Linear Detection Range Research Articles

Influence of the Gold Nanoparticle Size on the Colorimetric Detection of Histamine.

Histamine is a well-known biogenic amine (BA) that is often associated with allergic reactions and is a significant cause of foodborne illnesses resulting from the consumption of spoiled food. Detecting histamine is essential for maintaining food safety standards and preserving the quality. In this work, we developed a simple, low-cost, and rapid colorimetric method for detecting histamine. Gold nanoparticles (AuNPs) of different sizes (16, 25, and 40 nm) were synthesized by using the citrate reduction method. The particle size was controlled by adjusting the precursor molar ratio (MR), with smaller ratios leading to larger particles and a red-shift in the surface plasmon resonance (SPR) peak (520, 524, and 528 nm). The nanoparticles were allowed to interact with increasing concentrations of histamine (ranging from 1 to 100 ppm), and the changes in the absorbance spectra and color of the solution were monitored. AuNP aggregation was induced by interaction with histamine through amino and imidazole groups that will coordinate with the AuNP's surface via electrostatic and hydrogen-bonding interactions, causing the solution to turn blue from red. The size variations of AuNPs significantly affected the colorimetric response to histamine. Among the varied sizes, 25 nm AuNPs exhibited the lowest detection limit of 0.72 μM and a linear detection range of 1-10 ppm. Notably, this sensor offered rapid detection (under 1 min) and a remarkable selectivity toward histamine analyte, highlighting its potential for practical applications.

Ternary electrochemiluminescence biosensor based on Ce2Sn2O7@MSN luminophore and Au@NiO-CeO2 as a co-reaction accelerator for the detection of prostate specific antigen

A ternary ECL system was constructed with Ce2Sn2O7@MSN composite as luminophore, potassium persulfate as co-reactant and Au@NiO-CeO2 as co-reaction accelerator to realize ultra-sensitive biosensing detection of prostate specific antigen (PSA). The abundant oxygen vacancies in Ce2Sn2O7 endow it with powerful electrochemical redox ability, accelerate energy transfer, and ensure Ce2Sn2O7 excellent electrochemical luminescence performance as a luminophore. Furthermore, to optimize the luminescence energy, enhance stability, and reduce the background signal to improve its signal-to-noise ratio, a highly selective Ce2Sn2O7@MSN biological probe was obtained by coating cerium stannate (Ce2Sn2O7) with mesoporous silica nanospheres (MSN). Au@NiO-CeO2 with a large specific surface area and high oxygen vacancy activity was synthesized as the co-reaction accelerator, which promoted the generation of SO4•− through the rapid reversible oxidation and reduction of Ce4+/Ce3+, thereby the ECL signal amplified effectively. Under optimal conditions, the linear detection range of PSA spans from 100fg mL−1 to 100 ng mL−1, with a remarkable lowest detection limit of 0.037pg mL−1, showcasing significant application potential. This study provides a valuable reference for pyrochlore to be used as luminophore in the detection of various biomarkers by ECL biosensing.

Construction of aptamer-gated colorimetric sensor based on MIL-acetylcholinesterase to detect acrylamide in food

As one of Maillard’s hazards, acrylamide (AAm) can induce neurotoxicity, mutagenicity, and genotoxicity, and it’s urgent to construct a detection method for sensitive and specific monitoring of AAm. Herein, an aptamer-gated colorimetric sensor was developed to detect AAm in food. UiO-66-NH2 was selected to combine acetylcholinesterase (AChE) and the aptamer of AAm to construct the aptamer-gated probe UAzyme-Apt. The addition of AAm would detach Apt and expose the active sites of UAzyme, resulting in the transformation of acetylthiocholine (ATCh) into thiocholine (TCh) that could inhibit the oxidase mimic activity of MIL-53 (Fe/Mn). Consequently, the concentration of AAm was inversely proportional to the absorbance at 652 nm, thus providing a qualitative and quantitative detection of AAm. The aptamer-gated probe can recognize AAm to improve specificity and stability and regulate the enzyme activity of UAzyme. This aptasensor enhances the detection methods of AAm and broadens the scope of applications for AChE inhibition detection, and targets are not limited to the substrate or organophosphorus pesticides. The linear range and limit of detection were 0.05–100 μM (R2 = 0.992) and 9.94 nM, and spiked analysis revealed the efficiency and robustness of the developed assembly. The colorimetric aptasensor can specifically detect AAm at low concentrations, and will be a promising tool to ensure food safety in the coming future.

Ultrasensitive electrochemical microRNA-21 detection based on MXene and ATRP photocatalytic strategy.

ATi3C2TxMXene-based biosensor has been developedand the photocatalytic atom transfer radical polymerization (photo ATRP) amplification strategy appliedto detect target miRNA-21 (tRNA). Initially, Ti3C2TxMXene nanosheets were synthesized from the Ti3AlC2 MAX precursor via selective aluminum etching. Then, functionalization of Ti3C2TxMXene nanosheets with 3-aminopropyl triethoxysilane (APTES) via silylation reactions to facilitate covalent bonding with hairpin DNA biomolecules specifically designed for tRNA detection. Upon binding with the tRNA, the hairpin DNA liberated the azide (N₃) group, initiating a click reaction to affix to the photo ATRP initiator. Through the ATRP photoreaction, facilitated by an organic photoredox catalyst and light, a significant amount of ferrocenyl methyl methacrylate (FMMA) monomer was immobilized on the electrode. Therefore, the electrochemical signal is amplified. The electrochemical efficacy of the biosensor was assessed using square wave voltammetry (SWV). Under optimized conditions, the biosensor demonstrated remarkable sensitivity in detecting tRNA, with a linear detection range from 0.01 fM to 10pM and a detection limit of 2.81 aM. The findings elucidate that thedeveloped biosensor, in conjunction with the photo ATRP strategy, offers reproducibility, stability, and increasedsensitivity, underscoring its potential applications within the experimental medical sector of the biomolecular industry.

A high-sensitivity flexible piezoelectric tactile sensor utilizing an innovative rigid-in-soft structure

Piezoelectric tactile sensors are widely adopted to detect vibration and other stimuli. Among them, Polyvinylidene fluoride (PVDF) has the advantage of high flexibility, fast response and low cost. However, its sensitivity is restricted by the traditional d33 working mode. Herein, we proposed a rigid-in-soft structure with truncated pyramid shape and soft bottom layer to enhance the force-transmission efficiency. This design synergizes the d33 working mode and d31 working mode, thereby surpassing the sensitivity limit. The mechanism has been analyzed using Finite Element Modeling (FEM), and experiment results indicate that rigid-in-soft tactile sensor exhibits a sensitivity of 35.6 mV/N, along with a linear force detection range of 1–11 N. The sensitivity is approximately 1.7 times higher than that of control sensor without rigid pillar. Furthermore, the sensor displays a great flexibility and reliability, making it highly promising for detecting dynamic stimuli in robotics, such as slip and vibration.

Nanozyme-Catalyzed Colorimetric Detection of the Total Antioxidant Capacity in Body Fluids by Paper-Based Microfluidic Chips.

Total antioxidants play a crucial role in human health, and detection of the total antioxidant capacity (TAC) has broad application prospects in fields such as food safety, environmental assessment, and disease diagnosis. However, a long detection time, cumbersome steps, high cost, reliance on professional equipment, and nonportability still remain significant challenges. In this work, an efficient strategy of point-of-care testing (POCT) of the TAC in body fluids by nanozyme-catalyzed colorimetric paper-based microfluidic sensors is proposed. The paper-based microfluidic sensors coupled with a smartphone can reduce testing costs and provide portability. The nanozyme prepared by the solvothermal method presents Michaelis constants of 0.11 and 0.129 mM for H2O2 and TMB, respectively. A method for immobilizing nanozymes and chromogenic agents on a paper-based microfluidic chip is established. Based on smartphone photography and image grayscale extraction, the TAC can be qualitatively detected with a detection limit and linear range of 33.4 and 50-700 μM, respectively. Furthermore, the proposed sensor can realize the one-step quantitative analysis of the TAC in body fluids (blood, saliva, and sweat) within 15 min. The proposed nanozyme-catalyzed colorimetric paper-based microfluidic sensors presented in this study exhibit promising application prospects in the fields of biochemical analysis and POCT.

Electrochemical Detection of Ascorbic Acid by Fe₂O₃ Nanoparticles Modified Glassy Carbon Electrode.

Background The article delineates a strategy for detecting ascorbic acid (AA) through the use of iron oxide (Fe₂O₃) nanoparticles on an electrode. The Fe₂O₃ nanoparticles demonstrated effective electrocatalysis in the oxidation of AA, resulting in increased peak currents. The sensor showcased a wide linear detection range, a low detection limit, and high selectivity towards interferents, making it suitable for accurate AA measurement in food analysis and medical diagnostics applications. This emphasizes the potential of Fe₂O₃ nanoparticle-based sensors for precise AA detection. Aim The primary aim of this research is to develop an electrochemical sensing technique for the identification of ascorbic acid, with the use of Fe₂O₃ nanoparticles as the sensing matrix. Materials and methods The synthesis process involved the utilization of FeCl3.6H2O, ammonia solution, ethanol, and double-distilled water. FeCl3.6H2O was dissolved in ammonia water to produce a brown precipitate for the synthesis of Fe₂O₃ nanoparticles. Subsequently, the brown precipitate underwent hydrothermal treatment at 180 °C, resulting in the formation of a red product. Following centrifugation, washing, and drying steps, Fe₂O₃ nanoparticles were successfully synthesized. These nanoparticles were then utilized to modify the glassy carbon electrode (GCE). Prior to the modification, the GCE underwent polishing and cleaning procedures, after which it was coated with a suspension containing 5 mg of Fe₂O₃ nanoparticles in 10 mL of ethanol. The coated electrode was dried and deemed ready for application in electrochemical sensing. Results The hydrothermal method was employed in this research to synthesize Fe₂O₃ nanoparticles, which were subsequently subjected to a series of experiments to evaluate their electrochemical sensing capabilities. The resulting Fe₂O₃ nanoparticles were determined to possess a high level of purity and a crystalline structure through various analyses, including field emission-scanning electron microscopy (FE-SEM), cyclic voltammetric testing, X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy analysis, differential pulse voltammetry (DPV), and the current response of the Fe₂O₃-modified electrode towards ascorbic acid. The morphology of the Fe₂O₃ nanoparticles was observed to be uniform. The synthesized particles successfully fulfilled the study's objective by exhibiting remarkably sensitive and selective sensitivity towards ascorbic acid. Conclusion Our study underscores the potential of utilizing Fe₂O₃ nanoparticle-based electrochemical sensing to detect ascorbic acid, as evidenced by the notably high sensitivity of ascorbic acid towards Fe₂O₃ nanoparticles. The distinctive properties of Fe₂O₃ nanoparticles, which include their large surface area, efficient electron transport, and straightforward manufacturing process, significantly enhance the sensor's performance. Further research is crucial to exploring the wide-ranging applications of the sensor in fields such as food safety, environmental monitoring, and biological diagnostics and to overcome any existing limitations.

Electrochemical sensing of nitrate ions at Cu-immobilized gold electrode in neutral medium

The Cu-immobilized Au surface was electro-catalytically employed for nitrate ions reduction in a neutral solution. According to cyclic voltammetric studies, the Cu/Au electrode has an improved electro-catalytic impact on converting nitrate ions into nitrite ions, governed by a two-electron transfer system. This modified electrode demonstrated good performance in real sample analysis along with good sensitivity (3.2518 $ \mu A \mu M^{-1} cm^{-2}$), long linear detection range (1.2 to 111.4 $\mu M$), a very lower limit of detection (0.85 $\mu M$), an excellent reproducibility. Thus, to determine nitrate ions in an aqueous media, an electrochemical sensor based on a Cu/Au electrode is suggested. GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 10(1), 2023 P 75-85

Synergistic signal−amplification effect of silver nanowires and bifunctional monomers on molecularly imprinted electrochemical sensor for diuron analysis

Molecularly imprinted polymers (MIP) have been widely owing to their specificity, however, their singular structure imposes limitations on their performance. Current enhancement methods, such as doping with inorganic nanomaterials or introducing various functional monomers, are limited and single, indicating that MIP performances require further advancement. In this work, a dual−modification approach that integrates both conductive inorganic nanomaterials and diverse bifunctional monomers was proposed to develop a multifunctional MIP−based electrochemical (MMIP−EC) sensor for diuron (DU) detection. The MMIP was synthesized through a one−step electrochemical copolymerization of silver nanowires (AgNWs), o−phenylenediamine (O−PD), and 3,4−ethylenedioxythiophene (EDOT). DU molecules could conduct fluent electron transfer within the MMIP layer through the interaction between anchored AgNWs and bifunctional monomers, and the abundant recognition sites and complementary cavity shapes ensured that the imprinted cavities exhibit high specificity. The current intensity amplified by the two modification strategies of MMIP (3.7 times) was significantly higher than the sum of their individual values (3.2 times), exerting a synergistic effect. Furthermore, the adsorption performance of the MMIP was characterized by examining the kinetics and isotherms of the adsorption process. Under optimal conditions, the MMIP−EC sensor exhibits a wide linear range (0.2 ng/mL to 10 μg/mL) for DU detection, with a low detection limit of 89 pg/mL and excellent selectivity (an imprinted factor of 10.4). In summary, the present study affords innovative perspectives for the fabrication of MIP−EC sensor with superior analytical performance.

Quantitative SERS detection of serum protein biomarkers for assessment of tumor microwave ablation outcomes

Microwave ablation (MWA) is widely applied in the treatment of cancer, especially hepatocellular carcinoma (HCC). However, the lack of indicators for evaluating ablation completeness limits the success rate and wider application of MWA. This study therefore aims to identify novel serum biomarkers for evaluating the completeness of ablation. Multiple cytokines are preliminarily identified through cell experiments, and the potential as biomarkers is evaluated using clinical serum samples from patients with HCC before and after MWA. CCL20 and EGF are identified as promising biomarkers of the completeness of MWA. Additionally, we develop a highly sensitive and specific quantitative detection method for detecting CCL20 and EGF levels by fabricating a sandwich surface-enhanced Raman spectroscopy (SERS) nano-architecture amplification-based immunosensor. The linear detection range of this SERS platform is 0.1 pg/mL–1 ng/mL with the limit of detections (LoDs) decreasing to 0.082 pg/mL for CCL20 and 0.096 pg/mL for EGF. The remarkable consistency of the SERS immunosensor and ELISA in detecting CCL20 and EGF serum levels highlights the promising clinical utility of SERS in biomarker detection. The exceptional sensitivity of SERS in detecting CCL20 and EGF offers a potential avenue for enhancing the assessment of clinical MWA completeness, consequently leading to improved patient survival rates.

Electrolyte-Gated Carbon Nanotube Field-Effect Transistor-Based Sensors for Nanoplastics Detection in Seawater: A Study of the Interaction between Nanoplastics and Carbon Nanotubes.

Plastics accumulating in the environment are nowadays of great concern for aquatic systems and for the living organisms populating them. In this context, nanoplastics (NPs) are considered the major and most dangerous contaminants because of their small size and active surface, which allow them to interact with a variety of other molecules. Current methods used for the detection of NPs rely on bulky and expensive techniques such as spectroscopy. Here we propose, for the first time, a novel, fast, and easy-to-use sensor based on an electrolyte-gated field-effect transistor (EG-FET) with a carbon nanotube (CNT) semiconductor (EG-CNTFET) for the detection of NPs in aquatic environments, using polystyrene NPs (PS-NPs) as a model material. In particular, as a working mechanism for the EG-CNTFETs we exploited the ability of CNTs and PS to form noncovalent interactions. Indeed, in our EG-CNTFET devices, the interaction between NPs and CNTs caused a change in the electric double layers. A linear increase in the corrected on current (*ION) of the EG-CNTFETs, with a sensitivity of 9.68 μA/(1 mg/mL) and a linear range of detection from 0.025 to 0.25 mg/mL were observed. A π-π interaction was hypothesized to take place between the two materials, as indicated by an X-ray photoelectron spectroscopy analysis. Using artificial seawater as an electrolyte, to mimic a real-case scenario, a linear increase in *ION was also observed, with a sensitivity of 6.19 μA/(1 mg/mL), proving the possibility to use the developed sensor in more complex solutions, as well as in low concentrations. This study offers a starting point for future exploitation of electrochemical sensors for NP detection and identification.

Mechanism of high sensitivity proton acids doped polypyrrole molecularly imprinted electrochemical sensor and its application in urea detection

Molecularly imprinted electrochemical sensor is a kind of convenient, fast, and stable analyzer, but the conductivity of electrode materials and their affinity with the analyte affect its performance. A proton acid (PSS, SA, SSA) doping method was proposed to improve the electrochemical performance of the polypyrrole molecularly imprinted polymer (PPy-MIP), which promoted the electropolymerization of pyrrole, reduced the charge transfer resistance, and increased the electrochemical surface area. In terms of both improving conductivity and affinity, the response of the proton acids doped the polypyrrole molecularly imprinted electrochemical sensors (PPy-MIECS) to urea was improved by 25-fold (PSS), 5-fold (SA), and 3-fold (SSA) over that of PPy-MIECS. In addition, the PSS-PPy-MIECS was validated for the practical application with a linear detection range from 0.1 mM to 100 mM, high selectivity (α = 39.73), reusability (RSD% = 4.54 %), reproducibility (RSD% = 0.93 %), and stability (11 days). The advantage of proton acid doping method in PSS-PEDOT-MIECS to urea and PSS-PPy-MIECS to glucose extended its application in the performance enhancement of MIECS design.

A renewable screen-printed electrode based on magnetic NiCo@N-doped carbon nanotubes derived from Co-MOF for ractopamine detection.

A renewable electrochemical screen-printed electrode (SPE) is proposedbased on magnetic bamboo-like nitrogen-carbon (N-C) nanotubes loaded with nickel-cobalt alloy (NiCo) nanoparticles (NiCo@N-CNTs) for the determination of ractopamine (RAC). During the preparation of NiCo@N-CNTs, Co-MOF-67 (ZIF-67) was firstly synthesized, and then blended with dicyandiamide and nickel acetate, followed by a one-step pyrolysis procedure to prepare NiCo@N-doped carbon nanotubes. The surface morphology, structure, and chemical composition of NiCo@N-CNTs were characterized by SEM, TEM, XRD, XPS, and EDS. The electrocatalytic and electrochemical behavior of NiCo@N-CNTs were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that NiCo@N-CNTs possessed remarkable conductivity and electrocatalysis to the oxidation of ractopamine (RAC). By using screen-printed electrode (SPE), NiCo@N-CNTs, and a designed base support, a magnetic RAC sensor (NiCo@N-CNTs/SPE) was successfully constructed. It presented a detection linear range of 0.05-80μM with a detection limit of 12nM (S/N = 3). It also exhibited good sensitivity, reproducibility, and practicability in spiked real pork samples. Since the adhesion of NiCo/N-CNTs on SPE was controlled by magnet, the NiCo@N-CNTs was easily detached from theSPE surface by magnetism and thus displayed excellent renewability. This work broadened insights into portable devices for on-site and real-time analysis.

A signal-amplified electrochemical immunosensor for the detection of sulfadimidine in crayfish using COOH-MWCNTs-Fe3O4-GO nanohybrids modified working electrode

The label-free immunosensing technique is highly valued for its sensitivity and specificity, and advantages of simple preparation, fast detection (one-step), and rapid signal response. However, the sensitivity, stability, and specificity of this technique not only depend on the performance of antibodies, but also on the immunosensing interface of the bare glassy carbon electrode (GCE). This includes factors such as electrical conductivity, biocompatibility, and antibody loading capacity. In this study, carboxyl multiwalled carbon nanotubes-ferrosoferric oxide-graphene oxide (COOH-MWCNTs-Fe3O4-GO) was screened as the modified material of GCE to create an ideal immunosensing interface for the biological reaction between antibody-sulfadimidine (anti-SM2) and SM2. The structure of both nanomaterials and the immunosensor were characterized. The nanohybrid exhibited a uniform interwoven structure of laminar and tubular components. This unique structure allows for a higher capacity for antibody loading. Based on this, a novel electrochemical immunosensor was constructed using COOH-MWCNTs-Fe3O4-GO/GCE, which exhibited a high anti-SM2 loading capacity and a rapid detection time of 30 min. The immunosensor exhibited a linear detection range of 0.01–100 ng/mL for SM2, with a limit of detection (LOD) of 0.003 ng/mL and a limit of quantification (LOQ) of 0.01 ng/mL. Additionally, satisfactory recoveries ranging from 94.40% to 109.00% were achieved in crayfish samples, with a relative standard deviation (RSD) of 4.97–8.64%. A novel immunosensors for highly sensitive detection of SM2 has been developed, which may provide an alternative idea for determination of SM2 in crayfish and other seafood.

Electrochemical impedimetric enzyme-less detection of non-electroactive organophosphate pesticides using zirconium metal organic framework

Residues of pesticides found in fruits and vegetables pose a grave risk to organisms, potentially causing acute and chronic diseases when their levels surpass the maximum residual limits (MRLs) for human consumption. This study targeted to detect non-electroactive organophosphate pesticides (OPPs), including malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate using a zirconium-terephthalic acid combined metal organic framework (Zr-BDC) byelectrochemical impedance spectroscopy (EIS). Comprehensive analysis of the synthesized Zr-BDC showed an extensive specific surface area of 868 m2g−1. Nyquist plots and equivalent circuit models confirmed the higher adsorption of OPPs with P = S and P-S (malathion, dimethoate, chlorpyrifos) onto glassy carbon modified by Zr-BDC (Zr-BDC/GCE), in contrast to OPPs with P = O (monocrotophos, glyphosate, and non-OPPs). The Zr-BDC/GCE displayed a linear detection range of 5.0 nM to 70.0 μM, with limit of detections (LODs) of 3.6, 4.1, 4.5, 3.8, and 4.3 nM for malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate respectively. The sensor exhibited notable recovery 91.0 – 98.6 % and RSDs 1.19 – 1.97 % (n = 3) when tested with real samples (apple and cabbage) and demonstrating substantial reproducibility and long-term stability.

Label-Free and Ultrasensitive Detection of Cartilage Acidic Protein 1 in Osteoarthritis Using a Single-Walled Carbon Nanotube Field-Effect Transistor Biosensor.

Osteoarthritis (OA), a prevalent degenerative joint disease, significantly affects the well-being of afflicted individuals and compromises the standard functionality of human joints. The emerging biomarker, Cartilage acidic protein 1 (CRTAC1), intricately associates with OA initiation and serves as a prognostic indicator for the trajectory toward joint replacement. However, existing diagnostic methods for CRTAC1 are hampered by the limited abundance, thus restricting the precision and specificity. Herein, a novel approach utilizing a single-walled carbon nanotube field-effect transistor (SWCNTs FET) biosensor is reported for the direct label-free detection of CRTAC1. High-purity semiconducting carbon nanotube films, functionalized with antibodies of CRTAC1, provide excellent electrical and sensing properties. The SWCNTs FET biosensor exhibits high sensitivity, notable reproducibility, and a wide linear detection range (1 fg/mL to 100 ng/mL) for CRTAC1 with a theoretical limit of detection (LOD) of 0.2 fg/mL. Moreover, the SWCNTs FET biosensor is capable of directly detecting human serum samples, showing excellent sensing performance in differentiating clinical samples from OA patients and healthy populations. Comparative analysis with traditional enzyme-linked immunosorbent assay (ELISA) reveals that the proposed biosensor demonstrates faster detection speeds, higher sensitivity/accuracy, and lower errors, indicating high potential for the early OA diagnosis. Furthermore, the SWCNTs FET biosensor has good scalability for the combined diagnosis and measurement of multiple disease markers, thereby significantly expanding the application of SWCNTs FETs in biosensing and clinical diagnostics.

Spatially confined dual-emission nanoprobes assembled from silicon nanoparticles and gold nanoclusters for ratiometric biosensing.

Gold nanoclusters (AuNCs) possess weak intrinsic fluorescence, limiting their sensitivity in biosensing applications. This study addresses these limitations by developing a spatially confined dual-emission nanoprobe composed of silicon nanoparticles (SiNPs) and AuNCs. This amplified and stabilized fluorescence mechanism overcomes the limitations associated with using AuNCs alone, achieving superior sensitivity in the sensing platform. The nanoprobe was successfully employed for ratiometric detection of bleomycin (BLM) in serum samples, operating at an excitation wavelength of 365nm, with emission wavelengths at 480nm and 580nm. The analytical performance of the system is distinguished by a linear detection range of 0-3.5μM, an impressive limit of detection (LOD) of 35.27nM, and exceptional recoveries ranging from 96.80 to 105.9%. This innovative approach significantly enhances the applicability and reliability of AuNC-based biosensing in complex biological media, highlighting its superior analytical capabilities.

Iron metal organic framework decorated carbon nanofiber-based electrode for electrochemical sensing platform of chlorpyrifos in fruits and vegetables

Chlorpyrifos, a prime insecticide encountered in numerous agricultural products, is associated with an array of adverse health implications, notably endocrine disturbances and carcinogenic tendencies. Monitoring the environment and controlling quality requires a rapid and simple method for determining the organophosphate insecticide. Overcome the universal challenge postured by this contaminant, this study presents a novel strategy to fabricate an electrochemical sensor based on Iron MOFs, synthesized using 3,5-pyrazoledicarboxylic acid (PyDA) using one-pot solvothermal method with carbon nanofiber matrix for sensing the chlorpyrifos. Notably, this MOF anchored electrode owns important fundamental features such as an expansive surface area, abundant active sites, a vast operational spectrum linear range (1.0–150 μM), a minimal detection threshold (15.1 nM), and an amplified sensitivity towards chlorpyrifos. This Fe-PyDA/CNF/GCE electrode not only showcased more extraordinary electrochemical attributes, but its broad linear detection range and low detection threshold emphasize its ability for real-world applications with reasonable recoveries.

Four-core fiber-based multi-tapered WaveFlex biosensor for rapid detection of Vibrio parahaemolyticus using nanoparticles-enhanced probes.

Infections caused by Vibrio parahaemolyticus (V. parahaemolyticus) can be highly fatal, making rapid and sensitive detection of them is essential. A new optical fiber biosensor based on localized surface plasmon resonance (LSPR) phenomenon is developed in this paper. A tapered-in-tapered fiber structure based on MFM is constructed by using four-core fiber (FCF) and multi-mode fiber (MMF) to qualitatively detect different concentrations of V. parahaemolyticus. The sensor successfully excites the LSPR phenomenon and increases the attachment point of biomolecules on the probe surface by fixing gold nanoparticles (AuNPs), molybdenum disulfide nanoparticles (MoS2-NPs) and cerium dioxide nanorods (CeO2-NRs). The functionalization of polyclonal antibodies on the probe surface can improve the specificity of the sensor. The linear detection range of the developed sensor was 1 × 100-1 × 107 CFU/mL, the sensitivity was 1.61 nm/[CFU/mL], and the detection limit was 0.14 CFU/mL. In addition, the reusability, reproducibility, stability, and selectivity of the sensor probe are also tested, which shows that the sensor has great application prospects.

Construction of heterogeneously connected cobalt-based MOF-COF and its application in highly selective separation of trace lead ions

As a new type of porous crystalline composite material, MOF-COF has shown great advantages in metal separation. Herein, a CoMOF-COF was designed for highly selective separation of trace Pb2+ ions. The designed CoMOF-COF has a high density of nitrogen-oxygen functional groups and can selectively separate metal ions. There is a strong affinity between the designed CoMOF-COF material and metal Pb2+ ions, which can be attributed to the ordered heterogeneous porous structure and large amounts of nitrogen-and oxygen-containing functional groups. The composite showed high adsorption selectivity for Pb2+ ions and had adsorption capacity of 33 mg g−1, with high chemical stability. Based on this solid phase extraction material, a high sensitivity detection method for Pb2+ ions was established, which has the detection limit of 37.3 ng L−1, precision of 1.9 %. Linear detection range is 0.2–10 ng mL−1, and the detection of Pb2+ ions in actual water samples was realized. Through this study, it is proved that the strong affinity between the designed CoMOF-COF materials and metal Pb2+ ions can be attributed to the soft and hard acid-base theory, which reveals the structure-activity relationship between the porous heterostructure of such materials and metal separation, providing a highly selective separation material for the separation of other environmental pollutants.