MOFs@POMs-derived bimetallic oxide Fe2(MoO4)3 nanoparticles for sensitive colorimetric detection of salicylic acid in aspirin

A colorimetric sensing method for salicylic acid (SA) was developed by designing and fabricating bimetallic oxide nanozymes. Firstly, by calcinating MIL-100(Fe)@PMo12 (MOFs@POMs) at different temperature, Fe2(MoO4)3-Ts (T = 400℃, 500℃, 600℃, 700℃) nanoparticles (NPs) were successfully prepared. Secondly, by evaluating the peroxidase-like activities, Fe2(MoO4)3-600 NPs shows the best peroxidase-like activity attributed to the Fenton-like effect and the synergistic coupling interaction between Mo and Fe. Finally, based on the specific complexation between SA and Fe3+, a sensitive colorimetric sensor for SA was established, which exhibits superior selectivity and interference with a detection limit of 0.11 μM and a linear range of 10 to 100 μM, the lowest LOD for SA to date, to the best of our knowledge.

Mitochondrial topoisomerase 1 targeted anticancer therapy using irinotecan encapsulated mesoporous MIL-101(Fe) synthesized via a vapour assisted method

Mitochondrial topisomerase 1 (Top1mt) is critical for mtDNA replication, transcription, and energy production. Here, we investigate the carrier-mediated targeted delivery of the anticancer drug irinotecan into the mitochondria to selectively trap Top1mt covalent complexes (Top1mtcc) and its role in anticancer therapeutics. We have designed a biocompatible mesoporous metal-organic framework (MOF) material, namely MIL-101(Fe), as the drug delivery carrier that selectively localizes inside mitochondria. In contrast to the traditional way of synthesising MOFs, here we have employed a vapour-assisted solvothermal method for the synthesis of MIL-101(Fe) using terephthalic acid as the organic linker and Fe(III) as the metal source. The advantage of this method is that it recycles the excess solvent (DMF) and reduces the amount of washing solvent. We demonstrate that MIL-101(Fe)-encapsulated irinotecan (MIL-Iri) was selectively targeted towards the mitochondria to poison Top1mtcc in a dose-dependent manner and was achieved at a low nanomolar drug concentration. We provide evidence that Top1mtcc generated by MIL-Iri leads to mtDNA damage in human colon and breast cancer cells and plays a significant role in cellular toxicity. Altogether, this study provides evidence for a new and effective strategy in anticancer chemotherapy.

Rapidly and ultra-sensitive colorimetric detection of H2O2 and glucose based on ferrous-metal organic framework with enhanced peroxidase-mimicking activity

In this article, a novel metal-organic framework, namely MIL-101(Fe^II), was firstly synthesized via a facile method. In the presence of H₂O₂, MIL-101(Fe^II) possesses excellent peroxidase-like activity toward the classical chromogenic substrate, N,N-Diethyl-p-phenylenediamine sulfate salt (DPD). The substitution of Fe²⁺ enhances the construction of Fe(II)-oxo nodes and accelerates electrons transfer between DPD and H₂O₂, thereby improving the peroxidase-mimicking catalytic activity of MIL-101(Fe^II) nanoenzyme. Additionally, DPD molecules could be adsorbed readily onto the surface of the nanoparticles due to the π-π interaction. The study of Michaelis constant indicates that the MIL-101(Fe^II) exhibits a higher affinity towards DPD (0.16 mM) in contrast to horseradish peroxidase (0.78 mM). In view of the impressive catalytic performance of MIL-101(Fe^II), two reliable monitoring platforms for the rapid detection of H₂O₂ and glucose were established with extremely low detection limits of 18.04 nM and 0.87 μM in the ranges of 40-5000 nM and 1.2-300 μM, respectively. The study of the catalytic mechanism indicates that DPD oxidation is attributed to the hydroxyl radical (·OH) produced from the decomposition of H₂O₂ catalyzed by MIL-101(Fe^II). Furthermore, the developed sensor indicates high selectivity and stability and can be effectively appropriate for the detection of H₂O₂ and glucose in real samples. This work not only provides a novel nanozyme with superior catalytic performance for biological analysis, but also broadens the application field of MIL-101(Fe^II) material.

TiO2-In-MIL-101(Cr) with Visible Light-Induced Peroxidase Activity for Colorimetric Detection of Blood Glucose

In this work, metal-organic framework MIL-101(Cr) with regular morphology, stable structure, and good dispersion was prepared by the hydrothermal method. MIL-101(Cr) has two different sizes of pores, but after TiO₂ nanoparticles (NPs) were in situ prepared, the two pores disappear. The result demonstrates that TiO₂ NPs were located in the pores of MIL-101(Cr). TiO₂-decorated MIL-101(Cr) forms an inside type II heterojunction and the band gap energy is narrowed, which can promote electron-hole separation and enhance the light absorption. Therefore, the heterojunction shows a high visible light-induced peroxidase-like activity. Kinetic studies exhibit that the K _m value of TiO₂-in-MIL-101(Cr) to TMB is 0.17 mM, and the affinity of TiO₂-in-MIL-101(Cr) is higher than that of natural horseradish peroxidase (HRP). Then, a "turn-on" colorimetric assay based on TiO₂-in-MIL-101(Cr) was constructed for the detection of blood glucose. The detection range is 1-100 μM (R ² = 0.9950) with a limit of detection (LOD) of 1.17 μM. Compared with the clinical method, the constructed colorimetric method has accurate and reliable results for the clinical detection. The anti-interference experiment confirms that the method has high selectivity to glucose.

Engineering a thermostable biosensor based on biomimetic mineralization HRP@Fe-MOF for Alzheimer's disease

The development of disease detection by biosensors represents one of the key components of medical science. However, millions of people are still misdiagnosed each year due to the poor efficacy and thermal instability of biosensors. Using horseradish peroxidase (HRP) as a paradigm, we offer a rational design strategy to optimize the thermostability and activity of biosensors by biomimetic mineralization. To overcome the weak thermostability of the biosensor, the mineralization of Fe-MOF forms an armor on HRP that protects against high temperature. Additionally, the biomimetic mineralization HRP@Fe-MOF can double-catalyze the TMB/H₂O₂ chromogenic system for color development. The biosensor can also be recycled through simple heat treatment due to the thermally stable aptamer and biomimetic mineralization HRP@Fe-MOF. The optical biosensor based on this sensitive spectral transformation was successfully developed for the measurement of AβO with an outstanding linear range (0.0001-10 nM) and a low limit of detection (LOD) of 0.03 pM. This promising platform will open up new avenues for the detection of AβO in the early diagnosis of Alzheimer's disease (AD).

A colorimetric sensing platform for the determination of H2O2 using 2D-1D MoS2-CNT nanozymes

A novel colorimetric platform based on nano-composites of two-dimensional (2D) molybdenum disulfide nanosheets (MoS₂ NSs) and one-dimensional (1D) carbon nanotubes (CNTs), called 2D-1D MoS₂-CNT nanozyme, was fabricated for the selective and sensitive determination of hydrogen peroxide (H₂O₂) in soda water. The MoS₂-CNT nanozyme was synthesized through a one-step solvothermal reduction method. The introduced CNTs could effectively prevent the stacking of MoS₂ nanosheets (NSs) and not only expanded the interlayer distance of MoS₂ NSs from 0.620 nm to 0.710 nm but also improved their specific surface. Under acidic conditions, the as-prepared 2D-1D MoS₂-CNT nanozymes could oxidize the colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue-oxidized TMB (oxTMB) in the presence of H₂O₂, resulting in enhanced peroxidase-like (POD-like) activity. The kinetic study showed that MoS₂-CNT nanozyme had stronger catalytic activity than natural horseradish peroxidase (HRP). The linear range for H₂O₂ colorimetric determination was 5.00-500 μmol L^-1 with a limit of detection (LOD) of 1.40 μmol L^-1. Furthermore, the established determination method was applied to actual samples and the recoveries of H₂O₂ spiked in soda water were in the range of 92.3-107%, showing feasibility for the analysis of food.

Synthesis, modifications and applications of MILs Metal-organic frameworks for environmental remediation: The cutting-edge review

Ever-increasing anthropogenic activities are radically deteriorating the environment by causing severe pollution. Thus, curtailing the environmental pollution and promotion of sustainable development, are the hot issues confronted by scientists in this modern era. Metal-organic frameworks (MOFs) have been highly recognized as emerging promising materials for environmental remediation due to their versatile structure and extraordinary properties. Among them, MILs (MIL = Matérial Institute of Lavoisier) are the series of MOFs mostly known for their incredible stability, unique tailorable pore structures, and astounding versatile environmental applications. Their exclusive physiochemical properties and multifunctionality make them proficient for a wide range of pollutants removal in the exposure of versatile harsh environments, compared to other MOFs. This piece of research summarizes the state-of-the-art of development of MILs on the broad spectrum, highlighting their specificities, such as synthesis techniques, modifications and applications for environmental remediation. However, MILs wonderful properties and extraordinary applications in multiple fields, their deployment on practical and commercial-scale pollutants remediation is hindered by insufficient scientific research on underlying mechanisms and relationships. Henceforth, this review not only signifies the emerging importance of MILs for environmental applications but also indicates the urgency to maximize the scientific research for exploitation of MOFs on a practical level and promotion of green technologies for environmental remediation.

Advances in FePt-involved nano-system design and application for bioeffect and biosafety

The rapid development and wide application of nanomaterial-involved theranostic agents have drawn surging attention for improving the living standard of humankind and healthcare conditions. In this review, recent developments in the design, synthesis, biocompatibility evaluation and potential nanomedicine applications of FePt-involved nano-systems are summarized, especially for cancer theranostic and biological molecule detection. The in vivo multi-model imaging capability is discussed in detail, including magnetic resonance imaging and computed tomography. Furthermore, we highlight the significant achievements of various FePt-involved nanotherapeutics for cancer treatment, such as drug delivery, chemodynamic therapy, photodynamic therapy, radiotherapy and immunotherapy. In addition, a series of FePt-involved nanocomposites are also applied for biological molecule detection, such as H₂O₂, glucose and naked-eye detection of cancer cells. Ultimately, we also summarize the challenges and prospects of FePt-involved nano-systems in nanocatalytic medicine. This review is expected to give a general pattern for the development of FePt-involved nano-systems in the field of nanocatalytic medicine and analytical determination.

Design of Organic/Inorganic Hybrid Catalysts for Energy and Environmental Applications

Controlling selectivity between competing reaction pathways is crucial in catalysis. Several approaches have been proposed to achieve this goal in traditional heterogeneous catalysts including tuning nanoparticle size, varying alloy composition, and controlling supporting material. A less explored and promising research area to control reaction selectivity is via the use of hybrid organic/inorganic catalysts. These materials contain inorganic components which serve as sites for chemical reactions and organic components which either provide diffusional control or directly participate in the formation of active site motifs. Despite the appealing potential of these hybrid materials to increase reaction selectivity, there are significant challenges to the rational design of such hybrid nanostructures. Structural and mechanistic characterization of these materials play a key role in understanding and, therefore, designing these organic/inorganic hybrid catalysts. This Outlook highlights the design of hybrid organic/inorganic catalysts with a brief overview of four different classes of materials and discusses the practical catalytic properties and opportunities emerging from such designs in the area of energy and environmental transformations. Key structural and mechanistic characterization studies are identified to provide fundamental insight into the atomic structure and catalytic behavior of hybrid organic/inorganic catalysts. Exemplary works are used to show how specific active site motifs allow for remarkable changes in the reaction selectivity. Finally, to demonstrate the potential of hybrid catalyst materials, we suggest a characterization-based approach toward the design of biomimetic hybrid organic/inorganic materials for a specific application in the energy and environmental research space: the conversion of methane into methanol.

A novel molecularly imprinted sensor based on PtCu bimetallic nanoparticle deposited on PSS functionalized graphene with peroxidase-like activity for selective determination of puerarin

In this work, PtCu bimetallic nanoparticle was deposited on poly (styrene sulfonate) (PSS) functionalized graphene (Gr) to form a nanocomposite PtCu/PSS-Gr and its enzyme-like activity was investigated. Benefiting from the synergistic effect from Pt and Cu monometal as well as the superior properties of PSS-Gr, such as large surface area, good dispersity, strong adsorption of substrate and additional peroxidase-like activity, the PtCu/PSS-Gr nanocomposite was demonstrated as an excellent peroxidase mimic to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂. Combined with molecularly imprinted polymer (MIP), a new colorimetric approach for puerarin detection was proposed with the linear range of 2 × 10^-5-6 × 10^-4 mol L^-1 and LOD of 1 × 10^-5 mol L^-1. The combination of MIP with PtCu/PSS-Gr nanocomposite not only endowed the determination of puerarin with high selectivity, but also realized the detection of small molecules which are neither substrate of the nanozyme nor substances with strong oxidizing or reducing activity by using peroxidase-like catalytic activity of nanozyme, expanding the application of nanozyme.

Ultrathin PtNi nanozyme based self-powered photoelectrochemical aptasensor for ultrasensitive chloramphenicol detection

Nanozymes have gained increasing attention in the field of biosensing. Rationally designed nanozymes with excellent catalytic activity are accessible to substitute natural enzymes. Herein, a novel self-powered photoelectrochemical (PEC) aptasensor was constructed for ultrasensitive detection of chloramphenicol (CAP) based on ultrathin PtNi nanowires (NWs) as nanozyme and benzene-ring doped g-C₃N₄ (BR-CN) as the photoactive material. The prepared 1-nm-thick PtNi nanozyme acted as a peroxidase, possessing higher catalytic activity than natural horseradish peroxidase (HRP) and other Pt-based mimic enzymes. Through the biotin-streptavidin specific interaction, streptavidin modified PtNi nanozyme was introduced into the dual-stranded DNA (dsDNA) formed by complementary DNA and biotinylated CAP aptamer. The PtNi nanozyme catalyzed 4-chloro-1-naphthol (4-CN) oxidation to generate insoluble precipitation on the electrode surface, resulting in an obvious photocurrent reduction. In the presence of CAP, the CAP aptamer was released from the electrode due to strong affinity with CAP, causing the decrease of catalytic precipitation and consequently the generation of a high photocurrent signal. On the basis of PtNi nanozyme signal amplification, the developed self-powered PEC aptasensor showed a wide linear range of 0.1 pM-100 nM with an ultralow detection limit of 26 fM for the determination of CAP. This work provides a feasible strategy for the design of high-activity nanozyme and self-powered PEC biosensor to achieve the ultrasensitive detection of target analyte.