In Situ Nanoreactor for Photosynthesizing H2 Gas To Mitigate Oxidative Stress in Tissue Inflammation

Mitochondrial 'Birth-Death' coordinator: An intelligent hydrogen nanogenerator to enhance intervertebral disc regeneration

Currently, mitochondrial dysfunction caused by oxidative stress is a growing concern in degenerative diseases, notably intervertebral disc degeneration (IVDD). Dysregulation of the balance of mitochondrial quality control (MQC) has been considered the key contributor, while it's still challenging to effectively harmonize different MQC components in a simple and biologically safe way. Hydrogen gas (H2) is a promising mitochondrial therapeutic molecule due to its bio-reductivity and diffusibility across cellular membranes, yet its relationship with MQC regulation remains unknown. Herein, we propose a mitochondrial 'Birth-Death' coordinator achieved by an intelligent hydrogen nanogenerator (Fe@HP-OD), which can sustainably release H2 in response to the unique microenvironment in degenerated IVDs. Both in vitro and in vivo results prove alleviation of cellular oxidative stress and restoration of nucleus pulposus cells function, thereby facilitating successful IVD regeneration. Significantly, this study for the first time proposes the mitochondrial 'Birth-Death' coordination mechanism: 1) attenuation of overactivated mitochondrial 'Death' process (UPRmt and unselective mitophagy); and 2) activation of Adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway for mitochondrial 'Birth-Death' balance (mitochondrial biogenesis and controlled mitophagy). These pioneering findings can fill in the gaps in molecular mechanisms for H2 regulation on MQC homeostasis, and pave the way for future strategies towards restoring equilibrium of MQC system against degenerative diseases.

A biomimetic upconversion nanoreactors for near-infrared driven H2 release to inhibit tauopathy in Alzheimer's disease therapy

Abnormal hyperphosphorylation of tau protein is a principal pathological hallmark in the onset of neurodegenerative disorders, such as Alzheimer's disease (AD), which can be induced by an excess of reactive oxygen species (ROS). As an antioxidant, hydrogen gas (H2) has the potential to mitigate AD by scavenging highly harmful ROS such as •OH. However, conventional administration methods of H2 face significant challenges in controlling H2 release on demand and fail to achieve effective accumulation at lesion sites. Herein, we report artificial nanoreactors that mimic natural photosynthesis to realize near-infrared (NIR) light-driven photocatalytic H2 evolution in situ. The nanoreactors are constructed by biocompatible crosslinked vesicles (CVs) encapsulating ascorbic acid and two photosensitizers, chlorophyll a (Chla) and indoline dye (Ind). In addition, platinum nanoparticles (Pt NPs) serve as photocatalysts and upconversion nanoparticles (UCNP) act as light-harvesting antennas in the nanoreacting system, and both attach to the surface of CVs. Under NIR irradiation, the nanoreactors release H2 in situ to scavenge local excess ROS and attenuate tau hyperphosphorylation in the AD mice model. Such NIR-triggered nanoreactors provide a proof-of-concept design for the great potential of hydrogen therapy against AD.

Bone targeted nano-drug and nano-delivery

There are currently no targeted delivery systems to satisfactorily treat bone-related disorders. Many clinical drugs consisting of small organic molecules have a short circulation half-life and do not effectively reach the diseased tissue site. This coupled with repeatedly high dose usage that leads to severe side effects. With the advance in nanotechnology, drugs contained within a nano-delivery device or drugs aggregated into nanoparticles (nano-drugs) have shown promises in targeted drug delivery. The ability to design nanoparticles to target bone has attracted many researchers to develop new systems for treating bone related diseases and even repurposing current drug therapies. In this review, we shall summarise the latest progress in this area and present a perspective for future development in the field. We will focus on calcium-based nanoparticle systems that modulate calcium metabolism and consequently, the bone microenvironment to inhibit disease progression (including cancer). We shall also review the bone affinity drug family, bisphosphonates, as both a nano-drug and nano-delivery system for bone targeted therapy. The ability to target and release the drug in a controlled manner at the disease site represents a promising safe therapy to treat bone diseases in the future.

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.

The Landscape of Smart Biomaterial-Based Hydrogen Therapy

Hydrogen (H2) therapy is an emerging, novel, and safe therapeutic modality that uses molecular hydrogen for effective treatment. However, the impact of H2 therapy is limited because hydrogen molecules predominantly depend on the systemic administration of H2 gas, which cannot accumulate at the lesion site with high concentration, thus leading to limited targeting and utilization. Biomaterials are developed to specifically deliver H2 and control its release. In this review, the development process, stimuli-responsive release strategies, and potential therapeutic mechanisms of biomaterial-based H2 therapy are summarized. H2 therapy. Specifically, the produced H2 from biomaterials not only can scavenge free radicals, such as reactive oxygen species (ROS) and lipid peroxidation (LPO), but also can inhibit the danger factors of initiating diseases, including pro-inflammatory cytokines, adenosine triphosphate (ATP), and heat shock protein (HSP). In addition, the released H2 can further act as signal molecules to regulate key pathways for disease treatment. The current opportunities and challenges of H2-based therapy are discussed, and the future research directions of biomaterial-based H2 therapy for clinical applications are emphasized.

Structurally Oriented Carbon Dots as ROS Nanomodulators for Dynamic Chronic Inflammation and Infection Elimination

The selective elimination of cytotoxic ROS while retaining essential ones is pivotal in the management of chronic inflammation. Co-occurring bacterial infection further complicates the conditions, necessitating precision and an efficacious treatment strategy. Herein, the dynamic ROS nanomodulators are rationally constructed through regulating the surface states of herbal carbon dots (CDs) for on-demand inflammation or infection elimination. The phenolic OH containing CDs derived from honeysuckle (HOCD) and dandelion (DACD) demonstrated appropriate redox potentials, ensuring their ability to scavenge cytotoxic ROS such as ·OH and ONOO-, while invalidity toward essential ones such as O2·-, H2O2, and NO. This enables efficient treatment of chronic inflammation without affecting essential ROS signal pathways. The surface C-N/C═N of CDs derived from taxus leaves (TACD) and DACD renders them with suitable band structures, facilitating absorption in the red region and efficient generation of O2·- upon light irradiation for sterilization. Specifically, the facilely prepared DACD demonstrates fascinating dynamic ROS modulating ability, making it highly suitable for addressing concurrent chronic inflammation and infection, such as diabetic wound infection. This dynamic ROS regulation strategy facilitates the realization of the precise and efficient treatment of chronic inflammation and infection with minimal side effects, holding immense potential for clinical practice.

Harnessing Metal-Organic Frameworks for NIR-II Light-Driven Multiphoton Photocatalytic Water Splitting in Hydrogen Therapy

The construction of near-infrared (NIR) light-activated hydrogen-producing materials that enable the controlled generation and high-concentration release of hydrogen molecules in deep tumor tissues and enhance the effects of hydrogen therapy holds significant scientific importance. To address the key technical challenge of low-efficiency oxidation-reduction reactions for narrow-bandgap photocatalytic materials, this work proposes an innovative approach for the controllable fabrication of multiphoton photocatalytic materials to overcome the limitations imposed by traditional near-infrared photocatalysts with "narrow-bandgap" constraints. Herein, an NIR-responsive multiphoton photocatalyst, ZrTc-Co, is developed by utilizing a post-synthetic coordination modification strategy to introduce hydrogenation active site CoII into a multiphoton responsive MOF (ZrTc). The results reveal that with the introduction of the CoII site, electron-hole recombination can be efficiently suppressed, thus promoting the efficiency of hydrogen evolution reaction. In addition, the integration of CoII can effectively enhance charge transfer and improve static hyperpolarizability, which endows ZrTc-Co with excellent multiphoton absorption. Moreover, hyaluronic acid modification endows ZrTc-Co with cancer cell-specific targeting characteristics, laying the foundation for tumor-specific elimination. Collectively, the proposed findings present a strategy for constructing NIR-II light-mediated hydrogen therapeutic agents for deep tumor elimination.

Hydrogen therapy: recent advances and emerging materials

Hydrogen therapy, leveraging its selective attenuation of hydroxyl radicals (˙OH) and ONOO-, has emerged as a pivotal pathophysiological modulator with antioxidant, anti-inflammatory, and antiapoptotic attributes. Hydrogen therapy has been extensively studied both preclinically and clinically, especially in diseases with an inflammatory nature. Despite the substantial progress, challenges persist in achieving high hydrogen concentrations in target lesions, especially in cancer treatment. A notable breakthrough lies in water/acid reactive materials, offering enhanced hydrogen generation and sustained release potential. However, limitations include hydrogen termination upon material depletion and reduced bioavailability at targeted lesions. To overcome these challenges, catalytic materials like photocatalytic and sonocatalytic materials have surfaced as promising solutions. With enhanced permeability and retention effects, these materials exhibit targeted delivery and sustained stimuli-reactive hydrogen release. The future of hydrogen therapy hinges on continuous exploration and modification of catalytic materials. Researchers are urged to prioritize improved catalytic efficiency, enhanced lesion targeting effects, and heightened biosafety and biocompatibility in future development.

Nanomaterial-Based Repurposing of Macrophage Metabolism and Its Applications

Macrophage immunotherapy represents an emerging therapeutic approach aimed at modulating the immune response to alleviate disease symptoms. Nanomaterials (NMs) have been engineered to monitor macrophage metabolism, enabling the evaluation of disease progression and the replication of intricate physiological signal patterns. They achieve this either directly or by delivering regulatory signals, thereby mapping phenotype to effector functions through metabolic repurposing to customize macrophage fate for therapy. However, a comprehensive summary regarding NM-mediated macrophage visualization and coordinated metabolic rewiring to maintain phenotypic equilibrium is currently lacking. This review aims to address this gap by outlining recent advancements in NM-based metabolic immunotherapy. We initially explore the relationship between metabolism, polarization, and disease, before delving into recent NM innovations that visualize macrophage activity to elucidate disease onset and fine-tune its fate through metabolic remodeling for macrophage-centered immunotherapy. Finally, we discuss the prospects and challenges of NM-mediated metabolic immunotherapy, aiming to accelerate clinical translation. We anticipate that this review will serve as a valuable reference for researchers seeking to leverage novel metabolic intervention-matched immunomodulators in macrophages or other fields of immune engineering.

Engineering Photothermal Catalytic CO2 Nanoreactor for Osteomyelitis Treatment by In Situ CO Generation

Photocatalytic carbon dioxide (CO2) reduction is an effective method for in vivo carbon monoxide (CO) generation for antibacterial use. However, the available strategies mainly focus on utilizing visible-light-responsive photocatalysts to achieve CO generation. The limited penetration capability of visible light hinders CO generation in deep-seated tissues. Herein, a photothermal CO2 catalyst (abbreviated as NNBCs) to achieve an efficient hyperthermic effect and in situ CO generation is rationally developed, to simultaneously suppress bacterial proliferation and relieve inflammatory responses. The NNBCs are modified with a special polyethylene glycol and further embellished by bicarbonate (BC) decoration via ferric ion-mediated coordination. Upon exposure to 1064 nm laser irradiation, the NNBCs facilitated efficient photothermal conversion and in situ CO generation through photothermal CO2 catalysis. Specifically, the photothermal effect accelerated the decomposition of BC to produce CO2 for photothermal catalytic CO production. Benefiting from the hyperthermic effect and in situ CO production, in vivo assessments using an osteomyelitis model confirmed that NNBCs can simultaneously inhibit bacterial proliferation and attenuate the photothermal effect-associated pro-inflammatory response. This study represents the first attempt to develop high-performance photothermal CO2 nanocatalysts to achieve in situ CO generation for the concurrent inhibition of bacterial growth and attenuation of inflammatory responses.

Optical Fiber-Enabled In Situ Photocatalytic Hydrogen Generation for Infiltrating Tumor Therapy in Brain

In addition to repressing proliferation, inhibiting the infiltration of tumor cells is an important strategy to improve the treatment of malignant tumors. Herein, a photocatalyst (pCNMC@Pt) is designed by sequentially assembling manganese dioxide, chlorin e6, and platinum (Pt) nanoparticles onto protonated graphitic carbon nitride. With the help of a Z-scheme structure and near-infrared (NIR) photosensitizer, pCNMC@Pt is capable of responding to NIR light to generate large amounts of hydrogen (H2). Taking lactic acid in the tumor microenvironment as a sacrificial reagent, H2 therapy initiated by the NIR photocatalyst remarkably impedes the growth of glioblastoma (GBM). More importantly, it is found that H2 can suppress the stemness of glioma stem cells, curbing both proliferation and infiltration of GBM. Furthermore, since pCNMC@Pt and light source are precisely co-localized through a self-built loading and illumination system, GBM in mouse brains can be efficiently treated, providing an alternative gas therapy approach to cure infiltrating tumors.

Mesoporous carbon nanoparticles embedded with iron in hydrogen-photothermal synergistic therapy

We developed a new method to synthesize polyethylene glycol modified ultra small iron embedded in mesoporous carbon nanoparticle (C/Fe-PEG NP) for hydrogen (H2) assisted photothermal synergistic therapy. Herein, we use a simple in-situ reduction method to obtain the C/Fe NP in one-step carbonizing process, which is further modified by the biocompatible polyethylene glycol (PEG) on the surface of C/Fe NP to acquire high stability in physiological solutions. Utilizing the excellent photothermal property from the mesoporous carbon and the controllable H2 release property in the weakly acidic tumor microenvironment by the ultra-small Fe, the obtained C/Fe-PEG NPs can effective kill the cancer cells, meanwhile, protect normal cells without drugs. This selective anti-cancer mechanism of C/Fe-PEG NPs may because the produced H2 selective change the mitochondrial energy metabolism. In vivo results prove that the C/Fe-PEG NPs achieve excellent tumor ablation therapeutic effect and normal tissue protecting ability benefit from the H2-assisted photothermal therapy, promising the use of novel nanomaterials with more safety method for future cancer therapy.

NIR-II Absorption/Emission Dual Function Based 2D Targeted Nanotheranostics for Tunable Hydrogenothermal Therapy

Photothermal therapy (PTT) is a promising approach for treating tumors that offers multiple advantages. Nevertheless, its practical use in clinical settings faces several limitations, such as suboptimal delivery efficiency, uneven heat distribution, and challenges in predicting optimal treatment duration. In addition, the localized hyperthermia generated by the PTT method to induce cell apoptosis can result in the production of excessive reactive oxygen species (ROS) and the release of inflammatory cytokines, which can pose a threat to the healthy tissues surrounding the tumor. To address the above challenges, this work designs an integrated H2 delivery nanoplatform for multimodal imaging H2 thermal therapy. The combination of the second near-infrared window (NIR-II) fluorescence imaging (FL) agent (CQ4T) and the photothermal and photoacoustic (PA) properties of Ti3C2 (TC) enables real-time monitoring of the tumor area and guides photothermal treatment. Simultaneously, due to the acid-responsive H2 release characteristics of the nanoplatform, H2 can be utilized for synergistic photothermal therapy to eradicate tumor cells effectively. Significantly, acting as an antioxidant and anti-inflammatory agent, Ti3C2-BSA-CQ4T-H2 (TCBCH) protects peritumoral normal cells from damage. The proposed technique utilizing H2 gas for combination therapies and multimodal imaging integration exhibits prospects for effective and secure treatment of tumors in future clinical applications.

In Situ Piezoelectric-Catalytic Anti-Inflammation Promotes the Rehabilitation of Acute Spinal Cord Injury in Synergy

Relieving inflammation via scavenging toxic reactive oxygen species (ROS) during the acute phase of spinal cord injury (SCI) proves to be an effective strategy to mitigate secondary spinal cord injury and improve recovery of motor function. However, commonly used corticosteroid anti-inflammatory drugs show adverse side effects which may induce increased risk of wound infection. Fortunately, hydrogen (H2), featuring selective antioxidant performance, easy penetrability, and excellent biosafety, is being extensively investigated as a potential anti-inflammatory therapeutic gas for the treatment of SCI. In this work, by a facile in situ growth approach of gold nanoparticles (AuNPs) on the piezoelectric BaTiO3, a particulate nanocomposite with Schottky heterojunction (Au@BT) is synthesized, which can generate H2 continuously by catalyzing H+ reduction through piezoelectric catalysis. Further, theoretical calculations are employed to reveal the piezoelectric catalytic mechanism of Au@BT. Transcriptomics analysis and nontargeted large-scale metabolomic analysis reveal the deeper mechanism of the neuroprotective effect of H2 therapy. The as-prepared Au@BT nanoparticle is first explored as a flexible hydrogen gas generator for efficient SCI therapy. This study highlights a promising prospect of nanocatalytic medicine for disease treatments by catalyzing H2 generation; thus, offering a significant alternative to conventional approaches against refractory spinal cord injury.

Glutathione-triggered release of SO2 gas to augment oxidative stress for enhanced chemodynamic and sonodynamic therapy

Recently, gas therapy has emerged as a promising alternative treatment for deep-seated tumors. However, some challenges regarding insufficient or uncontrolled gas generation as well as unclear therapeutic mechanisms restrict its further clinical application. Herein, a well-designed nanoreactor based on intracellular glutathione (GSH)-triggered generation of sulfur dioxide (SO2) gas to augment oxidative stress has been developed for synergistic chemodynamic therapy (CDT)/sonodynamic therapy (SDT)/SO2 gas therapy. The nanoreactor (designed as CCM@FH-DNs) is constructed by employing iron-doped hollow mesoporous silica nanoparticles as carriers, the surface of which was modified with the SO2 prodrug 2,4-dinitrobenzenesulfonyl (DNs) and further coated with cancer cell membranes for homologous targeting. The CCM@FH-DNs can not only serve as a Fenton-like agent for CDT, but also as a sonosensitizer for SDT. Importantly, CCM@FH-DNs can release SO2 for SO2-mediated gas therapy. Both in vitro and in vivo evaluations demonstrate that the CCM@FH-DNs nanoreactor performs well in augmenting oxidative stress for SO2 gas therapy-enhanced CDT/SDT via GSH depletion and glutathione peroxidase-4 enzyme deactivation as well as superoxide dismutase inhibition. Moreover, the doped iron ions ensure that the CCM@FH-DNs nanoreactors enable magnetic resonance imaging-guided therapy. Such a GSH-triggered SO2 gas therapy-enhanced CDT/SDT strategy provides an intelligent paradigm for developing efficient tumor microenvironment-responsive treatments.

Near-infrared-driven upconversion nanoparticles with photocatalysts through water-splitting towards cancer treatment

Water splitting is promising, especially for energy and environmental applications; however, there are limited studies on the link between water splitting and cancer treatment. Upconversion nanoparticles (UCNPs) can be used to convert near-infrared (NIR) light to ultraviolet (UV) or visible (Vis) light and have great potential for biomedical applications because of their profound penetration ability, theranostic approaches, low self-fluorescence background, reduced damage to biological tissue, and low toxicity. UCNPs with photocatalytic materials can enhance the photocatalytic activities that generate a shorter wavelength to increase the tissue penetration depth in the biological microenvironment under NIR light irradiation. Moreover, UCNPs with a photosensitizer can absorb NIR light and convert it into UV/vis light and emit upconverted photons, which excite the photoinitiator to create H2, O2, and/or OH˙ via water splitting processes when exposed to NIR irradiation. Therefore, combining UCNPs with intensified photocatalytic and photoinitiator materials may be a promising therapeutic approach for cancer treatment. This review provides a novel strategy for explaining the principles and mechanisms of UCNPs and NIR-driven UCNPs with photocatalytic materials through water splitting to achieve therapeutic outcomes for clinical applications. Moreover, the challenges and future perspectives of UCNP-based photocatalytic materials for water splitting for cancer treatment are discussed in this review.

Metal-Phenolic Nanocapsules with Photothermal Antibacterial and Ros Scavenging Ability for Diabetic Wound Healing

The presence of bacteria in diabetic wounds not only leads to the formation of biofilms but also triggers oxidative stress and inflammatory responses, which hinder the wound-healing process. Therefore, it is imperative to formulate a comprehensive strategy that can proficiently eliminate bacteria and enhance the wound microenvironment. Herein, this work develops multifunctional metal-phenolic nanozymes (TA-Fe/Cu nanocapsules), wherein the one-pot coordination of tannic acid (TA)and Fe3+/Cu2+ using a self-sacrificial template afforded hollow nanoparticles (NPs) with exceptional photothermal and reactive oxygen species scavenging capabilities. After photothermal disruption of the biofilms, TA-Fe/Cu NPs autonomously capture bacteria through hydrogen bonding interactions with peptidoglycans (the bacterial cell wall component), ultimately bolstering the bactericidal efficacy. Furthermore, these NPs exhibit peroxidase-like enzymatic activity, efficiently eliminating surplus hydrogen peroxide in the vicinity of the wound and mitigating inflammatory responses. As the wound transitions into the remodeling phase, the presence of Cu2+ stimulates vascular migration and regeneration, expediting the wound-healing process. This study innovatively devises a minimalist approach to synthesize multifunctional metal-phenolic nanozymes integrating potent photothermal antibacterial activity, bacterial capture, anti-inflammatory, and angiogenesis properties, showcasing their great potential for diabetic wound treatment.

Recent Advances in Metal-Hydride-Based Disease Treatment

In comparison to traditional antioxidant treatment methods, the use of hydrogen to eliminate reactive oxygen species from the body has the advantages of high biological safety, strong selectivity, and high clearance rate. As an energy storage material, metal hydrides have been extensively studied and used in transporting hydrogen as clean energy, which can achieve a high hydrogen load and controlled hydrogen release. Considering the antioxidant properties of hydrogen and the delivery ability of metal hydrides, metal-hydride-based disease treatment strategies have attracted widespread attention. Up to now, metal hydrides have been reported for the treatment of tumors and a range of inflammation-related diseases. However, limited by the insufficient investment, the use of metal hydrides in disease treatment still has many shortcomings, such as low targeting efficiency, limited therapeutic activity, and complex material preparation process. Particularly, metal hydrides have been found to have a series of optical, acoustic, and catalytic properties when scaled up to the nanoscale, and these properties are also widely used to promote disease treatment effects. From this new perspective, we comprehensively summarize the very recent research progress on metal-hydride-based disease treatment in this review. Ultimately, the challenges and prospects of such a burgeoning cancer theranostics modality are outlooked to provide inspiration for the further development and clinical translation of metal hydrides.

pH-Responsive Injectable Multifunctional Pluronic F127/Gelatin-Based Hydrogels with Hydrogen Production for Treating Diabetic Wounds

Diabetic chronic wounds remain a major clinical challenge with long-term inflammatory responses and extreme oxidative damage. Hence, a pH-responsive injectable multifunctional hydrogel [Gel/CUR-FCHO/Mg (GCM) micromotors] via a Schiff base reaction between gelatin and benzaldehyde-grafted Pluronic F127 drug-loaded micelles (FCHO) was fabricated for the first time. Dynamic Schiff base linkage endowed the GCM hydrogel with the ability to be self-healing, injectable, and pH-responsive for on-demand drug delivery at the wound site. Curcumin (CUR), a hydrophobic drug with antioxidative, anti-inflammatory, and antibacterial activities, was encapsulated into the hydrogel matrix by micellization (CUR-FCHO micelles). Simultaneously, magnesium-based micromotors (Mg micromotors) were physically entrapped into the system for providing active hydrogen (H2) to scavenge reactive oxygen species and alleviate inflammatory responses. As a result, the GCM micromotor hydrogel displayed an inherent antibacterial property, extraordinary antioxidative performance, and remarkable biocompatibility. In the diabetic mouse with a full-thickness cutaneous defect wound, the GCM hydrogel could remodel the inflammatory microenvironment and stimulate vascularization and collagen deposition, thereby facilitating wound closure and enhancing tissue regeneration, which offered a promising therapeutic option for diabetic chronic wound management.

Nanoreactor-based catalytic systems for therapeutic applications: Principles, strategies, and challenges

Inspired by natural catalytic compartments, various synthetic compartments that seclude catalytic reactions have been developed to understand complex multistep biosynthetic pathways, bestow therapeutic effects, or extend biosynthetic pathways in living cells. These emerging nanoreactors possessed many advantages over conventional biomedicine, such as good catalytic activity, specificity, and sustainability. In the past decade, a great number of efficient catalytic systems based on diverse nanoreactors (polymer vesicles, liposome, polymer micelles, inorganic-organic hybrid materials, MOFs, etc.) have been designed and employed to initiate in situ catalyzed chemical reactions for therapy. This review aims to present the recent progress in the development of catalytic systems based on nanoreactors for therapeutic applications, with a special emphasis on the principles and design strategies. Besides, the key components of nanoreactor-based catalytic systems, including nanocarriers, triggers or energy inputs, and products, are respectively introduced and discussed in detail. Challenges and prospects in the fabrication of therapeutic catalytic nanoreactors are also discussed as a conclusion to this review. We believe that catalytic nanoreactors will play an increasingly important role in modern biomedicine, with improved therapeutic performance and minimal side effects.

Reactive oxygen species (ROS) scavenging biomaterials for anti-inflammatory diseases: from mechanism to therapy

Inflammation is a fundamental defensive response to harmful stimuli, but the overactivation of inflammatory responses is associated with most human diseases. Reactive oxygen species (ROS) are a class of chemicals that are generated after the incomplete reduction of molecular oxygen. At moderate levels, ROS function as critical signaling molecules in the modulation of various physiological functions, including inflammatory responses. However, at excessive levels, ROS exert toxic effects and directly oxidize biological macromolecules, such as proteins, nucleic acids and lipids, further exacerbating the development of inflammatory responses and causing various inflammatory diseases. Therefore, designing and manufacturing biomaterials that scavenge ROS has emerged an important approach for restoring ROS homeostasis, limiting inflammatory responses and protecting the host against damage. This review systematically outlines the dynamic balance of ROS production and clearance under physiological conditions. We focus on the mechanisms by which ROS regulate cell signaling proteins and how these cell signaling proteins further affect inflammation. Furthermore, we discuss the use of potential and currently available-biomaterials that scavenge ROS, including agents that were engineered to reduce ROS levels by blocking ROS generation, directly chemically reacting with ROS, or catalytically accelerating ROS clearance, in the treatment of inflammatory diseases. Finally, we evaluate the challenges and prospects for the controlled production and material design of ROS scavenging biomaterials.

Ultrasound-Driven Piezoelectrocatalytic Immunoactivation of Deep Tumor

Tumor heterogeneity makes routine drugs difficult to penetrate solid tumors, limiting their therapy efficacies. Based on high tissue penetrability of hydrogen molecules (H2 ) and ultrasound (US) and the immunomodulation effects of H2 and lactic acid (LA), this work proposes a novel strategy of US-driven piezoelectrocatalytic tumor immunoactivation for high-efficacy therapy of deep tumors by piezoelectrocatalytic hydrogen generation and LA deprivation. A kind of US-responsive piezoelectric SnS nanosheets (SSN) is developed to realize US-triggered local hydrogen production and simultaneous LA deprivation in deep tumors. The proof-of-concept experiments which are executed on an orthotopic liver cancer model have verified that intratumoral SSN-medicated piezoelectrocatalytically generated H2 liberates effector CD8+ T cells from the immunosuppression of tumor cells through down-regulating PD-L1 over-expression, and simultaneous LA deprivation activates CD8+ T cells by inhibiting regulatory T cells, efficiently co-activating tumor immunity and achieving a high outcome of liver tumor therapy with complete tumor eradication and 100% mice survival. The proposed strategy of US-driven piezoelectrocatalytic tumor immunoactivation opens a safe and efficient pathway for deep tumor therapy.

Gas-assisted phototherapy for cancer treatment

Phototherapies, mainly including photodynamic and photothermal therapy, have made considerable strides in the field of cancer treatment. With the aid of phototherapeutic agents, reactive oxygen species (ROS) or heat are generated under light irradiation to selectively damage cancer cells. However, sole-modality phototherapy faces certain drawbacks, such as limited penetration of phototherapeutic agents into tumor tissues, inefficient ROS generation due to hypoxia, treatment-induced inflammation and resistance of tumor to treatment (e.g., high levels of antioxidants, expression of heat shock protein). Gas therapy, an emerging therapy approach that damages cancer cells by improving the level of certain gas at the tumor site, shows potential to overcome the challenges associated with phototherapies. In addition, with the rapid development of nanotechnology, gas-assisted phototherapy based on nanomedicines has emerged as a promising strategy to enhance the treatment efficacy. This review summarizes recent advances in gas-assisted phototherapy and discusses the prospects and challenges of this strategy in cancer phototherapy.

Anti-inflammatory strategies for photothermal therapy of cancer

High temperature generated by photothermal therapy (PTT) can trigger an inflammatory response at the tumor site, which not only limits the efficacy of PTT but also increases the risk of tumor metastasis and recurrence. In light of the current limitations posed by inflammation in PTT, several studies have revealed that inhibiting PTT-induced inflammation can significantly improve the efficacy of cancer treatment. In this review, we summarize the research progress made in combining anti-inflammatory strategies to enhance the effectiveness of PTT. The goal is to offer valuable insights for developing better-designed photothermal agents in clinical cancer therapy.

Nanomaterials for photothermal cancer therapy

Cancer has emerged as a pressing global public health issue, and improving the effectiveness of cancer treatment remains one of the foremost challenges of modern medicine. The primary clinical methods of treating cancer, including surgery, chemotherapy and radiotherapy, inevitably result in some adverse effects on the body. However, the advent of photothermal therapy offers an alternative route for cancer treatment. Photothermal therapy relies on photothermal agents with photothermal conversion capability to eliminate tumors at high temperatures, which offers advantages of high precision and low toxicity. As nanomaterials increasingly play a pivotal role in tumor prevention and treatment, nanomaterial-based photothermal therapy has gained significant attention owing to its superior photothermal properties and tumor-killing abilities. In this review, we briefly summarize and introduce the applications of common organic photothermal conversion materials (e.g., cyanine-based nanomaterials, porphyrin-based nanomaterials, polymer-based nanomaterials, etc.) and inorganic photothermal conversion materials (e.g., noble metal nanomaterials, carbon-based nanomaterials, etc.) in tumor photothermal therapy in recent years. Finally, the problems of photothermal nanomaterials in antitumour therapy applications are discussed. It is believed that nanomaterial-based photothermal therapy will have good application prospects in tumor treatment in the future.

Mesocrystalline ZnS nanoparticles-augmented sonocatalytic full water splitting into H2/O2 for immunoactivating deep tumor

Therapeutic gas molecules have high tissue penetrability, but their sustainable supply and controlled release in deep tumor is a huge challenge. In this work, a concept of sonocatalytic full water splitting for hydrogen/oxygen immunotherapy of deep tumor is proposed, and a new kind of ZnS nanoparticles with a mesocrystalline structure (mZnS) is developed to achieve highly efficient sonocatalytic full water splitting for sustainable supply of H₂ and O₂ in tumor, achieving a high efficacy of deep tumor therapy. Mechanistically, locally generated hydrogen and oxygen molecules exhibit a tumoricidal effect as well as the co-immunoactivation of deep tumors through inducing the M2-to-M1 repolarization of intratumoral macrophages and the tumor hypoxia relief-mediated activation of CD8⁺ T cells, respectively. The proposed sonocatalytic immunoactivation strategy will open a new window to realize safe and efficient treatment of deep tumors.

Imaging Guided Endogenic H2 -Augmented Electrochemo-Sonodynamic Domino Co-therapy of Tumor in Vivo

Precise and on-demand release of sufficient hydrogen (H₂ ) to tumor sites remains a key challenge for emerging H₂ -oncotherapy, and little is known about the physiological effects of "abundant" H₂ on complex tumor microenvironments (TME). Here, a highly efficient and cost-effective imaging-guided/-assessed H₂ -therapy of tumors based on a joint electrochemo-sonodynamic treatment (H₂ -EC/SD co-therapy) with strong "domino effect" triggered by endogenous H₂ generation at tumor sites is reported to speedily eliminate tumor tissue (≤80 mm³ ) within 1 day. Adequate H₂ is controllably generated in tumor sites through mild electrochemistry in vivo due to acidic TME by using clinical acupuncture Fe needles as electrodes. Besides starvation damage due to gas blockage/destruction of vessels, nano-/micro-bubbles of H₂ formed in situ can elevate the tumor's internal temperature and burst vessels to further destroy the tumor under ultrasound irradiation. Remarkably, vulnerable homeostasis of TME is disturbed as H₂ also participates in the physiological activity of tumor cells, leading to tumor dysfunction. Last but not least, the body's inflammatory response to cancer is reduced after the treatment, which is beneficial for the body's immune system during post-treatment recovery. Based on all of these merits, the H₂ -EC/SD co-therapy provides a potentially safe and viable therapeutic strategy for future clinical applications.

Emerging plasmonic nanoparticles and their assemblies for cancer radiotherapy

Plasmonic nanoparticles and their assemblies have been widely used in biosensing, optical imaging, and biomedicine over the past few decades. Especially in the field of radiotherapy, the physicochemical properties of high-Z plasmonic nanomaterials endow them with the ability to sensitize radiotherapy. Compared with single particles, the assembled structure with tunable properties leads to versatile applications in drug delivery and cancer treatment. In this review, we focus on plasmonic nanoparticles and their assemblies for cancer radiotherapy. First, the sensitization mechanism of plasmonic radiosensitizers is briefly introduced. Subsequently, the recent progress in cancer radiotherapy is systematically discussed according to the structure and shape classification. Finally, the current challenges and future perspectives in this field are also discussed in detail.

Injectable spontaneous hydrogen-releasing hydrogel for long-lasting alleviation of osteoarthritis

Excessive production of reactive oxygen species (ROS) amplifies pro-inflammatory pathways and exacerbates immune responses, and is a key factor in the progression of osteoarthritis (OA). Therapeutic hydrogen gas (H₂) with antioxidative and anti-inflammatory effects, has a potential for OA alleviation, but the targeted delivery and sustained release of H₂ are still challenging. Herein, we develop an injectable calcium boride nanosheets (CBN) loaded hydrogel platform (CBN@GelDA hydrogel) as a high-payload and sustainable H₂ precursor for OA treatment. The CBN@GelDA hydrogel could maintain constant physiological pH conditions which further promotes more H₂ release than the CBN alone and lasts more than one week. The biocompatibility of this hydrogel with macrophages and chondrocytes is effectively enhanced. The experiments show that the CBN@GelDA hydrogel holds the ROS scavenging ability, reducing the expression of related inflammatory cytokines, lessening M1 macrophages but stimulating M2 phenotype, and thereby decreasing chondrocyte apoptosis, which facilitates to breaking of the vicious circle of OA progression. Furthermore, a single-time injection of the CBN@GelDA hydrogel markedly reduces joint destruction in OA rats. From what has been discussed above, this injectable spontaneous H₂-releasing hydrogel is promising for OA treatment. STATEMENT OF SIGNIFICANCE: Oxidative stress and inflammation play the key role in the occurrence and development of osteoarthritis (OA). The system of a hydrogel loaded with H₂ precursor calcium boride nanosheet (CBN), which is the first to use as an H₂ precursor, integrates superior injectable and biocompatible of hydrogel and the selection of antioxidant properties of H₂. This system can improve H₂ release behavior and achieve a single injection into the articular cavity to alleviate the progression of OA in rats. This study of the combination of a convenient long-acting injectable hydrogel and a safe therapeutic gas is of great value for improving the quality of life of clinical patients.

ROS-responsive magnesium-containing microspheres for antioxidative treatment of intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a degenerative disease characterized by lower-back pain, causing disability globally. Antioxidant therapy is currently considered one of the most promising strategies for IVDD treatment, given the crucial role of reactive oxygen species (ROS) in IVDD pathogenesis. Herein, a ROS-responsive magnesium-containing microsphere (Mg@PLPE MS) was constructed for the antioxidative treatment of IVDD. The Mg@PLPE MS has a core-shell structure comprising poly(lactic-co-glycolic acid) (PLGA) and ROS-responsive polymer poly(PBT-co-EGDM) as the shell and a magnesium microparticle as the core. The poly(PBT-co-EGDM) can be destroyed by H₂O₂ through the H₂O₂-triggered hydrophobic-to-hydrophilic transition, subsequently promoting an Mg-water reaction to produce H₂. Thus, Mg@PLPE MS provides a valuable platform for H₂O₂ elimination and controlled H₂ release. The generated H₂ scavenge for ROS by reacting with noxious •OH. Notably, the Mg@PLPE MS exerted significant antioxidative and anti-inflammatory effects in a disc degeneration rat model and alleviated extracellular matrix degradation and disc cells apoptosis, thereby underlining its efficacy in IVDD treatment. The Mg@PLPE MS also exhibited robust biocompatibility and negligible toxicity, presenting the promise for the antioxidative treatment of IVDD in vivo. STATEMENT OF SIGNIFICANCE: Antioxidant therapy is currently considered one of the most promising strategies for intervertebral disc degeneration (IVDD) treatment, given the crucial role of reactive oxygen species (ROS) in IVDD pathogenesis. Here, ROS-responsive magnesium-containing microspheres (Mg@PLPE MSs) were constructed to alleviate IVDD through controlled release of hydrogen gas. The Mg@PLPE MSs can effectively scavenge overproduced ROS by simultaneously reacting with H₂O₂ and •OH, thus creating a suitable microenvironment for inhibition of ECM degradation. As a result, Mg@PLPE MSs treated IVDD rats exhibit minimal nucleus pulposus decrease, less extracellular matrix degradation, minimal radial fissure of fibrous rings, and higher disc height index. Therefore, the as-prepared Mg@PLPE MSs may shed a new light on clinical treatment of IVDD.

Rational Design of Platinum-Bismuth Sulfide Schottky Heterostructure for Sonocatalysis-Mediated Hydrogen Therapy

Conventional sonodynamic therapy is unavoidably limited by the tumor microenvironment, although many sonosensitizers have been developed to improve them to a certain extent. Given this, a concept of sonocatalytic hydrogen evolution is proposed, which is defined as an oxygen-independent therapeutics. To demonstrate the feasibility of the concept, the narrow-bandgap semiconductor bismuth sulfide (Bi₂ S₃ ) is selected as the sonocatalyst and platinum (Pt) nanoparticles are grown in situ to optimize their catalytic performance. In this nanocatalytic system, the Pt nanoparticles help to capture sonoexcited electrons, whereas intratumoral overexpressed glutathione (GSH), as a natural hole sacrificial agent, can consume sonoexcited holes, which greatly improves the charge-separation efficiency and promotes controllable and sustainable H₂  generation. Even under hypoxic conditions, the Pt-Bi₂ S₃  nanoparticles can also produce sufficient H₂  under ultrasound irradiation. Mechanistically, mitochondrial dysfunction caused by H₂  and intratumoral redox homeostasis destruction by GSH depletion synergistically damage DNA to induce tumor cells apoptosis. At the same time, the Pt nanoparticles and holes can also trigger the decomposition of hydrogen peroxide into O₂  to relieve tumor hypoxia, thus being synergistic with GSH depletion to reverse tumor immunosuppressive microenvironment. The proposed sonocatalysis-mediated therapy will provide a new direction to realize facile and efficient cancer therapy.

Calcium Hydride-Based Dressing to Promote Wound Healing

Wound microenvironment with excess reactive oxygen species (ROS) can significantly inhibit wound healing. Encouraged by hydrogen molecules (H₂ ) with effective ROS scavenging and calcium hydride (CaH₂ ) with sufficient H₂ supply, the authors for the first time employed CaH₂ as a therapeutic H₂ donor and starch as a diluent to construct CaH₂ pulvis dressing for wound healing treatment. It has been found that CaH₂ by generating H₂ exhibited excellent ROS scavenging performance, favorable for preserving the oxidative-stress-induced cell death. After being applied onto the skin wound, the CaH₂ pulvis dressing with the unique ROS-scavenging ability can accelerate skin wound healing in healthy/diabetic mice (small animal models) and Bama mini-pigs (large animal model). Such CaH₂ dressing can release H₂ to relieve the inflammation levels, decrease the secretion of pro-inflammatory cytokines, increase the infiltration of inflammation-suppressive immune cells, and promote the regeneration of new blood vessels and collagens, thereby accelerating wound healing. This work highlighted that the integration of anti-oxidation and anti-inflammation functions based on CaH₂ dressing endowed it with a promising possibility for the treatment of inflammatory diseases.

Two-Dimensional Mg2 Si Nanosheet-Enabled Sustained Hydrogen Generation for Improved Repair and Regeneration of Deeply Burned Skin

Molecular hydrogen holds a high potential for wound healing owing to its anti-inflammatory effect and high biosafety, but commonly used hydrogen administration routes hardly achieve the sustained supply of high-dosage hydrogen, limiting hydrogen therapy efficacy. Here, two-dimensional Mg₂ Si nanosheet (MSN) is exploited as a super-persistent hydrogen-releasing nanomaterial with high biocompatibility, and the incorporation of MSN into the chitosan/hyaluronic acid hydrogel (MSN@CS/HA) is developed as a dressing to repair deeply burned skin. The MSN@CS/HA hydrogel dressing can continuously generate hydrogen molecules for about 1 week in the physiological conditions in support of local, long-term, and plentiful hydrogen supply and remarkably promotes the healing and regeneration of deep second-degree and third-degree burn wounds without visible scar and toxic side effect. Mechanistically, a sustained supply of hydrogen molecules induces anti-inflammatory M2 macrophage polarization in time by enhancing CCL2 (chemokine C-C motif ligand 2) expression to promote angiogenesis and reduce fibrosis and also enhances the proliferation and migration capability of skin cells directly and indirectly by locally scavenging overexpressed reactive oxygen species, synergistically favoring wound repair. The proposed synthesis method, therapeutic strategy, and mechanisms will open a window for synthesizing a variety of MSene nanomaterials and developing their various proangiogenesis applications besides wound healing.

Living Macrophage-Delivered Tetrapod PdH Nanoenzyme for Targeted Atherosclerosis Management by ROS Scavenging, Hydrogen Anti-inflammation, and Autophagy Activation

Atherosclerosis, driven by chronic inflammation in the artery walls, underlies several severe cardiovascular diseases. However, currently available anti-inflammatory-based strategies for atherosclerosis treatment suffer from compromised therapeutic efficacy and undesirable therapeutic outcome. Herein, a distinct tetrapod needle-like PdH nanozyme was designed and engineered for efficient atherosclerosis treatment by the combinatorial reactive oxygen species (ROS) scavenging, hydrogen anti-inflammation, and autophagy activation. After loading into macrophages and targeted delivery to arterial plaques, these multifunctional nanozymes efficiently decreased the ROS levels and significantly suppressed the inflammation-related pathological process, exerting the distinct antioxidation and anti-inflammatory performance for alleviating atherosclerosis development. Especially and importantly, the specific spiky morphology of the PdH nanoenzyme further triggered a strong autophagy response in macrophages, synergistically maintaining the cellular homeostasis and alleviating atherosclerosis development. Both in vitro and in vivo results confirmed the synergy among the antioxidation, anti-inflammatory, and autophagy activation, suggesting that the combinatorial engineering of nanomedicines with intrinsic multiple therapeutic functions and topology-induced biological effects is highly preferable and effective for achieving the high therapeutic performance and desirable therapeutic outcome on atherosclerosis management and therapy.

Photocatalytic glucose depletion and hydrogen generation for diabetic wound healing

High-glucose microenvironment in the diabetic foot ulcer (DFU) causes excessive glycation and induces chronic inflammation, leading to the difficulty of DFU healing. Hydrogen-rich water bath can promote the healing of DFU in clinic by virtue of the anti-inflammatory effect of hydrogen molecules, but the long-term daily soaking counts against the formation of a scab and cannot change the high-glucose microenvironment, limiting the outcome of DFU therapy. In this work, photocatalytic therapy of diabetic wound is proposed for sustainable hydrogen generation and local glucose depletion by utilizing glucose in the high-glucose microenvironment as a sacrificial agent. Hydrogen-incorporated titanium oxide nanorods are developed to realize efficient visible light (VIS)-responsive photocatalysis for glucose depletion and hydrogen generation, achieving a high efficacy of diabetic wound healing. Mechanistically, local glucose depletion and hydrogen generation jointly attenuate the apoptosis of skin cells and promote their proliferation and migration by inhibiting the synthesis of advanced glycation end products and the expression of their receptors, respectively. The proposed VIS-photocatalytic strategy provides a solution for facile, safe and efficient treatment of DFU.

Hydrogenation is a treatment for chronic inflammation caused by high glucose levels in diabetic ulcers, However, current therapies have limitations. Here, the authors report on the creation of a visible light photocatalytic agent which depletes glucose in the wound and generates hydrogen to aid in diabetic wound healing.

Water-Enabled H2 Generation from Hydrogenated Silicon Nanosheets for Efficient Anti-Inflammation

As an emerging therapeutic gas, hydrogen (H₂) is gifted with excellent biosafety, high tissue permeability, and radical-trapping capacity and is extensively considered as a highly promising antioxidant in clinics. However, a facile and effective strategy of H₂ production for major inflammatory disease treatments is still lacking. In this study, by a facile wet-chemical exfoliation synthesis, a hydrogen-terminated silicon nanosheet (H-silicene) has been synthesized, which can favorably react with environmental water to generate H₂ rapidly and continuously without any external energy input. Furthermore, theoretical calculations were employed to reveal the mechanism of enhanced H₂ generation efficacy of H-silicene nanosheets. The as-synthesized H-silicene has been explored as a flexible hydrogen gas generator for efficient antioxidative stress application for the first time, which highlights a promising prospect of this two-dimensional H-silicene nanomaterial for acute inflammatory treatments by on-demand H₂ production-enabled reactive oxygen species scavenging. This study provides a novel and efficient modality for nanomaterial-mediated H₂ therapy.

The Advancement of Gas-Generating Nanoplatforms in Biomedical Fields: Current Frontiers and Future Perspectives

Diverse gases (NO, CO, H₂ S, H₂ , etc.) have been widely applied in the medical intervention of various diseases, including cancer, cardiovascular disease, ischemia-reperfusion injury, bacterial infection, etc., attributing to their inherent biomedical activities. Although many gases have many biomedical activities, their clinical use is still limited due to the rapid and free diffusion behavior of these gases molecules, which may cause potential side effects and/or ineffective treatment. Gas-generating nanoplatforms (GGNs) are effective strategies to address the aforementioned challenges of gas therapy by preventing gas production or release at nonspecific sites, enhancing GGNs accumulation at targeted sites, and controlling gas release in response to exogenous (UV, NIR, US, etc.) or endogenous (H₂ O₂ , GSH, pH, etc.) stimuli at the lesion site, further maintaining gas concentration within the effective range and achieving the purpose of disease treatment. This review comprehensively summarizes the advancements of "state-of-the-art" GGNs in the recent three years, with emphasis on the composition, structure, preparation process, and gas release mechanism of the nanocarriers. Furthermore, the therapeutic effects and limitations of GGNs in preclinical studies using cell/animal models are discussed. Overall, this review enlightens the further development of this field and promotes the clinical transformation of gas therapy.

Microbial hydrogen "manufactory" for enhanced gas therapy and self-activated immunotherapy via reduced immune escape

BACKGROUND

As an antioxidant, hydrogen (H2) can selectively react with the highly toxic hydroxyl radical (·OH) in tumor cells to break the balance of reactive oxygen species (ROS) and cause oxidative stress. However, due to the high diffusibility and storage difficulty of hydrogen, it is impossible to achieve long-term release at the tumor site, which highly limited their therapeutic effect.

RESULTS

Photosynthetic bacteria (PSB) release a large amount of hydrogen to break the balance of oxidative stress. In addition, as a nontoxic bacterium, PSB could stimulate the immune response and increase the infiltration of CD4+ and CD8+ T cells. More interestingly, we found that hydrogen therapy induced by our live PSB did not lead to the up-regulation of PD-L1 after stimulating the immune response, which could avoid the tumor immune escape.

CONCLUSION

Hydrogen-immunotherapy significantly kills tumor cells. We believe that our live microbial hydrogen production system provides a new strategy for cancer hydrogen treatment combining with enhanced immunotherapy without up-regulating PD-L1.

Surfactant-Free Green Synthesis of Au@Chlorophyll Nanorods for NIR PDT-Elicited CDT in Bladder Cancer Therapy

The facile and straightforward fabrication of NIR-responsive theranostic materials with high biocompatibility is still an unmet need for nanomedicine applications. Here, we used a natural photosensitizer, iron chlorophyll (Chl/Fe), for the J-aggregate template-assisted synthesis of Au@Chl/Fe nanorods with high stability. The assembly of a high amount of Chl/Fe J-aggregate onto the Au surface enabled red-NIR fluorescence for monitoring and tracking residential tumor lesions. The Chl/Fe moieties condensed on the nanorods could change the redox balance by the photon induction of reactive oxygen species and attenuate iron-mediated lipid peroxidation by inducing a Fenton-like reaction. After conjugation with carboxyphenylboronic acid (CPBA) to target the glycoprotein receptor on T24 bladder cancer (BC) cells, the enhanced delivery of Au@Chl/Fe-CPBA nanorods could induce over 85% cell death at extremely low concentrations of 0.16 ppm_[Au] at 660 nm and 1.6 ppm_[Au] at 785 nm. High lipid peroxidation, as shown by BODIPY staining and GSH depletion, was observed when treated T24 cells were exposed to laser irradiation, suggesting that preliminary photodynamic therapy (PDT) can revitalize Fenton-like reaction-mediated chemodynamic ferroptosis in T24 cells. We also manipulated the localized administration of Au@Chl-Fe combined with PDT at restricted regions in orthotopic tumor-bearing mice to cure malignant BC successfully without recurrence. By intravesical instillation of the Au@Chl/Fe-CPBA nanorods, this localized treatment could prevent the material from entering the systemic circulation, thus minimizing systemic toxicity. Upon activating NIR-PDT-elicited chemodynamic therapy, ultrasound imaging revealed almost complete tumor remission. Anti-tumor efficacy and survival benefit were achieved with a green photosensitizer.

Magnesium galvanic cells produce hydrogen and modulate the tumor microenvironment to inhibit cancer growth

Hydrogen can be used as an anti-cancer treatment. However, the continuous generation of H₂ molecules within the tumor is challenging. Magnesium (Mg) and its alloys have been extensively used in the clinic as implantable metals. Here we develop, by decorating platinum on the surface of Mg rods, a Mg-based galvanic cell (MgG), which allows the continuous generation of H₂ in an aqueous environment due to galvanic-cell-accelerated water etching of Mg. By implanting MgG rods into a tumor, H₂ molecules can be generated within the tumor, which induces mitochondrial dysfunction and intracellular redox homeostasis destruction. Meanwhile, the Mg(OH)₂ residue can neutralize the acidic tumor microenvironment (TME). Such MgG rods with the micro-galvanic cell structure enable hydrogen therapy to inhibit the growth of tumors, including murine tumor models, patient-derived xenografts (PDX), as well as VX₂ tumors in rabbits. Our research suggests that the galvanic cells for hydrogen therapy based on implantable metals may be a safe and effective cancer treatment.

The production of hydrogen inside cells can stimulate cell death. Here, the authors made magnesium galvanic rods that continuously produce hydrogen and result in tumor inhibition in vitro and in vivo.

Nanotechnology Tools Enabling Biological Discovery

Over the years, the engineering aspect of nanotechnology has been significantly exploited. Medical intervention strategies have been developed by leveraging existing molecular biology knowledge and combining it with nanotechnology tools to improve outcomes. However, little attention has been paid to harnessing the strengths of nanotechnology as a biological discovery tool. Fundamental understanding of controlling dynamic biological processes at the subcellular level is key to developing personalized therapeutic and diagnostic interventions. Single-cell analyses using intravital microscopy, expansion microscopy, and microfluidic-based platforms have been helping to better understand cell heterogeneity in healthy and diseased cells, a major challenge in oncology. Also, single-cell analysis has revealed critical signaling pathways and biological intracellular components with key biological functions. The physical manipulation enabled by nanotools can allow real-time monitoring of biological changes at a single-cell level by sampling intracellular fluid from the same cell. The formation of intercellular highways by nanotube-like structures has important clinical implications such as metastasis development. The integration of nanomaterials into optical and molecular imaging techniques has rendered valuable morphological, structural, and biological information. Nanoscale imaging unravels mechanisms of temporality by enabling the visualization of nanoscale dynamics never observed or measured between individual cells with standard biological techniques. The exceptional sensitivity of nanozymes, artificial enzymes, make them perfect components of the next-generation mobile diagnostics devices. Here, we highlight these impactful cancer-related biological discoveries enabled by nanotechnology and producing a paradigm shift in cancer research and oncology.

Acid-Degradable Hydrogen-Generating Metal-Organic Framework for Overcoming Cancer Resistance/Metastasis and Off-Target Side Effects

The development of stimuli-responsively degradable porous carriers for both controlled drug release and high biosafety is vitally important to their clinical translation, but still challenging at present. A new type of porphyrin-iron metal organic framework (Fe-MOF) nanocrystals is engineered here as acid-degradable drug carrier and hydrogen donor by the coordination between porphyrin and zero-valence Fe atom. Fe-MOF nanocrystals exhibit excellent acid-responsive degradation for H₂ generation and simultaneous release of the loaded drug for combined hydrogen-chemotherapy of cancer multidrug resistance (MDR) and metastasis and for local hydrogen eradication of the off-target induced toxic side effects of the drug to normal cells/tissues. Mechanistically, released H₂ assists chemotherapeutic drug to efficiently inhibit cancer metastasis by immunoactivating intratumoral M1-phenotype macrophages and consequently downregulating the expression of metastasis-related matrix metalloproteinase-2 (MMP-2) and can also downregulate the expressions of both P-glycoprotein (P-gp) protein and adenosine triphosphate (ATP) in MDR cancer cells to sensitize chemotherapeutic drug for enhanced damage to mitochondria and DNA. High anti-MDR/antimetastasis efficacies and high biocompatibility endow Fe-MOF nanocrystals and the Fe-MOF-based nanomedicine with high potential for clinical translation.

Nanoreactor for cascade reaction between SOD and CAT and its tissue regeneration effect

Nanoreactors for scavenging reactive oxygen species (ROS), a major factor in inflammatory diseases, can reduce overproduced ROS, and thus can prevent further progress of the diseases or facilitate the regeneration of damaged inflamed tissues. Herein, we designed a pluronic-based nanocarrier loaded with dual antioxidant enzymes present in vivo (superoxide dismutase (SOD) and catalase (CAT)) as a nanoreactor system for the regeneration of inflammatory tissue. The catalytic activity of each enzyme was enhanced by loading it into the nanocarrier. More importantly, the nanocarrier could enhance the cascade reaction between SOD and CAT, which converts the superoxide anion to oxygen. The synergistic anti-inflammatory effect of the nanoreactor based on the cascade reaction was verified in vitro. Furthermore, in an inflammatory bowel disease (IBD) mouse model, the dual enzyme (SOD/CAT)-loaded nanocarrier could result in significantly enhanced tissue regeneration and notably alleviated inflammation activities upon intravenous administration of them compared to other control groups, including single enzyme (SOD or CAT)-loaded nanocarrier and the free mixture of both enzymes without the nanocarrier. Thus, the efficacy of the nanoreactor for the cascade reaction on tissue regeneration in vivo was proved. Accordingly, the nanoreactor could be applied for tissue regeneration therapy against various inflammatory diseases.

Design of therapeutic biomaterials to control inflammation

Inflammation plays an important role in the response to danger signals arising from damage to our body and in restoring homeostasis. Dysregulated inflammatory responses occur in many diseases, including cancer, sepsis and autoimmunity. The efficacy of anti-inflammatory drugs, developed for the treatment of dysregulated inflammation, can be potentiated using biomaterials, by improving the bioavailability of drugs and by reducing side effects. In this Review, we first outline key elements and stages of the inflammatory environment and then discuss the design of biomaterials for different anti-inflammatory therapeutic strategies. Biomaterials can be engineered to scavenge danger signals, such as reactive oxygen and nitrogen species and cell-free DNA, in the early stages of inflammation. Materials can also be designed to prevent adhesive interactions of leukocytes and endothelial cells that initiate inflammatory responses. Furthermore, nanoscale platforms can deliver anti-inflammatory agents to inflammation sites. We conclude by discussing the challenges and opportunities for biomaterial innovations in addressing inflammation.

Wound Dressing: From Nanomaterials to Diagnostic Dressings and Healing Evaluations

Wound dressings based on nanomaterials play a crucial role in wound treatment and are widely used in a whole range of medical settings, from minor to life-threatening tissue injuries. This article presents an educational review on the accumulating knowledge in this multidisciplinary area to lay out the challenges and opportunities that lie ahead and ignite the further and faster development of clinically valuable technologies. The review analyzes the functional advantages of nanomaterial-based gauzes and hydrogels as well as hybrid structures thereof. On this basis, the review presents state-of-the-art advances to transfer the (semi)blind approaches to the evaluation of a wound state to smart wound dressings that enable real-time monitoring and diagnostic functions that could help in wound evaluation during healing. This review explores the translation of nanomaterial-based wound dressings and related medical aspects into real-world use. The ongoing challenges and future opportunities associated with nanomaterial-based wound dressings and related clinical decisions are presented and reviewed.