Peroxidase-like activity of Fe3O4@carbon nanoparticles enhances ascorbic acid-induced oxidative stress and selective damage to PC-3 prostate cancer cells

Nanoenzymes: A Radiant Hope for the Early Diagnosis and Effective Treatment of Breast and Ovarian Cancers

Breast and ovarian cancers, despite having chemotherapy and surgical treatment, still have the lowest survival rate. Experimental stages using nanoenzymes/nanozymes for ovarian cancer diagnosis and treatment are being carried out, and correspondingly the current treatment approaches to treat breast cancer have a lot of adverse side effects, which is the reason why researchers and scientists are looking for new strategies with less side effects. Nanoenzymes have intrinsic enzyme-like activities and can reduce the shortcomings of naturally occurring enzymes due to the ease of storage, high stability, less expensive, and enhanced efficiency. In this review, we have discussed various ways in which nanoenzymes are being used to diagnose and treat breast and ovarian cancer. For breast cancer, nanoenzymes and their multi-enzymatic properties can control the level of reactive oxygen species (ROS) in cells or tissues, for example, oxidase (OXD) and peroxidase (POD) activity can be used to generate ROS, while catalase (CAT) or superoxide dismutase (SOD) activity can scavenge ROS. In the case of ovarian cancer, most commonly nanoceria is being investigated, and also when folic acid is combined with nanoceria there are additional advantages like inhibition of beta galactosidase. Nanocarriers are also used to deliver small interfering RNA that are effective in cancer treatment. Studies have shown that iron oxide nanoparticles are actively being used for drug delivery, similarly ferritin carriers are used for the delivery of nanozymes. Hypoxia is a major factor in ovarian cancer, therefore MnO2-based nanozymes are being used as a therapy. For cancer diagnosis and screening, nanozymes are being used in sonodynamic cancer therapy for cancer diagnosis and screening, whereas biomedical imaging and folic acid gold particles are also being used for image guided treatments. Nanozyme biosensors have been developed to detect ovarian cancer. This review article summarizes a detailed insight into breast and ovarian cancers in light of nanozymes-based diagnostic and therapeutic approaches.

pH-responsive iron-loaded carbonaceous nanoparticles for chemodynamic therapy based on the Fenton reaction

The Fenton reaction-based chemodynamic therapy is a form of cancer therapy, and its efficacy can be significantly improved by promoting catalytic reactions involving iron ions. A system with high catalytic capacity and low biological toxicity that effectively inhibits tumor progression is required for optimal treatment. In this study, iron-loaded carbonaceous nanoparticles (CNPs@Fe) with Fenton catalytic activity were fabricated and applied for the chemodynamic therapy of cancer. The carbonaceous nanoparticles derived from glucose via a caramelization reaction demonstrated high biocompatibility. Besides, aromatic structures in the carbonaceous nanoparticles helped accelerate electron transfer to enhance the catalytic decomposition of H2O2, resulting in the formation of highly reactive hydroxyl radicals (˙OH). At pH 6.0 (representing weak acidity in the tumor microenvironment), the Fenton catalytic activity of CNPs@Fe in the decomposition of H2O2 was 15.3 times higher than that of Fe2+ and 28.3 times higher than that of Fe3O4via a chromogenic reaction. The reasons for the enhancement were revealed by analyzing the chemical composition of carbonaceous nanoparticles using high-resolution mass spectra. The developed Fenton agent also demonstrated significant therapeutic effectiveness and minimal side effects in in vitro and in vivo anticancer studies. This work proposes a novel approach to promote the generation of reactive oxygen species (ROS) for the chemodynamic therapy of cancer.

Copper nitroprusside: An innovative approach for targeted cancer therapy via ROS modulation

The clinical application of nanomaterials for chemodynamic therapy (CDT), which generate multiple reactive oxygen species (ROS), presents significant challenges. These challenges arise due to insufficient levels of endogenous hydrogen peroxide and catalytic ions necessary to initiate Fenton reactions. As a result, sophisticated additional delivery systems are required. In this study, a novel bimetallic copper (II) pentacyanonitrosylferrate (Cu(II)NP, Cu[Fe(CN) 5 NO]) material was developed to address these limitations. This material functions as a multiple ROS generator at tumoral sites by self-inducing hydrogen peroxide and producing peroxynitrite (ONOO-) species. The research findings demonstrate that this material exhibits low toxicity towards normal liver organoids, yet shows potent antitumoral effects on High Grade Serous Ovarian Cancer (HGSOC) organoid patients, regardless of platinum resistance. Significantly, this research introduces a promising therapeutic opportunity by proposing a single system capable of replacing the need for H2O2, additional catalysts, and NO-based delivery systems. This innovative system exhibits remarkable multiple therapeutic mechanisms, paving the way for potential advancements in clinical treatments.

Smart Nanozymes for Cancer Therapy: The Next Frontier in Oncology

Nanomaterials that mimic the catalytic activity of natural enzymes in the complex biological environment of the human body are called nanozymes. Recently, nanozyme systems have been reported with diagnostic, imaging, and/or therapeutic capabilities. Smart nanozymes strategically exploit the tumor microenvironment (TME) by the in situ generation of reactive species or by the modulation of the TME itself to result in effective cancer therapy. This topical review focuses on such smart nanozymes for cancer diagnosis, and therapy modalities with enhanced therapeutic effects. The dominant factors that guide the rational design and synthesis of nanozymes for cancer therapy include an understanding of the dynamic TME, structure-activity relationships, surface chemistry for imparting selectivity, and site-specific therapy, and stimulus-responsive modulation of nanozyme activity. This article presents a comprehensive analysis of the subject including the diverse catalytic mechanisms of different types of nanozyme systems, an overview of the TME, cancer diagnosis, and synergistic cancer therapies. The strategic application of nanozymes in cancer treatment can well be a game changer in future oncology. Moreover, recent developments may pave the way for the deployment of nanozyme therapy into other complex healthcare challenges, such as genetic diseases, immune disorders, and ageing.

Engineering hetero-structural iron nanozyme decorated liposome with a self-cascade catalysis performance

Metal-based enzyme mimics are considered as acceptable agents in fabricating heterogeneous biocomposites through valency integrations because of their biomedical or biological properties. As the basic substitute, it delights us to utilize Fe3O4 nanoparticles (NPs) as metallic enzymes and overcome the limitation of peroxide-like enzymatic activity in physiological conditions. In this work, we present the fabrication of a soy phosphatidylcholine/Fe3O4@Ag/GOx (SFAG) biocomposite as a cascade enzyme, which exhibits a peroxidase-like property in kinetic processes, as shown from an analysis of the glucose detection processes. We also explored the mechanism of an ultrasound & microfluidic approach for the synthesis of SFAG. The resultant SFAG implies a characteristic absorption peak (652 nm), size (55 μm), and surface charge (-32.93 ± 2.58 mV). This is utilized to confirm the peroxidase-like activity by catalyzing 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 under physiological conditions. But also, SFAG conveys a positive effect on the peroxidase-like activity at pH = 5.8, 7.4, and 8.0. The Michaelis-Menten parameters (Km) and the Vmax values of H2O2 are 1.914 mM and 1.429 × 10-7 M s-1, which further confirms the catalytic performances of the SFAG structure. The established platform was also used successfully for the determination of glucose in PBS and diluted synthetic blood with excellent sensitivity and stability. The relative selection and sensitivity show that the SFAG structure has a great possibility as a cascade metallic enzyme in chemokinetic works.

Amorphous mixed-valent Mn-containing nanozyme with cocklebur-like morphology for specific colorimetric detection of cancer cells via Velcro effects

Designing nanozymes with excellent catalytic activity through valence state engineering and defect engineering is a widely applicable strategy. However, their development is hindered by the complexity of the design strategies. In this work, we employed a simple calcination method to regulate the valence of manganese and crystalline states in manganese oxide nanozymes. The oxidase-like activity of the nanozymes was found to benefit from a mixed valence state dominated by Mn (III). And the amorphous structure with more active defect sites significantly enhanced the catalytic efficiency. Moreover, we demonstrated that amorphous mixed-valent Mn-containing (amvMn) nanozymes with unique cocklebur-like biomimetic morphology achieved specific binding to cancer cells through the Velcro effects. Subsequently, the nanozymes mediated TMB coloration through their oxidase-like activity, enabling the colorimetric detection of cancer cells. This work not only provides guidance for optimizing nanozyme performance, but also inspire the development of equipment-free visual detection methods for cancer cells.

Fe3O4 Nanoparticles in Combination with 5-FU Exert Antitumor Effects Superior to Those of the Active Drug in a Colon Cancer Cell Model

(1) Background: Colon cancer is one of the most common cancer types, and treatment options, unfortunately, do not continually improve the survival rate of patients. With the unprecedented development of nanotechnologies, nanomedicine has become a significant direction in cancer research. Indeed, chemotherapeutics with nanoparticles (NPs) in cancer treatment is an outstanding new treatment principle. (2) Methods: Fe3O4 NPs were synthesized and characterized. Caco-2 colon cancer cells were treated during two different periods (24 and 72 h) with Fe3O4 NPs (6 μg/mL), various concentrations of 5-FU (4−16 μg/mL), and Fe3O4 NPs in combination with 5-FU (4−16 μg/mL) (Fe3O4 NPs + 5-FU). (3) Results: The MTT assay showed that treating the cells with Fe3O4 NPs + 5-FU at 16 µg/mL for 24 or 72 h decreased cell viability and increased their LDH release (p < 0.05 and p < 0.01, respectively). Furthermore, at the same treatment concentrations, total antioxidant capacity (TAC) was decreased (p < 0.05 and p < 0.01, respectively), and total oxidant status (TOS) increased (p < 0.05 and p < 0.01, respectively). Moreover, after treatment with Fe3O4-NPs + 5-FU, the IL-10 gene was downregulated and PTEN gene expression was upregulated (p < 0.05 and p < 0.01, respectively) compared with those of the control. (4) Conclusions: Fe3O4 NPs exert a synergistic cytotoxic effect with 5-FU on Caco-2 cells at concentrations below the active drug threshold levels.

Functionalized Magnetite Nanoparticles: Characterization, Bioeffects, and Role of Reactive Oxygen Species in Unicellular and Enzymatic Systems

The current study evaluates the role of reactive oxygen species (ROS) in bioeffects of magnetite nanoparticles (MNPs), such as bare (Fe3O4), humic acids (Fe3O4-HA), and 3-aminopropyltriethoxysilane (Fe3O4-APTES) modified MNPs. Mössbauer spectroscopy was used to identify the local surrounding for Fe atom/ions and the depth of modification for MNPs. It was found that the Fe3O4-HA MNPs contain the smallest, whereas the Fe3O4-APTES MNPs contain the largest amount of Fe2+ ions. Bioluminescent cellular and enzymatic assays were applied to monitor the toxicity and anti-(pro-)oxidant activity of MNPs. The contents of ROS were determined by a chemiluminescence luminol assay evaluating the correlations with toxicity/anti-(pro-)oxidant coefficients. Toxic effects of modified MNPs were found at higher concentrations (>10−2 g/L); they were related to ROS storage in bacterial suspensions. MNPs stimulated ROS production by the bacteria in a wide concentration range (10−15−1 g/L). Under the conditions of model oxidative stress and higher concentrations of MNPs (>10−4 g/L), the bacterial bioassay revealed prooxidant activity of all three MNP types, with corresponding decay of ROS content. Bioluminescence enzymatic assay did not show any sensitivity to MNPs, with negligible change in ROS content. The results clearly indicate that cell-membrane processes are responsible for the bioeffects and bacterial ROS generation, confirming the ferroptosis phenomenon based on iron-initiated cell-membrane lipid peroxidation.

Clear-Box Machine Learning for Virtual Screening of 2D Nanozymes to Target Tumor Hydrogen Peroxide

Targeting tumor hydrogen peroxide (H₂ O₂ ) with catalytic materials has provided a novel chemotherapy strategy against solid tumors. Because numerous materials have been fabricated so far, there is an urgent need for an efficient in silico method, which can automatically screen out appropriate candidates from materials libraries for further therapeutic evaluation. In this work, adsorption-energy-based descriptors and criteria are developed for the catalase-like activities of materials surfaces. The result enables a comprehensive prediction of H₂ O₂ -targeted catalytic activities of materials by density functional theory (DFT) calculations. To expedite the prediction, machine learning models, which efficiently calculate the adsorption energies for 2D materials without DFT, are further developed. The finally obtained method takes advantage of both interpretability of physics model and high efficiency of machine learning. It provides an efficient approach for in silico screening of 2D materials toward tumor catalytic therapy, and it will greatly promote the development of catalytic nanomaterials for medical applications.

Harnessing inorganic nanomaterials for chemodynamic cancer therapy

The most important aspect of chemodynamic therapy (CDT) is the harnessing of Fenton or Fenton-like chemistry for cancer therapy within the tumor microenvironment, which occurs because of the moderate acidity and overexpressed H₂O₂ in the tumor microenvironment. Hydroxyl radicals (^•OH) produced within tumor cells via Fenton and Fenton-like reactions cause cancer cell death. Reactive oxygen species-mediated CDT demonstrates a desired anticancer impact without the need for external stimulation or the development of drug resistance. Cancer therapy based on CDT is known as a viable cancer therapy modality. This review discusses the most recent CDT advancements and provides some typical instances. As a result, potential methods for further improving CDT efficiency under the guidance of Fenton chemistry are offered.

New Insight into Assembled Fe3O4@PEI@Ag Structure as Acceptable Agent with Enzymatic and Photothermal Properties

Metal-based enzyme mimics are considered to be acceptable agents in terms of their biomedical and biological properties; among them, iron oxides (Fe₃O₄) are treated as basement in fabricating heterogeneous composites through variable valency integrations. In this work, we have established a facile approach for constructing Fe₃O₄@Ag composite through assembling Fe₃O₄ and Ag together via polyethyleneimine ethylenediamine (PEI) linkages. The obtained Fe₃O₄@PEI@Ag structure conveys several hundred nanometers (~150 nm). The absorption peak at 652 nm is utilized for confirming the peroxidase-like activity of Fe₃O₄@PEI@Ag structure by catalyzing 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂. The Michaelis–Menten parameters (K_m) of 1.192 mM and 0.302 mM show the higher catalytic activity and strong affinity toward H₂O₂ and TMB, respectively. The maximum velocity (V_max) value of 1.299 × 10⁻⁷ M∙s⁻¹ and 1.163 × 10⁻⁷ M∙s⁻¹ confirm the efficiency of Fe₃O₄@PEI@Ag structure. The biocompatibility illustrates almost 100% cell viability. Being treated as one simple colorimetric sensor, it shows relative selectivity and sensitivity toward the detection of glucose based on glucose oxidase. By using indocyanine green (ICG) molecule as an additional factor, a remarkable temperature elevation is observed in Fe₃O₄@PEI@Ag@ICG with increments of 21.6 °C, and the absorption peak is nearby 870 nm. This implies that the multifunctional Fe₃O₄@PEI@Ag structure could be an alternative substrate for formatting acceptable agents in biomedicine and biotechnology with enzymatic and photothermal properties.

Fabrication of α-Fe2O3 Nanostructures: Synthesis, Characterization, and Their Promising Application in the Treatment of Carcinoma A549 Lung Cancer Cells

In the present work, iron nanoparticles were synthesized in the α-Fe₂O₃ phase with the reduction of potassium hexachloroferrate(III) by using l-ascorbic acid as a reducing agent in the presence of an amphiphilic non-ionic polyethylene glycol surfactant in an aqueous solution. The synthesized α-Fe₂O₃ NPs were characterized by powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet-visible spectrophotometry. The powder X-ray diffraction analysis result confirmed the formation of α-Fe₂O₃ NPs, and the average crystallite size was found to be 45 nm. The other morphological studies suggested that α-Fe₂O₃ NPs were predominantly spherical in shape with a diameter ranges from 40 to 60 nm. The dynamic light scattering analysis revealed the zeta potential of α-Fe₂O₃ NPs as -28 ± 18 mV at maximum stability. The ultraviolet-visible spectrophotometry analysis shows an absorption peak at 394 nm, which is attributed to their surface plasmon vibration. The cytotoxicity test of synthesized α-Fe₂O₃ NPs was investigated against human carcinoma A549 lung cancer cells, and the biological adaptability exhibited by α-Fe₂O₃ NPs has opened a pathway to biomedical applications in the drug delivery system. Our investigation confirmed that l-ascorbic acid-coated α-Fe₂O₃ NPs with calculated IC₅₀ ≤ 30 μg/mL are the best suited as an anticancer agent, showing the promising application in the treatment of carcinoma A549 lung cancer cells.

Recent Trends in Composite Nanozymes and Their Pro-Oxidative Role in Therapeutics

Nanozymes are inorganic nanostructures whose enzyme mimic activities are increasingly explored in disease treatment, taking inspiration from natural enzymes. The catalytic ability of nanozymes to generate reactive oxygen species can be used for designing effective antimicrobials and antitumor therapeutics. In this context, composite nanozymes are advantageous, particularly because they integrate the properties of various nanomaterials to offer a single multifunctional platform combining photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT). Hence, recent years have witnessed great progress in engineering composite nanozymes for enhanced pro-oxidative activity that can be utilized in therapeutics. Therefore, the present review traverses over the newer strategies to design composite nanozymes as pro-oxidative therapeutics. It provides recent trends in the use of composite nanozymes as antibacterial, antibiofilm, and antitumor agents. This review also analyzes various challenges yet to be overcome by pro-oxidative composite nanozymes before being used in the field.

Biological interactions of ferromagnetic iron oxide-carbon nanohybrids with alveolar epithelial cells

Iron oxide nanoparticles (IONPs) have been largely investigated in a plethora of biological fields for their interesting physical-chemical properties, which make them suitable for application in cancer therapy, neuroscience, and imaging. Several encouraging results have been reported in these contexts. However, the possible toxic effects of some IONP formulations can limit their applicability. In this work, IONPs were synthesized with a carbon shell (IONP@C), providing enhanced stability both as colloidal dispersion and in the biological environment. We conducted a careful multiparametric evaluation of IONP@C biological interactions in vitro, providing them with an in vivo-like biological identity. Our hybrid nanoformulation showed no cytotoxic effects on a widely employed model of alveolar epithelial cells for a variety of concentrations and exposure times. The IONP@C were efficiently internalized and TEM analysis allowed the protective role of the carbon shell against intracellular degradation to be assessed. Intracellular redistribution of the IONP@C from the lysosomes to the lamellar bodies was also observed after 72 hours.

Synthesis and biological impacts of pollen shells/Fe3O4 nanoparticles composites on human MG-63 osteosarcoma cells

INTRODUCTION

Cell-adhesive surfaces play a pivotal role in biomedical engineering, as most biological reactions take place on surfaces. Pollen shell (PSh) ofPistacia vera L., as a new medical device, has previously been reported to cause cytotoxicity and apoptosis in MG-63 bone cancer cells.

METHODS

Iron oxide nanoparticles (Fe3O4NPs) were synthesized and their reaction to PShs was gauged at different concentrations, and then characterized using field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy, energy dispersion X-ray spectrometer, X-ray diffraction spectra, dynamic light scattering, and vibrating sample magnetometer. Then, the biological impacts of PShs/Fe3O4NPs composites on MG-63 cells were investigated in-vitro using MTT assay, quantitative polymerase chain reaction (qPCR), Annexin V/propidium iodide, FESEM, and DAPI staining.

RESULTS

Fe3O4NPs with a size range of 24-40 nm and a zeta potential value of -37.4 mV were successfully assembled on the PShs. The viability of MG-63 cells was significantly decreased when cultured on the magnetic PShs as compared to non-magnetic PShs, in Fe3O4 concentration and time-dependent manner. In contrast, magnetic PShs had a positive effect on the viability of normal human bone marrow-derived mesenchymal stem cells (hBM-MSCs). The analysis of apoptosis-related genes in cancer cells revealed that loading Fe3O4NPs on PShs increased expression of BAX/BCL2 and caspase-3 genes. The increased apoptotic activity of combined PShs/Fe3O4NPs was further confirmed by flow cytometric measurement, morphological analysis, and DAPI staining.

CONCLUSION

The incorporation of Fe3O4NPs into PShs could effectively increase anticancer effects on MG-63 cells via the mitochondria-mediated apoptosis pathway, evident by upregulation of BAX/BCL2 ratio and caspase-3.

Designing CoS1.035 Nanoparticles Anchored on N-Doped Carbon Dodecahedron as Dual-Enzyme Mimics for the Colorimetric Detection of H2O2 and Glutathione

In recent years, the exploration of the nanozyme, an artificial enzyme with the structure and function of natural enzymes, has become a hot topic in this field. Although significant progress has been made, it is still a huge challenge to design nanozymes with multiple enzyme-like catalytic activities. In this work, we have successfully fabricated a colorimetric sensing platform to mimic peroxidase-like and oxidase-like activities by the CoS_1.035 nanoparticles decorated N-doped carbon framework porous dodecahedrons (abbreviated to CoS_1.035/N-C PDHs). And the catalytic mechanism of CoS_1.035/N-C PDHs toward the peroxidase-like and oxidase-like activities is systematically explored. The results display that CoS_1.035/N-C PDHs can catalyze the oxidation of the colorless substrate 3,3,'5,5'-tetramethylbenzidine (TMB) into blue oxidized TMB (ox-TMB) by disintegrating H₂O₂ or the physically/chemically absorbed O₂ into different ROS species (·OH or O₂ ^·-) in the presence or absence of H₂O₂. Therefore, on the basis of the dual-enzyme mimic activities of CoS_1.035/N-C PDHs, the bifunctional colorimetric sensing platform is established for H₂O₂ detection with a wide linear range of 0.5-120 μM and glutathione detection with a linear range of 1-60 μM, respectively. This work provides an efficient platform for dual-enzyme mimics, expanding the application prospect of Co-based chalcogenides as enzyme mimics in biosensing, medical diagnosis, and environment monitoring.

Structure and biological activity of particles produced from highly activated carbon adsorbent

Over the recent years, carbon particles have gained relevance in the field of biomedical application to diminish the level of endo-/exogenous intoxication and oxidative stress products, which occur at different pathological states. However, it is very important that such carbon particles, specially developed for parenteral administration or per oral usage, possess a high adsorption potential and can remove hazard toxic substances of the hydrophilic, hydrophobic and amphiphilic nature usually accumulated in the blood due to the disease, and be absolutely safe for normal living cells and tissues of organism. In this work, the stable monodisperse suspension containing very small-sized (D_hydro = 1125.3 ± 243.8 nm) and highly pure carbon particles with an excellent accepting ability were obtained. UV-spectra, fluorescence quenching constant and binding association constant were provided by the information about conformational alterations in an albumin molecule in presence of carbon particles, about the dynamic type of quenching process and low binding affinity between carbon and protein. The later was confirmed by DSC method. In vitro cell culture experiments showed that carbon particles did not possess any cytotoxic effect towards all testing the normal cell lines of different histogenesis, did not show genotoxic effects and were absolutely safe for experimental animals during and after their parenteral administration. These observations may provide more information about how to develop a safe preparation of carbon particles for different biomedical applications, in particular, as a mean for intracorporeal therapy of various heavy diseases accompanied by the increased endogenous intoxication and the level of oxidative stress.

Highly efficient recovery of heavy rare earth elements by using an amino-functionalized magnetic graphene oxide with acid and base resistance

In the application of various magnetic materials for water treatment, control of surface resistance to acid and alkali corrosion remains largely overlooked, which could greatly extend their service life. We herein prepare amino grafted magnetic graphene oxide composites using a simple one-step cross-link reaction between the graphene oxide and magnetic Fe₃O₄/C nanoparticles. The as-prepared magnetic graphene oxide composites have long-term stability under acid and alkali solutions and shows an excellent performance in removing Ho(III), a representative rare earth element (REE) from water. The observed adsorption capacity of 72.1 mg Ho(III)/g exceeded that of most magnetic materials previously reported. Regeneration of the magnetic composites was realized in acid and alkali solutions but their structural integrity and physicochemical properties retained even after 18 adsorption-desorption cycles. The current adsorbent also shows excellent adsorption performance for other heavy REEs, such as Er(III), Eu(III), Lu(III), Tm(III), Y(III) and Yb(III). This work can provide a new strategy for constructing an acid and base resistance magnetic graphene oxide for the high-efficient recovery of heavy REEs from aqueous solution.

Metal-free colorimetric detection of pyrophosphate ions by the peroxidase-like activity of ATP

Pyrophosphate (P₂O₇^4-, PPi) plays a vital role in ecological environment. Its elevated levels in water bodies can lead to eutrophication. Hence, its detection is extremely significant. Whereas most of the existing methods for the actual detection of PPi may cause environmental pollution or suffer from operational complexity. In this study, we introduced a sensitive and selective method for detecting PPi based on the fact that PPi can inhibit the peroxidase-like activity of adenosine 5'-triphosphate (ATP). This strategy not only eliminated the complexity of material preparation (ATP is commercialized), but also addressed the general need for metal ions in detecting PPi. The dynamic range of PPi detection was 1.0-200 μM and the detection limit was 74 nM. In addition, this strategy had been successfully applied to the determination of PPi in tap water and lake water. This work extends the application of natural biological small molecule ATP in the analysis and provides an innovative thought for the metal-free detection of PPi.

Atomically Dispersed Cu Nanozyme with Intensive Ascorbate Peroxidase Mimic Activity Capable of Alleviating ROS-Mediated Oxidation Damage

Ascorbate peroxidase (APX) as a crucial antioxidant enzyme has drawn attentions for its utilization in preventing cells from oxidative stress responses by efficiently scavenging H₂ O₂ in plants. For eliminating the specific inactivation of natural APXs and regulating the catalytic activity, single-atom nanozymes are considered as promising classes of alternatives with similar active sites and maximal atomic utilization efficiency to natural APXs. Herein, graphitic carbon nitride (g-C₃ N₄ ) anchored with isolated single copper atoms (Cu SAs/CN) is designed as an efficient nanozyme with intrinsic APX mimetic behavior. The engineered Cu SAs/CN exhibits comparable specific activity and kinetics to the natural APXs. Based on the density functional theory (DFT), Cu-N₄ moieties in the active center of Cu SAs/CN are determined to exert such favorable APX catalytic performance, in which the electron transfer between Cu and coordinated N atoms facilitates the activation and cleavage of the adsorbed H₂ O₂ molecules and results in fast kinetics. The constructed Cu SAs/CN nanozyme with superior APX-like performance and high biocompatibility can be applied for effectively protecting the H₂ O₂ -treated cells against oxidative injury in vitro. These findings report the single-atom nanozymes as a successful paradigm for guiding nanozymes to implement APX mimetic performance for reactive oxygen species-related biotherapeutic.

Controllable synthesis of variable-sized magnetic nanocrystals self-assembled into porous nanostructures for enhanced cancer chemo-ferroptosis therapy and MR imaging

Magnetic-based nanomaterials are promising for cancer diagnosis and treatment. Herein, we develop a self-assembled approach for the preparation of a porous magnetic nanosystem, DOX/Mn(0.25)-Fe₃O₄-III NPs, which can simultaneously achieve chemotherapy, ferroptosis therapy and MRI to improve the therapeutic efficacy. By tuning its porous structures, whole particle sizes and compositions, this nanosystem possesses both a high drug loading capacity and excellent Fenton reaction activity. Owing to the synergetic catalysis effect of iron and manganese ions, the Fenton catalytic activity of Mn(0.25)-Fe₃O₄-III NPs (K _cat = 1.2209 × 10^-2 min^-1) was six times higher than that of pure porous Fe₃O₄ NPs (K _cat = 1.9476 × 10^-3 min^-1), making them greatly advantageous in ferroptosis-inducing cancer therapy. Moreover, we found out that these Mn(0.25)-Fe₃O₄-III NPs show a pH-dependent Fenton reaction activity. At acidic tumorous pH, this nanosystem could catalyze H₂O₂ to produce the cytotoxic ˙OH to kill cancer cells, while in neutral physiological conditions it decomposed H₂O₂ into biosafe species (H₂O and O₂). In vivo studies demonstrated that DOX/Mn(0.25)-Fe₃O₄-III NPs exhibited a significant synergistic anticancer effect of combining chemotherapy and ferroptosis therapy and effective T₂-weighted MRI with minimal side effects. Therefore, this porous magnetic nanoplatform has a great potential for combined diagnosis and therapy in future clinical applications.

Precise Subcellular Organelle Targeting for Boosting Endogenous-Stimuli-Mediated Tumor Therapy

Though numerous external-stimuli-triggered tumor therapies, including phototherapy, radiotherapy, and sonodynamic therapy have made great progress in cancer therapy, the low penetration depth of the laser, safety concerns of radiation, the therapeutic resistance, and the spatio-temporal constraints of the specific equipment restrict their convenient clinical applications. What is more, the inherent physiological barriers of the tumor microenvironment (TME), including hypoxia, heterogeneity, and high expression of antioxidant molecules also restrict the efficiency of tumor therapy. As a result, the development of nanoplatforms responsive to endogenous stimuli (such as glucose, acidic pH, cellular redox events, and etc.) has attracted great attention for starvation therapy, ion therapy, prodrug-mediated chemotherapy, or enzyme-catalyzed therapy. In addition, nanomedicines can be modified by some targeted units for precisely locating in subcellular organelles and boosting the destroying of tumor tissue, decreasing the dosage of nanoagents, reducing side effects, and enhancing the therapeutic efficiency. Herein, the properties of the TME, the advantages of endogenous stimuli, and the principles of subcellular-organelle-targeted strategies will be emphasized. Some necessary considerations for the exploitation of precision medicine and clinical translation of multifunctional nanomedicines in the future are also pointed out.

Tumor microenvironment-responsive nanozymes achieve photothermal-enhanced multiple catalysis against tumor hypoxia

Reactive oxygen species (ROS)-mediated antitumor modalities that induced oxidative damage of cancer cells have recently acquired increasing attention on account of their noninvasiveness, low systemic toxicity, and high specificity. However, their clinical efficacy was often constrained by complex and various tumor microenvironment (TME), especially hypoxia characteristic and antioxidation effect of glutathione (GSH). Herein, we constructed a multinanozyme system based on hyaluronic acid (HA)-stabilized CuMnO_x nanoparticles (CMOH) loaded with indocyanine green (ICG) with high-efficient ROS generation, O₂ self-evolving function, GSH depletion ability and hyperthermia effect for achieving hypoxic tumor therapy. The CMOH nanozymes exhibited peroxidase-like and oxidase-like activities, which could efficiently catalyze H₂O₂ or O₂ to generate hydroxyl radicals (•OH) or superoxide radicals (•O₂^-) in acidic tumor microenvironment (TME), elevating oxidative stress of tumor. Indocyanine green (ICG) was further loaded into HA-CuMnO_x to form HA-CuMnO_x@ICG nanocomposites (CMOI NCs), which can effectively generate singlet oxygen (¹O₂) and local hyperthermia under light irradiation. The hyperthermia generated by CMOI NCs further enhances the catalytic activities of nanozymes for ROS generation. Meanwhile, the CMOI with catalase-like activity could catalyze H₂O₂ into O₂ for relieving tumor hypoxia and elevate O₂-dependent ROS generation. Notably, CMOI can consume endogenous GSH, thereby impairing tumor antioxidant system and enhancing ROS-based therapy efficacy. After modified with HA, CMOI NCs with tumor targeting ability realized synergistic PTT-enhanced tumor oxidation therapy based on their multimodal properties. Thus, this work contributes to design high-performance therapeutic reagent to overcome the limitation of hypoxia and high antioxidant defense of tumor. STATEMENT OF SIGNIFICANCE: Reactive oxygen species (ROS)-mediated antitumor modalities were often constrained by complex and various tumor microenvironment (TME), especially hypoxia characteristic and antioxidation effect of glutathione (GSH). In this work, a multinanozyme system based on hyaluronic acid (HA)-stabilized CuMnO_x nanoparticles (CMOH) loaded with indocyanine green (ICG) was designed to realize PTT-enhanced multiple catalysis tumor therapy. Although antitumor modalities based on multienzyme catalysis have been developed. Here, we highlighted the responsive catalysis of multienzyme system on tumor microenvironment (TME) and the promoting effect of photothermal effect on ROS production. Both in vitro and in vivo manifested that the enhanced anticancer efficacy of CMOI NCs due to their thermally amplified catalytic activity and TME regulation ability.

Tumor microenvironments self-activated nanoscale metal-organic frameworks for ferroptosis based cancer chemodynamic/photothermal/chemo therapy

Ferroptosis, as a newly discovered cell death form, has become an attractive target for precision cancer therapy. Several ferroptosis therapy strategies based on nanotechnology have been reported by either increasing intracellular iron levels or by inhibition of glutathione (GSH)-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4). However, the strategy by simultaneous iron delivery and GPX4 inhibition has rarely been reported. Herein, novel tumor microenvironments (TME)-activated metal-organic frameworks involving Fe & Cu ions bridged by disulfide bonds with PEGylation (FCSP MOFs) were developed, which would be degraded specifically under the redox TME, simultaneously achieving GSH-depletion induced GPX4 inactivation and releasing Fe ions to produce ROS via Fenton reaction, therefore causing ferroptosis. More ROS could be generated by the acceleration of Fenton reaction due to the released Cu ions and the intrinsic photothermal capability of FCSP MOFs. The overexpressed GSH and H₂O₂ in TME could ensure the specific TME self-activated therapy. Better tumor therapeutic efficiency could be achieved by doxorubicin (DOX) loading since it can not only cause apoptosis, but also indirectly produce H₂O₂ to amplify Fenton reaction. Remarkable anti-tumor effect of obtained FCSP@DOX MOFs was verified via both in vitro and in vivo assays.

Cr2O3-TiO2-Modified Filter Paper-Based Portable Nanosensors for Optical and Colorimetric Detection of Hydrogen Peroxide

In the present approach, a Cr₂O₃-TiO₂-modified, portable, and biomimetic nanosensor was designed to meet the requirement of a robust and colorimetric sensing of hydrogen peroxide. Cr₂O₃-TiO₂ nanocomposites prepared via the hydrothermal method were fabricated as a transducer surface on the filter paper using the sol-gel matrix. The color on the filter paper sensor changed from green to blue upon the addition of hydrogen peroxide in the presence of TMB. This change in the color intensity was linear with the concentration of H₂O₂. RGB software was used as a color analyzing model to evaluate the optical signals. This paper-based colorimetric platform provided us with an improved analytical figure of merit with a linear range of 0.005-100 μM with 0.003 μM limit of detection. The real sample analysis and excellent anti-interference potential results proved the good analytical performance of the proposed design, providing a more promising tool for colorimetric H₂O₂ detection. Introducing Cr₂O₃-TiO₂ nanocomposite-based paper sensors, being a novel method for optical and colorimetric detection, can pave the way for the development of other sensing devices for the detection of different analytes.

Reactive Oxygen Species and Endothelial Ca2+ Signaling: Brothers in Arms or Partners in Crime?

An increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) controls virtually all endothelial cell functions and is, therefore, crucial to maintain cardiovascular homeostasis. An aberrant elevation in endothelial can indeed lead to severe cardiovascular disorders. Likewise, moderate amounts of reactive oxygen species (ROS) induce intracellular Ca²⁺ signals to regulate vascular functions, while excessive ROS production may exploit dysregulated Ca²⁺ dynamics to induce endothelial injury. Herein, we survey how ROS induce endothelial Ca²⁺ signals to regulate vascular functions and, vice versa, how aberrant ROS generation may exploit the Ca²⁺ handling machinery to promote endothelial dysfunction. ROS elicit endothelial Ca²⁺ signals by regulating inositol-1,4,5-trisphosphate receptors, sarco-endoplasmic reticulum Ca²⁺-ATPase 2B, two-pore channels, store-operated Ca²⁺ entry (SOCE), and multiple isoforms of transient receptor potential (TRP) channels. ROS-induced endothelial Ca²⁺ signals regulate endothelial permeability, angiogenesis, and generation of vasorelaxing mediators and can be exploited to induce therapeutic angiogenesis, rescue neurovascular coupling, and induce cancer regression. However, an increase in endothelial [Ca²⁺]_i induced by aberrant ROS formation may result in endothelial dysfunction, inflammatory diseases, metabolic disorders, and pulmonary artery hypertension. This information could pave the way to design alternative treatments to interfere with the life-threatening interconnection between endothelial ROS and Ca²⁺ signaling under multiple pathological conditions.

Dual anticancer drug-loaded self-assembled nanomaterials delivery system for the treatment of prostate cancer

This study explains the engineering of polylactide-polyethylene succinate glycol nanomaterials (NMs), to achieve superior anticancer effectiveness in prostate cancer therapy as a carriers of crizotinib (CZT) and marizomib (MAR). We have shown that the block polymers and hydrophobic drugs can be self-assembled to construct a highly stable nanocarrier with highly adaptable to support the use of cancer medicines. The Drug Release analysis revealed that the interference in the hydrophobic cores of micelles was a continuous release series. In both PC3pip and LNCAP prostate cancer cells, CZT@MAR NMs demonstrated noticeable cytotoxic effects in a dose-responsive method. In addition, morphology analysis and the AO-EB and nuclear staining assay showed a higher effectiveness in prostate cancer for nanomaterials. The polymeric nanomaterials displayed a prominent existence in the cytoplasmic cell regions, which shows a characteristic cell uptake by endocytosis. A significant apoptosis, compared to free CZT@MAR apoptosis, was found in the FITC-Annexin V/PI staining-based apoptosis analysis. In this juncture, the alternative drug delivery mechanism for the improvement of CZT@MAR chemotherapeutic effectiveness in prostate cancer chemotherapy modification PLA nanoparticles.

Nanozyme for tumor therapy: Surface modification matters

As the next generation of artificial enzymes, nanozymes have shown unique properties compared to its natural counterparts, such as stability in harsh environment, low cost, and ease of production and modification, paving the way for its biomedical applications. Among them, tumor catalytic therapy mediated by the generation of reactive oxygen species (ROS) has made great progress mainly from the peroxidase-like activity of nanozymes. Fe₃O₄ nanozymes, the earliest type of nanomaterial discovered to possess peroxidase-like activity, has consequently received wide attention for tumor therapy due to its ROS generation ability and tumor cell killing ability. However, inconsistent results of cytotoxicity were observed between different reports, and some even showed the scavenging of ROS in some cases. By collectively studying these inconsistent outcomes, we raise the question whether surface modification of Fe₃O₄ nanozymes, either through affecting peroxidase activity or by affecting the biodistribution and intracellular fate, play an important role in its therapeutic effects. This review will go over the fundamental catalytic mechanisms of Fe₃O₄ nanozymes and recent advances in tumor catalytic therapy, and discuss the importance of surface modification. Employing Fe₃O₄ nanozymes as an example, we hope to provide an outlook on the improvement of nanozyme-based antitumor activity.

Peroxidase Mimetic Nanozymes in Cancer Phototherapy: Progress and Perspectives

Nanomaterial-mediated cancer therapeutics is a fast developing field and has been utilized in potential clinical applications. However, most effective therapies, such as photodynamic therapy (PDT) and radio therapy (RT), are strongly oxygen-dependent, which hinders their practical applications. Later on, several strategies were developed to overcome tumor hypoxia, such as oxygen carrier nanomaterials and oxygen generated nanomaterials. Among these, oxygen species generation on nanozymes, especially catalase (CAT) mimetic nanozymes, convert endogenous hydrogen peroxide (H2O2) to oxygen (O2) and peroxidase (POD) mimetic nanozymes converts endogenous H2O2 to water (H2O) and reactive oxygen species (ROS) in a hypoxic tumor microenvironment is a fascinating approach. The present review provides a detailed examination of past, present and future perspectives of POD mimetic nanozymes for effective oxygen-dependent cancer phototherapeutics.

X-ray-facilitated redox cycling of nanozyme possessing peroxidase-mimicking activity for reactive oxygen species-enhanced cancer therapy

Nanomaterials with shifting or mixed redox states is one of the most common studied nanozyme with peroxidase-like activity for chemodynamic therapy (CDT), which can decompose hydrogen peroxide (H₂O₂) of tumor microenvironment into highly toxic reactive oxygen species (ROS) by a nano-catalytic way. However, most of them exhibit an insufficient catalytic efficiency due to their dependence on catalytic condition. Herein, a potential methodology is proposed to enhance their enzymatic activity by accelerating the redox cycling of these nanomaterials with shifting or mixed redox states in the presence of X-ray. In this study, the nanocomposite consisting of SnS₂ nanoplates and Fe₃O₄ quantum dots with shifting or mixed redox states (Fe²⁺/Fe³⁺) is used to explore the strategy. Under external X-ray irradiation, SnS₂ cofactor as electron donor can be triggered to transfer electrons to Fe₃O₄, which promotes the regeneration of Fe²⁺ sites on the surface of the Fe₃O₄. Consequently, the regenerated Fe²⁺ sites react with the overexpressed H₂O₂ to persistently generate ROS for enhanced tumor therapy. The designed nanocomposite displays the synergistic effects of radiotherapy and CDT. The strategy provides a new avenue for the development of artificial nanozymes with shifting or mixed redox states in precise cancer treatments based on X-ray-enhanced enzymatic efficacy.

Cu-Ferrocene-Functionalized CaO2 Nanoparticles to Enable Tumor-Specific Synergistic Therapy with GSH Depletion and Calcium Overload

The conversion of endogenous H2 O2 into toxic hydroxyl radical (• OH) via catalytic nanoparticles is explored for tumor therapy and received considerable success. The intrinsic characteristics of microenvironment in tumor cells, such as limited H2 O2 and overexpressed glutathione (GSH), hinder the intracellular • OH accumulation and thus weaken therapeutic efficacy considerably. In this study, fine CaO2 nanoparticles with Cu-ferrocene molecules at the surface (CaO2 /Cu-ferrocene) are successfully designed and synthesized. Under an acidic condition, the particles release Ca2+ ions and H2 O2 in a rapid fashion, while they can remain stable in neutral. In addition, agitated production of • OH occurs following the Fenton reaction of H2 O2 and ferrocene molecules, and GSH is consumed by Cu2+ ions to avoid the potential • OH consumption. More interestingly, in addition to the exogenous Ca2+ released by the particles, the enhanced • OH production facilitates intracellular calcium accumulation by regulating Ca2+ channels and pumps of tumor cells. It turns out that promoted • OH induction and intracellular calcium overload enable significant in vitro and in vivo antitumor phenomena.

Peroxidase-mimetic activity of FeOCl nanosheets for the colorimetric determination of glutathione and cysteine

For the first time the enzyme mimic activity of iron oxychloride (FeOCl) nanosheets has been studied. The intrinsic peroxidase-mimetic activity of the nanosheets in the presence of H₂O₂ was approved by the efficient oxidation of tetramethylbenzidine (TMB). The Michaelis-Menten constant of the nanosheets toward TMB was about six times lower than that of natural horseradish peroxidase. The superiority of the nanosheets' catalytic property ascribes to their H₂O₂ activation ability. Based on the inhibition of the nanozymes' catalytic reaction, an assay was developed for the quantitative measurement of glutathione (GSH) and cysteine (Cys). The linear range for both biomolecules was over the range of 3-33 μM. The LOD values (3σ/slope) for GSH and Cys were 2.23 μM and 2.76 μM, respectively. Importantly, we succeeded in colorimetric discrimination of GSH and Cys kinetically. We achieved high selectivity toward GSH and Cys. This work extends the feasibility of using FeOCl as nanozymes to construct biosensors, colorimetric probes for medical diagnosis, and nanozyme-based cancer therapy.

Anderson polyoxometalates with intrinsic oxidase-mimic activity for "turn on" fluorescence sensing of dopamine

Anderson-type polyoxometalate containing Fe³⁺ and Mo⁶⁺, (NH₄)₃[H₆Fe(III)Mo₆O₂₄] (FeMo₆), was found to work as an oxidase-mimicking nanoenzyme for the first time, exhibiting the ability of catalytic oxidation of o-phenylenediamine (OPD), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTs), and 3,3',5,5'-tetramethylbenzidine (TMB), which features easy synthesis, low cost, simple operation, and low consumption. Attributed to the nature of FeMo₆ and Fenton-like effect, a novel sensor based on two consecutive "turn on" fluorescence was developed for detecting dopamine (DA) by employing the FeMo₆-OPD system, and the linear range was from 1 to 100 μM with the detection limit 0.0227 μM (3σ/s). Moreover, to increase oxidase-mimic activity of FeMo₆, reduced graphene oxide (rGO) loading FeMo₆ composites (FeMo₆@rGO (n), n = 5%, 10%, 15%) was fabricated, and results show that oxidase-like activities of FeMo₆@rGO (n) are dependent on the mass ratio of FeMo₆/rGO, and FeMo₆@rGO (10%) exhibits the highest oxidase-mimic activity and the fastest respond time (4 min) among all reported oxidase mimic of DA to date. Graphical abstract Anderson-type Mo-POMs FeMo₆ was found to work as an oxidase-mimicking nanoenzyme for the first time and was used to detect DA for two consecutive "turn on" fluorescence sensor modes.

Ferrite Nanoparticles-Based Reactive Oxygen Species-Mediated Cancer Therapy

Ferrite nanoparticles have been widely used in the biomedical field (such as magnetic targeting, magnetic resonance imaging, magnetic hyperthermia, etc.) due to their appealing magnetic properties. In tumor acidic microenvironment, ferrite nanoparticles show intrinsic peroxidase-like activities, which can catalyze the Fenton reaction of hydrogen peroxide (H₂O₂) to produce highly toxic hydroxyl free radicals (•OH), causing the death of tumor cell. Recent progresses in this field have shown that the enzymatic activity of ferrite can be improved via converting external field energy such as alternating magnetic field and near-infrared laser into nanoscale heat to produce more •OH, enhancing the killing effect on tumor cells. On the other hand, combined with other nanomaterials or drugs for cascade reactions, the production of reactive oxygen species (ROS) can also be increased to obtain more efficient cancer therapy. In this review, we will discuss the current status and progress of the application of ferrite nanoparticles in ROS-mediated cancer therapy and try to provide new ideas for this area.

Rough Carbon-Iron Oxide Nanohybrids for Near-Infrared-II Light-Responsive Synergistic Antibacterial Therapy

Infections caused by multidrug resistant bacteria are still a serious threat to human health. It is of great significance to explore effective alternative antibacterial strategies. Herein, carbon-iron oxide nanohybrids with rough surfaces (RCF) are developed for NIR-II light-responsive synergistic antibacterial therapy. RCF with excellent photothermal property and peroxidase-like activity could realize synergistic photothermal therapy (PTT)/chemodynamic therapy (CDT) in the NIR-II biowindow with improved penetration depth and low power density. More importantly, RCF with rough surfaces shows increased bacterial adhesion, thereby benefiting both CDT and PTT through effective interaction between RCF and bacteria. In vitro antibacterial experiments demonstrate a broad-spectrum synergistic antibacterial effect of RCF against Gram-negative Escherichia coli (E. coli), Gram-positive Staphylococcus aureus (S. aureus), and methicillin-resistant Staphylococcus aureus (MRSA). In addition, satisfactory biocompatibility makes RCF a promising antibacterial agent. Notably, the synergistic antibacterial performances in vivo could be achieved employing the rat wound model with MRSA infection. The current study proposes a facile strategy to construct antibacterial agents for practical antibacterial applications by the rational design of both composition and morphology. RCF with low power density NIR-II light responsive synergistic activity holds great potential in the effective treatment of drug-resistant bacterial infections.

Mn-DNA coordination of nanoparticles for efficient chemodynamic therapy

A kind of nanoparticle is developed for highly efficient chemodynamic therapy that only relies on the endogenous H2O2 of cancer cells. For this nanoparticle, high-molecular-weight DNA is used as the biocompatible carrier to load abundant Mn2+ ions. Therefore, the resultant Mn-DNA coordination nanoparticles can efficiently deliver and sensitively release Mn2+ in cancer cells, resulting in high toxicity through the Fenton-like reaction.

PDT-Enhanced Ferroptosis by a Polymer Nanoparticle with pH-Activated Singlet Oxygen Generation and Superb Biocompatibility for Cancer Therapy

In this study, we reported a nanocomplex (PAF) of PEGylated polygalacturonic acid, 5,10,15,20-tetrakis (4-aminophenyl) porphyrin (TAPP), and Fe³⁺ for photodynamic therapy (PDT)-enhanced ferroptosis in cancer treatment. PAF exhibited a size of 135 nm and a TAPP and Fe³⁺ loading content of 6.99 and 0.77%, respectively. The singlet oxygen (¹O₂) generation capacity of TAPP can be activated and significantly enhanced at acidic pH (4.5-5.0). Besides, the enhanced near-infrared absorption of TAPP at acidic pH enabled a further increase in ¹O₂ generation capability by a near-infrared laser (760 nm). The polysaccharide-based polymer carrier offers excellent biocompatibility, and PAF displayed a proliferative effect in both normal (L929) and cancer (B16) cells. However, upon light irradiation, PAF exhibited high toxicity to B16 melanoma cells by intracellular reactive oxygen species elevation, glutathione depletion, and lipid peroxidation. PAF displayed a much better anticancer effect than the nanocomplex containing Fe³⁺ or TAPP alone, indicating the PDT-enhanced ferroptosis in PAF. This study suggested that PDT-enhanced ferroptosis could be a facile and robust strategy of nanotherapeutics with high potency, tumor selectivity, and excellent biocompatibility.

Carbon-Coated Magnetic Iron Oxide Nanoparticles as Green Catalysts for Aromatic Nitration

Nitration of aromatic compounds is an important industrial process, which creates significant environmental pollution because of the harsh mineral acid catalysts. In this work, we report the synthesis and application of magnetic iron oxide nanoparticles as green catalysts for aromatic nitration. Magnetic iron oxide nanoparticles were synthesized by co-precipitation method and tested for nitration reactions on selected aromatic substrates, phenol, benzaldehyde, methylbenzoate, [Formula: see text]-cresol and [Formula: see text]-cresol. For the nitration reactions, sodium nitrite was used as the nitro-source and hydrogen peroxide as the oxidant. Effect of reaction conditions like, solvent, temperature and microwave treatment were studied. The magnetic nanoparticles were found to be more stable after coating with a carbon shell by a one-pot carbonization method. The reactions were fast with good product yield under solvent-free microwave conditions. The nano-catalyst was recovered magnetically after the reaction and reused for three batches of nitration, without significant loss in catalytic activity. The nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffractometry (XRD) and FTIR spectroscopy.

Mucosal Vaccination for Influenza Protection Enhanced by Catalytic Immune-Adjuvant

Influenza poses a severe threat to global health. Despite the whole inactivated virus (WIV)-based nasal vaccine being a promising strategy for influenza protection, the mucosal barrier is still a bottleneck of the nasal vaccine. Here, a catalytic mucosal adjuvant strategy for an influenza WIV nasal vaccine based on chitosan (CS) functionalized iron oxide nanozyme (IONzyme) is developed. The results reveal that CS-IONzyme increases antigen adhesion to nasal mucosa by 30-fold compared to H1N1 WIV alone. Next, CS-IONzyme facilitates H1N1 WIV to enhance CCL20-driven submucosal dendritic cell (DC) recruitment and transepithelial dendrite(TED) formation for viral uptake via the toll-like receptor(TLR) 2/4-dependent pathway. Moreover, IONzyme with enhanced peroxidase (POD)-like activity by CS modification catalyzes a reactive oxygen species (ROS)-dependent DC maturation, which further enhances the migration of H1N1 WIV-loaded DCs into the draining lymph nodes for antigen presentation. Finally, CS-IONzyme-based nasal vaccine triggers an 8.9-fold increase of IgA-mucosal adaptive immunity in mice, which provides a 100% protection against influenza, while only a 30% protection by H1N1 WIV alone. This work provides an antiviral alternative for designing nasal vaccines based on IONzyme to combat influenza infection.

Bifunctional antibody and copper-based metal-organic framework nanocomposites for colorimetric α-fetoprotein sensing

Cu²⁺ are found to greatly reduce the photoinduced oxidase activity of fluorescein and then inhibit the chromogenic reaction catalyzed by fluorescein. A simple colorimetric assay for Cu²⁺ is established. Based on this, bifunctional nanocomposites of α-fetoprotein (AFP) antibody (Ab) and copper-based metal-organic framework (Ab2@Cu-MOF) are synthesized by the simple self-assembly of AFP Ab2, Cu²⁺, and 4,4'-dipyridyl: the binding site of AFP Ab2 exposed on the surface of the nanocomposites can specifically recognize AFP antigen; Cu²⁺ in nanocomposites can inhibit the visible light-induced activity of fluorescein. The structure of Ab2@Cu-MOF disintegrate and Cu²⁺ is released in an acetate buffer solution. The higher the amount of AFP antigens, the more significant the inhibitory effect. Thus, the Ab2@Cu-MOF immunoassay for AFP determination is established using 3,3',5,5'-tetramethylbenzidine as chromogenic substrate with a detection limit of 35 pg.mL^-1. This simple, cheap, and sensitive method sheds substantial light on practical clinical diagnosis. Meanwhile, the mechanism of inhibition is revealed to facilitate the targeted selection of enzyme regulators. Graphical abstract Diagrammatic illustration of Cu²⁺ detection (part a) and Ab2@Cu-MOF immunoassay for sensing α-fetoprotein based on the synthesized Ab2@Cu-MOF nanocomposites (parts a and b).

ATP induced alteration in the peroxidase-like properties of hollow Prussian blue nanocubes: a platform for alkaline phosphatase detection

Breaking the pH limitation of the enzyme-like activity of nanomaterials is of great importance for extending their applications in environmental and biomedical fields. Herein, to mimic the role of histidine residues in horseradish peroxidase (HRP), adenosine 5'-triphosphate (ATP) is reported to improve the peroxidase-like activity of hollow Prussian blue nanocubes (hPBNCs). Due to the inherited porous structures, hPBNCs can expose all the binding sites as far as possible to ATP to significantly amplify their catalytic activity and broaden their applicable pH range up to pH 12. Introduction of ATP provides the possibility of realizing efficient catalytic reactions under alkaline conditions. Upon binding with hPBNCs, ATP can enhance the stability of hPBNCs, increase the affinities of the catalysts towards substrates and improve the conductivity of hPBNCs as well as change the decomposed product from H₂O₂. Moreover, on the basis of the different catalytic activities of hPBNCs towards ATP, adenosine 5'-diphosphate and adenosine 5'-monophosphate, hPBNCs-ATP is utilized to construct a novel colorimetric sensor for the detection of alkaline phosphatase (ALP) activity in biological fluids, which is significantly important for the clinical diagnosis of ALP-related diseases.