the catalytic activity of enzymes, and have been engineered for various biomedical applications, including complex gastrointestinal diseases (GI). Particularly, because of their distinctive metal coordination structure and ability to maximize atom use efficiency, single-atom nanozymes (SAzymes) with atomically scattered metal centers are becoming a more viable substitute for natural enzymes. Traditional nanozyme design strategies are no longer able to meet the current requirements for efficient and diverse SAzymes design due to the diversification and complexity of preparation processes. As a result, this review emphasizes the design concept and the synthesis strategy of SAzymes, and corresponding bioenzyme-like activities, such as superoxide dismutase (SOD), peroxidase (POD), oxidase (OXD), catalase (CAT), and glutathione peroxidase (GPx). Then the various application of SAzymes in GI illnesses are summarized, which should encourage further research into nanozymes to achieve better application characteristics.

Critical learning from industrial catalysis for nanocatalytic medicine

Systematical and critical learning from industrial catalysis will bring inspiration for emerging nanocatalytic medicine, but the relevant knowledge is quite limited so far. In this review, we briefly summarize representative catalytic reactions and corresponding catalysts in industry, and then distinguish the similarities and differences in catalytic reactions between industrial and medical applications in support of critical learning, deep understanding, and rational designing of appropriate catalysts and catalytic reactions for various medical applications. Finally, we summarize/outlook the present and potential translation from industrial catalysis to nanocatalytic medicine. This review is expected to display a clear picture of nanocatalytic medicine evolution.

Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics

Catalytic nanoparticles (CNPs) as heterogeneous catalyst reveals superior activity due to their physio-chemical features, such as high surface-to-volume ratio and unique optical, electric, and magnetic properties. The CNPs, based on their physio-chemical nature, can either increase the reactive oxygen species (ROS) level for tumor and antibacterial therapy or eliminate the ROS for cytoprotection, anti-inflammation, and anti-aging. In addition, the catalytic activity of nanozymes can specifically trigger a specific reaction accompanied by the optical feature change, presenting the feasibility of biosensor and bioimaging applications. Undoubtedly, CNPs play a pivotal role in pushing the evolution of technologies in medical and clinical fields, and advanced strategies and nanomaterials rely on the input of chemical experts to develop. Herein, a systematic and comprehensive review of the challenges and recent development of CNPs for biomedical applications is presented from the viewpoint of advanced nanomaterial with unique catalytic activity and additional functions. Furthermore, the biosafety issue of applying biodegradable and non-biodegradable nanozymes and future perspectives are critically discussed to guide a promising direction in developing span-new nanozymes and more intelligent strategies for overcoming the current clinical limitations.

Tunable Structured 2D Nanobiocatalysts: Synthesis, Catalytic Properties and New Horizons in Biomedical Applications

2D materials have offered essential contributions to boosting biocatalytic efficiency in diverse biomedical applications due to the intrinsic enzyme-mimetic activity and massive specific surface area for loading metal catalytic centers. Since the difficulty of high-quality synthesis, the varied structure, and the tough choice of efficient surface loading sites with catalytic properties, the artificial building of 2D nanobiocatalysts still faces great challenges. Here, in this review, a timely and comprehensive summarization of the latest progress and future trends in the design and biotherapeutic applications of 2D nanobiocatalysts is provided, which is essential for their development. First, an overview of the synthesis-structure-fundamentals and structure-property relationships of 2D nanobiocatalysts, both metal-free and metal-based is provided. After that, the effective design of the active sites of nanobiocatalysts is discussed. Then, the progress of their applied research in recent years, including biomedical analysis, biomedical therapeutics, pharmacokinetics, and toxicology is systematically highlighted. Finally, future research directions of 2D nanobiocatalysts are prospected. Overall, this review to provide cutting-edge and multidisciplinary guidance for accelerating future developments and biomedical applications of 2D nanobiocatalysts is expected.

Size-matching compositing nanoprobe of AIE-type gold nanocluster supramolecular nanogels wrapped by hypergravity-tailored MnO2 nanosheets for cellular glutathione detection

Compositing has been the main approach for material creation via wisely combining material components with different properties. MnO2 nanosheets (MNSs) with thin 2 D morphology are usually applied to composite molecules or nanomaterials for biosensing and bioimaging applications. However, such composition is actually structurally unmatched, albeit performance matching. Here, a series of benefits merely on the basis of structural match have been unearthed via tailoring MNSs with four sizes by synthesis under controllable hypergravity field. The classical fluorophore-quencher couple was utilized as the subject model, where the soft supramolecular nanogels based on aggregation-induced emission (AIE)-active gold nanoclusters were wrapped by MNSs of strong absorption. By comparative study of one-on-one wrapping and one-to-many encapsulation with geometrical selection of different MNSs, we found that the one-on-one wrapping model protected weakly-bonded nanogels from combination-induced distortion and strengthened nanogel networks via endowing exoskeleton. Besides, wrapping pattern and size-match significantly enhanced the quenching efficiency of MNSs towards the emissive nanogels. More importantly, the well-wrapped nanocomposites had considerable enhanced biological compatibility with much lower cytotoxicity and higher transfection capacity than the untailored MNSs composite and could serve as cellular glutathione detection.

Two-dimensional nanomaterials induced nano-bio interfacial effects and biomedical applications in cancer treatment

Two-dimensional nanomaterials (2D NMs), characterized by a large number of atoms or molecules arranged in one dimension (typically thickness) while having tiny dimensions in the other two dimensions, have emerged as a pivotal class of materials with unique properties. Their flat and sheet-like structure imparts distinctive physical, chemical, and electronic attributes, which offers several advantages in biomedical applications, including enhanced surface area for efficient drug loading, surface-exposed atoms allowing precise chemical modifications, and the ability to form hierarchical multilayer structures for synergistic functionality. Exploring their nano-bio interfacial interactions with biological components holds significant importance in comprehensively and systematically guiding safe applications. However, the current lack of in-depth analysis and comprehensive understanding of interfacial effects on cancer treatment motivates our ongoing efforts in this field. This study provides a comprehensive survey of recent advances in utilizing 2D NMs for cancer treatment. It offers insights into the structural characteristics, synthesis methods, and surface modifications of diverse 2D NMs. The investigation further delves into the formation of nano-bio interfaces during their in vivo utilization. Notably, the study discusses a wide array of biomedical applications in cancer treatment. With their potential to revolutionize therapeutic strategies and outcomes, 2D NMs are poised at the forefront of cancer treatment, holding the promise of transformative advancements.

"Three-in-One" Nanozyme Composite for Augmented Cascade Catalytic Tumor Therapy

Cascade catalytic reaction exhibits simple procedure and high efficiency, such as that from the orderly assembly of different enzymes in biological systems. Mimicking of the natural cascade procedure becomes critical, but the orderly assembly of different enzymes is still challenging. Herein, single Au-Pt nanozyme is reported with "three-in-one" functions to initiate cascade conversions for O2 supply as mimic catalase, H2 O2 production with its glucose oxidase-like property, and • OH generation as mimic peroxidase for chemodynamic therapy (CDT). Thus, the complex assembly and cross-talk among the different enzymes are avoided. To this end, metastable Cu2 O NPs, as scaffolds, are used to anchor ultrasmall Au-Pt nanozyme, while metal-organic framework (MOF) is used to encapsulate the nanozyme for tumor microenvironment response and shielding protein adsorption. Pluronic F127 is then modified on the surface to improve hydrophilicity and biocompatibility of the composite. The endogenous acidity and glutathione in tumor degrade MOF to expose nanozyme for cascade catalytic CDT. The high photothermal conversion ability also enhances the CDT, while Cu2+ ions consume GSH to further improve CDT efficiency as augmented cascade catalytic tumor therapy. Thus, a new paradigm is provided with drug-free single nanozyme for improving tumor therapeutic efficacy and minimizing side effects.

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

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

An NIR-II-photoresponsive CoSnO3 nanozyme for mild photothermally augmented nanocatalytic cancer therapy

The main challenges of nanozyme-based tumor catalytic therapy (NCT) lie in the unsatisfactory catalytic activity accompanied by a complex tumor microenvironment (TME). A few nanozymes have been designed to possess both enzyme-like catalytic activities and photothermal properties; however, the previously reported nanozymes mainly utilize the inefficient and unsafe NIR-I laser, which has a low maximum permissible exposure limit and a limited penetration depth. Herein, we report for the first time an all-in-one strategy to realize mild NIR-II photothermally amplified NCT by synthesizing amorphous CoSnO3 nanocubes with efficient triple enzyme-like catalytic activities and photothermal conversion properties. The presence of Co2+ and Sn4+ endows CoSnO3 nanocubes with the triple enzyme-like catalytic activities, not only achieving enhanced reactive oxygen species (ROS) generation through the Co2+-mediated peroxidase-like catalytic reaction to generate ˙OH and Sn4+-mediated depletion of overexpressed GSH, but also realizing the catalytic decomposition of endogenous H2O2 for relieving tumor hypoxia. More importantly, the obtained CoSnO3 nanocubes with a high photothermal conversion efficiency of 82.1% at 1064 nm could achieve mild hyperthermia (43 °C), which further improves the triple enzyme-like catalytic activities of the CoSnO3 nanozyme. The synergetic therapeutic efficacy of the NIR-II-responsive CoSnO3 nanozyme through mild NIR-II PTT-enhanced NCT could realize all-in-one multimodal tumor therapy to completely eliminate tumors without recurrence. This study will open a new avenue to explore NIR-II-photoresponsive nanozymes for efficient tumor therapy.

Trinity Strategy: Enabling Perovskite as Hydrophilic and Efficient Fluorescent Nanozyme for Constructing Biomarker Reporting Platform

Water instability and sensing homogeneity are the Achilles' heel of CsPbX3 NPs in biological fluids application. This work reports the preparation of Mn2+:CsPbCl3@SiO2 yolk-shell nanoparticles (YSNPs) in aqueous solutions created through the integration of ligand, surface, and crystal engineering strategies. The SN2 reaction between 4-chlorobutyric acid (CBA) and oleylamine (OAm) yields a zwitterionic ligand that facilitates the dispersion of YSNPs in water, while the robust SiO2 shell enhances their overall stability. Besides, Mn2+ doping in YSNPs not only introduces a second emission center but also enables potential postsynthetic designability, leading to the switching from YSNPs to MnO2@YSNPs with excellent oxidase (OXD)-like activity. Theoretical calculations reveal that electron transfer from CsPbCl3 to in situ MnO2 and the adsorption-desorption process of 3,3',5,5'-tetramethylbenzidine (TMB) synergistically amplify the OXD-like activity. In the presence of ascorbic acid (AA), Mn4+ in MnO2@YSNPs (fluorescent nanozyme) is reduced to Mn2+ and dissociated, thereby inhibiting the OXD-like activity and triggering fluorescence "turn-on/off", i.e., dual-mode recognition. Finally, a biomarker reporting platform based on MnO2@YSNPs fluorescent nanozyme is constructed with AA as the reporter molecule, and the accurate detection of human serum alkaline phosphatase (ALP) is realized, demonstrating the vast potential of perovskites in biosensing.

The energetic and physical concept of gold nanorod-dependent fluorescence in cancer treatment and development of new photonic compounds|review

The optical features of gold nanorods (GNR) may be precisely controlled by manipulating their size, shape, and aspect ratio. This review explores the impact of these parameters on the optical tuning of (GNR). By altering the experimental conditions, like the addition of silver ions during the seed-mediated growth process, the aspect ratio of (GNR) may be regulated. The shape is trans from spherical to rod-like structures resulting in noticeable changes in the nanoparticles surface plasmons resonance (SPR) bands. The longitudinal SPR band, associated with electron oscillations along the long axis, exhibits a pronounced red shift into the (NIR) region as the aspect ratio increases. In contrast, the transverse SPR band remains relate unchanged. Using computational methods like the discrete dipole approximation (DDA) allows for analyzing absorption, scattering, and total extinction features of gold (G) nanoparticles. Studies have shown that increasing the aspect ratio enhances the scattering efficiency, indicating a higher scattering quantum yield (QY). These findings highlight the importance of size, shape, and aspect ratio in controlling the optical features of (GNR) providing valuable insights for various uses in nanophotonics and plasmonic-dependent fluorescence in cancer treatment and developing new photonic compound NRs.

Black Phosphorus/MnO2 Nanocomposite Disrupting Bacterial Thermotolerance for Efficient Mild-Temperature Photothermal Therapy

The emergence of multi-drug resistant (MDR) pathogens is a major public health concern, posing a substantial global economic burden. Photothermal therapy (PTT) at mild temperature presents a promising alternative to traditional antibiotics due to its biological safety and ability to circumvent drug resistance. However, the efficacy of mild PTT is limited by bacterial thermotolerance. Herein, a nanocomposite, BP@Mn-NC, comprising black phosphorus nanosheets and a manganese-based nanozyme (Mn-NZ) is developed, which possesses both photothermal and catalytic properties. Mn-NZ imparts glucose oxidase- and peroxidase-like properties to BP@Mn-NC, generating reactive oxygen species (ROS) that induce lipid peroxidation and malondialdehyde accumulation across the bacterial cell membrane. This process disrupts unprotected respiratory chain complexes exposed on the bacterial cell membrane, leading to a reduction in the intracellular adenosine triphosphate (ATP) content. Consequently, mild PTT mediated by BP@Mn-NC effectively eliminates MDR infections by specifically impairing bacterial thermotolerance because of the dependence of bacterial heat shock proteins (HSPs) on ATP molecules for their proper functioning. This study paves the way for the development of a novel photothermal strategy to eradicate MDR pathogens, which targets bacterial HSPs through ROS-mediated inhibition of bacterial respiratory chain activity.

Nanozymes based on octahedral platinum nanocrystals with {111} surface facets: glucose oxidase mimicking activity in electrochemical sensors

The ability of shape-controlled octahedral Pt nanoparticles to act as nanozyme mimicking glucose oxidase enzyme is reported. Extended {111} particle surface facets coupled with a size comparable to natural enzymes and easy-to-remove citrate coating give high affinity for glucose, comparable to the enzyme as proven by the steady-state kinetics of glucose electrooxidation. The easy and thorough removal of the citrate coating, demonstrated by X-ray photoelectron spectroscopy analysis, allows a highly stable deposition of the nanozymes on the electrode. The glucose electrochemical detection (at -0.2 V vs SCE) shows a linear response between 0.36 and 17 mM with a limit of detection of 110 μM. A good reproducibility has been achieved, with an average relative standard deviation (RSD) value of 9.1% (n = 3). Similarly, a low intra-sensor variability has been observed, with a RSD of 6.6% (n = 3). Moreover, the sensor shows a long-term stability with reproducible performances for at least 2 months (RSD: 7.8%). Tests in saliva samples show the applicability of Pt nanozymes to commercial systems for non-invasive monitoring of hyperglycemia in saliva, with recoveries ranging from 92 to 98%.

Mechanism underlying the effect of MnO2 nanosheets for A549 cell chemodynamic therapy

MnO2 nanosheets (MnO2NSs) were synthesized by one-step method, and MnO2NSs were applied to A549 cell chemodynamic Therapy (CDT). The cytotoxicity, redox ability, and reactive oxygen species production of MnO2NSs have been investigated, and differences in cell metabolism during CDT were determined using liquid chromatography-mass spectrometry (LC-MS/MS). In addition, the metabolites of A549 lung cancer cells affected by MnO2NSs treatment are identified; metabolite differences were identified by PCA, PLS-DA, orthogonal PLS-DA, and other methods; and these differences were analyzed using non-targeted metabolomics. We found that A549 cells which were treated by MnO2NSs have 17 different metabolites and 9 metabolic pathways that varied markedly. Owing to their unique composition, structure, and physicochemical properties, MnO2NSs and their composites have become a favored type of nanomaterial used for CDT in cancer therapy. This work provides insights into the mechanism underlying the effects of MnO2NSs on the tumor microenvironment of A549 lung cancer cells, effectively making up for the deficiency of the study on cellular mechanism of CDT-induced apoptosis of cancer cells. It could aid the development of cancer CDT treatment strategies and help improve the use of nanomaterials in the clinical field.

Antioxidant and Prooxidant Nanozymes: From Cellular Redox Regulation to Next-Generation Therapeutics

Nanozymes, nanomaterials with enzyme-mimicking activity, have attracted tremendous interest in recent years owing to their ability to replace natural enzymes in various biomedical applications, such as biosensing, therapeutics, drug delivery, and bioimaging. In particular, the nanozymes capable of regulating the cellular redox status by mimicking the antioxidant enzymes in mammalian cells are of great therapeutic significance in oxidative-stress-mediated disorders. As the distinction of physiological oxidative stress (oxidative eustress) and pathological oxidative stress (oxidative distress) occurs at a fine borderline, it is a great challenge to design nanozymes that can differentially sense the two extremes in cells, tissues and organs and mediate appropriate redox chemical reactions. In this Review, we summarize the advances in the development of redox-active nanozymes and their biomedical applications. We primarily highlight the therapeutic significance of the antioxidant and prooxidant nanozymes in various disease model systems, such as cancer, neurodegeneration, and cardiovascular diseases. The future perspectives of this emerging area of research and the challenges associated with the biomedical applications of nanozymes are described.

Nanozyme-integrated microneedle patch for enhanced therapy of cutaneous squamous cell carcinoma by breaking the gap between H2O2 self-supplying chemodynamic therapy and photothermal therapy

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin cancers with increasing incidence worldwide. However, it is still challenging to prevent the relapse of cSCC due to poor drug penetration across the stratum corneum. Herein, we report the design of a microneedle patch loaded with MnO2/Cu2O nanosheets and combretastatin A4 (MN-MnO2/Cu2O-CA4) for the enhanced therapy of cSCC. The prepared MN-MnO2/Cu2O-CA4 patch could effectively deliver adequate drugs locally into the tumor sites. Moreover, the glucose oxidase (GOx)-mimicking activity of MnO2/Cu2O could catalyze glucose to produce H2O2, which combined with the released Cu to induce a Fenton-like reaction to efficiently generate hydroxyl radicals for chemodynamic therapy. Meanwhile, the released CA4 could inhibit cancer cell migration and tumor growth by disrupting the tumor vasculature. Moreover, MnO2/Cu2O was endowed with the ability of photothermal conversion under the irradiation of near-infrared (NIR) laser, which could not only kill the cancer cells but also promote the efficiency of the Fenton-like reaction. Significantly, the photothermal effect did not compromise the GOx-like activity of MnO2/Cu2O, which guaranteed enough production of H2O2 for the sufficient generation of hydroxyl radicals. This work may open avenues for constructing MN-based multimodal treatment for the efficient therapy of skin cancers.

Nanomaterials with Glucose Oxidase-Mimicking Activity for Biomedical Applications

Glucose oxidase (GOD) is an oxidoreductase that catalyzes the aerobic oxidation of glucose into hydrogen peroxide (H₂O₂) and gluconic acid, which has been widely used in industrial raw materials production, biosensors and cancer treatment. However, natural GOD bears intrinsic disadvantages, such as poor stability and a complex purification process, which undoubtedly restricts its biomedical applications. Fortunately, several artificial nanomaterials have been recently discovered with a GOD-like activity and their catalytic efficiency toward glucose oxidation can be finely optimized for diverse biomedical applications in biosensing and disease treatments. In view of the notable progress of GOD-mimicking nanozymes, this review systematically summarizes the representative GOD-mimicking nanomaterials for the first time and depicts their proposed catalytic mechanisms. We then introduce the efficient modulation strategy to improve the catalytic activity of existing GOD-mimicking nanomaterials. Finally, the potential biomedical applications in glucose detection, DNA bioanalysis and cancer treatment are highlighted. We believe that the development of nanomaterials with a GOD-like activity will expand the application range of GOD-based systems and lead to new opportunities of GOD-mimicking nanomaterials for various biomedical applications.

Manganese-Based Tumor Immunotherapy

As an essential micronutrient, manganese (Mn) participates in various physiological processes and plays important roles in host immune system, hematopoiesis, endocrine function, and oxidative stress regulation. Mn-based nanoparticles are considered to be biocompatible and show versatile applications in nanomedicine, in particular utilized in tumor immunotherapy in the following ways: 1) acting as a biocompatible nanocarrier to deliver immunotherapeutic agents for tumor immunotherapy; 2) serving as an adjuvant to regulate tumor immune microenvironment and enhance immunotherapy; 3) activating host's immune system through the cGAS-STING pathway to trigger tumor immunotherapy; 4) real-time monitoring tumor immunotherapy effect by magnetic resonance imaging (MRI) since Mn²⁺ ions are ideal MRI contrast agent which can significantly enhance the T₁ -weighted MRI signal after binding to proteins. This comprehensive review focuses on the most recent progress of Mn-based nanoplatforms in tumor immunotherapy. The characteristics of Mn are first discussed to guide the design of Mn-based multifunctional nanoplatforms. Then the biomedical applications of Mn-based nanoplatforms, including immunotherapy alone, immunotherapy-involved multimodal synergistic therapy, and imaging-guided immunotherapy are discussed in detail. Finally, the challenges and future developments of Mn-based tumor immunotherapy are highlighted.

Rough Nanovaccines Boost Antitumor Immunity Through the Enhancement of Vaccination Cascade and Immunogenic Cell Death Induction

Nanovaccines have attracted intense interests for efficient antigen delivery and tumor-specific immunity. It is challenging to develop a more efficient and personalized nanovaccine to maximize all steps of the vaccination cascade by exploiting the intrinsic properties of nanoparticles. Here, biodegradable nanohybrids (MP) composed of manganese oxide nanoparticles and cationic polymers are synthesized to load a model antigen ovalbumin to form MPO nanovaccines. More interestingly, MPO could serve as autologous nanovaccines for personalized tumor treatment taking advantage of in situ released tumor-associated antigens induced by immunogenic cell death (ICD). The intrinsic properties of MP nanohybrids including morphology, size, surface charge, chemical, and immunoregulatory functions are fully exploited to enhance of all steps of the cascade and induce ICD. MP nanohybrids are designed to efficiently encapsulate antigens by cationic polymers, drain to lymph nodes by appropriate size, be internalized by dendritic cells (DCs) by rough morphology, induce DC maturation through cGAS-STING pathway, and enhance lysosomal escape and antigen cross-presentation through the "proton sponge effect". The MPO nanovaccines are found to efficiently accumulate in lymph nodes and elicit robust specific T-cell immune responses to inhibit the occurrence of ovalbumin-expressing B16-OVA melanoma. Furthermore, MPO demonstrate great potential to serve as personalized cancer vaccines through the generation of autologous antigen depot through ICD induction, activation of potent antitumor immunity, and reversal of immunosuppression. This work provides a facile strategy for the construction of personalized nanovaccines by exploiting the intrinsic properties of nanohybrids.

Development of Two-Dimensional Functional Nanomaterials for Biosensor Applications: Opportunities, Challenges, and Future Prospects

New possibilities for the development of biosensors that are ready to be implemented in the field have emerged thanks to the recent progress of functional nanomaterials and the careful engineering of nanostructures. Two-dimensional (2D) nanomaterials have exceptional physical, chemical, highly anisotropic, chemically active, and mechanical capabilities due to their ultra-thin structures. The diversity of the high surface area, layered topologies, and porosity found in 2D nanomaterials makes them amenable to being engineered with surface characteristics that make it possible for targeted identification. By integrating the distinctive features of several varieties of nanostructures and employing them as scaffolds for bimolecular assemblies, biosensing platforms with improved reliability, selectivity, and sensitivity for the identification of a plethora of analytes can be developed. In this review, we compile a number of approaches to using 2D nanomaterials for biomolecule detection. Subsequently, we summarize the advantages and disadvantages of using 2D nanomaterials in biosensing. Finally, both the opportunities and the challenges that exist within this potentially fruitful subject are discussed. This review will assist readers in understanding the synthesis of 2D nanomaterials, their alteration by enzymes and composite materials, and the implementation of 2D material-based biosensors for efficient bioanalysis and disease diagnosis.

Recent Advances in Hydrogel-Based Phototherapy for Tumor Treatment

Phototherapeutic agent-based phototherapies activated by light have proven to be safe modalities for the treatment of various malignant tumor indications. The two main modalities of phototherapies include photothermal therapy, which causes localized thermal damage to target lesions, and photodynamic therapy, which causes localized chemical damage by generated reactive oxygen species (ROS). Conventional phototherapies suffer a major shortcoming in their clinical application due to their phototoxicity, which primarily arises from the uncontrolled distribution of phototherapeutic agents in vivo. For successful antitumor phototherapy, it is essential to ensure the generation of heat or ROS specifically occurs at the tumor site. To minimize the reverse side effects of phototherapy while improving its therapeutic performance, extensive research has focused on developing hydrogel-based phototherapy for tumor treatment. The utilization of hydrogels as drug carriers allows for the sustained delivery of phototherapeutic agents to tumor sites, thereby limiting their adverse effects. Herein, we summarize the recent advancements in the design of hydrogels for antitumor phototherapy, offer a comprehensive overview of the latest advances in hydrogel-based phototherapy and its combination with other therapeutic modalities for tumor treatment, and discuss the current clinical status of hydrogel-based antitumor phototherapy.

Targeting STING Activation by Antigen-Inspired MnO2 Nanovaccines Optimizes Tumor Radiotherapy

Immune checkpoint blockers therapy can improve the radiotherapy-induced immunosuppression by enhancing interferon secretion, but still suffer from low clinical response rate and potential adverse effects. Mn²⁺ -mediated activation of interferon gene stimulator (STING) pathway provides an alternative for combination radioimmunotherapy of tumor. However, it is still a challenge for specific delivery of Mn²⁺ to innate immune cells and targeting activation of STING pathway. Herein, a novel antigen-inspired MnO₂ nanovaccine is fabricated as Mn²⁺ source and functionalized with mannose, enabling it to target innate immune cells to activate the STING pathway. Meanwhile, the release of Mn²⁺ in the intracellular lysosomes can also be for magnetic resonance imaging to monitor the dynamic distribution of nanovaccines in vivo. The targeting activation of STING pathway can enhance radiotherapy-induced immune responses for inhibiting local and distant tumors, and resisting tumor metastasis. The study proposes an optimized radiotherapy strategy through targeting STING activation of antigen-inspired nanovaccines.

Smart Biomimetic Nanozymes for Precise Molecular Imaging: Application and Challenges

New nanotechnologies for imaging molecules are widely being applied to visualize the expression of specific molecules (e.g., ions, biomarkers) for disease diagnosis. Among various nanoplatforms, nanozymes, which exhibit enzyme-like catalytic activities in vivo, have gained tremendously increasing attention in molecular imaging due to their unique properties such as diverse enzyme-mimicking activities, excellent biocompatibility, ease of surface tenability, and low cost. In addition, by integrating different nanoparticles with superparamagnetic, photoacoustic, fluorescence, and photothermal properties, the nanoenzymes are able to increase the imaging sensitivity and accuracy for better understanding the complexity and the biological process of disease. Moreover, these functions encourage the utilization of nanozymes as therapeutic agents to assist in treatment. In this review, we focus on the applications of nanozymes in molecular imaging and discuss the use of peroxidase (POD), oxidase (OXD), catalase (CAT), and superoxide dismutase (SOD) with different imaging modalities. Further, the applications of nanozymes for cancer treatment, bacterial infection, and inflammation image-guided therapy are discussed. Overall, this review aims to provide a complete reference for research in the interdisciplinary fields of nanotechnology and molecular imaging to promote the advancement and clinical translation of novel biomimetic nanozymes.

Low-dimensional nanomaterials as an emerging platform for cancer diagnosis and therapy

The burden of cancer is increasing, being widely recognized as one of the main reasons for deaths among humans. Despite the tremendous efforts that have been made worldwide to stem the progression and metastasis of cancer, morbidity and mortality in malignant tumors have been clearly rising and threatening human health. In recent years, nanomedicine has come to occupy an increasingly important position in precision oncotherapy, which improves the diagnosis, treatment, and long-term prognosis of cancer. In particular, LDNs with distinctive physicochemical capabilities have provided great potential for advanced biomedical applications, attributed to their large surface area, abundant surface binding sites, and good cellular permeation properties. In addition, LDNs can integrate CT/MR/US/PAI and PTT/PDT/CDT/NDDS into a multimodal theranostic nanoplatform, enabling targeted therapy and efficacy assessments for cancer. This review attempts to concisely summarize the classification and major properties of LDNs. Simultaneously, we particularly emphasize their applications in the imaging, diagnosis, and treatment of cancerous diseases.

Amylase degradation enhanced NIR photothermal therapy and fluorescence imaging of bacterial biofilm infections

Effective treatment of bacterial biofilm-related infections is a great challenge for the medical community. During the formation of biofilms, bacteria excrete extracellular polymeric substances (EPS), including polysaccharides, proteins, nucleic acids, etc., to encapsulate themselves and form a "fort-like" structure, which greatly reduces the efficiency of therapeutic agents. Herein, we prepared a nanoagent (MnO₂-amylase-PEG-ICG nanosheets, MAPI NSs) with biofilm degradation capability for efficient photothermal therapy and fluorescence imaging of methicillin-resistant Staphylococcus aureus (MRSA) biofilm infections. MAPI NSs were constructed by sequentially modifying α-amylase, polyethylene glycol (PEG), and indocyanine green (ICG) on manganese dioxide nanosheets (MnO₂ NSs). Experimental results exhibited that MAPI NSs could accumulate in infected tissues after intravenous injection, degrade in the acidic biofilm microenvironment, and release the loaded ICG for near-infrared (NIR) fluorescence imaging of the infected tissues. Importantly, MAPI NSs could efficiently eliminate MRSA biofilm infections in mice by α-amylase enhanced photothermal therapy. In addition, MAPI NSs exhibited neglectable toxicity towards mice. Given the superior properties of MAPI NSs, the enzyme-degradation enhanced therapeutic strategy presented in this work offers a promising solution for effectively combating biofilm infectious diseases.

Hypoxia Alleviated and One Photo-Triggered Thermal/Dynamic Nanoplatform for Immunogenic Cell Death-Initiated Cancer Immunotherapy

Immunogenic cell death (ICD) induced by treatment modalities like chemotherapy, radiotherapy, and photothermal and photodynamic therapy has shown great potential to improve the low response rate of various solid tumors in cancer immunotherapy. However, extensive studies have revealed that the efficacy of cancer treatment is limited by the hypoxia and immunosuppression in the tumor microenvironment (TME). To address these challenges, a hypoxia alleviated and one phototriggered thermal/dynamic nanoplatform based on MnO₂@PDA/ICG-BSA (MPIB) is developed for oxygen (O₂) self-supply enhanced cancer phototherapy (PT). First, MnO₂ transfers intracellular overexpression H₂O₂ into O₂ in the acidic TME through its catalase-like activity to improve the hypoxia and also provide O₂ for the following photodynamic therapy. Then, under single NIR-808 nm light irradiation (called the "phototherapeutic window"), excellent photothermal and photodynamic performance of the MPIB is activated for combined PT. Finally, assisted with immune adjuvant cytosine-phospho-guanine, obvious ICD and systemic antitumor immunity was elicited in PT-treated mice and demonstrated significant growth inhibition on distant tumors. This MPIB-based nanoplatform highlights the promise to overcome the limitations of hypoxia and also challenges of immunosuppressive tumor microenvironments for improved cancer immunotherapy.

Facile synthesis of phycocyanin/polydopamine hierarchical nanocomposites for synergizing PTT/PDT against cancer

The exceptional biocompatibility and biosafety of natural proteins have made them a popular choice for tumor therapy in recent years, but their therapeutic effectiveness is severely constrained by factors including physiological instability, insufficient delivery, limited accumulation in tumor cells, etc. Here, a novel Mn-doped phycocyanin (Pc)/polydopamine (PDA) hierarchical nanostructure (MnPc@P) with excellent optical absorption, photothermal conversion, and photodynamic performances, is first designed and fabricated by a simply one-pot reaction, which not only successfully encapsulates natural protein Pc with intact activity in the nanostructure of MnPc@P but also gives them better biocompatibility. Upon laser irradiation, PDA-mediated hyperthermia and Pc-induced ROS elevation in tumor cells have been demonstrated, leading to drastic tumor cell death via combined PTT/PDT effect, greater than single PTT or PDT. In general, the expert fusion of Pc and PDA into a single nanomedicine opens fascinating perspectives in the delivery of natural proteins and tumor therapy.

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

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

Biomimetic Yolk-Shell Nanocatalysts for Activatable Dual-Modal-Image-Guided Triple-Augmented Chemodynamic Therapy of Cancer

Fenton reaction-based chemodynamic therapy (CDT), which applies metal ions to convert less active hydrogen peroxide (H₂O₂) into more harmful hydroxyl peroxide (·OH) for tumor treatment, has attracted increasing interest recently. However, the CDT is substantially hindered by glutathione (GSH) scavenging effect on ·OH, low intracellular H₂O₂ level, and low reaction rate, resulting in unsatisfactory efficacy. Here, a cancer cell membrane (CM)-camouflaged Au nanorod core/mesoporous MnO₂ shell yolk-shell nanocatalyst embedded with glucose oxidase (GOD) and Dox (denoted as AMGDC) is constructed for synergistic triple-augmented CDT and chemotherapy of tumor under MRI/PAI guidance. Benefiting from the homologous adhesion and immune escaping property of the cancer CM, the nanocatalysts can target tumor and gradually accumulate in tumor site. For triple-augmented CDT, first, the MnO₂ shell reacts with intratumoral GSH to generate Mn²⁺ and glutathione disulfide, which achieves Fenton-like ion delivery and weakening of GSH-mediated scavenging effect, leading to GSH depletion-enhanced CDT. Second, the intratumoral glucose can be oxidized to H₂O₂ and gluconic acid by GOD, achieving supplementary H₂O₂-enhanced CDT. Next, the AuNRs absorbing in NIR-II elevate the local tumor temperature upon NIR-II laser irradiation, achieving photothermal-enhanced CDT. Dox is rapidly released for adjuvant chemotherapy due to responsive degradation of MnO₂ shell. Moreover, GSH-activated PAI/MRI can be used to monitor CDT process. This study provides a great paradigm for enhancing CDT-mediated antitumor efficacy.

Research trends in biomedical applications of two-dimensional nanomaterials over the last decade - A bibliometric analysis

Two-dimensional (2D) nanomaterials with versatile properties have been widely applied in the field of biomedicine. Despite various studies having reviewed the development of biomedical 2D nanomaterials, there is a lack of a study that objectively summarizes and analyzes the research trend of this important field. Here, we employ a series of bibliometric methods to identify the development of the 2D nanomaterial-related biomedical field during the past 10 years from a holistic point of view. First, the annual publication/citation growth, country/institute/author distribution, referenced sources, and research hotspots are identified. Thereafter, based on the objectively identified research hotspots, the contributions of 2D nanomaterials to the various biomedical subfields, including those of biosensing, imaging/therapy, antibacterial treatment, and tissue engineering are carefully explored, by considering the intrinsic properties of the nanomaterials. Finally, prospects and challenges have been discussed to shed light on the future development and clinical translation of 2D nanomaterials. This review provides a novel perspective to identify and further promote the development of 2D nanomaterials in biomedical research.

Puffing ultrathin oxides with nonlayered structures

Two-dimensional (2D) oxides have unique electrical, optical, magnetic, and catalytic properties, which are promising for a wide range of applications in different fields. However, it is difficult to fabricate most oxides as 2D materials unless they have a layered structure. Here, we present a facile strategy for the synthesis of ultrathin oxide nanosheets using a self-formed sacrificial template of carbon layers by taking advantage of the Maillard reaction and violent redox reaction between glucose and ammonium nitrate. To date, 36 large-area ultrathin oxides (with thickness ranging from ~1.5 to ~4 nm) have been fabricated using this method, including rare-earth oxides, transition metal oxides, III-main group oxides, II-main group oxides, complex perovskite oxides, and high-entropy oxides. In particular, the as-obtained perovskite oxides exhibit great electrocatalytic activity for oxygen evolution reaction in an alkaline solution. This facile, universal, and scalable strategy provides opportunities to study the properties and applications of atomically thin oxide nanomaterials.

Fungus-Based MnO/Porous Carbon Nanohybrid as Efficient Laccase Mimic for Oxygen Reduction Catalysis and Hydroquinone Detection

Developing efficient laccase-mimicking nanozymes via a facile and sustainable strategy is intriguing in environmental sensing and fuel cells. In our work, a MnO/porous carbon (MnO/PC) nanohybrid based on fungus was synthesized via a facile carbonization route. The nanohybrid was found to possess excellent laccase-mimicking activity using 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the substrate. Compared with the natural laccase and reported nanozymes, the MnO/PC nanozyme had much lower K_m value. Furthermore, the electrochemical results show that the MnO/PC nanozyme had high electrocatalytic activity toward the oxygen reduction reaction (ORR) when it was modified on the electrode. The hybrid nanozyme could catalyze the four-electron ORR, similar to natural laccase. Moreover, hydroquinone (HQ) induced the reduction of oxABTS and caused the green color to fade, which provided colorimetric detection of HQ. A desirable linear relationship (0–50 μM) and detection limit (0.5 μM) were obtained. Our work opens a simple and sustainable avenue to develop a carbon–metal hybrid nanozyme in environment and energy applications.

Enzyme-Engineered Conjugated Polymer Nanoplatform for Activatable Companion Diagnostics and Multistage Augmented Synergistic Therapy

Companion diagnostics (CDx) provides critical information for precision medicine. However, current CDx is mostly limited to in vitro tests, which cannot accurately evaluate the disease progression and treatment response in real time. To overcome this challenge, herein a glucose oxidase (GOx)-engineered conjugated polymer (polyaniline, PANI) nanoplatform (denoted as PANITG) is reported for activatable imaging-based CDx and multistage augmented photothermal/starvation synergistic therapy. PANITG comprises a pH-activatable conjugated polymer as a photothermal convertor and photoacoustic (PA) emitter, a GOx as a cancer starvation inducer as well as a H₂ O₂ and acid producer, and a H₂ O₂ -cleavable linker as a "switch" for GOx activity. The in vivo PA imaging and photothermal therapy abilities are activated by acidic tumor microenvironment and self-augmented by the reaction between GOx and glucose. Meanwhile, the photothermal effect will enhance the GOx activity in turn. Such multistage augmentation of the therapeutic effects will facilitate effective cancer management. In addition, the in vivo PA imaging with PANITG reveals the tumor pH level which is correlated to the efficiency of the photothermal therapy and to the catalytic activity of GOx at each stage, enabling real-time activatable CDx.

Localized Hyperthermia Induced by Biogenic Synthesized Manganese Oxide Nanoparticles from Cannabis Sativa for Glioblastoma Photothermal Therapy

Glioblastoma is one of the most aggressive and fast-growing types of cancers which required sophisticated and effective therapeutic methods. In this work, we synthesized manganese oxide nanoparticles (MnO2 NPs) using a green synthesis approach. In this process, an aqueous extract of Cannabis sativa (CS) leaves was used as the reacting medium and reducing agent of manganese acetate. The characterizations showed that the synthesized NPs have a diameter of 25–35 nm and high purity. The thermal generating studies showed that the combination of the synthesized biogenic MnO2 NPs with near-infrared laser (NIR, 808 nm) produce considerable heat in a concentration and power density-dependent manner. In vitro studies revealed that the NPs are cytocompatible in concentration up to 80 μg/mL and induce negligible toxicity (p < 0.1). On the other hand, the treatment-induced considerably cell death on C6 glioma cells in an optimum concentration and generated heat (p < 0.05). This study showed the CS extract can synthesis MnO2 NPs and the synthesized NPs can be applied as the effective photothermal agent.

Two-Dimensional Nanomaterial-based catalytic Medicine: Theories, advanced catalyst and system design

Two-dimensional nanomaterial-based catalytic medicines that associate the superiorities of novel catalytic mechanisms with nanotechnology have emerged as absorbing therapeutic strategies for cancer therapy. Catalytic medicines featuring high efficiency and selectivity have been widely used as effective anticancer strategies without applying traditional nonselective and highly toxic chemodrugs. Moreover, two-dimensional nanomaterials are characterized by distinctive physicochemical properties, such as a sizeable bandgap, good conductivity, fast electron transfer and photoelectrochemical activity. The introduction of two-dimensional nanomaterials into catalytic medicine provides a more effective, controllable, and precise antitumor strategy. In this review, different types of two-dimensional nanomaterial-based catalytic nanomedicines are generalized, and their catalytic theories, advanced catalytic pathways and catalytic nanosystem design are also discussed in detail. Notably, future challenges and obstacles in the design and further clinical transformation of two-dimensional nanomaterial-based catalytic nanomedicine are prospected.

2D material-based peroxidase-mimicking nanozymes: catalytic mechanisms and bioapplications

The boom in nanotechnology brings new insights into the development of artificial enzymes (nanozymes) with ease of modification, lower manufacturing cost, and higher catalytic stability than natural enzymes. Among various nanomaterials, two-dimensional (2D) nanomaterials exhibit promising enzyme-like properties for a plethora of bioapplications owing to their unique physicochemical characteristics of tuneable composition, ultrathin thickness, and huge specific surface area. Herein, we review the recent advances in several 2D material-based nanozymes, such as carbonaceous nanosheets, metal-organic frameworks (MOFs), transition metal dichalcogenides (TMDs), layered double hydroxides (LDHs), and transition metal oxides (TMOs), clarify the mechanisms of peroxidase (POD)-mimicking catalytic behaviors, and overview the potential bioapplications of 2D nanozymes.

Nanozymes-recent development and biomedical applications

Nanozyme is a series of nanomaterials with enzyme-mimetic activities that can proceed with the catalytic reactions of natural enzymes. In the field of biomedicine, nanozymes are capturing tremendous attention due to their high stability and low cost. Enzyme-mimetic activities of nanozymes can be regulated by multiple factors, such as the chemical state of metal ion, pH, hydrogen peroxide (H₂O₂), and glutathione (GSH) level, presenting great promise for biomedical applications. Over the past decade, multi-functional nanozymes have been developed for various biomedical applications. To promote the understandings of nanozymes and the development of novel and multifunctional nanozymes, we herein provide a comprehensive review of the nanozymes and their applications in the biomedical field. Nanozymes with versatile enzyme-like properties are briefly overviewed, and their mechanism and application are discussed to provide understandings for future research. Finally, underlying challenges and prospects of nanozymes in the biomedical frontier are discussed in this review.