Recent Advances in Photoswitchable Fluorescent and Colorimetric Probes.

In recent years, significant advancements have been made in the research of photoswitchable probes. These probes undergo reversible structural and electronic changes upon light exposure, thus exhibiting vast potential in molecular detection, biological imaging, material science, and information storage. Through precisely engineered molecular structures, the photoswitchable probes can toggle between "on" and "off" states at specific wavelengths, enabling highly sensitive and selective detection of targeted analytes. This review systematically presents photoswitchable fluorescent and colorimetric probes built on various molecular photoswitches, primarily focusing on the types involving photoswitching in their detection and/or signal response processes. It begins with an analysis of various molecular photoswitches, including their photophysical properties, photoisomerization and photochromic mechanisms, and fundamental design concepts for constructing photoswitchable probes. The article then elaborates on the applications of these probes in detecting diverse targets, including cations, anions, small molecules, and biomacromolecules. Finally, it offers perspectives on the current state and future development of photoswitchable probes. This review aims to provide a clear introduction for researchers in the field and guidance for the design and application of new, efficient fluorescent and colorimetric probes.

Novel therapeutic role of Ganoderma Polysaccharides in a septic mouse model - The key role of macrophages.

Ganoderma lucidum polysaccharides (G. PS) have been recognized for their immune-modulating properties. In this study, we investigated the impact of G. PS in a sepsis mouse model, exploring its effects on survival, inflammatory cytokines, Treg cell differentiation, bacterial load, organ dysfunction, and related pathways. We also probed the role of macrophages through chlorphosphon-liposome pretreatment. Using the cecal ligation and puncture (CLP) model, we categorized mice into normal, PBS, and G. PS injection groups. G. PS significantly enhanced septic mouse survival, regulated inflammatory cytokines (TNF-α, IL-17A, IL-6, IL-10), and promoted CD4+Foxp3+ Treg cell differentiation in spleens. Additionally, G. PS reduced bacterial load, mitigated organ damage, and suppressed the NF-κB pathway. In vitro, G. PS facilitated CD4+ T cell differentiation into Treg cells via the p-STAT5 pathway. Chlorphosphon-liposome pretreatment heightened septic mortality, bacterial load, biochemical markers, and organ damage, emphasizing macrophages' involvement. G. PS demonstrated significant protective effects in septic mice by modulating inflammatory responses, enhancing Treg cell differentiation, diminishing bacterial load, and inhibiting inflammatory pathways. These findings illuminate the therapeutic potential of G. PS in sepsis treatment.

Phase-Transition of Mo2 C Induced by Tungsten Doping as Heterointerface-Rich Electrocatalyst for Optimizing Hydrogen Evolution Activity.

Electrochemical hydrogen evolution reaction (HER) from water splitting driven by renewable energy is considered a promising method for large-scale hydrogen production, and as an alternative to noble-metal electrocatalysts, molybdenum carbide (Mo2 C) has exhibited effective HER performance. However, the strong bonding strength of intermediate adsorbed H (Hads ) with Mo active site slows down the HER kinetics of Mo2 C. Herein, using phase-transition strategy, hexagonal ß-Mo2 C could be easily transferred to cubic δ-Mo2 C through electron injection triggered by tungsten (W) doping, and heterointerface-rich Mo2 C-based composites, including ß-Mo2 C, δ-Mo2 C, and MoO2 , are presented. Experimental results and density functional theory calculations reveal that W doping mainly contributes to the phase-transition process, and the generated heterointerfaces are the dominant factor in inducing remarkable electron accumulation around Mo active sites, thus weakening the Mo─H coupling. Wherein, the ß-Mo2 C/MoO2 interface plays an important role in optimizing the electronic structure of Mo 3d orbital and hydrogen adsorption Gibbs free energy (ΔGH* ), enabling these Mo2 C-based composites to have excellent intrinsic catalytic activity like low overpotential (η10 = 99.8 mV), small Tafel slope (60.16 dec-1 ), and good stability in 1 m KOH. This work sheds light on phase-transition engineering and offers a convenient route to construct heterointerfaces for large-scale HER production.

Nanocatalysts for modulating antitumor immunity: fabrication, mechanisms and applications.

Immunotherapy harnesses the inherent immune system in the body to generate systemic antitumor immunity, offering a promising modality for defending against cancer. However, tumor immunosuppression and evasion seriously restrict the immune response rates in clinical settings. Catalytic nanomedicines can transform tumoral substances/metabolites into therapeutic products in situ, offering unique advantages in antitumor immunotherapy. Through catalytic reactions, both tumor eradication and immune regulation can be simultaneously achieved, favoring the development of systemic antitumor immunity. In recent years, with advancements in catalytic chemistry and nanotechnology, catalytic nanomedicines based on nanozymes, photocatalysts, sonocatalysts, Fenton catalysts, electrocatalysts, piezocatalysts, thermocatalysts and radiocatalysts have been rapidly developed with vast applications in cancer immunotherapy. This review provides an introduction to the fabrication of catalytic nanomedicines with an emphasis on their structures and engineering strategies. Furthermore, the catalytic substrates and state-of-the-art applications of nanocatalysts in cancer immunotherapy have also been outlined and discussed. The relationships between nanostructures and immune regulating performance of catalytic nanomedicines are highlighted to provide a deep understanding of their working mechanisms in the tumor microenvironment. Finally, the challenges and development trends are revealed, aiming to provide new insights for the future development of nanocatalysts in catalytic immunotherapy.

Regulation Dipole Moments of N-Doped Graphene Coordinated with FePc Toward Highly Efficient Microwave Absorption Performance in C Band.

The development of composites with highly efficient microwave absorption (MA) performance deeply depends on polarization loss, which can be induced by charge redistribution. Considering the fact that polarization centers can be easily obtained in graphene, herein, iron phthalocyanine (FePc) is used as polarization site to coordinate with nitrogen-doped graphene (FePc/N-rGO) to optimize MA performance comprehensively. The factors influencing MA properties focus on the interaction between FePc and N-rGO, and the change of dipole moments. The density functional theory (DFT) results demonstrated that FePc has strong interaction with N defect sites in graphene. The charge loss for FePc and charge accumulation for N-rGO occurred, leading to great increase of dipole moment, and the increased dipole moment can be acted as a descriptor to evaluate the enhanced polarization loss. Due to high charge redistribution capacity of N defect sites and FePc polarization centers, the FePc/N-rGO showed excellent MA properties in C band, and the minimum reflection loss value can reach -49.3 dB at 5.4 GHz with thickness of 3.8 mm. In addition, the fabric loaded with FePc/N-rGO showed good heat dissipation property. This work opens the door to the development of MA performance bound to polarization site with dipole moment.

Nitric oxide-releasing multifunctional catechol-modified chitosan/oxidized dextran hydrogel with antibacterial, antioxidant, and pro-angiogenic properties for MRSA-infected diabetic wound healing.

The study presents a multifunctional catechol-modified chitosan (Chi-Ca)/oxidized dextran (Dex-CHO) hydrogel (CDP-PB) that possesses antibacterial, antioxidant, and pro-angiogenic properties, aimed at improving the healing of diabetic wounds. The achievement of the as-prepared CDP-PB hydrogel with superb antibacterial property (99.9 %) can be realized through the synergistic effect of phenylboronic acid-modified polyethyleneimine (PEI-PBA) and photothermal therapy (PTT) of polydopamine nanoparticles loaded with the nitric oxide (NO) donor BNN6 (PDA@BNN6). Notably, CDP-PB hydrogel achieves ∼3.6 log10 CFU/mL MRSA of inactivation efficiency under 808 nm NIR laser irradiation. In order to mitigate oxidative stress, the Chi-Ca was synthesized and afterward subjected to a reaction with Dex-CHO via a Schiff-base reaction. The catechol-containing hydrogel demonstrated its effectiveness in scavenging DPPH, •OH, and ABTS radicals (> 85 %). In addition, the cellular experiment illustrates the increased migration and proliferation of cells by the treatment of CDP-PB hydrogel in the presence of oxidative stress conditions. Moreover, the findings from the animal model experiments provide evidence that the CDP-PB hydrogel exhibited efficacy in the eradication of wound infection, facilitation of angiogenesis, stimulation of granulation, and augmentation of collagen deposition. These results indicate the potential of the CDP-PB hydrogel for use in clinical applications.

Recent Advances in Electrochemical Sensors for Formaldehyde.

Formaldehyde, a ubiquitous indoor air pollutant, plays a significant role in various biological processes, posing both environmental and health challenges. This comprehensive review delves into the latest advancements in electrochemical methods for detecting formaldehyde, a compound of growing concern due to its widespread use and potential health hazards. This review underscores the inherent advantages of electrochemical techniques, such as high sensitivity, selectivity, and capability for real-time analysis, making them highly effective for formaldehyde monitoring. We explore the fundamental principles, mechanisms, and diverse methodologies employed in electrochemical formaldehyde detection, highlighting the role of innovative sensing materials and electrodes. Special attention is given to recent developments in nanotechnology and sensor design, which significantly enhance the sensitivity and selectivity of these detection systems. Moreover, this review identifies current challenges and discusses future research directions. Our aim is to encourage ongoing research and innovation in this field, ultimately leading to the development of advanced, practical solutions for formaldehyde detection in various environmental and biological contexts.

A Mild Hyperthermia Hollow Carbon Nanozyme as Pyroptosis Inducer for Boosted Antitumor Immunity.

The immune checkpoint blockade (ICB) antibody immunotherapy has demonstrated clinical benefits for multiple cancers. However, the efficacy of immunotherapy in tumors is suppressed by deficient tumor immunogenicity and immunosuppressive tumor microenvironments. Pyroptosis, a form of programmed cell death, can release tumor antigens, activate effective tumor immunogenicity, and improve the efficiency of ICB, but efficient pyroptosis for tumor treatment is currently limited. Herein, we show a mild hyperthermia-enhanced pyroptosis-mediated immunotherapy based on hollow carbon nanozyme, which can specifically amplify oxidative stress-triggered pyroptosis and synchronously magnify pyroptosis-mediated anticancer responses in the tumor microenvironment. The hollow carbon sphere modified with iron and copper atoms (HCS-FeCu) with multiple enzyme-mimicking activities has been engineered to induce cell pyroptosis via the radical oxygen species (ROS)-Tom20-Bax-Caspase 3-gasdermin E (GSDME) signaling pathway under light activation. Both in vitro and in vivo antineoplastic results confirm the superiority of HCS-FeCu nanozyme-induced pyroptosis. Moreover, the mild photothermal-activated pyroptosis combining anti-PD-1 can enhance antitumor immunotherapy. Theoretical calculations further indicate that the mild photothermal stimulation generates high-energy electrons and enhances the interaction between the HCS-FeCu surface and adsorbed oxygen, facilitating molecular oxygen activation, which improves the ROS production efficiency. This work presents an approach that effectively transforms immunologically "cold" tumors into "hot" ones, with significant implications for clinical immunotherapy.

Artificial Macrophage with Hierarchical Nanostructure for Biomimetic Reconstruction of Antitumor Immunity.

Artificial cells are constructed from synthetic materials to imitate the biological functions of natural cells. By virtue of nanoengineering techniques, artificial cells with designed biomimetic functions provide alternatives to natural cells, showing vast potential for biomedical applications. Especially in cancer treatment, the deficiency of immunoactive macrophages results in tumor progression and immune resistance. To overcome the limitation, a BaSO4@ZIF-8/transferrin (TRF) nanomacrophage (NMΦ) is herein constructed as an alternative to immunoactive macrophages. Alike to natural immunoactive macrophages, NMΦ is stably retained in tumors through the specific affinity of TRF to tumor cells. Zn2+ as an "artificial cytokine" is then released from the ZIF-8 layer of NMΦ under tumor microenvironment. Similar as proinflammatory cytokines, Zn2+ can trigger cell anoikis to expose tumor antigens, which are selectively captured by the BaSO4 cavities. Therefore, the hierarchical nanostructure of NMΦs allows them to mediate immunogenic death of tumor cells and subsequent antigen capture for T cell activation to fabricate long-term antitumor immunity. As a proof-of-concept, the NMΦ mimics the biological functions of macrophage, including tumor residence, cytokine release, antigen capture and immune activation, which is hopeful to provide a paradigm for the design and biomedical applications of artificial cells.

Thermo-Responsive Hydrogels Coupled with Photothermal Agents for Biomedical Applications.

Intelligent hydrogels are materials with abilities to change their chemical nature or physical structure in response to external stimuli showing promising potential in multitudinous applications. Especially, photo-thermo coupled responsive hydrogels that are prepared by encapsulating photothermal agents into thermo-responsive hydrogel matrix exhibit more attractive advantages in biomedical applications owing to their spatiotemporal control and precise therapy. This work summarizes the latest progress of the photo-thermo coupled responsive hydrogel in biomedical applications. Three major elements of the photo-thermo coupled responsive hydrogel, i.e., thermo-responsive hydrogel matrix, photothermal agents, and construction methods are introduced. Furthermore, the recent developments of these hydrogels for biomedical applications are described with some selected examples. Finally, the challenges and future perspectives for photo-thermo coupled responsive hydrogels are outlined.

Nitrogen-Centered Lactate Oxidase Nanozyme for Tumor Lactate Modulation and Microenvironment Remodeling.

Designing nanozymes that match natural enzymes have always been an attractive and challenging goal. In general, researchers mainly focus on the construction of metal centers and the control of non-metallic ligands of nanozyme to regulate their activities. However, this is not applicable to lactate oxidase, i.e., flavoenzymes with flavin mononucleotide (FMN)-dependent pathways. Herein, we propose a coordination strategy to mimic lactate oxidase based on engineering the electronic properties at the N center by modulating the Co number near N in the Cox-N nanocomposite. Benefitting from the manipulated coordination fields and electronic structure around the electron-rich N sites, Co4N/C possesses a precise recognition site for lactate and intermediate organization and optimizes the absorption energies for intermediates, leading to superior oxidation of the lactate α-C-sp(3)-H bond toward ketone. The optimized nanozyme delivers much improved anticancer efficacy by reversing the high lactate and the immunosuppressive state of the tumor microenvironment, subsequently achieving excellent tumor growth and distant metastasis inhibition. The developed Co4N/C NEs open a new window for building a bridge between chemical catalysis and biocatalysis.

Piezoelectric Nanozyme for Dual-Driven Catalytic Eradication of Bacterial Biofilms.

Catalytic nanomedicine can in situ catalytically generate bactericidal species under external stimuli to defend against bacterial infections. However, bacterial biofilms seriously impede the catalytic efficacy of traditional nanocatalysts. In this work, MoSe2 nanoflowers (NFs) as piezoelectric nanozymes were constructed for dual-driven catalytic eradication of multi-drug-resistant bacterial biofilms. In the biofilm microenvironment, the piezoelectricity of MoSe2 NFs was cascaded with their enzyme-mimic activity, including glutathione oxidase-mimic and peroxidase-mimic activity. As a result, the oxidative stress in the biofilms was sharply elevated under ultrasound irradiation, achieving a 4.0 log10 reduction of bacterial cells. The in vivo studies reveal that the MoSe2 NFs efficiently relieve the methicillin-resistant Staphylococcus aureus bacterial burden in mice under the control of ultrasound at a low power density. Moreover, because of the surface coating of antioxidant poly(ethyleneimine), the dual-driven catalysis of MoSe2 NFs was retarded in normal tissues to minimize the off-target damage and favor the wound healing process. Therefore, the cascade of piezoelectricity and enzyme-mimic activity in MoSe2 NFs reveals a dual-driven strategy for improving the performance of catalytic nanomaterials in the eradication of bacterial biofilms.

Cold Nanozyme for Precise Enzymatic Antitumor Immunity.

Precise catalysis is pursued for the biomedical applications of artificial enzymes. It is feasible to precisely control the catalysis of artificial enzymes via tunning the temperature-dependent enzymatic kinetics. The safety window of cold temperatures (4-37 °C) for the human body is much wider than that of thermal temperatures (37-42 °C). Although the development of cold-activated artificial enzymes is promising, there is currently a lack of suitable candidates. Herein, a cold-activated artificial enzyme is presented with Bi2Fe4O9 nanosheets (NSs) as a paradigm. The as-obtained Bi2Fe4O9 NSs possess glutathione oxidase (GSHOx)-like activity under cold temperature due to their pyroelectricity. Bi2Fe4O9 NSs trigger the cold-enzymatic death of tumor cells via apoptosis and ferroptosis, and minimize the off-target toxicity to normal tissues. Moreover, an interventional device is fabricated to intelligently and remotely control the enzymatic activity of Bi2Fe4O9 NSs on a smartphone. With Bi2Fe4O9 NSs as an in situ vaccine, systemic antitumor immunity is successfully activated to suppress tumor metastasis and relapse. Moreover, blood biochemistry analysis and histological examination indicate the high biosafety of Bi2Fe4O9 NSs for in vivo applications. This cold nanozyme provides a strategy for cancer vaccines, which can benefit the precise control over catalytic nanomedicines.

Cascade Catalytically Released Nitric Oxide-Driven Nanomotor with Enhanced Penetration for Antibiofilm.

Nanodrugs are becoming increasingly important in the treatment of bacterial infection, but their low penetration ability to bacterial biofilm is still the main challenge hindering their therapeutic effect. Herein, nitric oxide (NO)-driven nanomotor based on L-arginine (L-Arg) and gold nanoparticles (AuNPs) loaded dendritic mesoporous silica nanoparticles (AG-DMSNs) is fabricated. AG-DMSNs have the characteristics of cascade catalytic reaction, where glucose is first catalyzed by the asymmetrically distributed AuNPs with their glucose oxidase (GOx)- mimic property, which results in unilateral production of hydrogen peroxide (H2 O2 ). Then, L-Arg is oxidized by the produced H2 O2 to release NO, leading to the self-propelled movement. It is found that the active movement of nanomotor promotes the AG-DMSNs ability to penetrate biofilm, thus achieving good biofilm clearance in vitro. More importantly, AG-DMSNs nanomotor can eliminate the biofilm of methicillin-resistant Staphylococcus aureus (MRSA) in vivo without causing damage to normal tissues. This nanomotor provides a new platform for the treatment of bacterial infections.

Functional Nanomaterials: From Structures to Biomedical Applications.

In recent decades, a number of functional nanomaterials have attracted a great amount of attention and exhibited excellent performance for biomedical and pharmaceutical applications [...].

Cold-catalytic antitumor immunity with pyroelectric black phosphorus nanosheets.

Catalytic nanomedicine with the innate features of catalysts brings incomparable properties to biomedicine over traditional drugs. The temperature-dependent activity of catalysts provides catalytic nanomedicines with a facile strategy to control their therapeutic performance. Tuning catalytic nanomedicine by cold treatment (4-37 °C) is safe and desired for practical applications, but there is a lack of cold-catalytic platforms. Herein, with black phosphorus (BP) as a model pyroelectric nanocatalyst, we explored the potential of cold-catalysts for antitumor therapy. BP nanosheets with pyro-catalytic activity catalyze the generation of oxidative stress to activate antitumor immunity under cold treatment. Due to the cold-catalytic immunomodulation, immune memory was successfully achieved to prevent tumor metastasis and recurrence. Considering the safety and conductive depth (>10 mm) of cold in the body, pyroelectric nanocatalysts open up exciting opportunities for the development of cold-catalytic nanomedicine.

Biocomputation with MnTiO3 Piezoelectric Enzymes for Programed Catalysis of Tumor Death.

Catalytic nanomedicine, especially artificial enzymes, exhibit obvious merits over traditional nanomedicine. However, the lack of controllability over an enzymatic process seriously challenges the therapeutic performance. Herein, we present a concept of using piezoelectric enzymes in combination with biocomputation ability. As a paradigm, MnTiO3 nanodisks were prepared with multiple enzyme-mimicking activity, including glutathione oxidase, peroxidase, and catalase. Different from the conventional artificial enzymes, the enzymatic activity of MnTiO3 nanodisks was activated by ultrasound and switched by a tumor microenvironment, which allows precise control over enzymatic catalysis in tumors. By virtue of the multiple artificial enzyme activity of MnTiO3 nanodisks, a biocomputing platform was constructed based on a Boolean logic-based algorithm. With ultrasound and tumor microenvironment as input signals, cytotoxicity was output via logic-based biocomputation for programed tumor killing. The concept of piezoelectric enzymes together with a biocomputation strategy provides an intelligent and effective approach for catalytic tumor eradication.

A Cascade Nanozyme with Amplified Sonodynamic Therapeutic Effects through Comodulation of Hypoxia and Immunosuppression against Cancer.

The tumor microenvironment (TME) featured by immunosuppression and hypoxia is pivotal to cancer deterioration and metastasis. Thus, regulating the TME to improve cancer cell ablation efficiency has received extensive interest in oncotherapy. However, to reverse the immunosuppression and alleviate hypoxia simultaneously in the TME are major challenges for effective cancer therapy. Herein, a multifunctional platform based on Au nanoparticles and a carbon dots modified hollow black TiO2 nanosphere (HABT-C) with intrinsic cascade enzyme mimetic activities is prepared for reversing immunosuppression and alleviating hypoxia in the TME. The HABT-C NPs possess triple-enzyme mimetic activity to act as self-cascade nanozymes, which produce sufficient oxygen to alleviate hypoxia and generate abundant ROS. The theoretical analysis demonstrates that black TiO2 facilitates absorption of H2O and O2, separation of electron-holes, and generation of ROS, consequently amplifying the sonodynamic therapy (SDT) efficiency. Specifically, HABT-C exhibits favorable inhibition of immunosuppressive mediator expression, along with infiltrating of immune effector cells into the TME and reversing the immunosuppression in the TME. As a result, HABT-C can effectively kill tumor cells via eliciting immune infiltration, alleviating hypoxia, and improving SDT efficiency. This cascade nanozyme-based platform (HABT-C@HA) will provide a strategy for highly efficient SDT against cancer by modulation of hypoxia and immunosuppression in the TME.

Nanomessenger-Mediated Signaling Cascade for Antitumor Immunotherapy.

Chemical messengers have been recognized as signaling molecules involved in regulating various physiological and metabolic activities. Nevertheless, they usually show limited regulatory efficiency due to the complexity of biological processes. Especially for tumor cells, antideath pathways and tumor metastasis are readily activated to resist chemical messenger regulation, further impairing antitumor outcomes. Therefore, it is imperative to develop strategies for tumor eradication with chemical messengers. Herein, a nanomessenger was prepared with signaling transduction cascades to amplify the regulatory activity of chemical messengers and mediate antitumor immunotherapy. Ca2+ and H2S as two chemical messengers were released from nanomessengers to synergistically elevate intracellular Ca2+ stress and mediate subsequent cell death. Meanwhile, zinc protoporphyrin (ZnPP) as a messenger amplifier suppressed the antideath effect of tumor cells. As a result, tumor cells underwent Ca2+-dependent cell death via signaling transduction cascades to release tumor-associated antigens, which further served as an in situ tumor vaccine to activate antitumor immunity. In vivo studies revealed that both primary tumors and distant metastases were markedly eradicated. Furthermore, immunological memory was fabricated to arrest tumor metastasis and recurrence. This work introduces cascade engineering into chemical messengers and thus offers a strategy for amplifying chemical messenger-mediated cellular regulation, which would promote the future development of chemical messenger-mediated immunotherapy.̀.