Wide Detection Research Articles

Ratiometric emission of Tb(III)-functionalized Cd-based layered MOFs for portable visual detection of trace amounts of diquat in apples, potatoes and corn

Diquat (DQ) is a typical bipyridine herbicide widely used to control weeds in fields and orchards. The severe toxicity of diquat poses a serious threat to the environment and human health. Metal-organic frameworks (MOFs) have received widespread attention due to their unique physical and chemical properties and applications in the detection of toxic and harmful substances. In this work, a two-dimensional (2D) Tb(III) functionalized MOF Tb(III)@1 (1 = [Cd(HTATB)(bimb)]n·H2O (Cd-MOF), H3TATB = 4,4′,4″-triazine-2,4,6-tribenzoicacid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene) has been prepared and characterized. Tb(III)@1 has excellent optical properties and high water and chemical stability. After the Tb(III) is fixed by the uncoordinated -COO- in the 1 framework, Tb(III)@1 emits the typical green fluorescence of the lanthanide ion Tb(III) through the “antenna effect”. It is worth noting that Tb(III)@1 can be used as a dual emission fluorescence chemical sensor for the ratio fluorescence detection of pesticide DQ, exhibiting a relatively low detection limit of 0.06 nM and a wide detection range of 0–50 nM. After the addition of DQ, a rapid color change of Tb(III)@1 fluorescence from green to blue was observed due to the combined effects of IFE, FRET and dynamic quenching. Therefore, a simple test paper box has been designed for direct on-site determination of pesticide DQ. In addition, the developed sensor has been successfully applied to the detection of DQ in real samples (fruits a Yin-Xia Sun and Bo-Tao Ji contributed equally to this work and should be considered co-first authors.nd vegetables) with satisfactory results. The results indicate that the probe developed in this study has broad application prospects in both real sample detection and actual on-site testing.

Superelastic carbon aerogels with anisotropic and hierarchically-enhanced cellular structure for wearable piezoresistive sensors

Elastic carbon aerogels have promising applications in the field of wearable sensors. Herein, a new strategy for preparing carbon aerogels with excellent compressive strength and strain, shape recovery, and fatigue resistance was proposed based on the structure design and carbonization optimization of nanocellulose-based precursor aerogels. By the combination of directional freezing and zinc ion cross-linking, bacterial cellulose (BC)/alginate (SA) composite aerogels with high elasticity and compressive strength were first achieved. The existance of zinc ions also significantly improved the carbon retention rate and inhibited structural shrinkage, thus making the carbon aerogels retain ultra-high elasticity and fatigue resistance after compression. Moreover, the carbon aerogel possessed excellent piezoresistive pressure sensing performance with a wide detection range of 0–7.8 kPa, high sensitivity of 11.04 kpa-1, low detection limit (2 % strain), fast response (112 ms), and good durability (over 1,000 cycles). Based on these excellent properties, the carbon aerogel pressure sensors were further successfully used for human motion monitoring, from joint motion to and speech recognition.

Electronic modulation caused by interfacial Fe-O-Co-O-Fe bonding for boosting highly efficient non-enzymic nitrite sensing

Rational electronic modulation of metal–organic frameworks (MOFs) derived electrocatalysts is an effective strategy for rendering them capable of enhanced sensing performance, but rather challenging. Herein, we propose a combination strategy of self-templated transformation and carbonization pyrolysis for elaborately synthesizing a MOF-derived non-planar FeCo hierarchical nest-like networks (n-FeCo-HNNs) heterojunction catalyst. Owing to the excellent electrical conductivity and active site density of n-FeCo-HNNs, such non-enzymic nitrite sensor displays a wide broad detection range, excellent sensitivity, and ultralow limit of detection. Experimental and theoretical calculations clarified the electrons are extracted and rapidly transferred to the surface-active sites through the Fe-O-Co-O-Fe bridge, and then improve the reaction kinetics and boost the sensing performance for nitrite. The synergistic effect of this chemical bond established in the heterostructure unveils a new avenue for efficient electrochemical sensing.

Surface-Activated Ti3C2Tx Adsorption of Acetylene Black Coupled with Polyaniline as a Signal Tag for the Detection of the ESAT-6 Antigen of Mycobacterium tuberculosis.

Early secretory antigenic target-6 (ESAT-6) is regarded as the most immunogenic protein produced by Mycobacterium tuberculosis, whose detection is of great clinical significance for tuberculosis diagnosis. However, the detection of the ESAT-6 antigen has been hampered by the expensive cost and complex experimental procedures, resulting in low sensitivity. Herein, we developed a titanium carbide (Ti3C2Tx)-based aptasensor for ESAT-6 detection utilizing a triple-signal amplification strategy. First, acetylene black (AB) was immobilized on Ti3C2Tx through a cross-linking reaction to form the Ti3C2Tx-AB-PAn nanocomposite. Meanwhile, AB served as a conductive bridge, and Ti3C2Tx can synergistically promote the electron transfer of PAn. Ti3C2Tx-AB-PAn exhibited outstanding conductivity, high electrochemical signals, and abundant sites for the loading of ESAT-6 binding aptamer II (EBA II) to form a novel signal tag. Second, N-CNTs were adsorbed on NiMn layered double hydride (NiMn LDH) nanoflowers to obtain NiMn LDH/N-CNTs, exhibiting excellent conductivity and preeminent stability to be used as electrode modification materials. Third, the biotinylated EBA (EBA I) was immobilized onto a streptavidin-coated sensing interface, forming an amplification platform for further signal enhancement. More importantly, as a result of the synergistic effect of the triple-signal amplification platform, the aptasensor exhibited a wide detection linear range from 10 fg mL-1 to 100 ng mL-1 and a detection limit of 4.07 fg mL-1 for ESAT-6. We envision that our aptasensor provides a way for the detection of ESAT-6 to assist in the diagnosis of tuberculosis.

Nitrate Sensor with a Wide Detection Range and High Stability Based on a Cu-Modified Boron-Doped Diamond Electrode.

This paper describes an electrochemical sensor based on a Cu-modified boron-doped diamond (BDD) electrode for the detection of nitrate-contaminated water. The sensor utilizes the catalytic effect of copper on nitrate and the stability of the BDD electrode. By optimizing the electrolyte system, the linear detection range was expanded, allowing the sensor to detect highly concentrated nitrate samples up to 100 mg/L with a low detection limit of 0.065 mg/L. Additionally, the stability of the sensor was improved. The relative standard deviation of the current responses during 25 consecutive tests was only 1.03%. The wide detection range and high stability of the sensor makes it suitable for field applications and the on-site monitoring of nitrate-contaminated waters.

A novel colormetric and light-up fluorescent sensor from flavonol derivative grafted cellulose for rapid and sensitive detection of Hg2+ and its applications in biological and environmental system

Mercury ion (Hg2+) is one of harmful heavy metal ions that can accumulate inside the human organism and cause some health problems. In the article, a highly effective fluorescent probe named EC-T-PCBM was prepared by grafting flavonol derivatives onto ethyl cellulose for the specific recognition of Hg2+. EC-T-PCBM exhibited a remarkable fluorescence light-up response toward Hg2+ with excellent sensitivity. EC-T-PCBM possessed several prominent sensing properties for Hg2+, such as low detection limit (43.9 nM), short response time (5 min), and wide detection pH range (6–9). The response mechanism of EC-T-PCBM to Hg2+ has been verified through 1H NMR titration and DFT computation. Additionally, EC-T-PCBM not only can be used for accurately determining trace amount of Hg2+ in actual environmental water samples, but also can serve as a portable and rapid device by loading it on test strips for sensitive and selective visualization of Hg2+. More importantly, the confocal fluorescence imaging of onion cells suggested the favorable cell membrane permeability of EC-T-PCBM and its prominent ability to continuously monitor the enrichment from Hg2+ within fresh plant tissues.

Synthesis of nanoflower-shaped covalent organic framework fluorescent probe for sensitive detection of aluminum ions

The widespread application of aluminum has led to numerous adverse effects on organisms due to aluminum pollution. In this study, we synthesized a two-dimensional fluorescent covalent organic framework (TAPB-DMTP-COF) material with nanoflower morphology for fluorescence detection of aluminum ions. The coordination binding of Al3+ with the nitrogen atoms on the imine bonds and the oxygen atoms on the methoxy groups restricts intramolecular rotation in TAPB-DMTP-COF, which inhibits the photo-induced electron transfer (PET) in the COF molecule and triggers the fluorescence emission "turn on" phenomena. A fluorescence method for Al3+ detection was established, and it was found that the method exhibits high sensitivity, selectivity, a wide detection range from 4.0 to 100.0 μM, and a low limit of detection (LOD) of 38.5 nM. This work provided new ideas for the convenient and rapid detection of aluminum ions in environmental analysis and expanded the application of fluorescence COFs in analytical sensing.

Thermophoretic Assay for Biosensing

AbstractThermophoresis refers to the directional movement of particles driven by temperature gradients, which is ubiquitous in nature. This phenomenon can be conveniently used to manipulate molecules and objects such as biomolecules, colloids, metal nanoparticles, and cells. Because of these advantages, thermophoresis is widely used in biosensing. In vitro diagnosis, as an important field of biosensing, is highly compatible with thermophoresis. Compared with traditional in vitro diagnostic techniques, thermophoretic diagnosis is a homogeneous system that boasts high efficiency and rapid detection as well as a wide detection range; thus, thermophoresis has a myriad of applications. The emergence of microscale and multifield coupling thermophoresis technologies yield widespread applications of thermophoresis in the field of in vitro diagnostics. This study presents the history of thermophoresis and reviews various cases of biosensors utilizing thermophoresis. Those biosensors are widely used in in vitro diagnostics, biomarker discovery, and other fields. Furthermore, it assesses the advantages of thermophoresis, and finally discusses its current challenges and future development.

A high sensitivity refractive index sensor based on microstructure fiber with simple structure and SPR effect

A novel dual-side polished photonic crystal fiber (PCF) based surface plasmon resonance (SPR) polarization filtering and refractive index (RI) sensor is presented in this paper. The cladding of PCF was composed of eight air holes and the outer surface was dual-sided polished and coated with gold film. Finite element method (FEM) was used for the simulation and design of the proposed sensor. Simulation results showed that sensor performance was better in analytes ranging from 1.33 to 1.42 RI. The wavelength and amplitude sensitivities at resonance wavelengths of 1269 and 995 nm were 27400 nm/RIU and −100.43 RIU−1 for an analyte of 1.42 and 1.41 RI, respectively, along with a spectral resolution of 3.64×10−6 RIU. Maximum loss of 52806 dB/m was obtained for an analyte of 1.41 RI towards Y-Polarization (Y-P). An extinction ratio of −105.374 dB was obtained using a fiber transferring length of 2 mm to achieve better polarization filtering effects. The proposed sensor is made of same size air holes which is easy to fabricate, cost effective, and shows better sensitivity and polarization filtering effects than several other sensors. It is expected that the sensor is suitable for wide RI detection range and capable of providing excellent polarization effect. The proposed sensor can be used for various applications including environmental detection, chemical sensing, biosensors, and pharmaceutical inspection.

Confinement Enrichment Effect in HoMS-BaTiO3 Microwave Gas Sensors for the Detection of 10 ppb-0.55 v/v% Ammonia at Room Temperature.

The construction of ammonia gas sensors with wide detection ranges is important for exhalation diagnosis and environmental pollution monitoring. To achieve a wide detection range, sensitive materials must possess excellent spatial confinement and large active surfaces to enhance gas adsorption. In this study, an ammonia microwave gas sensor with a wide detection range of 10 ppb-0.55 v/v% at room temperature was fabricated by incorporating hollow multishelled-structured BaTiO3 (HoMS-BaTiO3). The effect of the number of shells and the quantity of the sensitive material on the gas-sensing performance was investigated, and two-layered HoMS-BaTiO3 demonstrated the best response at high concentrations (0.15-0.55 v/v%). Conversely, single-layered HoMS-BaTiO3 displayed outstanding performance at low concentrations (10 ppb-0.15 v/v%). The lower the quantity of the sensitive material, the higher the response. This study offers a method for preparing room-temperature ammonia sensors with a wide detection range and reveals the link between the structure and quantity of sensitive materials and gas-sensing performance.

Improved Microelectrode Array Electrode Design for Heavy Metal Detection

Traditional working electrodes are not sufficient to realize the low detection limit and wide detection range necessary for the detection of heavy metals. In this study, a microelectrode array electrode was proposed using a design scheme based on microelectromechanical systems that was optimized with finite element software. The working electrode adopted an innovative composite structure to realize the integrated design of the working and counter electrodes, which improved the system integration. Performance tests showed that the electrode realized the quantitative analysis of Cd(II), Pb(II), and Cu(II) with a low detection limit (0.1 μg/L) and a wide detection range (0.1–3000 μg/L). The electrode successfully measured the lead and copper ion concentrations in the Sanya River, including both seawater and freshwater environments. The experimental results demonstrate that the electrode exhibits excellent adaptability to environmental conditions and can be potentially applied for technical support in environmental monitoring and sewage treatment.

Colorimetric and SERS dual-mode detection of GSH in human serum based on AuNPs@Cu-porphyrin MOF nanozyme

BackgroundRapid and accurate detection of glutathione content in human blood plays an important role in real-time tracking of related diseases. Currently, surface-enhanced Raman scattering/spectroscopy (SERS) combined with nanozyme material has been proven to have excellent properties in the detection applications compared to many other methods because of it combines the advantages of trace detection capability of SERS and efficient catalytic activity of nanozymes. However, there are still existing problems in real sample detection, and to achieve quantitative detection is still challenging. ResultsIn this study, gold nanoparticles (AuNPs) were synthesized in situ on the surface of two-dimensional Cu-porphyrin metal-organic framework (MOF) nanosheets to produce the AuNPs@Cu-porphyrin MOF nanozyme, which exhibited both oxidase-like activity and SERS detection ability. On one hand, the intrinsic oxidase-like activity of the nanozyme could be inhibited due to the chelation of glutathione (GSH) and Cu, which thus led to the visual color change of the solution. On the other hand, the abundant Raman “hot spots” at the nanogap generated by Au NPs and the internal standard (IS) signal provided by Cu-meso-tetra (4-carboxyphenyl) porphine (Cu-TCPP) MOF improved the sensitivity and quantitative accuracy of detection. Significance and noveltyA dual-mode signal output sensor based on the nanozyme was thus established, which could be used in the trace detection of GSH. Such a dual-mode sensor possesses excellent detection performance, with the advantage of both wide detection range from 1 to 300 μM in the colorimetric detection mode and high sensitivity with LOD of 5 nM in the SERS detection mode, and can be applied to GSH detection in actual serum samples with reliable results.

Ultrasensitive electrochemical sensor for fenitrothion based on MIL-125 derived iron/titanium bimetallic oxides doped porous carbon composite

Fenitrothion (FT) is a common organophosphorus pesticide widely used in agricultural. Residues of fenitrothion in crops can adversely affect human health. In this work, modified MIL-125-Fe was prepared by changing the solvent ratios and further etching with iron nitrate, followed by high-temperature pyrolysis to obtain modified-TiO2/FeTiO3-doped nitrogen-containing carbon framework (m-TiO2/FeTiO3@NCF). The porous carbon material of m-TiO2/FeTiO3@NCF was used to modify the GCE to produce FT electrochemical sensor. Under optimized conditions, the sensor exhibited good detection performance for FT with a low LOD of 0.96 nM and a wide detection linear range of 1–9000 nM, and also exhibited good reproducibility (RSD = 2.08 %), repeatability (RSD = 1.09 %) and anti-interference performance. The sensor was successfully applied in real sample tests showing the recovery rates of 98.7 %–101.2 %. The present study provides a new idea for the rapid and accurate detection of FT.

Anthropogenic-induced ecological risks on marine ecosystems indicated by characterizing emerging pollutants in Pearl River Estuary, China

Anthropogenic Contaminants of Emerging Concern (CECs) in marine environments have raised significant concerns. Yet, analyses detailing their origins, fate, and environmental effects are limited. This study employs an integrated non-target screening methodology to elucidate CECs existence across 46 sampling sites in the Pearl River Estuary (PRE) of the South China Sea. Assisted by advanced liquid chromatography-high resolution mass spectrometry, we discovered 208 chemicals in six usage categories, with pesticides (33 %) and pharmaceuticals (29 %) predominating. Several CECs drew attention for their consistent detections, profound abundance, and significant ecotoxicities. The wide detection of them at offshore sites further implies that anthropogenic activities may contribute to large-scale contamination. Meanwhile, distinct distribution patterns of CECs across PRE are evident in semi-quantitative results, indicating regional anthropogenic influences. Identified transformation products may establish a novel and non-negligible negative contribution to ecology through elevated environmental toxicities, exemplified by HMMM and atrazine. Based on the ecological risks, we compiled a prioritized list of 21 CECs warranting intensified scrutiny. Our findings indicate the introduction of various CECs into the South China Sea via PRE, emphasizing the urgent necessity for ongoing surveillance of discharged CECs at estuary areas and assessment of their marine ecological consequences.

Ultrasensitive and highly stretchable bilayer strain sensor based on bandage-assisted woven fabric with reduced graphene oxide and liquid metal

Flourishing flexible and wearable strain sensors still meet a challenge to realize ultrahigh sensitivity and wide working range simultaneously through a convenient strategy. Here, a strain sensor is designed based on natural rubber (NR) matrix and a bilayer structure composed of a highly stretchable liquid metal (LM) layer and a susceptible reduced graphene oxide (RGO)@carbonized bandage (CB) layer. By painting LM onto the surface of a graphene oxide (GO)-coated bandage template followed with a rapid flame pyrolysis, a dual conductive-layer woven fabric based on LM/RGO@CB was obtained. NR was then employed as an elastic substrate. Benefiting from the synergistic bilayer network and the high stretchability of the elastomer, the fabricated strain sensor exhibited ultrahigh sensitivity (gauge factor of up to 1.63 × 105), quite wide detection range (strain of 0 ∼ 515 %), low detection limit (0.25 %), fast response/recovery (135 ms/135 ms), and satisfactory durability (5700 cycles). The extraordinary strain-sensing performance allowed comprehensive monitoring of full-range (vigorous and subtle) human motions and physiological activities. This work provides a facile bilayer strategy for the preparation of high-performance strain sensors.

Soft crawling robot integrated with liquid metal-based flexible strain sensor and closed-loop feedback control

Due to the inherent softness and adaptability, soft robots have shown great application prospects in medical rehabilitation, environmental exploration, and other fields. However, the unpredictable and complex behaviors of the elastic materials greatly increased the difficulty in the control of soft robots. This study proposed an integrated soft crawling robot (ISCR) with flexible strain sensors to achieve the closed-loop feedback control of motion. First, a flexible strain sensor was fabricated by injecting liquid metal (LM) into an elastomer with a wavy structure. The key performances of the sensor were investigated. The developed flexible strain sensor can achieve a high gauge factor of 2.07, a low hysteresis of 1.902%, a wide detection range of 150% strain, a low detection limitation as low as 0.4% strain change, and an excellent stability and durability, which fully satisfy the requirements for the proprioception of soft robots. We built a closed-loop feedback control system to achieve closed-loop control of the ISCR. Finally, we successfully realized the continuous motion of the ISCR under closed-loop control. We believe this work will be helpful for the development of automation and intelligence of soft crawling robots.

A signal amplification strategy based on hexametaphosphate-stabilized BiVO4@CdS heterojunction with Mg2+-modulated surface charge for CEA detection

An ultrasensitive sensor with excellent photoelectrochemical (PEC) properties was developed based on the combination of electrostatic interactions between the hexametaphosphate (HMP)-coated BiVO4@CdS novel photoelectric material and the electron donor. Compared with the conventional BiVO4@CdS photoactive material, the HMP-modified BiVO4@CdS not only increases the stability, but also utilizes the electrostatic interactions between the negative charge carried by the phosphate group and the electron donor, which results to a significant increase in the photoelectric conversion ability after Mg2+ incubation. Specifically, carcinoembryonic antigen (CEA)-targeted immunorecognition was combined with MgCO3 antibody labelling inspired by the ability of HMP to complex with Mg2+. The released Mg2+ from the MgCO3 tag could neutralize the negative charge on the surface of BiVO4@CdS-HMP, and the electrostatic repulsion with the electron donor was suppressed, accelerating the electron transfer, and thus improving the electron-hole separation efficiency. A sensitive detection capability was demonstrated with CEA as the model target. Featuring a wide linear detection range with a detection limit as low as 60 fg/mL, this work provides a fresh perspective on the development of high-performance PEC biosensors.

A metal-organic framework-based sensor for specific detection of tetracycline in milk

Molecularly imprinted fluorescent sensors are of interest to researchers due to their specificity, high sensitivity, and stability. In this study, the fluorescence-imprinted sensor (NH2-MIL-53/MIP) for the detection of tetracycline (TC) in animal-derived foods was developed based on the characteristics of luminescent metal-organic frameworks (MOFs) and molecularly imprinted polymers (MIPs). The MOFs provide fluorescence sensing signals and large specific surface areas, while the MIPs provide the specific recognition sites for TC. As a result, the sensor exhibits a wide detection range (0.05–50 μg/mL), high sensitivity (LOD of 0.006 μg/mL), fast detection speed and good selectivity. The sensing principle can be attributed to photoinduced electron transfer. Furthermore, the sensor can determine TC in milk with good recovery rates (95.05–104.71 %). This work addresses the limitation of current molecularly imprinted sensors such as slow corresponding speed and limited detection capability, providing valuable insights for target determination in complex systems.

Carboxyethylsilanetriol-Coated Magnetic Nanoparticles as an Ultrasensitive Immunoplatform for Electrochemical Magnetosensing of Cotinine.

In the present study, an innovative and simple electrochemical magneto biosensor based on carboxyethylsilanetriol-modified iron oxide (Fe3O4) magnetic nanoparticles was designed for ultrasensitive and specific analysis of cotinine, an important marker of smoking. Anticotinine antibodies were covalently immobilized on carboxylic acid-modified magnetic nanoparticles, and the cotinine-specific magnetic nanoparticles created a specific surface on the working electrode surface. The use of magnetic nanoparticles as an immobilization platform for antibodies provided a large surface area for antibody attachment and increased sensitivity. In addition, the advantages of the new immobilization platform were reusing the working electrode numerous times, recording repeatable and reproducible signals, and reducing the necessary volume of biomolecules. The specific interaction between cotinine and cotinine-specific antibody-attached magnetic nanoparticles restricted the electron transfer of the redox probe and changed the impedimetric response of the electrode correlated to the concentration of cotinine. The magneto biosensor had a wide detection range (2-300 pg/mL), a low LOD (606 fg/mL), and an acceptable recovery (97.24-105.31%) in real samples. In addition, the current biosensor's measurement results were in good agreement with those found by the standard liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) methods. These results showed that a simple impedimetric immunosensing platform was generated for the cotinine analysis.

Development of piezoresistive poly(ɛ-caprolactone) sensor with unique flexibility and sensing performance for rehabilitative application

ABSTRACT Piezoresistive sensor is applied extensively in rehabilitative monitoring, to help with patients’ physical and mental health recovery. However, the manufacturing complexity of hierarchical structure in sensing element remains a major limitation to piezoresistive sensor. Here, we report a scalable and simple method for the preparation of piezoresistive sensing element. Based on biocompatible poly(ɛ-caprolactone) (PCL), uniaxial cold stretching resulted in a flexible sheet-like element with unique hierarchical geometries comprising highly aligned multiscale ridges on sheet’s double sides. This leads to higher mechanical elasticity of the hierarchitectured PCL element and enhanced resistance against plastic deformation due to the improved Young’s modulus. Further assembly of the piezoresistive sensor demonstrates a wide detection range of 25–4.7 × 104 Pa with rapid response and the high sensitivity of 1.37 kPa−1 at small pressure loadings. The sensor shows successful application in the monitoring physiological signals including pulse, speaking, face expression and limb motion.