Sensitive Simultaneous Detection Research Articles

Biomimetic Cell Membrane Layers for the Detection of Insulin and Glucagon.

The growing need for reliable and rapid insulin testing to enhance glycemic management has spurred intensive exploration of new insulin-binding bioreceptors and innovative biosensing platforms for detecting this hormone, along with glucagon, in biological samples. Here, by leveraging the native protein receptors on the HepG2 cell membrane, we construct a simple and chemical-free biomimetic molecular recognition layer for the detection of insulin and glucagon. Unlike traditional affinity sensors, which require lengthy surface modifications on the electrochemical transducers and use of two different capture antibodies to recognize each analyte, this new biomimetic sensing strategy employs a simple drop-casting of a natural cell membrane recognition layer onto the electrochemical transducer. This approach allows for the concurrent capture and detection of both insulin and glucagon. We investigate the presence of insulin and glucagon receptors on the HepG2 cell membrane and demonstrate its multiplexing bioelectronic sensing capabilities through the binding of the captured insulin and glucagon to enzyme-tagged signaling antibodies. This new molecular recognition layer offers highly sensitive simultaneous detection of insulin and glucagon under decentralized conditions, holding considerable promise for the management of diabetes and the development of diverse biomimetic diagnostic platforms.

Integration of bifunctional silver dendrite membranes with surface-enhanced Raman scattering for sensitive detection of polystyrene microplastics in aquatic environments

Microplastics (MPs) are emerging environmental pollutants that are present in aquatic environments and accumulate within the food chain, posing significant threats to human health. Over 8 million tons of MPs enter these ecosystems annually. However, existing rapid qualitative and quantitative analytical methods for trace MPs are limited, hindering comprehensive research on their impact in water environments. This study presents a novel composite membrane with both adsorption and filtration functions, integrated with surface enhanced-Raman scattering technology for detecting trace MPs in water. The silver dendrites, modified with n-hexanethiol and loaded onto filter paper, facilitate enhanced enrichment and simultaneous sensitive detection of MPs. The composite membrane exhibited excellent retention rates for standard polystyrene (PS) MPs of various sizes (200, 500, and 1000 nm), achieving high enrichment efficiency. Sensitive detection was realized with a linear response in a concentration range of 0.01 to 0.5 g/L, yielding optimal enhancement factors exceeding 2.92 × 103, enabling detection at μg/L levels. Recovery rates for PS in spiked environmental water samples ranged from 96.86 % to 102.96 %. This innovative method offers a promising approach for the rapid and sensitive detection of trace MPs in aquatic environments, contributing significantly to the assessment of MPs pollution.

Simultaneous Determination of Phenolic Pollutants based on Electrochemical Oxidation by Nanoporous Gold

Phenolic compounds, as highly toxic pollutants, can cause great harm to human beings and the environment even at very low concentrations. Therefore, the simultaneous detection of multiple phenolic pollutants is critically valuable for environmental monitoring. Here, an electrochemical sensor based on a glassy carbon electrode (GCE) modified by nanoporous gold (NPG) was successfully developed for the determination of phenolic pollutants including phenol (Ph), hydroquinone (HQ), catechol (CT), and o-nitrophenol (ONP), which realized not only the sensitive individual detection of each phenolic pollutant but also the sensitive simultaneous detection of these four phenolic pollutants. For the simultaneous detection, the limits of detection of Ph, HQ, CT, and ONP were 0.85, 0.17, 0.19, and 1.30 μM as well as the sensitivities of 0.24, 1.17, 1.08, and 0.16 μA μM−1 cm−2, respectively. Additionally, the NPG/GCE electrochemical sensor exhibited good stability and anti-interference capability. The recovery rates of Ph, HQ, CT, and ONP in seawater samples and wastewater samples ranged from 94.64% to 105.87%. These results indicated that the prepared NPG/GCE electrochemical sensor may be an ideal choice for the reliable simultaneous detection of multiple phenolic pollutants.

Dual-color immunochromatographic test strip for simultaneous sensitive detection of malachite green and leucomalachite green residues in fish and shrimp meat samples

A sensitive dual immunochromatographic test strip (dual-ICTS) was developed to detect malachite green (MG) and its metabolite, leucomalachite green (LMG), using two types of gold nanoparticles: round-shaped (red) and star-shaped (blue). The detection limits were determined to be 0.221 μg L−1 for MG and 0.214 μg L−1 for LMG, respectively. The dual-ICTS provided a cut-off value of 1.8 μg L−1 for MG and LMG detection. The dual-ICTS successfully detected MG and LMG in food samples, with recovery rates ranging from 86 % to 116 %. The dual-ICTS was evaluated by correlation analysis between the proposed assay and the well-established enzyme-linked immunosorbent assay in the MG and LMG detection. This is the first report on the development of the ICTS that can detect both MG and LMG at the same time within only 5 min, making it a sensitive and rapid tool for on-site detection.

Development and Validation of the MAST ISOPLEX®VTEC Kit for Simultaneous Detection of Shiga Toxin/Verotoxin 1 and 2 (stx1/vt1 and stx2/vt2) with Inhibition Control (IC) in a Rapid Loop-Mediated Isothermal Amplification (LAMP) Multiplex Assay.

Loop-mediated isothermal amplification (LAMP) is a cost-effective, rapid, and highly specific method of replicating nucleic acids. Adding multiple targets into a single LAMP assay to create a multiplex format is highly desirable for clinical applications but has been challenging due to a need to develop specific detection techniques and strict primer design criteria. This study describes the evaluation of a rapid triplex LAMP assay, MAST ISOPLEX®VTEC, for the simultaneous detection of Shiga toxin/verotoxin 1 and 2 (stx1/vt1 and stx2/vt2) genes in verotoxigenic Escherichia coli (E. coli) (VTEC) isolates with inhibition control (IC) synthetic DNA using a single fluorophore-oligonucleotide probe, MAST ISOPLEX®Probes, integrated into the primer set of each target. MAST ISOPLEX®Probes used in the MAST ISOPLEX®VTEC kit produce fluorescent signals as they integrate with reaction products specific to each target, allowing tracking of multiple amplifications in real time using a real-time analyzer. Initial validation on DNA extracts from fecal cultures and synthetic DNA sequences (gBlocks) showed that the MAST ISOPLEX®VTEC kit provides a method for sensitive simultaneous triplex detection in a single assay with a limit of detection (LOD) of less than 100 target copies/assay and 96% and 100% sensitivity and specificity, respectively.

Simultaneous Electrochemical Detection of Catechol and Hydroquinone Based on a Carbon Nanotube Paste Electrode Modified with Electro-Reduced Graphene Oxide.

Effectively detecting catechol (CC) and hydroquinone (HQ) simultaneously is crucial for environmental protection and human health monitoring. In the study presented herein, a novel electrochemical sensor for the sensitive simultaneous detection of CC and HQ was constructed based on an electrochemically reduced graphene oxide (ERGO)-modified multi-walled carbon nanotube paste electrode (MWCNTPE). Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electrochemical techniques were utilized to characterize the sensing interface and investigate the sensing mechanism. Under the optimal detection conditions, the oxidation peak currents of CC and HQ show a good linear relationship with their concentrations in the range of 0.4-400 μM with a detection limit of 0.083 μM for CC and 0.028 μM for HQ (S/N = 3). Moreover, the sensor exhibits good performance and can be applied successfully in the simultaneous detection of CC and HQ in tap water samples and urine samples with satisfactory results, indicating its promising application prospects.

Multifunctional spatial-potential resolved electrochemiluminescence biosensor for dual-channel simultaneous detection of hepatitis A virus and hepatitis C virus DNA

Highly sensitive simultaneous detection of dual-target is one of the main research directions of electrochemiluminescence (ECL), but the traditional three-electrode system makes it difficult to realize this aim. This work designed a multifunctional spatial-potential resolved ECL biosensor for dual-channel simultaneous detection of hepatitis A virus (HAV) and hepatitis C virus (HCV) DNA. Self-luminescent dual-ligand metal organic framework (D-MOF) and cerium MOF (Ce-MOF) were modified on two parts of the ITO electrode to achieve dual-channel simultaneous detection. One ligand of D-MOF acted as the luminophore and the other as the co-reactant, so D-MOF could emit excellent positive potential ECL signal without requiring external co-reactants. In channel A, the Ag nanoparticles (Ag NPs) quenching probes were introduced to D-MOF through hybridization of HAV with “Y” type DNA. Positive potential signal of D-MOF was decreased for HAV DNA detection based on resonance energy transfer (RET). In channel B, the CdSe quantum dots (QDs) were introduced to Ce-MOF through hybridization of HCV with “Y” type DNA. Due to the excellent ECL performance of CdSe QDs, negative potential signal was increased for HCV DNA detection. In this work, an ingenious spatial-potential resolved ECL biosensor was developed for simultaneous detection of dual-target by simple sealing film isolation, which opened a new strategy for dual-target detection in general ECL assays with three-electrode system.

Sensitive dual-channel lateral flow immunoassay tagged with high brightness latex microsphere for simultaneous detection of respiratory viral antigens

Respiratory infectious diseases pose a serious threat to human health worldwide. Timely diagnosis is crucial for effective clinical management and infection control. Herein, we developed a dual-channel lateral flow immunoassay (DC-LFIA) for simultaneous sensitive detection of influenza A virus (IAV) and respiratory syncytial virus (RSV) nucleoprotein (NP) antigens. The high brightness latex microspheres (HB-LMs) exhibiting typical absorption peak at 540 nm with uniform size and excellent optical stability, were prepared by a simple surfactant-free emulsion polymerization by mixing Sudan red, which overcame the complexity and color instability met for traditional synthesis methods. After affinity evaluation, two antibody pairs have good affinity for IAV NP and RSV NP were separately identified. Then, combining antibody pairs as probes and HB-LMs as based signal tag, a DC-LFIA was constructed, by which the visual limit of detection is 25 pg/mL, 100 pg/mL for IAV NP and RSV NP, respectively, 10-fold more sensitive than gold nanoparticles based LFIA. The calculated limit of detection (S/N=3) of IAV NP and RSV NP was improved 22.8- and19.5-fold, respectively, in comparison with gold nanoparticles based LFIA. Additionally, the developed sensor shows excellent specificity and reproducibility. Furthermore, the as-proposed method was validated through the analysis of clinical samples, in good agreement with commercial colloidal gold kits. Thus, the developed DC-LFIA has great potential for clinical application in the multiplex detection of respiratory viral antigens.

Simultaneous and sensitive detection of methylparaben and its metabolites by using molecularly imprinted solid-phase microextraction fiber array technique

BackgroundMethylparaben (MP), a commonly used antibacterial preservative, is widely used in personal care products, foods, and pharmaceuticals. MP and its metabolites are easy to enter the water environment, and their exposure and accumulation have negative effects on the ecological environment and human health, and have endocrine disrupting activity and potential physiological toxicity. It is still the primary issue of environmental analysis and ecological risk assessment to develop simple and reliable methods for simultaneous sensitive detection of these compounds in environmental water. ResultsIn this paper, a flexible molecularly imprinted fiber array strategy is proposed for simultaneous enrichment and detection of trace MP and its four main metabolites. The experimental results showed that the three-fiber imprinted fiber array constructed by MP imprinted fiber had the best effect on the simultaneous enrichment of these five target analytes. The enrichment capacity of the imprinted fiber array was 214–456 times, 314–1201 times and 38–685 times that of commercial PA, PDMS and PDMS/DVB fiber arrays, respectively. The limit of detection (LOD) of this method was 0.033 μg L−1. The spiked recovery rate was 86.78–113.96 %, and RSD was less than 9.17 %. In addition, this molecularly imprinted SPME fiber array has good stability, long service life and can be used repeatedly at least 100 times. SignificanceThis molecularly imprinted fiber array strategy can flexibly assemble different molecularly imprinted SPME fibers together, effectively improve the enrichment ability and detection sensitivity, and achieve simultaneous selective enrichment and detection of several analytes. This is an easy, efficient and reliable method for monitoring several trace analytes simultaneously in intricate environmental matrices.

A disposable sensor based on one-pot synthesized tungsten oxide nanostructure-modified screen printed electrodes for selective detection of dopamine and uric acid.

Here, screen-printed carbon electrodes (SPCEs) were modified with ultrafine and mainly mono-disperse sea urchin-like tungsten oxide (SUWO3) nanostructures synthesized by a simple one-pot hydrothermal method for non-enzymatic detection of dopamine (DA) and uric acid (UA) in synthetic urine. Sea urchin-like nanostructures were clearly observed in scanning electron microscope images and WO3 composition was confirmed with XRD, Raman,FTIR and UV-Vis spectrophotometer. Modification of SPCEs with SUWO3 nanostructures via the drop-casting method clearly reduced the Rct value of the electrodes, lowered the ∆Ep and enhanced the DA oxidation current due to high electrocatalytic activity. As a result, SUWO3/SPCEs enabled highly sensitive non-enzymatic detection of DA (LOD: 51.4nM and sensitivity: 127µAmM-1cm-2) and UA (LOD: 253nM and sensitivity: 55.9µAmM-1cm-2) at low concentration. Lastly, SUWO3/SPCEs were tested with synthetic urine, in which acceptable recoveries for both molecules (94.02-105.8%) were obtained. Given the high selectivity, the sensor has the potential to be used for highly sensitive simultaneous detection of DA and UA in real biological samples.

MoS2 embedded triangular silver nanosheets modified MOF-808 as electrochemical sensing platform for highly sensitive simultaneous detection of ACOP and 4-AP

The detection of acetaminophen (ACOP) and its toxic hydrolyzed product p-aminophenol (4-AP) is very significant for clinical diagnosis and quality control of drug formulation. In this study, a novel electrochemical sensor based on MoS2 embedding triangular Ag nanoplates (Tri-AgNPs) coated MOF-808 was developed for simultaneous and sensitive detection of ACOP and 4-AP. The morphology and structure MOF-808@MoS2/Tri-AgNPs nanocomposite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and so on. The electrochemical and electrocatalytic properties of the composite electrode were evaluated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results demonstrated that the constructed sensor had excellent electrochemical performance for ACOP and 4-AP detection due to the synergistic interaction among MOF-808, MoS2 and Tri-AgNPs. The proposed sensor exhibited a wide linear range (1–450 μM) and low limits of detection for detection of ACOP (0.054 μM) and 4-AP (0.046 μM). At the same time, the sensor also showed outstanding repeatability, reproducibility, stability and selectivity. In addition, MOF-808@MoS2/Tri-AgNPs/GCE was also employed to determine ACOP and 4-AP in acetaminophen tablets and Yellow River water samples with satisfactory recovery rates, which indicated the feasibility of the developed electrochemical sensor in the actual sample analysis.

Flower-like imide covalent organic framework as an electrochemical platform catcher for simultaneous sensitive detection of trace Pb(II) and Cd(II)

Heavy metal pollution in aquatic environment poses an enormous risk to ecosystems and human health. In this study, a flowerlike covalent organic framework (TpTa-COF) was synthesized by one-step solvothermal method with 2,4,6-triformylphloroglucinol (Tp) and 4, 4-diamino-tribiphenyl (Ta) as building elements. Then it was used as an effective trap to establish an electrochemical sensing platform for simultaneously sensitive detection of trace Pb(II) and Cd(II) in water. This three-dimensional flower-shaped structure exhibited exceptional adsorption capacity, large surface area, high stability, and all of which enhanced the detection sensitivity of the sensor and facilitated full contact between ions and substrate. The high oxygen content in the structure provided abundant active sites for Pb(II) and Cd(II), further enhancing its electrochemical response. The constructed sensor exhibited a linear response to Pb(II) within the concentration range of 3–60 µg/L under the optimal conditions, with a detection limit of 0.16 µg/L. Similarly, a linear response was observed for Cd(II) in the concentration range of 5–60 µg/L, with a detection limit of 0.29 µg/L. Low detection limits, excellent sensitivity, and strong stability were all features of the suggested approach. It has been successfully employed in determining Pb(II) and Cd(II) concentrations in two actual water samples. XPS, SEM-EDS mapping, and density functional theory calculations confirmed that TpTa-COF interacted with metal ions mainly via coordination with carbonyl oxygen atoms in the structure. Overall, these findings will broaden the applications of COF in the field of chemical analysis.

A novel electrochemical sensor based on DUT-67/ZnCo2O4-MWCNTs modified glassy carbon electrode for the simultaneous sensitive detection of dopamine and uric acid

Uric acid and dopamine are closely related to the health of the organism, so it is important to determine them simultaneously and efficiently. In this paper, the metal-organic framework DUT-67 was in situ grown on the surface of bimetallic oxide ZnCo2O4 nanoflowers, and then ultrasonically compounded with multi-walled carbon nanotubes (MWCNTs) to prepare DUT-67/ZnCo2O4-MWCNTs composite. The prepared composite was characterized by XRD, SEM, XPS, FTIR, BET and other techniques. Finally, an electrochemical sensor based on DUT-67/ZnCo2O4-MWCNTs composite modified glassy carbon electrode for simultaneous detection of dopamine (DA) and uric acid (UA) was fabricated. The introduction of ZnCo2O4 into the composite efficiently overcame the disadvantage of the easy aggregation of DUT-67 and produced a synergistic effect with MWCNTs. The electron transfer rate between the electrode and the electrolyte solution was accelerated, and the detection signals of the target molecules were amplified. After characterizing the electrochemical properties of the composite electrode, it was found that the constructed electrochemical sensor showed low detection limits for DA and UA, which were 12 nM and 8.7 nM, respectively, and the wide linear range of 1.0–180.0 μM. Besides, the sensor had excellent reproducibility, repeatability, anti-interference and stability. The proposed sensor was also successfully used to determine the contents of DA and UA in dopamine injection and urine samples with relatively satisfactory recovery rates. This work not only provides a new strategy for the preparation of MOF modified electrodes, but also has a potential application prospect in bioassays.

Dual potential- and waveband-resolved electrochemiluminescence platform for simultaneous determination of three lung cancer biomarkers

The sensitive simultaneous detection of multiplex biomarkers is critical for the early cancer diagnosis. Herein, a dual potential- and waveband-resolved electrochemiluminescence (ECL) platform is reported for multiplexing immunoassay, using a rotating band-pass filter array for ECL spectrum discrimination. Three lung cancer biomarkers, neuron-specific enolase (NSE), carcinoembryonic antigen (CEA) and cytokeratin 19 fragment antigen (CYFRA21–1) were adopted as model analytes, with nanocomposites of gold nanoparticles/graphene oxide/N, N′- dicaproate sodium-3,4,9,10-perylenedicarboximide (AuNPs/GO/PDI), CdSe nanocrystals (NCs) and CdTe NCs as ECL tags, respectively. After forming corresponding sandwich-type immune-complexes on the surface of modified electrode via an one-pot immune-reaction, the intensities from the ECL tags of AuNPs/GO/PDI (Ep = −0.41∼ −0.46 V), CdSe NCs (λmax = 550 nm, Ep = −1.44∼ −1.46 V), and CdTe NCs (λmax=750 nm, Ep = –1.49 ∼ −1.51 V) in the signal antibody bio-conjugates were measured in a single cathodic potential scan run with K2S2O8 as the coreactant. The interference from the ECL of O2/S2O82- enhanced by the three ECL tags was corrected by the intensity at 649 nm in the waveband-resolved ECL mode. Under optimized conditions, NSE, CYFRA21–1 and CEA were simultaneously quantified with the detection limit values of 0.86, 2.6 and 0.53 fg mL−1, respectively.

LC-MS/(MS) confirmatory doping control analysis of intact phase II metabolites of methenolone and mesterolone after Girard's Reagent T derivatization.

In the present study, the application and evaluation of Girard's Reagent T (GRT) derivatization for the simultaneous detection and significantly important identification of different phase II methenolone and mesterolone metabolites by LC-MS/(MS) are presented. For the LC-MS analysis of target analytes two complementary isolation methods were developed; a derivatization and shoot method in which native urine is diluted with derivatization reagent and is injected directly to LC-MS and a liquid-liquid extraction method, using ethyl acetate at pH 4.5, for the effective isolation of both sulfate and glucuronide metabolites of the named steroids as well as of their free counterparts. For the evaluation of the proposed protocols, urine samples from methenolone and mesterolone excretion studies were analyzed against at least one sample from a different excretion study. Retention times, along with product ion ratios, were evaluated according to the WADA TD2021IDCR requirements, in order to determine maximum detection and identification time windows for each metabolite. Established identification windows obtained after LC-MS/(MS) analysis were further compared with those obtained after GC-MS/(MS) analysis of the same samples from the same excretion studies, for the most common analytes monitored by GC-MS/(MS). Full validation was performed for the developed derivatization and shoot method for the identification of methenolone metabolite, 3α-hydroxy-1-methylen-5α-androstan-17-one-3-glucuronide (mth3). Overall, the GRT derivatization presented herein offers a tool for the simultaneous sensitive detection of free, intact glucuronide and sulfate metabolites by LC-MS/(MS) that enhance significantly the detection and identification time windows of specific methenolone and mesterolone metabolites for doping control analysis.

A novel electrochemical sensor based on MoS2 electrospun nanofibers and polyoxometalate composite for the simultaneous detection of ractopamine and clenbuterol

A novel electrochemical sensor based on MoS2 nanofibers and polyoxometalate H3PMo12O40 (HPMo) composite was used for the highly selective and sensitive simultaneous detection of ractopamine (RAC) and clenbuterol (CLB). The electrochemical sensor was prepared firstly by MoS2 electrospun nanofibers as polyoxometalate (POM) carrier. Then, the morphology structure and physicochemical properties of the nanofiber composites modified electrode were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM), nitrogen adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and electrochemical technologies. The results showed that HPMo decorated MoS2 electrospun nanofibers as modified electrodes can not only promote electron transfer but also enhance electrochemical sensing ability towards RAC and CLB. Differential pulse voltammetry (DPV) results proved that the proposed sensor exhibits good stability, high sensitivity and selectivity in terms of a wide range of 1–70 μM for RAC and 1–350 μM for CLB and a low detection limit of 0.056 μM for RAC and 0.085 μM for CLB, respectively. Furthermore, the proposed sensors were applied to real pork sample analysis, which the recovery of RAC and CLB were 98.5 % − 105.6 % and 98.9 % − 103.1 %, respectively. The results indicate that the electrochemical sensors have a wide application prospect in the detection of β-agonists in animal food sample.

Solvothermal synthesis of organoclay/Cu-MOF composite and its application in film modified GCE for simultaneous electrochemical detection of deoxyepinephrine, acetaminophen and tyrosine.

An organoclay/copper-based metal-organic framework (MOF) composite was synthesized using a solvothermal method by growing a Cu-BTC (copper(ii) benzene-1,3,5-tricarboxylate) MOF from a mixture of the MOF precursor solution in which various amounts of organoclay had been dispersed. The organoclay was obtained by intercalating a cationic dye, namely thionin, into a natural Cameroonian clay sampled in Sagba deposit (North West of Cameroon). The organoclay and the as-synthesized composites were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer, Emmett and Teller (BET) techniques. From Scherrer's equation, the crystallite size of the composite was found to be between 55 and 58 nm, twice as large as the pristine MOF's crystallite size. The organoclay/Cu-MOF composite (Sa-TN50/Cu3(BTC)2) exhibiting a BET surface area of 192 m2 g-1, about twice that of pristine clay and about one seventh that of pristine MOF, was then utilized to form a stable thin film onto glassy carbon electrodes (GCE) by drop coating (Sa-TN50/Cu3(BTC)2/GCE). These electrodes demonstrated electrocatalytic behavior toward deoxyepinephrine (DXEP) and thus enabled selective and simultaneous sensitive detection of three analytes: DXEP, acetaminophen (AC) and tyrosine (TYR) compared with bare GCE and clay modified electrode. Under optimum conditions, Sa-TN50/Cu3(BTC)2/GCE exhibited good performance including large calibration curves ranging from 5.0 μM to 138.0 μM for DXEP, 4.0 μM to 153.0 μM for AC and 1.0 μM to 29.4 μM for TYR. The detection limits were found to be, 0.4 μM, 0.7 μM and 0.2 μM for DXEP, AC and TYR, respectively. The developed sensors have been applied successfully in the quantification of AC in a commercial tablet of AC, and DXEP, AC and TYR in tap water.

Screen printing and laser-induced flexible sensors for the simultaneous sensitive detection of uric acid, tyrosine, and ascorbic acid in sweat.

A wearable sweat sensor, which could continuously monitor biomolecules related to the human physiological state, is emerging as a promising piece of health surveillance equipment. However, current sensors cannot simultaneously achieve a detection performance that equates to that of traditional sensors and satisfactory mechanical strength. Herein, a wearable sweat sensor with excellent detection performance and mechanical stability is designed and fabricated. Based on the integration of laser-induced graphene electrodes and a screen printing technique, this wearable sweat sensor could realize both the separate and simultaneous detection of uric acid (UA), tyrosine (Tyr), and ascorbic acid (AA) with high sensitivity. Good UA sensing performance in artificial sweat could be maintained even after 20 000 bends. In addition, the sensor can operate well in the wearing state or in a complex bovine whole blood sample. For the detection of human sweat, the changes in UA concentration after a purine-rich meal are continuously monitored and the results are in accordance with the corresponding serum UA detection results tested with a commercial serum UA meter. These results suggest its application potential in health monitoring for both gout patients and healthy humans.

A Novel Sensor Based on Cu2O/Mo2C@C Derived from MOF Composites for Simultaneous Detection of Catechol and Hydroquinone

Herein, the copper-based metal organic framework (CuBDC) modified with MoO3 nanorods uniformly distributed on its surface (MoO3@CuBDC) was synthesized by a one-step solvothermal method, and then was treated with high temperature calcination. A series of characterizations demonstrate that MoO3@CuBDC was transformed into a ternary composite of Cu2O nanospheres, Mo2C, and carbon material (Cu2O/Mo2C@C) after the treatment. Moreover, a novel electrochemical sensor based on Cu2O/Mo2C@C modified glassy carbon electrode (GCE) was constructed for simultaneous sensitive detection of catechol (CC) and hydroquinone (HQ). Due to the excellent electrocatalytic ability of Cu2O/Mo2C@C, the prepared sensor exhibits good electroanalytical performance, which shows good linearity in the concentration ranges of 0.50–200.00 μM for CC and HQ with the limits of detection of 0.38 μM and 0.13 μM. In addition, this sensor can be used to detect CC and HQ simultaneously in real samples with satisfactory results.

Selective and sensitive simultaneous detection of tartrazine and Hg2+ based on N-doped yellow-green fluorescent carbon dots

Tartrazine preferred in food and textile industries, but excessive consumption threats human health. Due to toxicity, non-biodegradability, and trace accumulation in the food chains, Hg2+ has attracted people's attention. Thus, it is important to detect tartrazine and Hg2+ with sensitivity way. Using VB2 and citrate as precursors, yellow-green fluorescent carbon dots were prepared by hydrothermal method. The N-CDs were purified by dialysis, thin layer chromatography and chromatographic column. Excellent linear ranges of 0.25–5 μM and 5–50 μM of tartrazine were obtained with low detection limits 34.98 nM, while good linear ranges of 0.25–5 μM and 10–50 μM of Hg2+ with low detection limits 29.64 nM, respectively. In addition, the quenching mechanisms of targets to the fluorescent of N-CDs were illuminated. Furthermore, the nanoprobe was efficiently applied to determine the content of tartrazine in carbonated drink, fruit jelly and sugar samples, and Hg2+ in tap water, lake water, and river water samples. It showed great potential to detect tartrazine and Hg2+.