ACS Sensors最新文献

Ethylene glycol (C₂H₆O₂) is a widely used yet toxic compound, requiring energy-efficient detection methods beyond prevalent high-temperature sensors. Here, an imine covalent organic framework (COF-TPC) was synthesized at room temperature (RT) using 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (Tp) and 2,5-dichlorobenzene-1,4-diamine (Pa-Cl) as ligands, with acetic acid as a catalyst. The structure-property relationship was investigated by controlling Schiff base reaction time (1-70 h), yielding four sensors (COF-T-30, COF-T-40, COF-T-50, and COF-T-60) for testing. Gas sensing data revealed that the COF-T-50 sensor exhibited a response of 6107% to 500 ppm C₂H₆O₂, significantly outperforming the other sensors. It also exhibited outstanding selectivity toward C₂H₆O₂ among 13 gases, along with excellent repeatability and moisture resistance. DFT calculations elucidated the adsorption mechanism and the origin of its exceptional selectivity. This work provides a new approach for rapid, stable C₂H₆O₂ detection using COFs, expanding their application scope.

Ion gradients play a vital role in cellular signaling, mechanobiology, and organ-level homeostasis. Despite their importance, accurately mapping these spatial gradients at biologically relevant length scales remains a challenge due to the limited tunability and spatial resolution of conventional fluorescent sensors. Here, we present a DNA origami-based sensor (NanoDyn) with tunable sensitivity that enables the detection of Na⁺-ion gradients across micron to millimeter scales. The sensor design leverages programmable DNA base-pairing interactions to control both the detection range and sensitivity of the sensor. Using fluorescence spectroscopy, we show that NanoDyn can exhibit programmable sensing ranges spanning ∼100-1675 mM Na⁺. To validate the ability to quantify ion gradients and investigate their spatial resolution, we use a custom microfluidic gradient generator, showing that NanoDyn can resolve changes in ion gradients across multiple scales and over distances as little as ∼6 μm, which, here, is limited by the resolution of the microfluidic device. By highlighting the potential of DNA nanodevices as multiscale, tunable ion-gradient sensors, together with their biocompatibility, high temporal resolution, and potential for multiplexed functionalization, this work expands on the role that DNA nanodevices can play in spatial sensing to study ion-mediated processes in microenvironments. Overall, this work advances DNA nanotechnology as a versatile foundation for biosensing with capabilities to probe ion-mediated signaling in health and disease.

Two-dimensional conductive MOFs (2Dc-MOFs), with their large specific surface area and pore size, demonstrate great potential as chemiresistive gas sensors for the portable detection of exhaled biomarkers, which is crucial for the early diagnosis and management of respiratory diseases. However, their clinical application remains limited by insufficient sensitivity, poor reversibility, and inadequate environmental/mechanical stability. Here, we report a high-performance sensor based on templated two-dimensional conductive MOF (T-2Dc-MOF) aerogels for the detection of fractional exhaled nitric oxide (FeNO). The sensor was fabricated by in situ conversion of three-dimensional insulating MOF templates into 2Dc-MOFs, followed by integration with carboxylated carbon nanotubes (C-CNTs) to construct heterostructures that regulate hole density in the sensing system, and subsequent embedding of the composite into a polymer aerogel. This design achieves an ultralow detection limit (3.0 ppb), rapid response/recovery (4 s/9 s, over three times faster than current sensors), and outstanding durability-retaining 83.4% of its performance after 500 compression cycles at 70% relative humidity, compared with only 3.2% in the control group. The developed portable FeNO monitor enables real-time tracking of patients' FeNO levels. By combining heterostructure engineering with sensor model construction, this study advances intelligent healthcare and home-based respiratory management systems.

Achieving a single-molecule level for RNA detection remains a significant challenge in point-of-care settings. We present CCHP, a Cas13-Csm6-horseradish peroxidase three-step enzymatic cascade assay that enables amplification-free RNA detection with a simple colorimetric readout at 450 nm within 1 h under standard conditions. Across diverse viral and non-coding targets, CCHP spans a dynamic range of 10-10⁷ copies per reaction, showing strong agreement with RT-qPCR on serial dilutions (|r| ≈ 0.95). In a small blinded feasibility comparison using extracted RNA from infected versus uninfected cells, CCHP showed concordance with the reference method (κ = 1.0). In representative matrices spiked with synthetic RNA and without nucleic acid extraction or purification, positive events were observed near the single-molecule input level for H1N1-NP in oropharyngeal swabs and for SARS-CoV-2-N in oropharyngeal swabs and plasma, consistent with stochastic initiation of the cascade by single-molecule inputs under Poisson-limited conditions. Under these conditions, the assay maintains stable low-copy detection performance. A physics-guided minimal model integrating deterministic kinetics and stochastic partition statistics informed assay design and sensitivity projection, which were subsequently validated experimentally. By coupling single-molecule-level initiation with ultralow-copy detection and operational simplicity, CCHP advances point-of-care RNA diagnostics and surveillance.

Rapid and sensitive detection of antibiotic-resistant bacteria (ARB) remains a critical challenge in clinical and public health settings. This study describes the successful construction of a portable DNA activator-triggered entropy-driven catalysis-modulated CRISPR/Cas12a-based sensor (PSDA) for the ultrasensitive and rapid detection of multiple ARB. This PSDA platform utilizes a CRISPR/Cas12a-mediated signal transduction strategy, in which a target-specific DNA activator initiates an entropy-driven dynamic DNA network for signal amplification. To further enhance detection performance, a 3D-printed microfluidic chip device with a smartphone-based readout system has been integrated into the sensor, using green-emitting Zn₂GeO₄:Mn persistent luminescent nanoparticles as a novel molecular beacon for fluorescence enhancement. This platform enables the simultaneous detection of methicillin-resistant Staphylococcus aureus, carbapenem-resistant Pseudomonas aeruginosa, and Klebsiella pneumoniae carbapenemase 2 (KPC-2)-expressing Klebsiella pneumoniae (KPC-2 KP) with a broad dynamic range (1-10⁷ CFU/mL), an ultralow detection limit (1 CFU/mL), and rapid analysis (∼45 min). The assay results are also highly consistent with those of conventional plate counting methods (95.48-115.15%). Overall, this study presents a cost-effective, rapid-response biosensing platform for the simultaneous detection of multiple ARB, with direct applications in clinical diagnostics, food safety monitoring, and environmental surveillance.

The rational design of chiral interfaces that emulate the sophisticated recognition of biological systems remains a persistent challenge in sensing, demanding molecular recognition with high specificity and affinity. Progress in this area is crucial for advancing sensing capabilities, particularly in the precise quantification of biomarkers, including urinary L-cystine for human cystinuria and cellular glutathione disulfide (GSSG) for vivo oxidative stress. Herein, we report a homochiral metal-organic framework (MOF), Zn-TMTyrBa, engineered as an electrochemical sensing platform for the specific detection of L-cystine and GSSG. By leveraging synergistically integrated binding sites, this MOF achieves ultra-low detection limits (46.1 pM for L-cystine and 0.12 pM for GSSG) and unprecedented chiral selectivity between cystine enantiomers (I_L/I_D = 55.2; ΔE = 200 mV). The sensor demonstrates reliable quantitative capability for target analytes in complex matrices, including racemic mixtures, artificial cerebrospinal fluid, and fetal bovine serum, and has been applied to quantify L-cystine in human urine, yielding results that fall within the typical physiological range for healthy individuals. Mechanistic studies reveal that the superior performance arises from a synergy between the configurational match of the chiral microenvironment of the MOF with the target analytes and the complementary specific binding interactions of its integrated multifunctional groups with corresponding analyte moieties. This work establishes a viable strategy that utilizes multisite synergy in MOFs to significantly enhance sensing specificity, thereby providing new insights for the design of high-performance chiral sensing interfaces.

Flexible pressure sensors hold great promise for applications in motion monitoring and human signal recognition. However, conventional devices with fixed structure-performance coupling often fail to meet the diverse demands of different body sites and multi-scenario monitoring. Herein, we propose a polyvinyl alcohol (PVA)-hydroxyethane diphosphonic acid (HEDP) hydrogel iontronic sensor (PHHIS) with modulus programmability regulated by the Hofmeister effect. By introducing weakly hydrated I^- and strongly hydrated SO₄^2-, we constructed soft-mode and hard-mode PHHIS, enabling precise acquisition of both low- and high-pressure human signals. The soft mode achieves ultrahigh sensitivity (238.4 kPa^-1, 0-50 kPa), ideal for subtle signals such as pulse and vocalization, while the hard mode maintains stable linearity (1.5 kPa^-1, 0-800 kPa), suitable for limb movement monitoring. Eight classes of human signals were precisely recognized with 100% accuracy through feature extraction combined with linear discriminant analysis, hierarchical cluster analysis, and artificial neural network analysis. This work demonstrates the promise of Hofmeister effect-regulated hydrogel design for programmable modulus control, enabling high-performance signal recognition and advancing flexible iontronic sensors for intelligent health monitoring.

Internet of Things advancement requires sustainable, environmentally adaptive self-powered sensing. Triboelectric nanogenerators (TENGs) are promising self-powered sensors but exhibit poor environmental compatibility, humidity stability, and contact/noncontact sensing efficiency. Herein, a composite aerogel was fabricated using ammonium-salt-modified cellulose fibers and microfibrillated cellulose to form a multiscale entangled network skeleton, incorporating plant-leaf-derived ash (PLSH) as a functional dopant via low-temperature freezing (-5 °C) and ambient drying. The aerogel exhibits excellent mechanical properties, recyclability, and biodegradability. Synergistic PLSH and ammonium salt modification enhances charge density through ion/interface polarization, enabling an aerogel-based TENG to deliver outstanding electrical output performance: an open-circuit voltage of 442.9 V, a maximum power density of 154.5 μW/cm², high pressure sensitivity (20.65 V/N, 1-10N), remarkable humidity adaptability, and fatigue resistance (stability over 14,000 cycles at 83% RH). The output performance was effectively tuned by adjusting ammonium salt concentration, PLSH content, and MFC dosage. The process accommodates diverse PLSH sources. The TENG powers 632 LEDs and enables wireless contact/noncontact modes for human-activity monitoring. This work provides a scalable route to eco-compatible, humidity-adaptive cellulose TENGs for energy harvesting and intelligent multifunctional sensing.

The pressing need for rapid, direct diagnostic tests for infectious diseases is exemplified by Lyme disease. Human cases of this tick-vectored bacterial infection continue to rise globally, yet the conventional laboratory diagnostic is inadequate in capturing early disease, treatment outcome, and reinfection. Direct detection of a pathogen marker from human biological fluid is a coveted strategy that has, until now, presented immense challenges due to the low circulating burden of the Lyme Borrelia pathogen. The current study demonstrates specific, label-free, quantitative, real-time sensing of Borrelia outer surface protein A (OspA) in 0.5 μL whole blood samples with the recently introduced meta-nano-channel field-effect transistor (MNC-FET) biosensor. The MNC-FET biosensor is specifically designed to address the transduction of nonuniform surface distribution of molecular interactions while maintaining the biomolecules in thermal and electrochemical equilibria. The sensing is performed directly in unprocessed blood and without the conventionally employed premeasurement washings, rendering the proposed technology suitable for a fast, simple, self-use diagnostic kit for Lyme disease. The study demonstrates OspA sensing with a limit of detection of 1 fg/mL, a dynamic range of 8 orders of magnitude, and with excellent sensitivity and linearity. The MNC-FET biosensor is fabricated in a complementary metal-oxide-silicon (CMOS) process ensuring superb electronic grade in terms of noise levels and amplification, robustness, stability, and ultimate miniaturization suitable for future multiplexed sensing. The unique MNC-FET biosensor design addressing challenges associated with molecular sensing, coupled with CMOS technology potential for high volume production of high-end chips, provides a viable technology for a low-cost Lyme disease diagnostic kit with excellent quantitative performance in ultra-small unprocessed blood drops.