Search Results (93)

The Signal Amplification By Reversible Exchange (SABRE) technique provides enhancement of Nuclear Magnetic Resonance (NMR) signals up to several orders of magnitude using chemical exchange of a substrate and parahydrogen on an iridium complex. Therefore, the availability of such a catalytic complex to a broader community is an absolutely vital step for dissemination of the groundbreaking SABRE methodology. The most common SABRE catalyst, which is activated in situ, is based on Ir-IMes system (IMes = 1,3-Bis(2,4,6-trimethylphenyl)imidazol-2-ylidene). Earlier approaches for the synthesis of this catalyst often relied on specialized equipment and were limited to a comparatively small scale. This, in turn, increased the barrier of entry for new scientists to the area of SABRE hyperpolarization. Here, we present a robust, inexpensive, and easy to reproduce synthetic procedure for the preparation of this SABRE catalyst, which does not require specialized inert atmosphere equipment like a glove box or Schlenk line. The synthesis was validated on the scale of several grams vs. tens of milligrams scale in the reported approaches. The resulting SABRE catalyst, [Ir(IMes)(COD)Cl], was activated in situ and further evaluated in hyperpolarization experiments resulting in signal enhancements comparable to (or higher than) those for the catalyst prepared using Schlenk line equipment. Full article

Hydroxyl radicals (·OH) offer exceptional potential for cancer treatment through reactive oxygen species (ROS) amplification and apoptotic induction. However, conventional Fe-based metal–organic framework (Fe-MOF) nanomaterials are limited by inadequate Fe²⁺ concentrations, resulting in suboptimal Fenton catalytic performance. This study presents concave octahedral Fe-MOF nanomaterials with integrated bimetallic Fe/Zn centers through controlled solvothermal synthesis. The nanoplatform exhibits high specific surface area (559 m²/g) and 5-fluorouracil (5-FU) loading efficiency (58.7%). These structural properties establish it as a potential nanobuilding block for constructing stimuli-responsive gels. With optimized Fe²⁺ content (57.3%), the Fe-MOF material shows enhanced nanozyme-like activity (V_max = 4.58 × 10⁻⁷ M/s, K_cat = 1.83 × 10⁻³ s⁻¹) for H₂O₂-mediated ·OH generation. The Fe-MOF@FU demonstrates pH-responsive drug release (76.5% at pH 5.0) and glutathione (GSH) depletion, synergistically enhancing oxidative stress. Biocompatibility studies confirm safety, while in vitro investigations show remarkable anticancer activity against 4T1 cells with 17.8% viability, supporting its dual role as an independent therapeutic agent and a functional component for future gel-based delivery systems. Full article

MicroRNAs are closely associated with various physiological and pathological processes, making their in situ fluorescence imaging crucial for functional studies and disease diagnosis. Current methods for the in situ fluorescence imaging of microRNA predominantly rely on linear signal amplification, resulting in relatively weak imaging signals. This study introduces a Y-shaped cascade assembly (YCA) method for high-brightness microRNA imaging in cells. Triggered by target microRNA, catalytic hairpin assembly forms double-stranded DNA (H). Through annealing and hybridization, a Y-shaped structure (P) is created. These components assemble into DNA nanofluorescent particles with multiple FAM fluorophores, significantly amplifying fluorescence signals. Optimization experiments revealed that a 1:1 ratio of P to H and an assembly time of 60 min yielded the best results. Under these optimal conditions, the resulting fluorescent nanoparticles exhibited diameters of 664.133 nm, as observed by DLS. In Huh7 liver cancer cells, YCA generated DNA nanoparticles with a fluorescence intensity increase of 117.77%, triggered by target microRNA-21, producing high-intensity fluorescence images and enabling qualitative detection of microRNA-21. The YCA in situ imaging method offers excellent imaging quality and high efficiency, providing a robust and reliable analytical tool for the diagnosis and monitoring of microRNA-related diseases. Full article

Salmonella poses a severe global threat to food safety and public health, necessitating rapid, sensitive, and reliable detection methods. Conventional techniques often suffer from complexity, time consumption, cost, or limited sensitivity. To address this, we developed a novel enzyme-free fluorescence detection platform, termed the MTAI-CHA system, integrating magnetic nanoparticle-based triangle multivalent aptamer-initiators (MTAI) with catalytic hairpin assembly (CHA) signal amplification. The triangular DNA nanostructure contained significantly enhanced binding affinity of multivalent aptamers, increasing the sensitivity compared to monovalent aptamers. The optimized MTAI-CHA system demonstrated exceptional performance: a low detection limit of 10 CFU/mL and excellent specificity against non-target pathogens. This sensitive, specific, and robust strategy, leveraging multivalent aptamer recognition and enzyme-free signal amplification, holds significant potential for rapid pathogen screening in food safety, clinical diagnostics, and environmental monitoring, with adaptability to other targets via aptamer substitution. Full article

Enteric viruses are a major cause of waterborne infections due to their high environmental stability and extremely low infectious dose. Current molecular diagnostic methods, while accurate, often depend on thermal cycling and centralized laboratory facilities, limiting their applicability in decentralized or resource-limited settings. In this study, we developed an isothermal biosensor based on a split deoxyribozyme that reconstitutes its catalytic core upon hybridization with a conserved sequence of enteroviral RNA. This activation leads to site-specific cleavage of a fluorogenic substrate, producing a quantifiable fluorescent signal. The system was experimentally validated using both synthetic enteroviral RNA and RNA extracted from environmental water samples. To enhance detection sensitivity, the DNAzyme-based assay was coupled with isothermal RNA amplification. The results demonstrate high selectivity and compatibility with real-world samples, supporting the sensor’s utility for field-deployable viral RNA detection. Overall, this study highlights the potential of the DNAzyme-based platform as a portable, sequence-specific, and amplification-assisted diagnostic tool for environmental surveillance of enteric viruses. Full article

DNA methylation, as a critical epigenetic modification, plays a central role in gene regulation and has emerged as a powerful biomarker for early disease diagnostics, particularly in cancer. Owing to the limitations of traditional bisulfite sequencing—such as high cost, complexity, and chemical degradation—electrochemical biosensors have gained substantial attention as promising alternatives. This review summarizes recent advancements in electrochemical platforms for bisulfite-free detection of DNA methylation, encompassing direct oxidation strategies, enzyme-assisted recognition (e.g., restriction endonucleases and methyltransferases), immunoaffinity-based methods, and a variety of signal amplification techniques such as rolling circle amplification and catalytic hairpin assembly. Additional approaches, including strand displacement, magnetic enrichment, and adsorption-based detection, are also discussed. These systems demonstrate exceptional sensitivity, often down to the attomolar or femtomolar level, as well as high selectivity, reproducibility, and suitability for real biological matrices. The integration of nanomaterials and redox-active probes further enhances analytical performance. Importantly, many of these biosensing platforms have been validated using clinical samples, reinforcing their translational relevance. The review concludes by outlining current challenges and future directions, emphasizing the potential of electrochemical biosensors as scalable, cost-effective, and minimally invasive tools for real-time epigenetic monitoring and early-stage disease diagnostics. Full article

Nanomaterials with large specific surface area (SSA) have emerged as pivotal platforms for energy storage and environmental remediation, primarily due to their enhanced active site exposure, improved mass transport capabilities, and superior interfacial reactivity. Among them, polymeric carbon nitride (g-C₃N₄) has garnered significant attention in energy and environmental applications owing to its visible-light-responsive bandgap (~2.7 eV), exceptional thermal/chemical stability, and earth-abundant composition. However, the practical performance of g-C₃N₄ is fundamentally constrained by intrinsic limitations, including its inherently low SSA (<20 m²/g via conventional thermal polymerization), rapid recombination of photogenerated carriers, and inefficient charge transfer kinetics. Notably, the theoretical SSA of g-C₃N₄ reaches 2500 m²/g, yet achieving this value remains challenging due to strong interlayer van der Waals interactions and structural collapse during synthesis. Recent advances demonstrate that state-of-the-art strategies can elevate its SSA to 50–200 m²/g. To break this surface area barrier, advanced strategies achieve SSA enhancement through three primary pathways: pre-treatment (molecular and supramolecular precursor design), in process (templating and controlled polycondensation), and post-processing (chemical exfoliation and defect engineering). This review systematically examines controllable synthesis methodologies for high-SSA g-C₃N₄, analyzing how SSA amplification intrinsically modulates band structures, extends carrier lifetimes, and boosts catalytic efficiencies. Future research should prioritize synergistic multi-stage engineering to approach the theoretical SSA limit (2500 m²/g) while preserving robust optoelectronic properties. Full article

We are reporting the development of a high-performance, non-enzymatic electrochemical biosensor for selective lactate detection, integrating laser-induced graphene (LIG), gold nanoparticles (AuNPs), and a molecularly imprinted polymer (MIP) synthesized from poly(3,4-ethylenedioxythiophene) (PEDOT). The LIG electrode offers a highly porous, conductive scaffold, while electrodeposited AuNPs enhance catalytic activity and signal amplification. The PEDOT-based MIP layer, electropolymerized via cyclic voltammetry, imparts molecular specificity by creating lactate-specific binding sites. Cyclic voltammetry confirmed successful molecular imprinting and enhanced interfacial electron transfer. The resulting LIG/AuNPs/MIP biosensor demonstrated a wide linear detection range from 0.1 µM to 2500 µM, with a sensitivity of 22.42 µA/log(µM) and a low limit of detection (0.035 µM). The sensor showed excellent selectivity against common electroactive interferents such as glucose and uric acid, long-term stability, and accurate recovery in artificial saliva (>95.7%), indicating strong potential for practical application. This enzyme-free platform offers a robust and scalable strategy for continuous lactate monitoring, particularly suited for wearable devices in sports performance monitoring and critical care diagnostics. Full article

In the past decade, nanozymes have been attracting increasing interest in academia due to their stable performance, low cost, and easy modification. With the catalytic signal amplification feature, nanozymes not only find wide use in traditional “lock-and-key” single-target detection but hold great potential in high-throughput multiobjective analysis via fabricating sensor arrays. In particular, the rise of machine learning in recent years has greatly advanced the design, construction, signal processing, and utilization of sensor arrays. The constructive collaboration of nanozymes, sensor arrays, and machine learning is accelerating the development of biochemical sensors. To highlight the emerging field, in this minireview, we created a concise summary of machine-learning-assisted nanozyme-based sensor arrays. First, the construction of nanozyme-involved sensor arrays is introduced from several aspects, including nanozyme materials and activities, sensing variables, and signal outputs. Then, the roles of machine learning in signal treatment, information extraction, and outcome feedback are emphasized. Afterwards, typical applications of machine-learning-assisted nanozyme-involved sensor arrays in environmental detection, food analysis, and biomedical sensing are discussed. Finally, the promise of machine-learning-assisted nanozyme-based sensor arrays in biochemical sensing is highlighted, and some future trends are also pointed out to attract more interest and effort to promote the emerging field for better practical use. Full article

The timely and accurate detection of cancer is crucial for preventing disease progression and for the early treatment of confirmed cases. MiRNAs are cancer markers. In this study, a simple miRNA detection method is proposed. Three hairpins were designed based on gold nanoparticles combined with catalytic hairpin assembly nucleic acid amplification technology. The low-pH method was used for rapid coupling, and hairpin H1 was opened by miR-378, triggering the cycle reaction and signal amplification and finally forming a Y-shaped structure, thereby narrowing the distance between gold nanoparticles and achieving colorimetric detection. The absorbance change (A₆₂₀/A₅₂₀) was proportional to the concentration of miR-378 (0.05–5 nM), with a detection limit of 0.05 nM. This method also has an evident detection effect on real samples. HeLa and L-02 cell extracts were analyzed using this method. The former showed no obvious color change, whereas the maximum absorption peak of the latter showed a red shift, and the color changed from red to purple. The minimum number of cells that could be detected using HeLa cells was 500 cells/mL. Full article

We demonstrate a rapid and sensitive boron detection method through current amplification mediated by supramolecular interaction. Oxidation peak currents obtained by cyclic voltammetry (CV) measurements of a ferrocene/catechol-functionalized β-cyclodextrin inclusion complex were amplified through an EC’ reaction (where EC’ denotes an electrochemical step followed by a catalytic chemical step). However, the amplified current was decreased by boric acid (the primary form of boron in water) addition at pH 8.6 owing to interactions of boron with the cis-diol structure of dihydroxybenzoic acid-β-cyclodextrin and ferrocene for ester formation. We determined the optimum CyD functionalization sites and measurement conditions and obtained a limit of detection of 0.16 mg B L⁻¹ for ferrocene/3,4-dihydroxybenzoic acid-β-cyclodextrin (Fc/3,4-DHBA-β-CyD). The binding constant (assuming a 1:1 binding model) for the interaction between Fc/3,4-DHBA-β-CyD and boric acid was estimated to be approximately 1500 M⁻¹. Boron concentrations in spiked real samples showed good recoveries and linear calibration curves. The electrochemical response of this system was not significantly affected by the presence of other anions or cations. We also found that an aqueous solution of 3,4-DHBA-β-CyD remained stable for at least 112 days. Full article

The rapid and accurate detection of viral infections is of paramount importance, given their widespread impact across diverse demographics. Common viruses such as influenza, parainfluenza, rhinovirus, and adenovirus contribute significantly to respiratory illnesses. The pathogenic nature of certain viruses, characterized by rapid mutations and high transmissibility, underscores the urgent need for dynamic detection methodologies. Quantitative reverse transcription PCR (RT-qPCR) remains the gold-standard diagnostic tool. Its reliance on costly equipment, reagents, and skilled personnel has driven explorations of alternative approaches, such as catalytic DNA nanomachines. Diagnostic platforms using catalytic DNA nanomachines offer amplification-free nucleic acid detection without the need for protein enzymes and demonstrate feasibility and cost-effectiveness for both laboratory and point-of-care diagnostics. This study focuses on the development of multicomponent DNA nanomachines with catalytic proficiency towards a fluorescent substrate, enabling the generation of a fluorescent signal upon the presence of target nucleic acids. Specifically tailored variants are designed for detecting human parainfluenza virus type 3 (HPIV) and respiratory syncytial virus (RSV). The engineered DNA nanomachine features six RNA-binding arms for recognition and unwinding of RNA secondary structures, along with a catalytic core for nucleic acid cleavage, indicating potential utility in real clinical practice with minimal requirements. This research showcases the potential of DNA nanomachines as a reliable and sensitive diagnostic tool for RNA virus identification, offering promising prospects for clinical applications in the realm of infectious disease management. Full article

Seeking a supramolecular chiral system induced by trace chiral molecules instead of traditional complex and expensive chiral ligands to achieve high yield or ee value conversion of the products is of great significance in asymmetric synthesis but still remains a challenge. Herein, two types of double helical supramolecular chiral systems, (M)-Helix and (P)-Helix, with opposite chiral optics were constructed in situ using tyrosine-functionalized pillar[5]arene as inducers. These systems exhibit chiroptical stability and enable remarkable chirality amplification from 7 mol% chiral seeds. When applied to intermolecular olefin cyano-trifluoromethylation, (M)-Helix exhibits remarkable catalytic efficiency (yield up to 89%), whereas (P)-Helix achieves higher enantioselectivity (ee up to 84%). This research will provide new ideas for supramolecular chiral catalysts in organic asymmetric catalysis applications. Full article

In this study, novel fluorescent DNA biosensors for mercury (Hg²⁺) and silver (Ag⁺) ions were developed based on thymine (T)- and cytosine (C)-rich recognition elements in combination with exonuclease III and a mismatch-catalyzed hairpin assembly (MCHA)-based cascade isothermal signal-amplification strategy. In the presence of the respective target analytes, the recognition element terminals form so-called T-Hg²⁺-T or C-Ag⁺-C structures, resulting in cleavage by Exo III and the release of the trigger strand for MCHA. This binds to the H1 hairpin, which is fluorescently labeled with carboxyfluorescein (FAM) and tetramethylrhodamine (TAMRA), disrupting fluorescence resonance energy transfer between them and, thus, restoring FAM fluorescence, generating a strong signal at 520 nm. The linear range of the Hg²⁺ sensor is 0.5 to 3 pM, with a detection limit of 0.07 pM. The recovery range in actual spiked water samples is between 98.5% and 105.2%, with a relative standard deviation (RSD) ranging from 2.0% to 4.2%. The linear range of the Ag⁺ sensor is 10 to 90 pM, with a detection limit of 7.6 pM. The recovery range in actual spiked water samples is between 96.2% and 104.1%, with an RSD ranging from 3.2% to 6.3%. The cascade isothermal signal amplification strategy effectively enhances sensor sensitivity, while MCHA decreases the false-positive rate. The aptamer sensor exhibits high specificity, is resistant to interference, and can be used for the detection of Hg²⁺ and Ag⁺ in environmental water samples. Full article

Monitoring of immune factors, including interferon-gamma (IFN-γ), holds great importance for understanding immune responses and disease diagnosis. Wearable sensors enable continuous and non-invasive detection of immune markers in sweat, drawing significant attention to their potential in real-time health monitoring and personalized medicine. Among these, electrochemical sensors are particularly advantageous, due to their excellent signal responsiveness, cost-effectiveness, miniaturization, and broad applicability, making them ideal for constructing wearable sweat sensors. In this study, we present a flexible and sensitive wearable platform for the detection of IFN-γ, utilizing a DNA hydrogel with favorable loading performance and sample collection capability, and the application of mobile software achieves immediate data analysis and processing. This platform integrates three-dimensional DNA hydrogel functionalized with IFN-γ-specific aptamers for precise target recognition and efficient sweat collection. Signal amplification is achieved through target-triggered catalytic hairpin assembly (CHA), with DNA hairpins remarkably enhancing sensitivity. Ferrocene-labeled reporting strands immobilized on a screen-printed carbon electrode are displayed via CHA-mediated strand displacement, leading to a measurable reduction in electrical signals. These changes are transmitted to a custom-developed mobile application via a portable electrochemical workstation for real-time data analysis and recording. This wearable sensor platform combines the specificity of DNA aptamers, advanced signal amplification, and the convenience of mobile data processing. It offers a high-sensitivity approach to detecting low-abundance targets in sweat, paving the way for new applications in point-of-care diagnostics and wearable health monitoring. Full article