Detection Range Research Articles

The synthesis and application of MRI-fluorescence dual mode materials with absorption ability on quantitative analysis of malachite green

The histidine/Mn3O4/CdTe quantum dots (HMQ) composites with good magnetic resonance/fluorescent imaging and absorbance performance have been prepared based on biomimetic mineralization method, on which the peptide served as a carrier to guide the formation of Mn3O4 and CdTe quantum dots. The fluorescence of HMQ could be quenched by malachite green (MG), whereas the magnetic resonance signal (T1-MRI) was enhanced. Also, there is a linear correlation between the concentrations of MG added and the decreasing fluorescence intensity of HMQ (F0/F), the detection range is 0.06851–1.096 nmol l−1, and the LOD is 0.02750 nmol l−1. The corresponding T1WI detection range is 13.7–95.9 nmol l−1, and the LOD is 7.617 nmol l−1. Furthermore, the fluorescence quenching spectra of the HMQ adopted by MG have been analyzed, of which the data fit well with the law of pseudo-second-order kinetics, indicating that the prepared HMQ has good absorption properties. Therefore, HMQ could be used as an MRI/fluorescent dual sensor for the detection of MG.

Robust Indoor Positioning with Smartphone by Utilizing Encoded Chirp Acoustic Signal.

Recently, indoor positioning has been one of the hot topics in the field of navigation and positioning. Among different solutions on indoor positioning, positioning with acoustic signals has its promise due to its relatively high accuracy in the line of sight scenarios, low cost, and ease of being implemented in smartphones. In this work, a novel acoustic positioning method, called RATBILS, is proposed, in which encoded chirp acoustic signals are modulated and transmitted by different acoustic base stations. The smartphones receive the signals and perform the following three steps: (1) preprocessing; (2) time of arrival (TOA) estimation; and (3) time difference of arrival (TDOA) calculation and location estimation. In the preprocessing stage, we use band pass filters to filter out low-frequency noise from the environment. At the same time, we perform a signal decoding function in order to lock onto the positioning source. In the TOA estimation stage, we conduct both coarse and fine detection to enhance the accuracy and robustness of TOA estimation. The primary goal of coarse detection is to establish a noise range for fine detection. The main objective of fine detection is to emphasize the intensity of the first arrival diameter and resistance with multipath and non-line-of-sight (NLOS) caused by human body obstruction. In the TDOA calculation and location estimation stage, we estimate the TDOA based on the TOA estimation and then use the TDOA results for position estimation. In order to evaluate the performance of the proposed RATBILS system, two indoor field tests are carried out. The test results show that the RATBILS system achieves a positioning error of 0.23 m at 92% in region 1 of scene 1 and is superior to the traditional threshold method. The RATBILS system achieves a positioning error of 0.56 m at 92% in region 2 of scene 1 and is superior to the traditional threshold method. In scene 2, the maximum average positioning error was 1.26 m, which is better than the 3.33 m and 3.87 m of the two traditional threshold methods.

First detection of Jingmen tick virus in Corsica with a new generic RTqPCR system

Jingmen tick virus (JMTV) is a recently discovered segmented RNA virus, closely related to flaviviruses. It was identified for the first time in 2014, in China and subsequently in Brazil. Following this discovery, JMTV-related sequences have been identified in arthropods, vertebrates (including humans), plants, fungus, and environmental samples from Asia, America, Africa, Europe, and Oceania. Several studies suggest an association between these segmented flavi-like viruses, termed jingmenviruses, and febrile illness in humans. The development of rapid diagnostic assays for these viruses is therefore crucial to be prepared for a potential epidemic, for the early detection of these viruses via vector surveillance or hospital diagnosis. In this study, we designed a RT-qPCR assay to detect tick-associated jingmenviruses, validated it and tested its range and limit of detection with six tick-associated jingmenviruses using in vitro transcripts. Then, we screened ticks collected in Corsica (France) from different livestock species, in order to determine the distribution of these viruses on the island. In total, 6269 ticks from eight species were collected from 763 cattle, 538 horses, 106 sheep, and 218 wild boars and grouped in 1715 pools. We report the first detection of JMTV in Corsica, in Rhipicephalus bursa, Hyalomma marginatum and R. sanguineus ticks collected from cattle and sheep. The highest prevalence was found in the Rhipicephalus genus. The complete genome of a Corsican JMTV was obtained from a pool of Rhipicephalus bursa ticks and shares between 94.7% and 95.1% nucleotide identity with a JMTV sequence corresponding to a human patient in Kosovo and groups phylogenetically with European JMTV strains. These results show that a Mediterranean island such as Corsica could act as a sentinel zone for future epidemics.

Development and Validation of LC-MS method for determination of Genotoxic Impurity N, O-Dimethyl Hydroxylamine by Chemical Derivatization in Investigational Drug Substance

Background: Conventional chromatographic techniques and direct analysis pose challenges in detecting certain potential genotoxic impurities, primarily due to factors such as the absence of a chromophore, low molecular weight, and insufficient chromatographic retention caused by high polarity. One such compound, N, O-Dimethyl Hydroxylamine, is of particular concern due to its structural similarity to Hydroxylamine, a recognized genotoxic impurity. Method: In response to this challenge, this article proposes a rapid derivatization approach utilizing Dansyl Chloride, coupled with Liquid Chromatography-Mass Spectrometry (LC-MS) for the detection of the derivatized product in the investigational drug substance. To preserve confidentiality, the specific name and structure of the drug substance have not been disclosed. Results: The developed method exhibits a reliable range of detection spanning from 5 ppm to 60 ppm with respect to a nominal drug substance concentration of 10 mg/mL. Throughout the method validation process, it demonstrated specificity, sensitivity, linearity, accuracy, and repeatability. Conclusion: This methodology presents a versatile solution applicable in scenarios where N, ODimethyl Hydroxylamine serves as a reagent in the synthesis process of drug substances.

One-step cascade amplification system based on entropy-driven catalysis and DNAzyme triggered DNA walker for label-free detection of acetamiprid

Herein, an electrochemical aptasensor for highly sensitive detection of acetamiprid (ACE) was constructed based on a one-step cascade amplification strategy. This innovative strategy integrated DNA walker containing DNAzyme sequence into entropy-driven catalysis (EDC) system. The trigger strand was released by aptamer-specific binding to ACE, initiating the EDC amplification circuit and delivering DNA walker strands. The dangling DNA walker continuously bound and cleaved hairpin substrate to form G-quadruplex fragments with the assistance of Mg2+. The G-quadruplex fragments folded and captured hemin to form multitudinous G-quadruplex/hemin complexes in the presence of K+, generating significantly enhanced current, enabling enzyme-free, label-free and highly sensitive detection of ACE, with a linear detection range of 100 fM to 50 nM and a detection limit of 68.36 fM (S/N = 3). The constructed aptasensor achieved the reliable detection of ACE in vegetable soil and cucumber samples, demonstrating its potential application prospects in environmental protection and food supervision.

A Label-Free Electrochemical Aptamer Sensor for Sensitive Detection of Cardiac Troponin I Based on AuNPs/PB/PS/GCE.

Cardiac troponin I (cTnI) monitoring is of great value in the clinical diagnosis of acute myocardial infarction (AMI). In this paper, a highly sensitive electrochemical aptamer sensor using polystyrene (PS) microspheres as the electrode substrate material in combination with Prussian blue (PB) and gold nanoparticles (AuNPs) was demonstrated for the sensitive and label-free determination of cTnI. PS microspheres were synthesized by emulsion polymerization and then dropped onto the glassy carbon electrode (GCE); PB and AuNPs were electrodeposited on the electrode in corresponding electrolyte solutions step by step. The PS microsphere substrate provided a large surface area for the loading mass of the biological affinity aptamers, while the PB layer improved the electrical conductivity of the modified electrode, and the electroactive AuNPs exhibited excellent catalytic performance for the subsequent electrochemical measurements. In view of the above mentioned AuNPs/PB/PS/GCE sensing platform, the fabricated label-free electrochemical aptamer sensor exhibited a wide detection range of 10 fg/mL~1.0 μg/mL and a low detection limit of 2.03 fg/mL under the optimal conditions. Furthermore, this biosensor provided an effective detection platform for the analysis of cTnI in serum samples. The introduction of this sensitive electrochemical aptamer sensor provides a reference for clinically sensitive detection of cTnI.

Graphene oxide functionalized with silatrane as probe for electrochemical recognition of acetaminophen in pharmaceuticals tablets

Acetaminophen, commonly known as paracetamol, is a widely used analgesic and antipyretic drug that is frequently found in over-the-counter and prescription medications. Due to its extensive use, precise monitoring of acetaminophen levels is crucial for ensuring patient safety, especially to prevent accidental overdoses which can lead to severe liver damage. In this study, a novel electrochemical sensor based on graphene oxide (GO) functionalized with silatrane was developed for the detection of acetaminophen. The hybrid material was synthesized and electrodeposited on a glassy carbon electrode, providing a highly selective, sensitive, and reproducible platform for acetaminophen detection. The sensor exhibited a linear detection range from 2.5 to 100 μM with a limit of detection of 84.8 nM. The effectiveness of this GO-based sensing platform was demonstrated through the successful quantification of acetaminophen in pharmaceutical tablets such as Dolo 650, Paracip, and Crocin. The results highlight the potential application of this sensor in quality control and safety monitoring of pharmaceutical formulations, ensuring accurate determination of acetaminophen content.

Dual-Responsive MnO2-Loaded Carbonaceous Nanobottle Motors Fabricated by Interfacial Superassembly for On-The-Fly MicroRNA Sensing.

Diverse nanomotors with advanced motion manipulation have been proposed to revolutionize the way problems in many fields are solved. However, rational and controllable synthetic methods of multifunctional nanomotor are still limited. Herein, dual-responsive MnO2-loaded carbonaceous nanobottle motors (MnO2 NBMs) are developed through an interfacial superassembly strategy. Asymmetric carbonaceous nanobottles are first synthesized, and the reductive carbonaceous shell induces an oxidation-reduction reaction with KMnO4 for in-situ growth of MnO2 nanosheets, which enables the nanomotor to perform either self-diffusiophoretic or self-thermophoretic motion in response to H2O2 and near-infrared light, respectively. Inspired by bioaffinity sensing, the nanomotors are sequentially assembled with functional nanoparticles and hairpin DNA to construct swimming functional MnO2 NBMs (MnO2 FNBMs) probes. The probes can move around complex samples to improve target miRNA transport and accelerate receptor-target interaction. Coupling with the photocurrent-signal amplification, the self-assembly of photoelectrochemical (PEC) biosensors has been achieved for sensitive microRNA detection. Trace amounts of miRNA-155 can be quickly detected with a wide detection range (100 fM to 100nM). Moreover, the direct detection of microRNA in tumor cell lysates by the biosensor is demonstrated. Given the merits of automation and miniaturization, the proposed strategy provides a promising method for fast and effective self-assembly of biosensors.

Electrochemical sensor for acetylcholine detection based on WO3 nanorods-modified glassy carbon electrode

Acetylcholine (ACH) is one of the excitatory neurotransmitter in the human body. It is the most abundant neurotransmitter responsible for triggering the activation of postsynaptic neurons, leading to an excitatory response. ACH plays a crucial role in various physiological processes, including muscle contraction, autonomic nervous system regulation, and cognitive functions such as learning and memory. In this study, an electrochemical sensor was prepared based on WO3 nanorods modified glassy carbon electrode for the detection of ACH. The WO3 nanorods provided excellent properties for the electrochemical determination of ACH. The proposed sensor exhibited a wide linear detection range of (0.1 to 400.0 µM) and a low detection limit of 0.025 µM for ACH. These results demonstrate the sensor's high sensitivity in detecting this important neurotransmitter. In addition the developed sensor showed good ability for ACH determination in real samples. This study offers an innovative strategy for the electrochemical detection of ACH, showcasing the potential of nanomaterials in the development of advanced sensing technologies.

Hybrid recognition-enabled ratiometric electrochemical sensing of Staphylococcus aureus via in-situ growth of MOF/Ti3C2Tx-MXene and a self-reporting bacterial imprinted polymer

Rapid and effective analysis of foodborne bacteria is crucial for preventing and controlling bacterial infections. Here, we present the synthesis of a self-reporting molecularly imprinted polymer (MIP) as an inner reference probe (IR), and the in-situ growth of metal-organic frameworks on transition metal carbon nitrides (MOF/Ti3C2TX-MXene) as a signaling nanoprobe (SP). These advancements are then applied in a ratiometric electrochemical bioassay for Staphylococcus aureus (S. aureus) using a hybrid recognition mechanism. When S. aureus is present, the aptamer-integrated MIP (MIP@Apt) efficiently captures it, followed by binding with SP to form a sandwich structure. This leads to decreased current response of IR (IIR) and increased current intensity of SP (Isp), enabling quantification through utilization of the ISP to IIR ratio. The biosensor shows a wide detection range (10–108 CFU mL−1) and low detection limit of 1.2 CFU mL−1. Its feasibility for testing complex samples indicates the potential application in food analysis.

Ecological Assessment of Soil Samples Around Refuse Dump Sites Within the Metropolis of Enugu State, Nigeria

This study looked at assessing the impact of solid wastes within Enugu metropolis on heavy metal concentrations and otherphysicochemical properties of soil samples from the site locations. Physicochemical analysis of the soil from the respectiverefusedump sites showed pH of 4.24, 6.3 and 5.87 respectively in the presence of the control experiment which maintained atpH of 7.6 throughout the experiment. Soil conductivity of the respective refuses ites within Enugu municipal showed a progressive increase of soil conductivity. Mineral contents were found in the following order: Cl>Ca>Mg>K>PO<sub>3</sub>. Heavy metals of Hg, As and Cd were found at below detectable limit range (BDL) in both the sampled soils from the respective refuse dumpsite andcontrol experiment. Cu, and Pb were significantly high in all the sampled soil from the dumpsites however, Cd was only detected in the soil sample from refuse dump III. Fe showed a progressive decrease across the dumpsites oil samples.

Fabrication of a Heptapeptide-Modified Poly(glycidyl Methac-Rylate) Nanosphere for Oriented Antibody Immobilization and Immunoassay

Oriented antibody immobilization has been widely employed in immunoassays and immunodiagnoses due to its efficacy in identifying target antigens. Herein, a heptapeptide ligand, HWRGWVC (HC7), was coupled to poly(glycidyl methacrylate) (PGMA) nanospheres (PGMA-HC7). The antibody immobilization behavior and antigen recognition performance were investigated and compared with those on PGMA nanospheres by nonspecific adsorption and covalent coupling via carbodiimide chemistry. The antibodies tested included bovine, rabbit, and human immunoglobulin G (IgG), while the antigens included horseradish peroxidase (HRP) and β-2-Microglobulin (β2-MG). The nanospheres were characterized using zeta potential and particle size analyzers, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and reversed-phase chromatography, proving each synthesis step was succeeded. Isothermal titration calorimetry assay demonstrated the strong affinity interaction between IgG and PGMA-HC7. Notably, PGMA-HC7 achieved rapid and extremely high IgG adsorption capacity (~3 mg/mg) within 5 min via a specific recognition via HC7 without nonspecific interactions. Moreover, the activities of immobilized anti-HRP and anti-β2-MG antibodies obtained via affinity binding were 1.5-fold and 2-fold higher than those of their covalent coupling counterparts. Further, the oriented-immobilized anti-β2-MG antibody on PGMA-HC7 exhibited excellent performance in antigen recognition with a linear detection range of 0–5.3 μg/mL, proving its great potential in immunoassay applications.

Fungi-derived Chitosan-CTAB composite-based electrode for electrochemical simultaneous detection of Cd (II) and Pb (II)

Organic polymers have found diverse applications in the industrial and scientific world. One such application is using chitosan-based electrochemical sensors, which have gained rapid popularity due to their unique properties. To further enhance the material's porosity and adsorption capacity, the incorporation of a surfactant into the film has been explored. This study focuses on a rarely investigated combination of fungi-derived chitosan and cationic surfactant N-Cetyl-N, N, N-trimethyl-ammonium bromide (CTAB). The resultant composite was transformed into a thin film on the surface of a graphite electrode, by drop casting method, followed by curing at 65 °C hot air. The low-cost sensor thus obtained was characterized by electrochemical studies, and surface study techniques including AFM, SEM, and XPS. The results showed the properties of the film were strongly governed by the ratio of components in the composite. Under optimal conditions, the affinity for composite film increased 3 to 4 folds for Pb and Cd. The developed electrochemical sensors had a limit of detection of 0.317 μM and 0.572 μM for Pb and Cd respectively. The linear range of detection was found to be 1 × 10−6 M to 1.2 × 10−4 M for Pb (II) and 2 × 10−6 M to 1.4 × 10−4 M for Cd (II).

Bioflocculant polymer reduced CuO/NiO binary transition metal oxide nanocomposite: Application as an effective non-enzymatic glucose sensor

A bimetallic copper oxide/nickel oxide nanocomposite (CuO/NiO NCs) was synthesized via direct carbonization method by using microbial polymer as reducing agent. This nanocomposite was employed as a viable non-enzymatic electrocatalyst in the glucose detection. It was completely characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopic (EDX) methods and revealed the obtained porous nanoflower morphology with particle sizes of 100–200 nm in a monoclinic face-centered cubic crystalline structure. FT-IR spectra confirmed the presence of functional groups and the purity of the nanocomposite. Electrocatalytic performance for glucose oxidation was evaluated through cyclic voltammetric (CV) and amperometric i-t techniques. The observation demonstrated that the CuO/NiO NCs exhibited a remarkable electro-oxidation activity against glucose, attributed to the synergistic effects of the bimetallic components. As an electrode surface modifier, the CuO/NiO NCs facilitated an enhanced glucose oxidation over a linear range of 1–9 mM via CV, while amperometric i-t measurements achieved a detection range from 0.04 μM to 4.86 mM in a 0.1 M NaOH (pH ∼ 13) electrolyte solution. These eco-friendly and in-expensive nanoflowers displayed excellent selectivity, stability, and reproducibility, underscoring their potential in diabetes monitoring and the subsequent scientific analysis.

Zero-crosstalk silicon photonic refractive indexsensor with subwavelength gratings.

Silicon photonic index sensors have received significant attention for label-free bio and gas-sensing applications, offering cost-effective and scalable solutions. Here, we introduce an ultra-compact silicon photonic refractive index sensor that leverages zero-crosstalk singularity responses enabled by subwavelength gratings. The subwavelength gratings are precisely engineered to achieve an anisotropic perturbation-led zero-crosstalk, resulting in a single transmission dip singularity in the spectrum that is independent of device length. The sensor is optimized for the transverse magnetic mode operation, where the subwavelength gratings are arranged perpendicular to the propagation direction to support a leaky-like mode and maximize the evanescent field interaction with the analyte space. Experimental results demonstrate a high wavelength sensitivity of - 410nm/RIU and an intensity sensitivity of 395dB/RIU, with a compact device footprint of approximately 82.8μm2. Distinct from other resonant and interferometric sensors, our approach provides an FSR-free single-dip spectral response on a small device footprint, overcoming common challenges faced by traditional sensors, such as signal/phase ambiguity, sensitivity fading, limited detection range, and the necessity for large device footprints. This makes our sensor ideal for simplified intensity interrogation. The proposed sensor holds promise for a range of on-chip refractive index sensing applications, from gas to biochemical detection, representing a significant step towards efficient and miniaturized photonic sensing solutions.

Multi-Frequency Asymmetric Absorption-Transmission Metastructures-Photonic Crystals and Their Application as a Refractive Index Sensor.

In this paper, a kind of metastructure-photonic crystal (MPC) with multi-frequency asymmetric absorption-transmission properties is proposed. It is composed of various dielectric layers arranged in a periodically tilting pattern. When electromagnetic waves (EMWs) enter from the opposite direction, MPC shows an obvious asymmetry. EMWs are absorbed at 13.71 GHz, 14.37 GHz, and 17.10 GHz in forward incidence, with maximum absorptions of 0.919, 0.917, and 0.956, respectively. In the case of backward incidence, transmission above 0.877 is achieved. Additionally, the MPC is utilized for refractive index (RI) sensing, allowing for wide RI range detection. The refractive index unit is denoted as RIU. The RI detection range is 1.4~3.0, with the corresponding absorption peak variation range being 17.054~17.194 GHz, and a sensitivity of 86 MHz/RIU. By adjusting the number of MPC cycles and tilt angle, the sensing performance and operating frequency band can be tailored to meet various operational requirements. This MPC-based RI sensor is simple to fabricate and has the potential to be used in the development of high-performance and compact sensing devices.

A cooperative perception based adaptive signal control under early deployment of connected and automated vehicles

Connected vehicle-based adaptive traffic signal control requires certain market penetration rates (MPRs) to be effective, usually exceeding 10%. Cooperative perception based on connected and automated vehicles (CAVs) can effectively improve overall data collection efficiency and reduce required MPR. However, the distribution of observed vehicles under cooperative perception is highly skewed and imbalanced, especially under very low CAV MPRs (e.g., 1%). To address this challenge, this paper proposes a novel deep reinforcement learning-based adaptive traffic signal control (RL-TSC) method that integrates a traffic flow model, known as the cell transmission model (CTM), denoted as CAVLight. Traffic states estimated from the CTM are integrated with the data collected from the cooperative perception environment to update the states in the CAVLight model. The design of reward function aims for reducing total vehicle delays and stabilizing agent behaviors. Extensive numerical experiments under a real-world intersection with varying traffic demand levels and CAV MPRs are conducted to compare the performance of CAVLight and other benchmark algorithms, including a fixed-time controller, an actuated controller, the max pressure model, and an optimization-based adaptive TSC. Results demonstrate the superiority of CAVLight in performance and generalizability over benchmarks, especially under 1% CAV MPR scenario with high traffic demands. The influence of CTM integration on CAVLight is further explored through RL agent policy visualization and sensitivity analysis in CTM parameters and CAV perception capabilities (i.e., detection range and detection accuracy).

High-Resolution Dipole Remote Detection Logging Based on Optimal Nonlinear Frequency Modulation Excitation.

In order to improve the detection range and imaging resolution of dipole remote detection logging, an optimal nonlinear frequency modulation (ONLFM) excitation method is proposed in this paper. In this method, the optimal waveform model of the sound source is designed with objective functions of SNR and resolution to obtain the highest resolution under the condition of the required SNR. This optimal model is a multi-constraint optimization problem, and the simulated annealing method has been used to solve it. Solving the optimal model can obtain the optimal spectrum, and the ONLFM waveform can be designed by using the stationary phase principle. Compared with the electric pulse sound source used in traditional technology, this ONLFM sound source can improve the energy and extend the frequency band range of the reflected wave, which can provide the higher resolution and SNR. The simulation results show that the ONLFM sound source can effectively improve the SNR and resolution of the reflected wave, and the detection range and imaging resolution of dipole shear wave remote detection will be improved.

Manganese Sulfanyl Porphyrazine-MWCNT Nanohybrid Electrode Material as a Catalyst for H2O2 and Glucose Biosensors.

The demetallation reaction of sulfanyl magnesium(II) porphyrazine with N-ethylphthalimide substituents, followed by remetallation with manganese(II) salts, yields the corresponding manganese(III) derivative (Pz3) with high efficiency. This novel manganese(III) sulfanyl porphyrazine was characterized by HPLC and analyzed using UV-Vis, MS, and FT-IR spectroscopy. Electrochemical experiments of Pz3 conducted in dichloromethane revealed electrochemical activity of the new complex due to both manganese and N-ethylphthalimide substituents redox transitions. Subsequently, Pz3 was deposited on multiwalled carbon nanotubes (MWCNTs), and this hybrid material was then applied to glassy carbon electrodes (GC). The resulting hybrid electroactive electrode material, combining manganese(III) porphyrazine with MWCNTs, showed a significant decrease in overpotential of H2O2 oxidation compared to bare GC or GC electrodes modified with only carbon nanotubes (GC/MWCNTs). This improvement, attributed to the electrocatalytic performance of Mn3+, enabled linear response and sensitive detection of H2O2 at neutral pH. Furthermore, a glucose oxidase (GOx)-containing biosensing platform was developed by modifying the prepared GC/MWCNT/Pz3 electrode for the electrochemical detection of glucose. The bioelectrode incorporating the newly designed Pz3 exhibited good activity in the presence of glucose, confirming effective electronic communication between the Pz3, GOx and MWCNT surface. The linear range for glucose detection was 0.2-3.7 mM.

Ultra-sensitive nitrate-ion detection via transconductance-enhanced graphene ion-sensitive field-effect transistors

Current potentiometric sensing methods are limited to detecting nitrate at parts-per-billion (sub-micromolar) concentrations, and there are no existing potentiometric chemical sensors with ultralow detection limits below the parts-per-trillion (picomolar) level. To address these challenges, we integrate interdigital graphene ion-sensitive field-effect transistors (ISFETs) with a nitrate ion-sensitive membrane (ISM). The work aims to maximize nitrate ion transport through the nitrate ISM, while achieving high device transconductance by evaluating graphene layer thickness, optimizing channel width-to-length ratio (RWL), and enlarging total sensing area. The captured nitrate ions by the nitrate ISM induce surface potential changes that are transduced into electrical signals by graphene, manifested as the Dirac point shifts. The device exhibits Nernst response behavior under ultralow concentrations, achieving a sensitivity of 28 mV/decade and establishing a record low limit of detection of 0.041 ppt (4.8 × 10−13 M). Additionally, the sensor showed a wide linear detection range from 0.1 ppt (1.2 × 10−12 M) to 100 ppm (1.2 × 10−3 M). Furthermore, successful detection of nitrate in tap and snow water was demonstrated with high accuracy, indicating promising applications to drinking water safety and environmental water quality control.