Although glyphosate is widely applied as a non-selective herbicide in agricultural production, its rapid and on-site monitoring remains challenging. Building upon magnetic effervescent tablets (METs) previously developed by our group, we designed novel METs-based colorimetric tablets (MCTs) using Ru-doped Fe-MOF (Ru40/Fe-MOF) with significantly enhanced peroxidase-mimetic activity. MCTs were integrated with smartphone-based digital-image chromogenesis (SDC) for visual quantitation of glyhosate in surface waters and liquid drinks. Ru-doping not only increased the specific surface area and regulated MOFs’ morphology, but also prominently improved the underlying catalytic activity. Upon the addition of H2O2, Ru40/Fe-MOF catalyzed the chromogenic substrate ABTS to form a green oxidized product oxABTS, yielding a bright green solution. However, glyphosate could inhibit the aforementioned catalytic activity through coordination and/or H-bonding interactions with the surface groups of Ru40/Fe-MOF (-COOH, -NH2, Fe-OH, and Ru sites). MCTs enabled rapid auto-dispersion and chromogenic development upon contact with water, thereby eliminating the need for external stirring, shaking or heating. Under optimized conditions, the MCTs-SDC platform exhibited an excellent linearity for glyphosate with a detection limit of 0.006 µg/mL by UV-vis measurement and 0.03 µg/mL by grayscale analysis via a self-developed “Thing Identify” APP. In the lake water and liquid drink samples, the fortified recoveries (94.5-112.2
Accurate and efficient detection of catecholamines (CAs) is of great importance for the diagnosis and treatment of neuroendocrine-related diseases. However, developing convenient sensing platforms that combine high sensitivity, high selectivity, and multi-mode validation capabilities still faces challenges. To address this issue, an irregular octahedral cobalt-iron bimetallic organic framework (io-CoFe-MIL) nanozyme with excellent peroxidase-like activity was synthesized via a solvothermal method. The nanozyme can efficiently catalyze the oxidation of substrate 3,3’,5,5’-tetramethylbenzidine (TMB), generating blue oxidized TMB (TMBox). The inhibitory effect of CAs on such TMB catalytic oxidation process leads to changes in both solution color and system temperature. Thus, a colorimetric/photothermal dual-mode sensing platform was constructed for catecholamines detection, as epinephrine (EP), dopamine (DA), and norepinephrine (NE). The colorimetric sensor exhibited sensitive responses toward various CAs with limit of detection (LOD) of 0.03 µM for EP, 0.055 µM for DA, and 0.08 µM for NE. While in the photothermal mode, the LODs for EP, DA, and NE were 0.027 µM, 0.74 µM and 1.2 µM, respectively. The presented dual-mode methods can be well used for sensitive detection of EP, DA, and NE in actual porcine serum samples, that are in consistent with those obtained from the instrument of HPLC, demonstrating the reliability and practical applicability of the method. This work provides a promising strategy for highly sensitive and multi-mode detections of CAs based on the synergistic integration of colorimetric and photothermal dual-signal responses.
A self-signaling electrochemical sensor based on molecular imprinting technology for the detection of Bisphenol A (BPA) in food samples. The sensor was constructed through sequential modification of the electrode with reduced graphene oxide (RGO) and CoNiFe Prussian blue analogue (CoNiFe-PBA), followed by electropolymerization of an MIP film using BPA as template and o-phenylenediamine as monomer. CoNiFe-PBA provides an intrinsic signal at 0.47 V without external probes, originating from synergistic redox interactions among Co, Ni, and Fe. BPA rebinding reduces the signal via steric hindrance, enabling sensitive detection in food samples. Under optimal conditions, the sensor demonstrated a wide linear detection range (0.5–500 nM) and a low detection limit (0.19 nM). Owing to its high selectivity, sensitivity, and accuracy, the sensor offers a reliable approach for precise quantification of trace BPA in complex food matrices.
Acute kidney injury (AKI) is a serious clinical condition with high morbidity and mortality, yet early detection and effective treatment remain challenging. Herein, we developed ultrasmall quantum dots (QDs) for dual-modal imaging-guided early detection and antioxidant therapy of AKI. Benefiting from the ultrasmall hydrodynamic size, the as‑prepared Ag₂Se@Mn QDs exhibit favorable renal clearance and prolonged retention in injured kidneys. The QDs possess concentration-dependent T1-weighted magnetic resonance imaging (MRI) contrast and near-infrared fluorescence properties, enabling real-time, non-invasive visualization of cisplatin-induced AKI progression. Especially, MRI revealed renal dysfunction up to 66 h earlier than conventional clinical indicators, providing a critical window for early intervention. Furthermore, the inherent ROS-scavenging activity of Mn²⁺ endows QDs with potent antioxidant capacity by efficiently eliminating hydroxyl radicals (·OH) and superoxide anions (O₂•-), and thus comprehensively alleviate renal damage and recover renal functions without obvious side-effects. This “all-in-one” theranostic strategy offers an alternative approach for precision management of AKI.
Building on the precursor probe BMQ-1 with A−π−A configuration, a new optimized fluorescent probe, XYT, for the determination of sulfur dioxide was developed by extending the π-conjugation through replacing the electron acceptor 1-(4-dimethylaminophenyl)-2-cyanoacrylonitrile with 1-(7-diethylaminocoumarin-3-yl)-2-cyanoacrylonitrile. This modification resulted in a redshift of XYT in emission wavelength from 590 nm to 603 nm upon reaction with sulfite. The probe demonstrated rapid colorimetric and fluorogenic changes (≈ 10 s), with the solution turning from colorless to red and emitting strong red fluorescence. XYT exhibited high selectivity, photostability, and sensitivity, achieving a detection limit as low as 49.9 nM. In practical detection scenarios, XYT was adopted to measure residual SO2 contents in commercially available food samples, among which the analytical data of some specimens were verified via comparative analysis with the official Chinese national standard GB 5009.34–2022. Beyond in vitro assays on food matrices, XYT also enables fluorescence imaging of exogenous and endogenous SO2 in live cells and zebrafish. These properties suggest that XYT holds substantial potential for pathological studies and clinical diagnostics involving SO2.
Long-wavelength carbon dots (L-CDs) were fabricated via hydrothermal route using neutral red and p-aminobenzoic acid as precursors under hydrochloric acid conditions, and further explored for nitrite (NO2⁻) sensing. The L-CDs displayed outstanding optical characteristics and exhibited excellent selectivity toward NO2⁻. Upon exposure to NO2⁻, the fluorescence of L-CDs was remarkably quenched via a static quenching mechanism. A favorable linear correlation was achieved between 5 and 100 µM, yielding a calculated limit of detection of 2.89 µM. This method demonstrated satisfactory recoveries and minimal relative standard deviations when utilized for NO2⁻ determination analysis in actual samples. Moreover, the L-CDs proved effective for fluorescence imaging of NO2⁻ in living cells and zebrafish, revealing their promising application potential in the field of biosensing.
By exploiting the dual-quenching effect of CuBi2O4@PDA on Sm-MOF@Ag, we developed a signal-on/signal-off electrochemiluminescence (ECL) immunosensor for the sensitive detection of anti-Müllerian hormone (AMH). A novel samarium-based metal-organic framework (Sm-MOF) was employed as the luminophore, with K2S2O8 used as the co-reactant to generate a stable ECL signal. Silver nanoparticles were in situ decorated on the Sm-MOF surface to act as co-reactant accelerators, promoting SO4•− generation and significantly enhancing the ECL intensity. For signal quenching, energy transfer from the Sm-MOF@Ag donor to the CuBi2O4 acceptor was rationally designed based on their matched energy levels, resulting in pronounced attenuation of the ECL emission. Meanwhile, the polydopamine shell further improved the quenching efficiency by scavenging SO4•− radicals. Under optimized conditions, the proposed ECL immunosensor exhibited a wide linear range from 10 fg·mL− 1 to 100 ng·mL− 1 and a detection limit of 2.6 fg·mL− 1. This dual-quenching strategy represents a novel method for the detection of AMH, with substantial potential for implementation in clinical diagnostics.
A novel electrochemical sensing platform was developed using copper-modified and alkali-activated peanut shell biochar (CuPS-OH) for the selective and sensitive detection of glufosinate ammonium (GLA) in food and environmental samples. The sensor operates on the basis of solid-state electrochemical signal amplification from in situ-formed CuCl, which is generated via the reaction between surface Cu species and Cl⁻. GLA specifically binds to copper active sites and competitively suppresses the CuCl signal, enabling quantitative detection. Material characterization confirmed that alkaline treatment significantly improved the conductivity and electroactive surface area of the biochar composite. Under optimized conditions, the sensor exhibited a wide linear range of 0.2–200 µM and a low detection limit of 58 nM. It demonstrated outstanding anti-interference capability, stability, and accuracy in real-sample analyses (grape, river water, and soil), with recoveries ranging from 96.0
Reliable total antioxidant capacity (TAC) detection in foods is of considerable practical importance for evidence-based dietary guidance and disease prevention. We designed a core-shell Au@Pt nanozyme with enhanced peroxidase (POD)-like activity, driven by electron transfer from the Au core to the Pt shell. This interfacial charge modulation lowers the catalytic energy barrier, as confirmed by structural characteristic characterization and density functional theory (DFT) calculations. The Au@Pt nanozyme also exhibits excellent long-term stability and low batch-to-batch variation. Leveraging these advantages, we developed a sensitive colorimetric platform for ascorbic acid detection, in which Au@Pt serves as the signal transducer and 3,3′,5,5′-tetramethylbenzydine (TMB) as the chromogenic substrate. The assay relies on the ability of AA to quench reactive oxygen species and reduce oxidized TMB. This platform exhibits high selectivity, with negligible interference from common ions, small biomolecules, or other antioxidants. We further validated the method by determining total antioxidant capacity in commercial vitamin C tablets, beverages, and fresh fruit juices, with results expressed as mg AA equivalent per liter. The values obtained were consistent with those from the standard cupric reducing antioxidant capacity (CUPRAC) method. This work presents a rational nanozyme design via interfacial engineering and offers a practical tool for antioxidant assessment in complex food matrices.
Mesenchymal stem cells (MSCs) have great potential for use in regenerative medicine owing to their multipotent characteristics and immunomodulatory properties; however, maintaining their cell surface phenotype and stemness during their in-vitro culture is one of the major challenges. To adress this issue an electrochemical biosensor has been developed for the detection of MSCs based on the expression of their surface marker CD105. This device has been fabricated through the process of electrospinning of PCL-gelatin nanofibers incorporated with AmGn and AuNPs composites to create a conductive interface. Also, the nanofibrous composite created an increase in electroactive area and improved cell-electrode interactions, while EDC/NHS coupling chemistry enabled stable and covalent immobilization of CD105 Ab. The biosensor demonstrated a linear and proportional electrochemical response to MSCs over the range of 78 − 10,000 cells, with a practical detection limit of 312 cells. The device showed negligible cross reactivity and was validated using fluorescence-activated cell sorting (FACS) analysis to confirm the sensor’s reliability and accuracy. The biosensor remained above 70
Diabetic nephropathy (DN) is a serious complication of diabetes mellitus (DM), characterized by progressive renal impairment and limited biomarkers for early diagnosis. Herein, we developed CZY, a mitochondria-localizing activatable fluorescent probe for superoxide anion (O2·−). CZY showed high selectivity toward O2·−, chemical stability, and favorable biocompatibility. In mIMCD-3 cells, CZY enabled time-dependent visualization of O2·−-associated oxidative activity. Additionally, CZY could enable visualization of O2·− and support it as an effective molecular imaging platform for monitoring O2·− variation in DN model. Collectively, this study clarifies oxidative stress level in DN and provides a useful basis for subsequent diagnostic and therapeutic exploration.
Hydrogen-bonded organic frameworks (HOFs) are promising porous crystalline materials for sensing, but their weak intrinsic enzyme-like activity limits nanozyme applications. Herein, a Ru-functionalized HOF material (Ru-HOFs) was fabricated through Ru–N coordination. In this material, the HOFs framework anchors and stabilizes the Ru sites. The resulting Ru-HOFs exhibited enhanced peroxidase-like activity toward hydrogen peroxide (H2O2)-mediated oxidation of o-phenylenediamine (OPD), with favorable catalytic stability and substrate affinity. Density functional theory (DFT) calculations suggest that Ru-N coordination modulates the local electronic structure and provides a more favorable free-energy profile for H2O2 adsorption and subsequent activation. By coupling Ru-HOFs with D-amino acid oxidase (DAAO), a cascade colorimetric platform was developed for salivary D-proline (D-Pro) and D-alanine (D-Ala), two reported gastric cancer (GC)-related D-amino acids (DAAs). Under individual assay conditions, the platform showed linear ranges of 2–150 µmol L⁻¹ for D-Pro and 5–100 µmol L⁻¹ for D-Ala, with limits of detection of 0.6112 and 2.299 µmol L⁻¹, respectively. Smartphone-based red–green–blue (RGB) analysis enabled visual readout and quantitative determination under controlled conditions. Spiked saliva tests showed satisfactory recoveries, demonstrating the applicability of the proposed assay to saliva matrices for the analysis of reported GC-related salivary DAAs. This work also provides a useful strategy for constructing coordination-regulated HOF-based nanozymes with improved catalytic performance for colorimetric sensing applications.
A dual-robust, portable colorimetric sensing platform was developed by integrating purple sweet potato-derived carbon dots (PF-CDs) with machine learning-assisted signal processing. Serving as a highly stable, green nano-reductant, the PF-CDs effectively circumvent the autoxidation issues of conventional reagents, efficiently triggering the molybdenum blue reaction to produce a reliable macroscopic colorimetric response. To decouple these signals from environmental and matrix noise, a smartphone-based imaging system coupled with an machine learning algorithm was deployed for precise color recognition and automated quantitative determination. This integrated platform enables rapid phosphate detection within 60 min, exhibiting a broad linear range of 0.1-5.0 mM, a low limit of detection (LOD) of 0.03 mM, and an exceptional prediction accuracy of 99
Levodopa is a first-line therapeutic agent for Parkinson’s disease, and real-time monitoring of its plasma concentration is crucial for optimizing personalized treatment strategies. In this study, iron/carbon nanohorn composites (Fe/CNHs(2)) featuring a dual-form Fe structure, in which atomically or sub-nanocluster dispersed Fe species coexist with Fe nanoparticles, were synthesized via a one-step positive-pressure arc-discharge method. The fabricated Fe/CNHs(2)-based sensing electrode exhibited excellent electrocatalytic activity toward levodopa, achieving a high sensitivity of 0.062 µA µM⁻¹ and a low detection limit of 0.75 µM. Moreover, the sensor enabled stable levodopa detection over a broad pH range of 3.6–9.5. Kinetic studies revealed that the wide pH tolerance originated from the enhanced structural stability provided by strong Fe–C interfacial interactions, together with an adsorption-controlled reaction process in which the rate-determining step showed limited dependence on proton concentration. Theoretical calculations further confirmed that the introduction of Fe active centers substantially decreased the reaction energy barrier. This work provides a new design strategy for metal–carbon composites with dual-functional synergy, and the developed sensor holds considerable potential for monitoring levodopa levels during Parkinson’s disease treatment.
Cardiac troponin I (cTnI), the most sensitive and specific biomarker of myocardial injury, enables early detection of subclinical cardiotoxicity. Highly sensitive cTnI testing is therefore crucial for early safety assessment of TCM. This study developed an electrochemical immunosensor for cTnI using a carboxylated multi-walled carbon nanotube/poly(o-phenylenediamine) (MWCNTs-COOH/PoPD) composite sensing membrane. This design leverages the large surface area and high conductivity of MWCNTs-COOH along with PoPD’s biocompatibility to enhance electrochemical performance. Antibodies achieved controllable covalent immobilization with preferential orientation via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) cross-linking, facilitating specific recognition of cTnI. Under optimized conditions, the sensor exhibited excellent linearity across the ranges of 0.2–40 pg/mL and 0.05–50 ng/mL, with detection limits of 0.06 pg/mL and 4.17 pg/mL, respectively, demonstrating high sensitivity, specificity, and stability. Successfully applied to screen cardiotoxic TCM components, the sensor accurately detected cTnI released from cardiomyocytes, enabling precise quantification of toxins such as aconitine. It was also extended to evaluate myocardial protectants such as baicalin and their synergistic detoxification effects. This work establishes an efficient, sensitive platform for early TCM cardiotoxicity warning and toxic substance identification based on cTnI, while also supporting the screening of protective components. It is crucial for safeguarding the clinical safety of TCM and fostering the sustainable development of its industry.
The development of an ultrasensitive electrochemical biosensor for the label-free detection of HER2-positive breast cancer cells is reported. The developed platform leverages a novel hierarchical nanoarchitecture to achieve superior analytical performance. The nanofabricated system was constructed by depositing a carbon-gold nanoparticle (C-AuNP) layer on a fluorine-doped tin oxide (FTO) electrode via ultrasonic spray pyrolysis, in the first step. The process was followed by the electrochemical growth of gold nanostructures (AuNS) to form a conductive C-AuNP@AuNS nanocomposite. This tailored nanofabrication, dramatically enhanced the electrode’s conductivity and provided an optimal substrate for bioreceptor immobilization. The surface was functionalized with Herceptin antibody for specific cell capture. Quantitative performance was evaluated using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The biosensor demonstrated a wide linear response from 2.5 × 102 to 1 × 104 cells mL⁻¹, an exceptionally low limit of detection (LOD) of 2 cells mL⁻¹, and high specificity against HER2-negative MCF7 cells, confirming minimal non-specific adsorption. The sensor’s robustness was validated by its stable biorecognition layer, which retained functionality for over three months. This work advances the field by integrating a scalable spray pyrolysis step with precise electrochemical nanostructuring to create a high-performance interface. The achieved metrics, combining an ultra-low LOD, and operational stability in complex media, represent a significant improvement over existing HER2 cell sensors. In addition, these results underscore the platform’s strong potential for translation into early, point-of-care cancer diagnostics.
Accurate in vivo microRNA (miRNA) detection is of great significance for disease diagnosis and therapy, but traditional methods face limitations in terms of sensitivity, penetration depth, and dynamic monitoring capabilities. Nanomaterial-based detection technologies provide innovative analytical platforms to overcome these challenges. This review systematically summarizes the research progress on in vivo miRNA detection technologies over the past decade, covering fluorescence detection, near-infrared imaging, magnetic resonance imaging, and multimodal composite detection platform design strategies and performance. The review also analyzes the applications and technical advantages of each method. Finally, the challenges and opportunities in developing these detection platforms are discussed, providing a reference for further research and clinical application of in vivo miRNA detection technologies.
The bioamines spermine and spermidine, which are structurally similar and often coexist in complex matrices, still pose substantial challenges for achieving efficient detection of one another. To address this, a novel coumarin-based fluorescent probe, DX-Cl-CN has been developed. By introducing a chlorine atom and a vinylene-linked dicyanopropene motif as two dual reactive sites, the probe enables specific, differential responses toward spermine and spermidine across various bioamines. In DMSO, its maximum emission wavelength reaches 598 nm. Increasing solvent polarity induces a red shift in emission due to excited-state stabilization and enhanced molecular planarity. When interacting with spermine or spermidine, the probe exhibits a distinctive two-stage blue shift in fluorescence emission: its emission peak first shifts from 598 to 550 nm, then further to 486 nm. Ratiometric fluorescence analysis based on I550/I486 exhibits excellent linearity. Nanofibrous thin films prepared via electrospinning enable naked-eye visualization to discriminate among gaseous biogenic amines. Theoretical calculations revealed a two-step reaction mechanism in which the DX‑Cl‑CN first undergoes a Michael addition to the primary amine of spermine or spermidine, via the vinyl-dicyanide double bond, followed by intramolecular cyclization induced by the secondary amine via chlorine displacement. DX-Cl-N offers dual-application potential in solution and solid-state film systems, providing a new strategy for rapid, visual detection of spermine and spermidine in complex environments.
The development of a highly efficient photoelectrochemical (PEC) platform for the sensitive and selective detection of dopamine (DA) is of significant importance. In this study, an amine-propyl-functionalized perylene diimide (PA-PDI) self-assembly block material was fabricated and demonstrated a pronounced photoanodic current response under visible-light irradiation at 630 nm. Upon introduction of Cu2+, PA-PDI underwent structural reorganization from nanoflakes into nanobelts, leading to the in situ formation of a PA-PDI/CuO p–n heterojunction. This heterojunction markedly enhanced charge separation efficiency, resulting in a remarkable increase in photocurrent. Notably, the presence of DA triggered a substantial decrease in the photocurrent, which was proposed to arise from the likely formation of polydopamine (PDA) on the surface of PA-PDI/CuO via Cu2+-catalyzed oxidation of DA; the resulting PDA layer was suggested to act as an insulating layer and effective electron acceptor, thereby suppressing interfacial electron transfer within the heterojunction. Leveraging this proposed PEC transduction mechanism, a label-free PEC sensor was developed for the quantitative detection of DA, exhibiting a wide linear range from 10− 2 µM to 102 µM (R2 = 0.998) and a low limit of detection of 5.38 nM (S/N = 3). Furthermore, satisfactory recoveries (96.8–100.6
