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
Piezoelectric pumps have garnered significant interest in such systems owing to their compact form factor, ease of integration, rapid response, and precise fluid delivery. However, simultaneously achieving high output and stable flow remains challenging due to internal flow losses and flow field fluctuations. To overcome this limitation, we propose a piezoelectric pump with a flow-concentrating chamber (PPFC) for multifunctional microfluidic applications. The flow-concentrating chamber creates a low-resistance pathway within the pump chamber, which regulates hydraulic resistance distribution and enhances directional fluid transport. The performance of the PPFC was systematically characterized through numerical simulations, prototype fabrication, and experimental measurements, including on-chip particle tracking velocimetry (PTV). Compared with a standard piezoelectric pump, the PPFC achieved an approximately 30
As a third-generation fluoroquinolone antibiotic, levofloxacin (LEV) residue in biological and environmental samples has aroused widespread public concern. In this work, NH2-UiO-66 was in-situ synthesized via a solvothermal route on MoO3 surface. Subsequent covalent modification with ferrocene (Fc) afforded a ratiometric electrochemical sensor denoted as Fc-NH2-UiO-66/MoO3/GCE for LEV quantification. The anchored Fc units not only construct an internal self-calibration system with stable reference signal to greatly improve detection reliability, but also boost the electrical conductivity of the composite electrode. The as-fabricated sensor exhibits favorable analytical performance toward LEV, featuring a wide linear range of 0.6 µM-600 µM and a low limit of detection of 0.032 µM, together with stable anti-interference capability. Moreover, the developed electrode was successfully employed to determine LEV in practical specimens including serum, urine and commercial LEV eye drops. This reliable and sensitive analytical strategy exhibits promising prospects for clinical diagnosis and pharmaceutical analysis.
Arginine surface-engineered 6-aza-2-thiothymine gold nanoclusters (Arg/ATT-AuNCs) via host-guest assembly were synthesized which exhibit exceptional catalytic activity and intense photoluminescence. Arg/ATT-AuNCs enhanced the CL intensity from NaIO4-H2O2 system by 1200-fold. The CL mechanistic studies revealed that Arg/ATT-AuNCs not only accelerated decay of H2O2 to form reactive oxygen species, but also acted as efficient energy acceptors of singlet oxygen (1O2) via a CL resonance energy transfer (CRET) pathway. It was observed that doxorubicin (DOX) quenches the CL signal through an inner filter effect that disrupts the CRET process. Based on this, a straightforward, rapid, and highly sensitive biosensor has been developed for the detection of DOX in human serum samples, achieving a low detection limit of 0.029 µM. The biosensor was applied to DOX determination in human serum samples with recoveries ranging from 91.1 to 106.2
Fluorescent nanozymes have increasingly drawn attention as a unique type of nanozyme-like materials, whose value lies not in a single characteristic but in the combination of catalytic performance and fluorescence within one material system. Traditional nanozyme sensing systems are based on colorimetric detection methods that, although simple in operation, suffer from poor sensitivity and are easily influenced by coloured or turbid samples. The fluorescence approach addresses most of these issues, enabling sensitive detection, real-time monitoring of the signal, and suitability for microscale measurements-all of which play an important role in transferring research laboratory experiments into diagnostic tests at the point of care. In addition to sensitivity, fluorescent nanozymes still preserve such practical characteristics as high stability, long-term shelf life, cost-effective production, and tunability of surface chemistry for modulation of catalytic and fluorescent properties. In this review, recent progress in the field of fluorescent nanozyme-based biosensors has been analysed with an emphasis placed equally on accomplishments and limitations in the area. The classification of fluorescent nanozymes is explored based on different criteria, such as compositional, dimensional, catalytic and fluorescent types, as one single classification approach would be inadequate for describing the existing diversity of fluorescent nanozyme-based sensing platforms. A key aspect that needs to be considered is the catalytic reactions utilised to generate or enhance fluorescence signals, namely, peroxidase-like, oxidase-like and Fenton/Fenton-like mechanisms, with inherent mechanistic benefits and practical challenges associated with their utilisation that are not always addressed properly in experimental work. Potential applications of fluorescent nanozymes have also been discussed, particularly about performance that is relevant for each application domain, rather than just analytical capabilities. Concurrently, various issues are discussed in depth, including substrate specificity, that is often inadequate in most systems, insufficient understanding of catalysis mechanisms in many materials, fluorescence quenching due to biological matrices, and a lack of standardised testing protocols for nanozyme assays. The challenges mentioned above not only pose technical problems but also act as major hurdles for the further development of nanozyme technology to achieve translational validity. This review concludes by discussing strategies for developing highly selective and sensitive fluorescent nanozymes suitable for practical biosensing applications.
Galectin-3 (Gal-3) is a critical biomarker for the diagnosis and prognosis of cardiovascular diseases and tumors, necessitates highly sensitive detection for clinical applications. In this study, a dual-quenching electrochemiluminescence (ECL) immunosensor was developed for the ultrasensitive detection of Gal-3. The sensor employed an N-(4-aminobutyl)-N-ethylisoluminol (ABEI) @Fe3O4@PDA-PdPt composite as an efficient luminophore, where the material’s exceptional conductivity and catalytic properties significantly amplified the ECL signal. For signal quenching, secondary antibody-labeled copper-deficient copper sulfide nanoflowers (Ab2-Cu2−xS NFs) were introduced. These nanoflowers enabled a dual-quenching effect through the synergistic mechanisms of resonance energy transfer (RET) and defect-assisted electron dissipation. A sandwich-type ECL immunosensing platform was constructed by sequentially immobilizing the capture antibody, target antigen, and Ab2-Cu2−xS NFs. Under optimized conditions, the proposed immunosensor demonstrated a broad linear detection range for Gal-3 from 1 pg·mL⁻¹ to 500 ng·mL⁻¹, with an exceptionally low detection limit of 24 fg·mL⁻¹. Additionally, the sensor exhibited outstanding specificity, stability, and reproducibility. This work presents a novel strategy for the highly sensitive detection of Gal-3, leveraging the synergistic dual-quenching mechanism to achieve excellent analytical performance, thereby holding significant promise for clinical diagnostics and early disease monitoring applications. The successful construction of this platform also provides a valuable reference for developing advanced ECL systems for other biomarkers.
A distinctive adsorption behavior of serotonin in ultrastable Y-type molecular sieve (USY) has been found in 13 molecular sieves, which is suggestive of a unique capability of USY as a dispersive solid-phase microextraction (D-µSPE) agent. Experimental analysis and GFN2-xTB calculation reveal that the adsorption of serotonin in USY conforms to Langmuir isotherm model, and the electrostatic interactions and the plausible horizontal adsorption mode between serotonin and USY are main factors for efficient adsorption in solution. Under the optimal conditions, the D-µSPE-LC-MS/MS method shows lower instrumental detection limit and method detection limit at around 0.5 and 0.025 µg L–1 for serotonin, with the intra-day and inter-day precision and recoveries in the range of 2.7–5.1
Three exosome fluorescence-labeling workflows based on azide-functionalized cholesterol anchoring and copper-free click chemistry were systematically optimized and comparatively evaluated. A549 cell-derived exosomes were used as the primary model. By varying the sequence of azide introduction and fluorescent click reaction, one-step, two-step, and three-step protocols were compared. Under the tested conditions, the two-step protocol provided the most favorable overall balance among exosome recovery, fluorescence intensity normalized to exosome particle concentration, dye consumption, reaction volume, and operational simplicity. After labeling, the exosomes retained their typical morphology, particle size distribution, while the representative exosome-associated proteins CD63, CD81, and TSG101 remained detectable. The fluorescence intensity of the labeled exosomes showed a strong linear correlation with particle concentration, supporting its potential for rapid quantitative analysis. Cellular uptake experiments confirmed the feasibility of the labeled exosomes for in vitro imaging, and fluorescence remained detectable during the 24-h in vivo observation period. Overall, this study identifies an optimized two-step workflow for exosome fluorescence labeling and provides a practical approach for exosome visualization and tracking under the evaluated experimental conditions.
Two zinc-based metal-organic frameworks were synthesized via a solvothermal method using ascorbic acid and 1,3,5-benzenetricarboxylic acid. X-ray diffraction analysis revealed that the ascorbic acid composite exhibits two crystalline phases, whereas the other composite exhibits a single monoclinic phase. TEM analysis shows homogeneous nanoparticles ranging from 10 to 90 nm. The biphasic composite emits red-orange fluorescence at 612 nm, with quenching dependent on the concentration of oxytetracycline, reaching a detection limit of 1.86 nM under optimized conditions. It demonstrates exceptional selectivity toward oxytetracycline, with a selectivity factor of 39.3. No interference effect was noted with amino acids or milk ions. The method was successfully applied to tap water and milk samples, with recoveries ranging from 98.34
Microenvironmental viscosity constitutes a critical physical parameter that modulates biological behaviors, material performances and chemical reaction processes. Accordingly, developing fluorescent probes capable of sensitive and visual detection of microenvironmental viscosity is of great significance. This study designed and synthesized a novel viscosity-responsive fluorescent probe (TPA-Q) based on triphenylamine and hydroxyethyl quinolinium iodide. The probe exhibits weak fluorescence in low-viscosity solvents, but in high-viscosity environments or aggregated states, its intramolecular motion is restricted, leading to significant fluorescence enhancement and thus demonstrating excellent aggregation-induced emission (AIE) properties and viscosity sensitivity. Utilizing this unique characteristic, we successfully utilized this single probe for multi-scenario applications. For food science field, TPA-Q could evaluate the thickening effects of various thickening agents and distinguish the viscosity differences of the actual samples. Moreover, the probe can be used for fingerprint imaging through the method of solution immersion with low concentration. Furthermore, bioimaging experiments verified that TPA-Q could target mitochondria and monitor the viscosity fluctuations under various stimuli. As an AIE probe, TPA-Q displays strong flexibility and practical value of for bioimaging, fingerprint visualization and food quality monitoring.
Amaranth (AM) is a widely used synthetic azo food colorant that poses severe toxicological risks upon excessive consumption, creating an urgent need for its ultra-sensitive detection. We report a high-performance electrochemical sensor based on the electrostatic co-aggregation of V2O3@NC and NHCS for the high-fidelity quantification of AM. A unique “capture-and-catalysis” synergistic mechanism governs this composite interface. Specifically, the highly porous NHCS framework provides exceptional capacity to capture and pre-concentrate target molecules while acting as a highly conductive “electronic bridge.” Subsequently, the abundant mixed-valence (V3+/V5+) sites of the V2O3@NC serve as a robust electrocatalytic engine to drive the catalysis, significantly amplifying the AM oxidation signal. Combining electrochemical kinetic analysis with DFT calculations (including HOMO and MEP), we reveal that this electrocatalytic evolution proceeds via a directional 1 H+/2e− transfer mechanism. Under optimal conditions, the V2O3@NC/NHCS sensor exhibits a broad linear range (0.01–12 µM) and an extremely low LOD of 0.80 nM. Practical analysis of commercial beverages yielded recoveries of 95.0
