Metal oxide nanozymes are widely used in biosensors but face challenges such as weak selectivity, low efficiency and poor stability. In this work, magnetic CoFe2O4@covalent organic frameworks (COFs) core-shell composites with CoFe2O4 as the core and COFs as the shell were prepare conveniently by the one-pot ultrasonic method, the resultant composites were used as highly efficient and selective nanozyme for electrochemical sensors. By adjusting the COFs ligand and reaction time, the COFs shells with controllable pore sizes, functional groups and shell thickness were designed precisely to improve the efficiency and selectivity of CoFe2O4@COFs nanozymes. The as-synthesized core-shell CoFe2O4@COFs nanozymes were convenient for purification and separation, and the materials were analyzed by different characterization methods. The efficiency and selectivity of CoFe2O4@COFs nanozymes for catalytic performance were evaluated through glucose electrochemical sensing. The CoFe2O4@COFs glucose sensors exhibited excellent performance with higher sensitivity, better selectivity and stability than pure CoFe2O4. This study sheds new light on enhancing the catalytic performance of metal oxide nanozymes, which is of great scientific significance and application prospect.

Silver ions (Ag+) are highly toxic heavy metal pollutants. Conventional electrochemical methods for Ag+ detection typically involve complex ionophore preparation, long preconcentration/stripping steps, or costly biorecognition agent. Here, we report a Cu-Zn-MOF supported CuNPs composite (Cu-Zn-MOF/CuNPs) for Ag+ detection. The composite is prepared via a two-step room temperature mixing process. The nest-like Cu-Zn-MOF, composed of stacked two-dimensional nanosheets, provides a high specific surface area and accessible active sites for CuNPs deposition, which improves conductivity and generates a detectable redox signal. The presence of Cl− enhances the Cu redox signal due to the formation of electroactive CuCl. In the presence of Ag+, this signal enhancement is suppressed due to the competitive binding that forms AgCl precipitates. Leveraging this “amplification-inhibition” response, the Cu-Zn-MOF/CuNPs modified electrode allows for Ag+ detection with two linear ranges (5 nM–100 nM and 100 nM–1100 nM), a detection limit of 1.4 nM, and recoveries ranging from 96.5% to 104.5% in spiked real water samples. The preparation procedure and detection protocol are relatively straightforward, and the sensing mechanism offers an alternative pathway for heavy metal ion detection.

Carbendazim, a systemic benzimidazole fungicide, is frequently applied to control fungal diseases in tomato cultivation. Due to its high lipid solubility, relatively long half-life, and systemic nature that enables absorption and translocation within plant tissues, carbendazim tends to accumulate in plant fruits, thereby compromising food safety. This study combined a hollow microneedle array and a plant-wearable ratiometric electrochemical sensor for the in-situ detection of carbendazim in a minimally invasive manner in tomato fruits. The hollow microneedle array, which was created using inexpensive 3D printing, enables an efficient means for the direct collection of plant tissue fluid. The laser-induced graphene (LIG) electrode was first transferred to a polydimethylsiloxane (PDMS) substrate, and then modified sequentially with platinum nanoparticles (PtNPs) and silver nanoparticles (AgNPs) to enhance target outcome precision. Results showed that this ratiometric electrochemical sensor (PDMS/LIG/Pt-Ag) exhibited good analytical performance with high sensitivity, reproducibility, and selectivity for carbendazim detection. Adopting this “sampling-detection” strategy, our proposed minimally invasive ratiometric electrochemical sensing device can be applied for the in-situ monitoring of carbendazim in tomato fruits, which could offer valuable insights for evaluating systemic pesticide migration in plants to ensure food and environmental safety.

The rapid, in-situ detection of fungicide residues on fruits is critical for food safety. However, conventional methods often involve complex operations and poor portability. Here, a covalent organic framework (COF) synthesized from 4,4',4″-(1,3,5-triazine-2,4,6-triyl) tris[benzaldehyde] (TTB) and 3,3'-dihydroxybenzidine (DHB) was grown on carbon paper (CP) to prepare COFTTB-DHB@CP. Subsequently, COFTTB-DHB@CP was assembled with Ag/AgCl and carbon black to fabricate the COFTTB-DHB@flexible all-in-one electrode (FAE). Benefiting from electron-rich property of TTB, and excellent electrical conductivity of CP, the COFTTB-DHB@FAE sensor enables rapid, sensitive, and efficient in-situ detection of thiabendazole (TBZ), with a sensitivity of 0.0216 mA cm-2 μM-1 and a limit of detection (LOD) as low as 0.15 μM. Integrated with a portable analyzer and smartphone via Bluetooth, it enables in-situ detection of TBZ and real-time remote monitoring. This work provides a novel strategy for developing flexible electrode sensors for fungicide in-situ detection.

In this paper, a photoacoustic spectroscopy (PAS) gas sensing system based on a semi-ellipsoidal resonant photoacoustic cell (SER-PAC) is proposed for the detection of two-component gas. The SER-PAC consists of two differently sized semi-ellipsoidal resonators and a hemispherical buffer chamber. Each resonator has its independent acoustic properties, allowing a single microphone to detect photoacoustic (PA) signals from both resonators simultaneously. A comparative analysis of the acoustic properties (resonant frequency and acoustic pressure distribution) was conducted for cylindrical, conical, and semi-ellipsoidal resonators using COMSOL Multiphysics. The results demonstrate that the semi-ellipsoidal resonators generate a significantly stronger PA signal than conventional cylindrical and conical structures under identical buffer chamber conditions. In addition, compared to the traditional cylindrical buffer chamber, the proposed hemispherical design effectively reduces gas flow rates and minimizes flow-induced noise interference while maintaining a compact structure. Combined with the dual advantages of the semi-ellipsoidal resonator to enhance the PA signal and the hemispherical buffer chamber to reduce the gas flow rate, the volume of the SER-PAC developed for two-component gas detection is only about 2.5 mL. Methane (CH4) and acetylene (C2H2) were selected as the target gases, and the minimum detection limits (MDLs) of the two gases were 0.81 ppm and 0.14 ppm, respectively. In general, the SER-PAC for two-component gas detection developed in this paper provides a new PAC structure for the field of PAS gas detection. In addition, the proposed PAS gas detection system based on a SER-PAC has the advantages of two-component simultaneous detection, high integration, PA enhancement and noise interference reduction, which provides a promising solution for advancing trace gas detection technology.

In view of the widespread application of norfloxacin (NOR) and the potential environmental and health risks posed by its residues, a visual approach for the portable yet efficient detection of NOR was presented by using red-light covalent organic frameworks (COFs) based on benzothiadiazole (BTD) as the linkage center. The aggregation-caused quenching (ACQ) effect of BTD-COFs could be suppressed effectively by precisely designing another monomer's structure to enhance the fluorescence of BTD-COFs. Leveraging the red fluorescence of BTD-COFs and the intrinsic blue emission of NOR, ratiometric fluorescence sensors were constructed, achieving visual detection of NOR. Among these BTD-COFs, the COFBTD-TP can enrich NOR well owing to its appropriate pores and numerous hydroxyl groups, showing best performance for NOR detection with a detection limit of 0.012 μM and a linear range of 0.036-18.08 μM. More importantly, it displayed a distinct and vivid multicolor fluorescence change from red to pink, purple, and finally blue under UV light during NOR detection, enabling visual discrimination by the naked eye. When combined with a smartphone APP, the sensor enabled portable and visual monitoring NOR, exhibiting a detection limit of 0.45 μM and a linear range of 1.35 μM to 30.1 μM. This study not only provides new ideas for designing COFs with red-light emission but also showcases their broad potential applications in environmental monitoring and food safety detection.

To achieve high-performance supercapacitors (SCs), the development of highly electrochemically active materials combined with a well-engineered structural design is crucial. In this work, a hierarchical ZnCo2O4/ZnCo2S4 heterostructured (HS-ZCO/ZCS) electrode is synthesized on nickel foam (NF) via a hydrothermal process followed by annealing treatment. The integration of ZnCo2O4 with an optimized nanostructure significantly enhances the electrochemical results of the hybrid electrode. The fabricated electrode exhibits remarkable electrochemical performance, delivering a high specific capacitance (C-s) of 3097.9 F/g at a current density of 0.5 A/g. It also maintains an admirable rate capability, retaining similar to 1152.0 F/g even at 70 A/g. Moreover, the electrode demonstrates outstanding cycling stability, preserving around 88.87 % of its initial capacitance after 10,000 charge-discharge cycles at 10 A/g. An asymmetric device (HS-ZCO/ZCS//AC) is also assembled, operating within a voltage window of 1.6 V. This device achieves a maximum energy density (E-d) of similar to 108.9 Wh/kg at a power density (P-d) of 799.9 W/kg, along with excellent long-term durability, maintaining similar to 83.56 % capacitance retention over 15,000 cycles at 10 A/g with nearly 100 % Coulombic efficiency. These results highlight the high potential of this hybrid electrode material for advanced energy storage applications.

Hierarchical porous metal-organic frameworks (MOFs) integrating micro- and mesopores hold promise for advanced separations but often suffer from understudied negative pore synergy, where interconnected pores compromise selectivity and diffusion. Using the zirconium-based porous coordination network (PCN) PCN-608 as a model, we identify that rapid analyte translocation between meso-hexagonal and micro-triangular channels induces chaotic diffusion, undermining separation efficiency. A channel-isolation strategy is then developed via solvent-assisted installation of barrier ligands (BDC/NH2BDC) at interconnecting windows. PCN-608-BDC with isolated pores exhibit 8-13 times higher diffusion coefficients for xylene isomers than the pristine PCN-608 monitored by inverse gas chromatography (IGC). Molecular dynamics simulations confirm the restriction of cross-pore migration and the acceleration of diffusion kinetics in PCN-608-BDC. The PCN-608-BDC shows obviously better performance than the pristine material as GC stationary phases and breakthrough adsorbents in separation xylene isomers. All PCN-608 series with a micro-mesoporous mixed structure exhibit excellent xylene uptake. Similar improvements in separation performance are also observed for NU-1000 with isolated pores, validating the universality of the phenomena. By balancing pore connectivity and active site availability, this work establishes channel isolation as a generalizable design principle for optimizing hierarchical MOFs to eliminate the negative pore synergy, offering simultaneous enhancements in selectivity, and stability for gas separations.

Flexible piezoresistive sensors are extensively applied in human physiological monitoring and dexterous hand motion detection. However, they often suffer from a trade-off between high sensitivity and wide sensing range, as well as limited linearity induced by the intrinsic microstructural drawbacks. In this study, we propose a flexible piezoresistive sensor featuring a well-ordered and three-level pyramidal microstructure (OTPm) fabricated by laser direct writing and wet etching to overcome such limitations. Benefiting from stress concentration at pyramid tips and stepwise interfacial contact, the OTPm sensor achieves progressive conduction behavior, which effectively enhances sensitivity and suppresses pressure saturation. Notably, the OTPm sensor exhibits three linear sensitivity stages of 77.80, 39.84, and 19.20 kPa-1, a broad detection range up to 800 kPa, a low limit of detection of 98 Pa, and a response time of 91.2 ms, coupled with stable sensing performance over 10,000 cycling tests. These sensing features enable the sensor to effectively detect various physiological signals and dynamic human motion changes. Furthermore, the developed 3×3 sensor array realizes three-dimensional(3D) pressure distribution imaging and validates reliable mechanical sensing capability during grasping motions. With the balanced sensing performance, the proposed sensor presents great application potential for medical rehabilitation, robotic control, and human-machine interaction.

Rationally designing adsorbents for the effective and selective removal of 99TcO4- from a water environment is extremely desired but remains a challenge. In this study, we successfully constructed a nonporous cationic metal-organic framework (MOF-1) with a three-dimensional architecture. Remarkably, nonporous MOF-1 exhibits extremely fast adsorption kinetics toward ReO4- (a nonradioactive analog for 99TcO4-), achieving adsorption equilibrium within 1 min. And the maximum adsorption capacity of MOF-1 for ReO4- is 375 mg/g. Furthermore, MOF-1 exhibits exceptional selectivity for ReO4- removal in the presence of large excesses of competing anions such as NO3-, SO42-, and Cl-, as even 6000 times of SO42- in excess does not significantly affect the sorption of ReO4-. Additionally, MOF-1 shows excellent ReO4- removal efficiency over a broad pH range (2.0-11.0), and it can still remove 97% of ReO4- after four recycles. Furthermore, a combination of characterization analyses, molecular dynamics simulations, and density functional theory calculations is utilized to clearly elucidate the adsorption mechanism of MOF-1 toward 99TcO4-/ReO4-. MOF-1 holds superior adsorption performance and significant potential for large-scale preparation and is proven to be a highly promising material for removing 99Tc from contaminated water sources.

Surface-enhanced Raman scattering (SERS) technology, with its molecular fingerprint recognition, high sensitivity, rapid detection, and non-destructive analysis, has become a key research direction in the detection of pesticide residues in food. However, critical challenges remain, including poor uniformity, insufficient stability, and difficulty in large-scale fabrication of SERS substrates, as well as interference from complex food matrices that affects detection accuracy. This review systematically summarizes the most commonly used preparation and optimization strategies for SERS substrates, which provides theoretical support and practical references for the rational design of SERS substrates, the improvement of fabrication processes, and the development of anti-interference algorithms. Furthermore, focusing on the detection advances (2020-present) of four typical classes of pesticide residues (organophosphorus, benzimidazole, neonicotinoid, and carbamate) in food, this review elaborates on the core SERS detection principles, technical advantages, practical limitations, and corresponding solution strategies. This work clarifies the research advances and technical challenges of SERS in the detection of pesticide residue in food, offering clear guidance and references for improving the technical framework and promoting future research in this field.

Organophosphorus pesticides (OPPs) are extensively applied in agriculture to enhance crop yields, yet the excessive residues of multiple OPPs pose significant threats to ecosystems and human health. However, most existing methods focus on either detection or removal, making them insufficient for addressing complex and dynamically evolving practical scenarios. Herein, a multifunctional fluorescent sensor array aerogel based on ratiometric metal-organic frameworks (Ru@ZrMOFs) was developed for the first time, enabling the simultaneous capture, identification, and detection of multiple OPPs. This sensor array effectively identified and discriminated three structurally similar OPPs (fenitrothion (FTT), methyl parathion (MPT), and glyphosate (GPS)), as well as their binary and ternary mixtures at different concentration ratios. Blind validation assays achieved 100% recognition accuracy for unknown samples. In addition, the constructed sensor array demonstrated excellent anti-interference capability for the quantitative analysis of OPPs in complex river water samples, yielding recovery rates ranging from 84.43% to 105.49%. These results were consistent with those obtained by HPLC, confirming the practicality and reliability of the sensor array. More importantly, the aerogel array exhibited remarkable adsorption performance toward OPPs, with maximum adsorption capacities of 220.89mg/g, 212.66mg/g, and 192.69mg/g for FTT, MPT, and GPS, respectively. Therefore, this ratiometric fluorescent MOFs-based multifunctional nanocomposite provides an innovative strategy with great potential for the simultaneous adsorption and monitoring of multiple harmful residues.

It is highly desirable to achieve both high Xe uptake and big Xe/Kr selectivity for Xe/Kr separation but it remains a long-term challenging issue due to an inherent trade-off between Xe uptake and Xe/Kr selectivity. We herein show a general and convenient digging-patching (DP) strategy in a covalent organic framework for simultaneously boosting Xe uptake and Xe/Kr selectivity. Notably, this DP method plays dual functions, creating dual micropores to match the kinetic diameter of Xe and increasing the porosity with surface areas from 573 m2/g to 1134 m2/g. As a result, we observed a large enhancement in both Xe uptake and selectivity from 1.37 to 2.29 mmol/g and from 14.6 to 22.0. It was found that structural design by the digging (D) operation in the DP strategy functions to create dual adsorption sites for Xe, which helps to improve Xe uptake, while the patching (P) operation functions to optimize the second adsorption site with its size close to the kinetic diameters of Xe, which helps to improve Xe/Kr selectivity, finally breaking the inherent trade-off between Xe uptake and Xe/Kr selectivity. The actual Xe-Kr separation capability was further confirmed by breakthrough experiments. This work highlights a fundamental structural design of two-dimensional COFs for size-based gas separation.

Wound healing is often disrupted by multiple factors, with the process being slowed by various mechanisms including oxidative stress, microbial infection, and delayed coagulation. The work developed a novel multifunctional wound dressing based on a composite of tannic acid-silver self-assembled nanoparticles (TA-AgNPs) and electrospun nanofiber membranes (NFMs). Constructed via electrospinning, the dressing exhibits high specific surface area and porosity, enabling efficient exudate absorption. The incorporation of TA-AgNPs significantly enhances antimicrobial activity, achieving inhibition rates of 99.66

Given the challenges posed by persistent bleeding, easy bacterial infections, high oxidative stress, and vascular damage within diabetic wounds, it is highly necessary to develop multifunctional wound dressings for wound healing in diabetic patients. Here, a injectable hydrogel wound dressing was developed by self-assembling chlorogenic acid (CA) and tobramycin (TOB) to chelate Fe3+ with the catechol part of the bioactive complex in Gelatin methacrylate (GelMA). The Fe-CA-TOB/GelMA integrated photothermal, antibacterial, and antioxidant functions. The resulting Fe-CA-TOB/GelMA hydrogel demonstrated sterilization efficacy of 99% against S. aureus and 95% against E. coli. The Fe-CA-TOB/GelMA also exhibited enhanced antioxidant capabilities. Notably, the Fe-CA-TOB/GelMA hydrogels were also capable of sustaining the release of both CA and TOB. The Fe-CA-TOB/GelMA hydrogels can also maintain a moist wound environment to facilitate re-epithelialization by eradicating bacteria, reducing excess reactive oxygen species (ROS), promoting macrophage polarization, and enhancing angiogenesis. This study introduces a novel approach for the incorporation of self-assembled bioactive complexes into hydrogels for the treatment of diabetic infected wounds, potentially advancing the application of high-performance hydrogels in biomedical contexts.

Enhancing the aggregation-induced emission (AIE) activity and hydrophilicity of AIE-covalent organic framework nanosheets (CONs) is important for improving the sensitivity of sandwich-type fluorescence-on immunosensors. This work developed 2,2',2″,2‴-(ethene-1,1,2,2-tetrayltetrakis([1,1'-biphenyl]-4',4-diyl))tetraacetonitrile-based AIE-CONs containing cyano and hydroxyl groups with high AIE activity and hydrophilicity to construct a highly sensitive immunosensor for detecting carbohydrate antigen 19-9.

Engineering the electronic microenvironments of supported metal catalysts is significant but remains a pivotal challenge for efficient catalysis. Herein, we develop a facile heterometal-incorporating strategy to modulate the surface electron density of Pt nanoparticles anchored in ordered-mesoporous SnO2 single crystals (OM-SnO2) for efficient biomass valorization. We demonstrate that Mn, Ti, Ce, or Zr elements with different electronegativities can be successfully incorporated into the OM-SnO2 lattices to motivate controllable lattice distortion and charge redistribution, thereby synergistically optimizing the surface electron density of its anchored Pt nanoparticles. Impressively, the resultant Pt/OM-Mn-SnO2, featuring the lowest Pt surface electron density, exhibits the highest turnover frequency of 6587.8 h-1 for the hydrogenation of biomass-derived levulinic acid (LA) to gamma-valerolactone (GVL), which is similar to 10.6 times that of the Pt/OM-Zr-SnO2 counterpart featuring the highest Pt surface electron density. Furthermore, this electronic structure tuning strategy also endows Pt/OM-Mn-SnO2 with remarkably enhanced activities for the selective hydrogenation of biomass-derived benzaldehyde and furfural. Mechanistic studies demonstrate that the lowest Pt surface electron density of Pt/OM-Mn-SnO2 can not only reduce the energy barriers for LA hydrogenation and H2 dissociation, but also facilitate the desorption of GVL via weakening the electronic interaction between GVL and Pt, which jointly account for its remarkably-enhanced catalytic performance.

This study successfully prepared a core-shell structured nitrogen-doped carbon-coated ZnS (ZnS@NC) composite material using a MOF/COF synergistic derivation strategy to enhance the electrochemical performance of lithium-ion battery anode materials. Using the zinc-based metal-organic framework (Zn-MOF) as the precursor, ZnS@NC composites were constructed by growing a covalent organic framework (COFTBDP) on Zn-MOF surface followed by pyrolysis. By adjusting the thickness of COFTBDP-derived nitrogen-doped carbon shell, this study revealed that the ordered porous carbon structure not only significantly shortens the Li+ transport pathway but also effectively mitigates the volume expansion of ZnS during charge/discharge cycles through its flexible framework, thereby improving the cycling stability of the material. The optimized ZnS@NC-2 sample maintained a reversible capacity of 579.4 mAh g-1 after 125 cycles at the current density of 0.1 A g-1. This research provides a novel approach for designing transition metal sulfide/carbon-based composite electrode materials and demonstrates promising potential for applications in lithium-ion batteries.