High Selectivity For Detection Research Articles

Biomimetic gas sensor derived from pine tree for highly sensitive and selective detection of C2H6O2

Pine tree was successfully carbonized into carbon materials with a similar structure to that of dog turbinate at different temperatures, realizing the high sensitivity, stability and selective detection of C2H6O2.

Bismuth-doped carbon quantum dots as an effective fluorescent probe for metronidazole detection through inner filter effect, cytotoxicity studies, and bioimaging in Zebrafish

Herein we report that Walnut Shell-derived bismuth-doped Carbon Quantum Dots (Bi-CQDs) in rice morphology with an average size of 3–4 nm were used for the highly selective nanomolar (nM) detection of metronidazole (MNZ) through the inner filter effect (IFE). The excitation-dependent Bi-CQDs show high selectivity, sensitivity, and fluorescence detection on different pH (1 → 13) with a limit of detection (LoD) of 15.72 nM (R2 = 0.99092). The fluorescence quenching mechanism was evaluated by the interaction of Bi-CQSs with various MNZ concentrations (200 nM–2 μM), with binding constant as Ka = 1.081 × 10−3 M−1, increase in fluorescence lifetime values (5.60 → 5.88 ns). The interference studies, the effect of pH, the effect of time on MNZ detection, and the stability of the Bi-CQD•MNZ complex were also investigated. Further, in vitro bioimaging of Zebra fish and cytotoxicity studies were also conducted. Fluorescence imaging of Bi-CWDS in Zebra fishes distinguishes the morphology changes and embryogenesis. These results suggest that the developed sensor is highly biocompatible for fluorescence sensing and biological applications.

Mixed Potential Type Acetone Sensor with Ultralow Detection Limit for Diabetic Ketosis Breath Analysis.

Breath analysis using gas sensors is an emerging method for disease screening and diagnosis. Since it is closely related to the lipid metabolism and blood ketone concentration of the body, the detection of acetone content in exhaled breath is helpful for the screening and monitoring of diabetes and ketosis. The development of an acetone sensor with high selectivity, stability, and low detection limit has been the research focus for this purpose. Here, we developed a mixed potential type acetone sensor based on Gd2Zr2O7 solid electrolyte and CoSb2O6 sensing electrode. The developed sensor exhibits an extremely low detection limit of 10 ppb, enabling linear detection for acetone in an extremely wide range of 10 ppb-100 ppm. The good results of systematic evaluation on selectivity, repeatability, and stability prove the superior reliability of the sensor, which is a prerequisite for the application in actual breath detection. The ability of the sensor to distinguish healthy people from diabetic ketosis patients was confirmed by using the sensor to detect the breath of healthy people and diabetic patients, proving the feasibility of the sensor in the diagnosis and monitoring of diabetic ketosis.

Methods for the Determination of Aflatoxins and Ochratoxin A in Medicinal Plant Raw Materials (Review)

Introduction. Aflatoxins and ochratoxin A are secondary metabolites of microscopic mold fungi. They seriously threaten human and animal health. These toxins are carcinogenic, teratogenic, hepatotoxic, nephrotoxic substances. International Agency for Research on Cancer (IARC) has classified them as class IA and IIB carcinogens. The maximum permissible concentrations of aflatoxins and ochratoxin A in the Russian Federation are currently regulated only in food products according to the Technical Regulation of the Customs Union 021 "On Food Safety". The content of aflatoxins and ochratoxin A in medicinal plant raw materials is not regulated in any way. Harmful environmental and biological conditions such as temperature, humidity, air quality, insects and others during post-harvest handling can lead to contamination of medicinal raw materials with aflatoxins and ochratoxin A. Therefore, the detection of these toxins is one of the problems of raw materials quality control.Text. The present review summarizes the following methods of sample purification, used at the sample preparation stage: solid-phase extraction, immunoaffin column and QuEChERS. This review also summarizes the following modern analysis methods for the identification of aflatoxin and ochratoxin A in medicinal plant raw materials: thin-layer chromatography, liquid chromatography, gas chromatography and screening methods.Conclusion. The QuEChERS method has been identified as the most popular method for preparing samples for analysis. It is based on solid phase extraction technology. This method combines the variability of approaches to sample purification and allows people to study a wider range of toxins. The high-performance liquid chromatography method has been identified as the most popular method for qualitative and quantitative analysis. It has high selectivity, multicomponent analysis and low detection limits.

Zinc stannate oxide perovskite nanomaterial based electrochemical detection of ammonia

Metal oxide perovskites are promising for sensing harmful chemicals at room temperature with high accuracy, sensitivity, selectivity, and ultra-low detection limit. There is a need for material that can have high sensitivity toward hazardous chemicals like ammonia. In this paper, a one-step hydrothermal process has been successfully used for the synthesis of ZnSnO3 nanopowder. With the presence of ample oxygen vacancies and a large surface area, ZnSnO3 nanopowder facilitates excellent electrochemical sensing properties. Here, the electrochemical ammonia sensing was investigated in potentiometric and amperometric modes. At room temperature, ammonia was detected within a linear concentration range from 10 nM to 60 nM, utilizing a low potential of 20 mV. The fabricated ammonia sensor based on ZnSnO3 nanopowder can detect at an ultra-low detection limit of 0.851 pM with a high sensitivity value of 4.548 mAcm−2nM−1. The reproducibility, repeatability, and stability of the ammonia sensor are also reported.

MXene-activated graphene oxide enhancing NO2 capture and detection of surface acoustic wave sensors

Surface acoustic wave (SAW) technology has been widely used in the field of harmful gas detection, but there remain a lot of challenges, such as long response/recovery time as well as poor selectivity and repeatability. Herein, we activate graphene oxide (GO) using MXene with excellent adsorption capacity (MXene/GO) to realize efficient NO2 gas detection. The SAW sensor assembled with the multilayered MXene/GO composite showcases an enhanced gas sensing performance to the NO2 gas (1–200 ppm) enabling high sensitivity (Δf=260 Hz/ppm), fast response/recovery time, excellent selectivity, and good repeatability at room temperature. The enhanced high sensitivity and selectivity detection of NO2 gas is attributed to the large pore size, hydrophilicity, and abundant surface functional groups of the multilayered MXene/GO composite. This elaborate design is expected to propel the development of next-generation acoustic gas phase sensors.

Novel Cu nanocluster superlattice/MBene-induced ECL enhancement strategy for miRNA-221 detection

In this paper, copper nanoclusters with superlative structure (Cu NCSL) were developed as luminescence probe for miRNA-221 detection. The tightly aligned superlattice structure of Cu NCSL effectively reduced the disordered and chaotic accumulation of nanoparticles, which further limited the intramolecular vibration and internal rotation of Cu NCs. Meanwhile, the compact particle stacking in the superlattice structure greatly improved the electron transport efficiency. As a result, the luminescence of Cu NCSL was enhanced greatly with the increase of radiation energy transfer rate. Furthermore, the two-dimensional MBene with good electrical conductivity and high electrochemical performance has been prepared as electrode modification material. In the constructed electrochemiluminescence (ECL) sensor for miRNA-221 detection, the ECL signal of Cu NCSL was amplified by the MBene nanosheets effectively. Finally, the results in the actual tumor tissues showed that the Cu NCSL/MBene-based biosensor has high selectivity, stability and low detection limit in the clinical cancer detection.

Facile synthesis of ionic liquid mobilized ZnO@Ti3C2Tx composite nanosheets for high charged transfer, sensitive and selective electrochemical detection of 5-flurouracil in waste water and urine samples

Controlling and monitoring the concentration of anticancer drugs in physiological fluids and water bodies are crucial for successful cancer treatment and environmental considerations. However, the development of electrochemical-based sensors having high charge transfer rate, high conductivity, sensitivity and selectivity for anticancer drugs (ACDs) have been limited research due to their poor oxidation–reduction behaviour and complex structures. To address this issue, we pursuit a simple and efficient synthesis route of zinc nanowires (ZnO NWs) decorated on MXene (Ti3C2Tx) nanosheets and utilized for the electrochemical detection of antimetabolite drug namely, 5-fluorouracil (5-FU). We enhance the charge transfer between two nanostructures by incorporating an ionic liquid (ILs). Detailed spectroscopic analysis demonstrates the interaction between ZnO and MXene, which is further improved by the addition of ILs through metal–oxygen bonds. XRD patterns also indicated an intensity reduction and shifting of the MXene’s (002) peak which supporting the spectroscopic results. Moreover, the results confirm that ILs enhance the interfacial connectivity between ZnO NWs and MXene nanosheets through electrostatic interactions, improving the charge transfer rate, sensing capability, and signal intensity for anticancer drug detection. The optimized ILs_ZnO@MX composite exhibits a 10-fold lower limit of detection for 5-FU (0.03 µM) compared to bare ZnO@MX.

Semiconductor-Type Triethylamine Sensor for Food Detection Based on WO3 Nanomaterials

Triethylamine is an effective indicator for evaluating seafood freshness. Therefore, a device capable of real-time monitoring of triethylamine is required. In this study, WO3 nanomaterials prepared using sodium tungstate as the tungsten source were used to assemble semiconductor sensors to detect low concentrations of triethylamine at low temperatures. To investigate the effects of different structural guides on the sensor performance, citric and oxalic acids were used as structural guiding agents to obtain WO3 nanoplates and nanoparticles, respectively. At an optimal operating temperature of 255 °C, the WO3 nanoplate sensor exhibited a response of 56.57 to 10 ppm triethylamine, with a sensitivity of 50 in the tested concentration range of 2.5–25 ppm triethylamine, and response/recovery times of 9 s/69 s. WO3 nanoplates performed better than that of WO3 nanoparticles. In addition, the effect of different structural guiding agents on the sensor properties was explored, and the response mechanism of the semiconductor sensor was investigated. WO3 nanoplate shows fast response time, high selectivity and low detection limit, that is an excellent TEA sensor, which makes it more promising used in food detection for practical applications.

New Rhodamine-based sensor for high-sensitivity fluorescence tracking of Cys and simultaneously colorimetric detection of H2S

Sulfhydryl-containing compounds including cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H2S) are involved in many physiological processes. The development of single-molecule optical sensor for the distinguish detection of these bio-thiols is a critical and challenging effort. In this work, we designed a one-step synthesis of the Rhodamine-based sensor FR for specific fluorescent response of Cys and simultaneously colorimetric detection of H2S, in which the aldehyde and fluorine groups act as response sites. Sensor FR displays significant fluorescence enhancement at 565 nm toward Cys with high selectivity and low detection limits (49 nM) due to the low background fluorescent signal of the spirocyclic closed-state in Rhodamine structure. Meantime, after treatment of H2S, the color of the sensor changes significantly from colorless to blue-purple, which can be used as a visual colorimetric method to detect H2S. These response mechanisms were systematically characterized by 1H NMR and Mass spectrometry. Finally, sensor FR could be used to monitor exogenous and endogenous of intracellular Cys changes.

Label-Free Neuropeptide Detection beyond the Debye Length Limit.

Biosensors with high selectivity, high sensitivity, and real-time detection capabilities are of significant interest for diagnostic applications as well as human health and performance monitoring. Graphene field-effect transistor (GFET) based biosensors are suitable for integration into wearable sensor technology and can potentially demonstrate the sensitivity and selectivity necessary for real-time detection and monitoring of biomarkers. Previously reported DC-mode GFET biosensors showed a high sensitivity for sensing biomarkers in solutions with a low salt concentration. However, due to Debye length screening, the sensitivity of the DC-mode GFET biosensors decreases significantly during operation in a physiological fluid such as sweat or interstitial fluid. To overcome the Debye screening length limitation, we report here alternating current (AC) mode heterodyne-based GFET biosensors for sensing neuropeptide-Y (NPY), a key stress biomarker, in artificial sweat at physiologically relevant ionic concentrations. Our AC-mode GFET biosensors show a record ultralow detection limit of 2 × 10-18 M with an extensive dynamic range of 10 orders of magnitude in sensor response to target NPY concentration. The sensors were characterized for various carrier frequencies (ranging from 30 kHz to 2 MHz) of the applied AC voltages and various salt concentrations (10, 50, and 100 mM). Contrary to DC-mode sensing, the AC-mode sensor response increases with an increase in salt concentration in the electrolyte. The sensor response can be further enhanced by tuning the carrier frequency of the applied AC voltage. The optimum response frequency of our sensor is approximately 400-600 kHz for salt concentrations of 50 and 100 mM, respectively. The salt-concentration- and frequency-dependent sensor response can be explained by an electrolyte-gated capacitance model.

Development of amine-based transition metal MOFs as efficient electrochemical sensors for the detection of chloramphenicol in food and pharmaceutical samples

Antibiotic overuse leads to accumulation in the environment and the human body. Detecting antibiotics is essential, and Metal-organic frameworks (MOFs) are gaining recognition for their flexibility and large surface area. In this study, amine-based MOFs are synthesized using a facile solvothermal method to detect chloramphenicol (CAP), an antibiotic widely used in livestock farming. Fe-MOF, Ni-MOF, Zn-MOF, and Ti-MOF are evaluated through XRD, FT-IR, FE-SEM, BET, and TGA. The electroactivity of these MOFs is investigated through CV and DPV. For the first time, Fe-MOF displayed a high current response and selective CAP detection, even in the presence of interfering substances. This electrochemical sensor exhibited an outstanding sensitivity of 1.237 µA µM−1 cm−2, with a detection limit of 0.011 µM in the linear range of 0.04–68.18 µM. Remarkably, the sensor achieved a high sensing efficiency of 98.9 % in detecting CAP in milk and eyedrops. This work demonstrates the potential of Fe-MOF as a promising material for selective and sensitive CAP detection, with significant applications in food safety and environmental monitoring.

Perovskite-structured LaFeO3 modified In2O3 gas sensor with high selectivity and ultra-low detection limit for 2-butanone

LaFeO3 material with excellent performance and unique perovskite structure has attracted more and more attention in the field of VOC gas detection. However, simultaneously achieving low detection limits and high sensitivity at low temperatures is still a very valuable topic. In this study, LaFeO3-In2O3 material was prepared by hydrothermal method and used to detect 2-butanone gas. Various characterization results displayed that the LaFeO3-In2O3 material was successfully obtained. Compared with the pure In2O3 material, the LaFeO3-In2O3 material had more outstanding gas-sensing properties for 2-butanone. The response value (425) of 1% LaFeO3-In2O3 gas sensor to 100 ppm 2-butanone at 210 ℃ was nearly three times that of pure In2O3. Moreover, the 1% LaFeO3-In2O3 sensor had a very low detection limit (10 ppb), excellent selectivity, repeatability, and long-term stability. The greatly enhanced sensing performance for 2-butanone can be attributed to the heterojunction-induced changes in surface properties and electronic structure, the catalytic effect of LaFeO3, and there is a synergistic effect between these two components. This study provides a very simple synthesis method, which can greatly improve the gas sensing properties of 2-butanone, which is very promising and valuable for industrial production and life.

Novel fluorescent sensor for Al3+ based on a bis-tetraphenylimidazole Schiff base

Although some detection methods for Al3+ have been presented, the rapid, simple and in-situ detection on Al3+ with high selectivity and sensitivity was still anticipated. In this work, a “turn-on” and color-changed fluorescence sensor for Al3+ was reported with the high selectivity and low detection limitation. A bis-tetraphenylimidazole Schiff base (bis-TPMS) was prepared by simple “1 + 2” condensation in 80 % yield. It displayed the strong “turn-on” purple fluorescence on sensing Al3+ selectively among various metallic ions and anions. The detection limitation was as low as 1.56 × 10-8 M. The sensing mechanism was deduced as Al3+ was located in the opening cavity composed of HC = N, OH and NH groups. This sensing ability of bis-TPMS for Al3+ was successfully used in test paper, on-site detection for real samples of gastric tablets, indicating the good application prospect in the simple, rapid and in-situ detection for Al3+ in real samples.

A novel AIE peptide-based fluorescent probe for highly selective detection of mercury(II) ions and its application in food samples and cell imaging

A novel peptide-based fluorescent probe TPE-PGH was firstly developed based on aggregation-induced emission (AIE) effect. The fluorescence intensity of TPE-PGH was largely ignored in the low water fraction, whereas bright blue fluorescence was observed in the high water fraction. TPE-PGH achieved high selectivity and rapid detection of Hg2+, and has excellent sensitivity to detect Hg2+ with low LOD (58.1 nM). Interestingly, TPE-PGH provided a significant color changed from dark blue to bright cyan upon binding with Hg2+ ions under UV lamp (365 nm). In addition, TPE-PGH was able to simultaneously visualize Hg2+ in living cells with different fluorescence intensities based on excellent cells permeability and low toxicity. Further, TPE-PGH exhibited high precision (RSD < 4 %), and was successfully applied for detecting Hg2+ in real food samples, such as milk, soda drink, red wine, cucumber, tomato and carrot. Successful test strips responses also demonstrated that the potential of TPE-PGH for portable detection of Hg2+ in real samples. Especially, AIE based-test strips soaked in different Hg2+ concentrations was successfully utilized for semi-quantitative detection of Hg2+ using the RGB APP installed on a smartphone, which will provide a new approach for smart and portable detection of contaminated heavy metal ions in food samples.

A water-stable metal–organic framework Zn-MOF as a chemical sensor for efficient detection of Cr(VI) (Cr2O72- and CrO42-) anions in water

The luminescent three-dimensional Zn(II) metal–organic framework (Zn-MOF) was successfully synthesized via a hydrothermal method. The structure of the compound is denoted as [Zn3(μ3-OH)(L)·(H2O)]n, where H5L represents 3,5-bis(3,5-dicarboxyphenoxy)benzoic acid. Remarkably, this framework exhibits excellent stability in water and pH (3–13) conditions. Intriguingly, the compound shows high selectivity, sensitivity, and low detection limits (4.10 μM for Cr2O72- and 6.63 μM for CrO42-) in aqueous solution. Furthermore, the material proves to be easily regenerable. Additionally, the competition between analyte absorption and the excitation/emission of Zn-MOF elucidates the fluorescence sensing mechanism of Cr2O72-/CrO42- ions. These findings unequivocally establish Zn-MOF as a highly selective and recyclable fluorescence sensing material for the quantitative detection of Cr(VI) ions in aqueous solutions.

Synthesis of a lanthanide-based bimetallic-metal-organic framework for luminescence sensing anthrax biomarker

Lanthanide luminescence sensors have attracted extensive attention in the detection of 2, 6-pyridinedicarboxylic acid (DPA), the main biomarker of anthrax. In previous reports detecting DPA, luminescence probes may not have high selectivity and high specificity for identification. In the present study, a highly specific and sensitive luminescence probe was synthesized. In this paper, [TbxGd1-x (PBA)2NO3·2H2O]n is synthesized by solvothermal method using HPBA = 3.5-bis(triazol-1-yl)benzoic acid and Ln (NO3)3·6H2O (Ln = Tb, Gd). Through modulating the molar ratio of Tb3+ ions and Gd3+ ions, the distance between Ln3+ ions is changed, leading to a change in the energy transfer from the ligand to Tb3+, which in turn leads to an increase in luminescence intensity. Meanwhile the luminous colour is regulated by the ratio of Tb/Gd, which changes from green to white as the Gd ion gradually increases. The bimetallic ratiometric luminescence sensor realized accurate, high sensitivity (LOD is 1.03 × 10−6 M) and high selectivity detection of DPA. Due to the simple synthesis method and low technical requirements, this work provides a good strategy for the development of simple and effective bimetallic ratiometric luminescence sensors.

Fabrication of a Co-Ni/TiO2 Core-Shell Sensor for Label-Free Quantification of Human Serum Albumin in Hepatitis C Virus Patients

Liver cirrhosis is a life-threatening disorder characterized by severe hepatitis C. Early detection of hepatitis C is crucial since HCV infection has few symptoms, and the patient may remain unaware for many years. The early-stage detection can assist in the treatment and prevent further virus transmission. Abnormally varying albumin concentrations in hepatitis C patients can lead to hypoalbuminemia. Herein, a novel Co-Ni/TiO2 core–shell-based electrochemical sensor is developed for facile and ultra-sensitive human serum albumin (HSA) detection in HCV patients. Co-Ni/TiO2 core shells are fabricated via coprecipitation and hydrothermal methods and used for non-enzymatic detection albumin with high sensitivity, selectivity, and lower detection limits. Cyclic voltammetry, chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) is performed for albumin detection via Co-Ni/TiO2 modified GCE at different scan rates, pH, and concentrations. The linear range and limit of detection (LOD) obtained for the Co-Ni/TiO2 electrode are 0–30 μM and 0.019 μM, respectively. The utility of Co-Ni/TiO2 electrodes is extended to HSA sensing from HCV-infected patients. Albumin recovery at room temperature ranged from 81.0% to 91.3% in diluted human serum samples. The developed electrochemical analysis method is superior for HSA detection and can be a tool for clinical diagnosis in the future.

(Invited) CMOS-Based Multimodal Sensing

In the coming Society 5.0, information will be collected, aggregated, and utilized in a wide range of areas through the IoT, and as the concept of "Trillion Sensors" states, the importance of "sensors" as an interface between physical space and cyberspace is increasing. In the development of sensor devices to meet this demand attempts to realize the sensing of multiple items by integrating single-function sensors with high detection selectivity have been the main focus in the past. On the other hand, our research group has proposed the measurement concept of multimodal sensing, in which sensors with broad detection characteristics are used to realize the sensing of multiple items, and has developed semiconductor CMOS-based sensors to realize this concept. In this talk, we introduce ion image sensors and odor sensors as examples of CMOS-based sensors suitable for multimodal sensing, and data analysis using machine learning, which is important for this measurement concept will be mentioned and introduce an example of machine learning-based sensing. The application of these sensors to smart agriculture and other fields will also be discussed, as well as the current status and issues for the practical application of sensor systems.An ion-sensitive transistor (ISFET) can be fabricated by changing the MOSFET's gate to an ion-sensitive membrane. An ion image sensor can be constructed by arraying ion-sensitive elements that operate based on the same principle using CMOS image sensor technology. This sensor visualizes the solution's hydrogen ion concentration (pH) and enables real-time observation of ion dynamics in the solution. By changing the ion-sensitive membrane of the sensor, it is possible to image specific ions such as potassium and calcium, and by adding an enzyme-immobilized membrane, it is also possible to capture chemical substances such as lactic acid. By combining these methods, the development of a multimodal sensor that can simultaneously image multiple ions and chemical substances is in progress as an approach from the hardware side. The future approach from the software side is expected to include measurement data processing by machine learning, thereby expanding the range of substances to be measured. In addition, making this sensor extremely thin makes it possible to perform ion imaging by inserting it into the object to be measured. Functional demonstration of visualization of ion distribution in a plant stem has been performed successfully, and we are currently studying its application in the field of smart agriculture.Since the ion image sensor mentioned above captures minute changes in electric potential generated by ion-sensitive membranes, it can be operated as a gas sensor by forming a membrane on the sensor whose electric properties change depending on gas adsorption. Certain polymer membranes respond to a wide range of gases, they can be used as odor-sensitive membranes. When multiple gas- and odor-sensitive membranes with different response characteristics are formed on a CMOS sensor, gas- and odor-specific response patterns can be obtained. Machine learning is effective in analyzing these patterns, and this presentation will introduce an example of gas-type discrimination.

Al and W co-doped NiO nanoflowers with low crystallinity and rich oxygen vacancies for high stability and selective triethylamine detection

In this work, pure NiO, Al-doped NiO, W-doped NiO and a series of Al/W co-doped NiO nanoflowers were successfully prepared through a simple solvothermal method. Various characterization methods, such as XRD, SEM, TEM, HRTEM and XPS, were used to confirm the physical and chemical properties of the sensitive materials in terms of micro-nano structures, compositions and elemental distributions. The as-obtained Al/W co-doped NiO showed a nanoflower structure with an approximate size of ∼ 200 nm. What's more, among six sensors constructed from the sensitive materials, the sensor based on 3 at% Al3+/3 at% W6+ co-doped NiO (3Al3W-NiO) achieved the highest response (Rg/Ra=112) toward 100 ppm triethylamine with a low detection limit (1 ppm) at 325 ℃. Besides, this sensor also exhibited excellent response/recovery characteristics and long-term stability. These favorable sensing performances of the 3Al/3 W co-doped NiO sensor are not only modulated by the initial resistance (Ra), but are also closely related to the large specific surface area, porous structures, low crystallinity, rich oxygen vacancies and high Ni3+/Ni2+ ratio in the composite nanomaterials.