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The electrochemical property of Mo2C nanoparticles (NPs) depends on the structure and crystal planes. Herein, Mo2C nanoparticles were prepared and dispersed on carbon nanosheets by the construction of a biomass-derived carbon precursor, and the exposed dual crystal planes were also controlled by optimal conditions. The structure, compositions, and morphology of the carbon-based Mo2C were characterized, and the Mo2C NPs were well dispersed on the carbon nanosheets. The electrochemical study shows that optimal Mo2C exhibits excellent electrochemical properties for the oxidation of nicotine compared with other materials in the broad linear range of 0.2–300 μM. In particular, it displays a remarkable oxidation ability for the low-concentration nicotine (0.2–5 μM), and the detection limit is about 0.17 μM. Furthermore, the exposed dual crystal planes of Mo2C play a critical role in the oxidation. Notably, this characteristic of Mo2C NPs makes it possible to detect nicotine from the extracted solution and be used for chip electrodes to detect nicotine quickly via wireless response, which exhibits actual application prospects for portable detection. The results indicate that the as-prepared Mo2C material could be effective and low-cost for nicotine analysis in the sectors of health management and medical fields. [ABSTRACT FROM AUTHOR]

The impact of P-type doping level on InAs quantum dot (QD) lasers grown on GaAs (001) was investigated through the device performance characterization, i.e., measurements of threshold current, output slope efficiency, and temperature characteristics of lasers. The lasers are characterized under continuous wave operation with a ridge waveguide of 6 × 4000 μm2. In comparison to un-doped lasers, it has been demonstrated that an appropriate P-type doping level in the entire spacer can reduce the threshold current density of lasers from 215 to 86.8 A/cm2 for a doping concentration of 10 holes per QD at room temperature. Additionally, an improvement in output power slope efficiency from 0.108 to 0.191 W/A has been obtained, along with an enhanced characteristic temperature from 34.4 to 67.5 K (20–100 °C). Moreover, modulation doping has been explored to further reduce the threshold current density down to 77.9 A/cm2 at room -temperature and raise the output power, while entire spacer doping may enhance device performance at high operating temperatures. By optimization of P-type doping, remarkable enhancements in the performance of QD lasers can be achieved, which might have potential applications in cost-effective high-performance photonic integrated circuits. [ABSTRACT FROM AUTHOR]

A guided ion beam tandem mass spectrometer was used to study the reactions of U+ with N2 and NO. Reaction cross sections were measured over a wide range of energy for both systems. In each reaction, UN+ is formed by an endothermic process, thereby enabling the direct measurement of the threshold energy and determination of the UN+ bond dissociation energy. For the reaction of U+ + N2, a threshold energy (E0) of 4.02 ± 0.11 eV was measured, leading to D0 (UN+) = 5.73 ± 0.11 eV. The reaction of U+ + NO yields UO+ through an exothermic, barrierless process that proceeds with 94 ± 23% efficiency at the lowest energy. Analysis of the endothermic UN+ cross section in this reaction provides E0 = 0.72 ± 0.11 eV and, therefore, D0 (UN+) = 5.78 ± 0.11 eV. Averaging the values obtained from both reactions, we report D0 (UN+) = 5.76 ± 0.13 eV as our best value (uncertainty of two standard deviations). Combined with precise literature values for the ionization energies of U and UN, we also derive D0 (UN) = 5.86 ± 0.13 eV. Both bond dissociation energies agree well with high-level theoretical treatments in the literature. The formation of UN+ in reaction of U+ with NO also exhibits a considerable increase in reaction probability above ∼3 eV. Theory suggests that this may be consistent with the formation of UN+ in excited quintet spin states, which we hypothesize are dynamically favored because the number of 5f electrons in reactants and products is conserved. [ABSTRACT FROM AUTHOR]

We designed a trigonal symmetric imine-linked covalent organic framework (COF), TFPC-DAB, with control over the angularity of the building units, where a bent C2-symmetric diamine, such as 1,3-diaminobenzene (1,3-DAB or DAB), with an exo-angle of 120° was used instead of those with an exo-angle of 180°, in combination with a C3-symmetric trialdehyde, such as tri(4-formylphenoxy)cyanurate (TFPC). Its synthesis was accomplished by reacting the building units in a mixture of mesitylene/dioxane/6 M acetic acid under solvothermal conditions. The phase purity, thermal stability, and porosity of TFPC-DAB were established by various analytical techniques. Utilizing the Density Functional Tight Binding (DFTB+) simulation and Pawley refinement, the best fit of the small angle x-ray pattern was found to have an AA stacking of TFPC-DAB in the trigonal space group P3 with low refinement parameters. Such smart materials are in huge demand to detect hazardous corrosive chemicals, such as HCl and NH3. The dual features of electron deficient π-acidic triazine moiety and heteroatoms (N/O) from TFPC and electron rich phenyl units from DAB embodied in the framework enhance its luminescent property and thereby make it suitable for solvent-based HCl and NH3 sensing. The detection limits for HCl and NH3 in methanol were found to be 14 and 82 ppb, respectively. The effect of solvent polarity on the sensing studies was observed with much lower detection limits in dioxane: 2.5 and 11 ppb for HCl and NH3, respectively. A detailed theoretical calculation using density functional theory and configurational bias Monte Carlo modules was conducted for understanding interactions between the COF and HCl or NH3 analytes. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) detection with novel sensing properties such as higher response and minimum detection limit at room temperature is essential to ensure the safety of humans and the environment. A hydrothermal method was utilized to synthesize NiO–ZnCo2O4 heterostructures. The purpose of these materials was to fabricate gas sensors and detect different hazardous gases. The intrinsic properties of synthesized products were studied to check the microstructure and morphological properties of the heterostructures. Different gas sensors performed gas sensing properties, and the significant properties such as high response (ratio of response in gas and response in air R g ∕ R a = 2 9 0) towards 20 ppm H2S, short response/recovery time (32/20 s), a low detection limit (0.5 ppm), and great selectivity were detected based on the gas sensor of NZCO-5 (5% NiO–ZnCo2O4) compared with other sensors NiO, NZCO-0 (0% NiO–ZnCo2O4) and NZCO-10 (10% NiO–ZnCo2O4). The significant H2S gas sensing improvement in this study could be a potential route for saving human lives. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Liothyronine (T3) is a thyroid hormone, which is frequently administered alongside thyroxine in the treatment of hypothyroidism. However, several market withdrawals have been called for due to persistent quality issues with liothyronine tablets. Given its narrow therapeutic index, maintaining optimal liothyronine levels is imperative, highlighting the criticality of ensuring quality both during manufacturing and at the patient's bedside. In this study, we introduce a pioneering electroanalytical biosensor designed for liothyronine estimation using molecularly imprinted poly‐pyrrole (MIP‐Ppy). Notably, the sensor demonstrates linear response within the concentration range of 50–300 pg/mL (r2 = 0.986) with a remarkable limit of detection (LOD) of 80 pg/mL. Interference studies were performed to validate the sensor's robustness, displaying negligible response alterations. This method was used for the assay of liothyronine tablets and was compared with the traditional HPLC method. The MIP‐Ppy biosensor showed 90.7% recovery with a minimal relative standard deviation of 0.093 whereas HPLC showed 91.2% recovery with RSD 0.052. These findings underscore the biosensor's potential as a cost‐effective alternative to sophisticated chromatographic methods for liothyronine estimation in pharmaceutical tablets. This advancement lays the groundwork for the development of a user‐friendly point‐of‐care device. [ABSTRACT FROM AUTHOR]

Sensitive detection of antibiotic residues in food is of great significance for food safety monitoring. Herein, a novel nucleic acid amplification sensing platform for protein enzyme-free, label-free, and homogeneous fluorescence detection of kanamycin was established by combining a catalytic hairpin assembly (CHA) circuit and double-end G-quadruplex signal amplification. Here, kanamycin initiated the CHA circuit between two assembled probes by specifically binding to an aptamer sequence. Each of the two assembled probes encapsulated a G-rich sequence in the stem region such that the kanamycin-catalyzed CHA circuit produced active double-end G-quadruplex assemblies under the action of K+. The double-end G-quadruplex assemblies were further combined with N-methylmesoporphyrin IX to induce a distinctly amplified fluorescence signal. The CHA-based double-end G-quadruplex signal amplification significantly improved the detection sensitivity of kanamycin. The fluorescence signal increment confirmed that the result of double-end G-quadruplex assemblies was more than twice that of single-end G-quadruplex assemblies. The system exhibited a wide linear range of 1–500 nM for kanamycin, with a limit of detection (LOD) and a limit of quantification (LOQ) of 0.27 nM and 0.89 nM, respectively. In addition, the sensing system effectively distinguished kanamycin from other antibiotics, thus exhibiting high selectivity for kanamycin. Moreover, the method successfully detected spiked kanamycin in cow milk samples, and the recoveries of spiked kanamycin were in the range of 99.00%–100.23% with RSDs in the range of 1.71–2.63%. All results confirm the application potential of this system in the field of food monitoring. [ABSTRACT FROM AUTHOR]

Cysteine (Cys) is closely associated with many physiological and pathological processes in organisms and cells. The establishment of a molecular tool for the rapid and simple selective recognition of Cys would be of great benefit in the diagnosis and prevention of related diseases. In this paper, we developed a turn-on fluorescent probe BMBA, 3-(benzo[d]thiazol-2-yl)-4′-morpholino-[1,1′-biphenyl]-4-yl acrylate, designed with an acryloyl ester group to initiate the reaction and a benzothiazole moiety serving as the fluorescent component. Compared with other biological thiols, the probe BMBA possessed exceptional sensitivity and specificity for detecting Cys, boasting a low detection limit at 28.6 nM and a response duration of merely 5 min. The single-crystal data for the probe BMBA and compound 2 were successfully obtained and the recognition mechanism of Cys was investigated by FTIR spectroscopy and 1H NMR. Most importantly, we effectively utilized BMBA for the detection of Cys in calf serum and living cells. [ABSTRACT FROM AUTHOR]

Early detection of biomarkers has a crucial role in preventing blindness caused by diabetic retinopathy (DR). In this work, we developed a rapid, highly sensitive method for the simultaneous detection of DR-related biomarkers (miR-21 and miR-152) based on an Au nano-hexagon (AuNHs) integrated microarray chip combined with a competitive recognition strategy. The nucleic acid aptamer-modified AuNHs array served as capture substrate, while Au nano-trisoctahedrons (AuNTs) with complementary strands of nucleic acid aptamers mounted on their surface and Raman signaling molecules served as SERS probes (AuNTs@4-MBA@H1 and AuNTs@DTNB@H2). SERS probes carrying Raman signaling molecules (4-MBA and DTNB) were displaced by the target miRNAs in the experiments because they had a higher binding affinity to nucleic acid aptamers than their structural analogs (H1 and H2). This approach led to a notable decrease in the Raman signal. The competitive recognition strategy was straightforward and useful, and required only a one-step dropwise reaction to detect both miRNAs simultaneously and effectively. The microarray chip designed accordingly had the advantages of sensitive, rapid and high-throughput detection, and the detection time was only 8 min. The limits of detection (LOD) for miR-21 and miR-152 were as low as 2.76 × 10−14 M and 1.94 × 10−14 M, respectively. The utility of the method in complex systems was verified by detecting miRNAs in the serum of DR rats, and the accuracy of the method was verified against the detection results of a RT-qPCR method. This method provides a new idea and manner for the detection of miRNAs in serum, which is crucial for the early diagnosis of DR. [ABSTRACT FROM AUTHOR]

A portable gas chromatograph–mass spectrometer (GC-MS) is an effective instrument for rapid on-site detection of volatile organic compounds (VOCs). Current instruments typically adsorb samples at ambient temperature, challenging the detection of low-boiling VOCs. In this study, a low-temperature adsorption thermal desorption method is proposed for sample enrichment in a portable GC-MS. The refrigeration module adopts a thermoelectric cooler (TEC), and a heating wire directly heats the adsorption tube to reduce the heat capacity. The miniaturization and low-power design make this module integrable into portable GC-MS devices. This module can reduce the temperature to around 0 °C within ten minutes for sample enrichment, and the heating system can increase the temperature to 260 °C within 20 seconds to ensure rapid desorption and injection of samples. Due to the miniaturization design, the total weight of the portable GC-MS is 21.7 kg, and the volume is 48 cm × 38 cm × 17 cm. Within merely 10 minutes, it completely separated and detected 65 VOCs in the TO-15 standard substance, with a detection limit down to 0.12 μg L−1 for toluene. The detection performance for low-boiling substances could be enhanced by up to 17 times compared to ambient temperature adsorption thermal desorption, such as 1,3-butadiene. Moreover, the results demonstrated long-term stability (RSD < 10% for 98% of the substances, with recovery rates from 91.66% to 109.12%). This study provides a feasible strategy for the rapid and reliable detection of VOCs in the air, holding great potential in the field of environmental monitoring. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are considered reliable biomarkers for a variety of diseases. However, their low abundance in organisms and high sequence similarity of homologous miRNAs make their accurate detection challenging. Here, we constructed a novel fluorescent biosensor for the detection of miRNA-155, a potential biomarker of neuroinflammation, based on duplex-specific nuclease (DSN) assisted amplification and DNA-templated silver nanoclusters (DNA-AgNCs) as fluorescence signal probes. DSN-assisted amplification can transform unstable miRNA into stable DNA and amplify the miRNA signal at the same time. Using DNA-AgNCs as fluorescence signal probes for biosensors can avoid complex labeling processes and reduce costs. The biosensor shows excellent selectivity, reproducibility, a wide linear range (1–600 nM) with a detection limit of 0.86 nM, and potentiality for real sample detection. This work provides a potential universal biosensing platform for miRNA detection. [ABSTRACT FROM AUTHOR]

Developing low-cost self-service portable sensors to detect viruses is an important step in combating the spread of viral outbreaks. Here, we describe the development of an aptamer-free paper-based molecularly imprinted sensor for the instrument-free detection of influenza virus A (H5N1). In this sensor, Whatman paper loaded with Fe3O4 nanoparticles (WP@Fe3O4) was prepared as a substrate upon which silicon imprinting occurred in the presence of the template virus H5N1. After removal of the template virus, Fe3O4 which exposed in the imprinted cavities was able to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) by hydrogen peroxide to form blue TMB + ions. Therefore, the concentration of virus can be semi-quantified by the color change of the solution after the catalytic reaction in the absence of any instruments. The color reaction can be clearly observed within 20 min. In addition, the remaining TMB could be quantified fluorometrically, with a limit of detection of 1.16 fM and an imprinting factor of 4.7. As far as we know, this sensor detects the target with the highest sensitivity that has yet been achieved in aptamer-free molecular imprinting sensors. Importantly, the cost of materials used for each sensor was as low as 4 cents (0.23 Yuan) per sensor. This sensitive self-service sensor, which is relatively easy and inexpensive to produce, will provide an effective new avenue for the rapid detection of viruses. [ABSTRACT FROM AUTHOR]

A distorted low-symmetry Eu4L4 tetrahedral cage was fabricated through the self-assembly of europium ions and C3-symmetric bowl-shaped ligands containing a phosphangulene core. X-ray crystallography confirmed its unique architecture, featuring significant structural distortion and solvent-accessible coordination sites. This cage showcases exceptional luminescence-based sensitivity for formaldehyde detection compared to other analogs, achieving an impressive detection limit of 19.4 ppb. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (L. monocytogenes) is one of the most prevalent foodborne pathogens. It causes intestinal infections as well as severe meningitis and septicemia, representing a significant risk to food safety and human health. Consequently, the present study proposes a novel method based on the combination of saltatory rolling circle amplification (SRCA) technology and Safranine O for the rapid, sensitive and visual detection of L. monocytogenes in food. In the presence of L. monocytogenes, the SRCA amplification reaction yields copious quantities of double-stranded DNA. Following the addition of Safranine O and the oxidant, Safranine O is oxidized to form Safranine O oligomer. The electrostatic interactions between the positively charged Safranine O oligomers and the negatively charged SRCA amplification product result in the formation of dark red visible aggregates, the absorbance value also decreases with the formation of aggregates. The method has low detection limit, high specificity, straightforward and time efficient (DNA amplification for 40 min, aggregation for 10 min). The visual qualitative detection limit was 2.7 × 101 CFU/mL, and the limit of detection quantitative detection was 3.4 CFU/mL. In comparison with the SRCA electrophoresis detection method, the visual detection limit was enhanced by 10 times. Comparison with ISO method, the sensitivity, specificity and accuracy of the method for the detection of real samples were 100%, 96.2% and 96.7%, respectively. This method offers a straightforward and accurate qualitative and quantitative approach for the identification of L. monocytogenes in food, and is particularly suited to the detection of pathogenic bacteria in food in resource-poor areas. [ABSTRACT FROM AUTHOR]

Background: Quantitative CT imaging, particularly iodine and calcium quantification, is an important CT-based biomarker. Purpose: This study quantifies sources of errors in quantitative CT imaging in both single-energy and spectral CT. Materials and methods: This work examines the theoretical relationship between CT numbers, linear attenuation coefficient, and material quantification. We derive four understandings: (1) CT numbers are not proportional with element mass in vivo, (2) CT numbers are proportional with element mass only when contained in a voxel of pure water, (3) iodine-water material decomposition is never accurate in vivo, and (4) for error-free material decomposition a voxel must only consist of the basis decomposition vectors. Misinterpretation-based errors are calculated using the National Institute of Standards and Technology (NIST) XCOM database for: tissue chemical compositions, clinical concentrations of hydroxyapatite (HAP), and iodine. Quantification errors are also demonstrated experimentally using phantoms. Results: In single-energy CT, misinterpretation-induced errors for HAP density in adipose, muscle, lung, soft tissue, and blood ranged from 0–132%, i.e., a mass error of 0–749 mg/cm3. In spectral CT, errors with iodine in the same tissues resulted in a range of < 0.1–33% error, resulting in a mass error of < 0.1–1.2 mg/mL. Conclusion: Our work demonstrates material quantification is fundamentally limited when measured in vivo due to measurement conditions differing from assumed and the errors are at or above detection limits for bone mineral density (BMD) and spectral iodine quantification. To define CT-derived biomarkers, the errors we demonstrate should either be avoided or built into uncertainty bounds. Clinical relevance statement: Improving error bounds in quantitative CT biomarkers, specifically in iodine and BMD quantification, could lead to improvements in clinical care aspects based on quantitative CT. Key Points: CT numbers are only proportional with element mass only when contained in a voxel of pure water, therefore iodine-water material decomposition is never accurate in vivo. Misinterpretation-induced errors ranged from 0–132% for HAP density and < 0.1–33% in spectral CT with iodine. For error-free material decomposition, a voxel must only consist of the basis decomposition vectors. [ABSTRACT FROM AUTHOR]

Cardiovascular disease, characterized by acute onset and high mortality rates, necessitates continuous daily monitoring of blood pressure (BP). Recently, advancements in flexible pressure sensing and intelligent wearable technology offer new solutions for non-invasive ambulatory BP monitoring. However, measuring BP with pressure sensors remain challenging due to the weak nature of skin pulse waves, making it difficult to obtain high-fidelity signals. This work introduced a piezoresistive sensor based on polydopamine and carbon nanotubes, which demonstrated high sensitivity (6.23 kPa−1), excellent linearity (R2 = 0.996) across a broad pressure range (0–350 kPa), and maintained a stable electrical response after 10000 compression cycles. It featured a low detection limit (less than 100 Pa) and a rapid response time (100 ms), enabling the detection of pulse waves at multiple regions. Additionally, this study established a multi-parameter BP estimation model using the pulse wave velocity method, which significantly outperformed three simple models in terms of fitting accuracy. Concurrently, a dual-channel pulse wave measurement system was developed to estimate BP values, and its results were consistent with those from commercial sphygmomanometers. This work provided a simple, low-cost approach for the long-term monitoring of cardiovascular diseases, presenting a competitive alternative to current complex systems. [ABSTRACT FROM AUTHOR]

Determination of free cyanide (fCN) is required for various industrial, environmental, food, and clinical samples. Enzymatic methods are not widely used in this field despite their selectivity and mild conditions. Therefore, we present here a proof of concept for new spectrophotometric enzymatic assays of fCN. These are based on the hydrolysis of fCN affording the readily detectable NADH. fCN is hydrolyzed either in one step by cyanide dihydratase (CynD) or in two steps by cyanide hydratase (CynH) and formamidase (AmiF). An advantage of the latter route is the higher activity of CynH and AmiF compared to CynD. In both cases, the resulting formate is then transformed by an NAD-dependent formate dehydrogenase (FDH). The NADH thus formed is quantified colorimetrically using a known method based on a reduction of a tetrazolium salt (WST-8) with NADH. The developed assays of fCN are selective except for formic acid interference, proceed under mild conditions, and, moreover, fCN is detoxified during the reactions. The assays proceeded in a microtiter plate format. The limit of detection (LOD) and the limit of quantification (LOQ) were lower for the three-enzyme (CynH-AmiF-FDH) method (7.00 and 21.2 µmol/L, respectively) than for the two-enzyme (CynD-FDH) method (10.7 and 32.4 µmol/L, respectively). In conclusion, the new fCN assays presented in this work are selective, high-throughput, do not require harsh conditions, and use only small amounts of chemicals and enzymes. [ABSTRACT FROM AUTHOR]

This work presents the development and optimisation of an amperometric biosensor for determining aspartate aminotransferase (AST) activity in blood serum, using glutamate oxidase and platinum disc electrodes. AST is a key biomarker for diagnosing cardiovascular and liver diseases. The biosensor's bioselective membrane composition and formation protocol and the working solution (aspartate 8 mM, α-ketoglutarate 2 mM, pyridoxal-5-phosphate 100 µM) were optimised. The sensor demonstrated high selectivity, stability (70% retention over 2 months at − 18 °C), and sensitivity (2.37 nA min⁻1 per 10 U L⁻1), with a dynamic range of 0–500 U L⁻1 and a limit of detection of 1 U L⁻1. Comparative analysis showed the calibration curve method outperforms the standard addition method for AST measurement in serum samples. Additionally, a reference spectrophotometric technique was adapted for AST level determination, showing a strong correlation (r = 0.989) with the biosensor results. This research offers a fast, affordable, and accurate tool for early check-ups of liver and heart conditions. The biosensor's flexibility and ease of use make it suitable for further development into point-of-care testing and personalised healthcare techniques. [ABSTRACT FROM AUTHOR]

Here, we provide a straightforward, highly selective, and sensitive voltammetric technique that uses a poly (glycine)-modified graphite carbon paste electrode (PGMGCPE) to measure melatonin (MT). It has been demonstrated that PGMGCPE responded sharply to MT oxidation. MT's maximum potential was measured at 0.235 V relative to SCE. Conditions including pH, accumulation time, and scan rate were carefully optimized for the voltammetric measurement of MT. The relationship between oxidation peak current and MT concentration (4.0–30.0 μM) exhibits a broad range linear response. It was discovered that the MT limit of detection (LOD) on PGMGCPE was 0.73 μM. When MT was detected in the presence of different interfering ions, the suggested approach exhibits good selectivity. The technique was successfully used to analyze MT in actual sample. The approach provides good selectivity for MT detection at comparatively low potential as well as acceptable LOD and linear range. [ABSTRACT FROM AUTHOR]

2,4,6-Trinitrophenol (TNP) has high explosive risks and biological toxicity, and there has been considerable concern over the determination of TNP. In the present work, fluorescent carbon dots (CDs) stemmed from a green carbon source of pinecone by the facile hydrothermal approach. A novel environment- friendly fluorescent probe was developed to efficiently detect TNP by using the obtained CDs with remarkable fluorescence stability. The fluorescent CDs exhibited obvious excitation dependence with the highest peaks for excitation and emission occurring at 321 and 411 nm, respectively. The fluorescence intensity is significantly reduced by TNP owing to the inner filter effect with the CDs. The probe exhibited good linearity with TNP concentrations in the range of 0.025–20 μg mL−1, and the limit of detection was as low as 8.5 ng mL−1. Additionally, the probe proved successful in sensing TNP quantitatively in actual environmental samples with satisfied recoveries of 95.6–99.6%. The developed fluorescent probe offered an environment-friendly, efficient, rapid, and reliable platform for detecting trace TNP in the environmental field. Highlights Novel carbon dots were synthesised from green precursors of pineal powder. The highly effective quenching process was put down to the inner filter effect. The as-constructed fluorescent probe was successfully utilised for sensing 2,4,6-trinitrophenol in environmental samples. The proposed method was simple, rapid, efficient, economical, and eco-friendly. [ABSTRACT FROM AUTHOR]

Deoxynivalenol (DON) contaminates various complex matrices, necessitating straightforward, effective cleanup and precise detection methods. This study employed immunomagnetic beads for sample purification and utilized a competitive time-resolved fluoro-immuno-chromatographic assay to achieve quantitative detection of DON in corn and its by-products. The limits of detection and quantification were 104 μg/kg and 243 μg/kg, respectively. Significant cross-reactivity was absent with most common toxins, except for 3-acetyl-deoxynivalenol, which exhibited a cross-reaction rate of 3167%. The recovery rates ranged from 86% to 117%, with coefficients of variation between 6.9% and 9.5%. The correlation coefficient with HPLC was 0.977. This method is rapid, accurate, and requires no large-scale equipment, facilitating on-site detection directly. [ABSTRACT FROM AUTHOR]

Methanol contamination of the Philippine coconut spirit lambanog (often called coconut wine) is the major cause of lambanog-related deaths in the country. Hence, a strict quality control and detection method must be established for methanol in tandem with ethanol analysis. In this study, a quantitative Nuclear Magnetic Resonance spectroscopy (qNMR) method using 1H analysis was developed to quantify the methanol and ethanol in 26 lambanog samples collected from four different provinces in Luzon, Philippines. A certified qNMR standard was used as an internal standard for the 1H NMR analyses to increase the accuracy of the measurements. The calculated limit of detection and limit of quantification of methanol with values of 0.076%(v/v) and 0.25%(v/v), respectively, were sufficiently low and allow the monitoring of methanol within the acceptable safety level. Moreover, the results of methanol and ethanol analysis using the proposed method were in good agreement with those obtained from GC-FID analysis which is the conventional method for alcohol analysis. In contrast to GC-FID, the qNMR method for simultaneous alcohol analysis can provide results in a shorter period. The results of this study show the potential of the qNMR method to be used as an alternative analytical method which widens the range of analytical possibilities to detect methanol in lambanog samples for the safety of the consumers. [ABSTRACT FROM AUTHOR]

This study covered the evaluation of performance characteristics and validation of five commercial ELISA kits for the detection of a banned antimicrobial, chloramphenicol (CAP), in muscle and aquaculture products. CAP has been banned in the European Union since 1994, but is still authorised in some countries in the world. In 2019, the European Union set a new Reference Point for Action (RPA), decreasing the acceptable limit of CAP in animal tissues for human consumption from 0.30 µg/kg to 0.15 µg/kg. Validations were performed according to the European Regulation EC/2021/808 and to the European Guideline on Screening Method Validation (2023). The detection capabilities CCβ were all determined under the RPA, but were 3 to 15 times higher than the announced limit of detection (LOD). False negative rates were satisfactory for all the kits (≤ 5%) and false positive rates were acceptable. All of them were found out to be applicable to aquaculture products and meat at a common CCβ. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, the hydrothermal method has been used for the synthesis of a manganese dioxide/nitrogen-doped reduced graphene oxide (α-MnO2/N-rGO) composite. The physical–chemical properties of the synthesized α-MnO2/N-rGO were examined by different techniques such as powder X-ray diffractometer (XRD), energy dispersive X-ray analysis (EDX), and scanning electron microscopy (SEM). The synthesized α-MnO2/N-rGO was further used as the catalyst towards the fabrication of a hydrazine (Hz) sensor. The screen-printed carbon (SPC) electrode was modified with α-MnO2/N-rGO via the drop-cast method. Linear sweep voltammetry (LSV) was used for the determination of Hz, and observations showed that the α-MnO2/N-rGO/SPC electrode has decent performance in terms of sensitivity, detection limit, and selectivity. The detection limit of 0.08 µM and sensitivity of 2.47 µA/µM.cm2 were obtained using this modified electrode. [ABSTRACT FROM AUTHOR]

Purpose: In cases of radiological or nuclear events, biological dosimetry enables decisions whether an individual was exposed to ionizing radiation and the estimation of the dose. Several statistical methods are used to assess uncertainties. The stringency of the applied method has an impact on the lowest dose that can be detected. To obtain reliable and comparable results, it is crucial to harmonize the applied statistical methods. Materials and methods: The decision threshold and detection limit of the statistical methods were derived for variable cell numbers. The coverage of the 95% confidence intervals as well as the false-positive and false-negative rates of the methods were compared based on simulations. The evaluated methods included a graphical method, the propagation of errors and a Bayesian method. Results: The minimum resolvable doses, the doses at the detection limit and the coverage were relatively variable between the compared methods. The Bayesian method showed the best coverage, lowest resolvable doses and had false-positive rates close to 5%. The graphical method with the combination of two 83% confidence intervals also showed promising results. The other methods were either too conservative or underestimated the uncertainties for some doses or cell numbers. Conclusions: The assessment of the lower dose limits is a central part of biological dosimetry and the applied statistical methods have a strong influence on the interpretation of the results. Simulations enable comparisons between methods and provide important information for the harmonization and standardization of the uncertainty assessment. [ABSTRACT FROM AUTHOR]

The article discusses the importance of radiologic measurements, such as the lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA), in assessing hip stability and dysplasia risk. Advanced imaging techniques, like 3D reconstruction using CT and MRI, are being explored to enhance diagnostic accuracy and patient management. The study by Rivas et al. utilizes a novel 3D methodology to evaluate acetabular osseous areas contributing to the radiographic sourcil, emphasizing the need for comprehensive preoperative understanding of acetabular anatomy for tailored treatment strategies. Future research should focus on standardized protocols for emerging technologies and patient-specific evaluation to enhance diagnostic accuracy and treatment strategies in hip preservation. [Extracted from the article]

Ultra-supercritical coal-fired power plants in Japan and globally experience creep damage in the welded parts of their high-chromium steel assets. As the creep damage advances, voids develop at depth by preference and become dense and cause accidents. The voids cannot be detected using existing non-destructive methods, causing the unreasonable and uneconomic management of plants. To establish a non-destructive examination method that can be used for practical and economic maintenance, a detection method for dense creep voids using ultrasonic backscattered waves is proposed herein. The creep-damaged structures are modelled using a transducer and the transmission and reception characteristics are discussed. These characteristics are considered using the finite element method, as they cannot be measured through normal experiments. The results show that without a focusing process at the time of reception, changes in the amplitude of backscattered waves cannot be confirmed; thus, the contribution of transmission focus to creep void detection is limited. Conversely, it is confirmed that when the received backscattered waves in the direction normal to the transducer are integrated and the phase matching is reflected, the amplitude of the scattered waves increases with creep void density. The reception focus considerably contributes towards dense creep void detection. [ABSTRACT FROM AUTHOR]

The ICP-MS method was used to determine the concentrations of five heavy metals: Cadmium (Cd), lead (Pb), zinc (Zn), mercury (Hg), and nickel (Ni). A total of 36 samples of cosmetic products (makeup, eye shadow, and mascara) of various brands were chosen from those available in Riyadh, Saudi Arabia. Several analytical parameters, such as accuracy, precision, linearity, the lower limit of quantification (LOQ), and the lower limit of detection (LOD), were assessed to determine the validity of the proposed method. The determination of Cd, Pb, Zn, Hg, and Ni was verified for accuracy and precision. The results of the determination of studied heavy metals concentration in cosmetic samples reveal that, the concentrations of Cd, Pb, Zn, Hg and Ni ranged from 0.03–0.53, 10.28–107.01, 14.49–867.12, 1.75–6.45 and 4.22–31.36 µg/g, respectively. In all samples of cosmetic products, the concentrations of Cd and Hg were deemed to be within the normal range. However, the concentration of Pb was higher than the recommended value by the World Health Organization (WHO). Nickel concentration was measured with a detection limit lower than the WHO recommended level, but no suggested value for Zn, which is critical for mitochondria, was found. Health risks related to these metal intakes through dermal exposure pathways are assessed using the total hazard quotient (THQs), total hazard index (HI), chronic daily intake (CDI), and hazard quotient (HQ). Despite the low risks of cancer and non-cancer caused by using these cosmetic products, testing results for cancer and non-cancer risks for these products must be regularly examined. Therefore, constant monitoring of cosmetic products, particularly with regard to heavy metal contamination, should be implemented to maintain human safety and security. [ABSTRACT FROM AUTHOR]

While researchers and practitioners are seamlessly trying to develop methods for minimizing the effect of outliers in control charts, detecting and screening these outliers continue to pose serious challenges. Keeping in view, the researchers rely on robust estimators to modify the detection limits structure so that the chart can be more sensitive against outliers. In this study, we propose a robust S2${S}^2$ control chart based on Pn${P}_n$, MAPD,$\ MAPD,$AADM$AADM$, GMD$\ GMD$, PSD$PSD$, and τau$\tau au$ estimators, whilst the process parameter is estimated from Phase‐I. Through intensive Monte‐Carlo simulations, the study presents how the estimation of parameter(s) and presence of outliers affect the efficacy of the S2${S}^2$ chart, and then how the proposed outlier detectors bring the chart back to normalcy by restoring its efficacy and sensitivity. Average ARL$ARL$ properties are used as the performance measures. The AARL$AARL$ properties establish the superiority of the proposed scheme over MAD$\ MAD$ and Tukey's outlier detectors. The applicability of the study includes the effectiveness of the proposed detectors in industrial data set but is not limited to manufacturing industries. [ABSTRACT FROM AUTHOR]

Solution cathode glow discharge atomic emission spectrometry (SCGD-AES) using wide-bandpass (10-nm) interference filters (IF) as a spectral discrimination device was used for the determination of thallium (Tl) in surface water. The use of wide-bandpass interference filters greatly reduces the cost of traditional detection instruments. The influence of solution flow rate, discharge current and pH on the detection limit was characterized. Moreover, matrix effect experiments were performed to study the effect of different concentrations of Na+, K+, Ca2+, and Mg2+ on the Tl signal intensity. Using a solution flow rate of 2.8 mL/min, a discharge current of 50 mA, and pH of 1.0 with HNO3 as the supporting electrolyte, SCGD coupled with an interference filter provided a detection limit of 7.76 μg/L for Tl in water samples, comparable to traditional SCGD-AES. Furthermore, the spiked recovery rate of Tl is quantitative in real water samples and comparable to the performance of inductive coupled plasma – optical emission spectrometry (ICP-OES). [ABSTRACT FROM AUTHOR]

Milk is a major dietary source of calcium; thus, accurate and precise quantification of calcium in milk and other dairy products is necessary for quality control. Conventional instrumental methods are sensitive and accurate but require expensive instrumentation, sample pretreatment, skilled personnel, and a long detection time. Herein, a microfluidic paper-based analytical device (µPAD) was developed to quantify calcium ions (Ca2+) in milk using a smartphone as a detector. The method utilized a complexometric reaction between Ca2+ and ethylene diamine tetraacetic acid with murexide as an indicator. The response was the average color intensity at the detection zones measured using the Color Picker application. The proposed µPAD exhibited a good linear detection range (1 to 10 mM), a low detection limit of 0.42 mM, and a short analysis time of 2 min. The determination of Ca2+ in milk samples using the proposed µPAD was consistent with a potentiometric method. The proposed µPAD demonstrates many advantages, including rapid detection, acceptable accuracy, low cost, low sample volume, and suitability for on-site quantification of Ca2+ in real samples. [ABSTRACT FROM AUTHOR]

Evaluating the methicillin resistance of Staphylococcus aureus (S. aureus) is highly important for adapting nursing strategies. Nevertheless, the identification of methicillin-resistant S. aureus (MRSA) that is both sensitive and reliable continues to pose a significant obstacle. This study describes a method for detecting MRSA using a combination of fixed rolling circle amplification (RCA) and the exonuclease-iii (Exo-iii) assisted CRISPR-Cas12a system for signal amplification. When MRSA is present, the interaction between the "b" chain in the capture probe and MRSA allows the "a" chain to be exposed. This "a" chain acts as a primer to initiate the fixed RCA process. The H probe, which includes the crRNA segment, forms a bond with the RCA product and then releases the crRNA segment with the aid of Exo-iii. The Cas12a protein, when combined with the crRNA, generates an activated CRISPR-Cas12a system that cleaves the "Reporter" probe, resulting in the production of fluorescent signals. Furthermore, this fluorescent test has been utilized for the examination of clinical samples with a satisfactory rate of retrieval. Based on the elegant design, the proposed method exhibited a low detection limit of 4.6 cfu/mL, while maintaining a high specificity for MRSA even from a mixture of several interfering bacteria. Due to its cost-effectiveness, simplicity, and adaptability, the sensing system shows potential as a platform for detecting MRSA and evaluating postoperative nursing for stomach cancer patients. [ABSTRACT FROM AUTHOR]

An 18-connected {Mo16Ni16P24}-based 2-D layered network was constructed for photoelectrochemical sensing of levofloxacin, and it represents the highest connection number of the {Mo16Ni16P24} wheel cluster to date. The detection limit is as low as 6.46 nM with a high sensitivity of 110.87 μA μM−1 and good practicality in a milk sample. [ABSTRACT FROM AUTHOR]

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Copper ions are a significant concern to people's health and wine quality. By adopting a "one-pot" approach, tetra(4-carboxyphenyl)porphyrin (TCPP) molecules were integrated into UiO-66-NH2 metal–organic frameworks, forming TCPP@UiO-66-NH2 dual-emission fluorescence sensing platform towards copper ions. The blue fluorescence of UiO-66-NH2 at 466 nm was deemed an internal reference signal; thus, the built-in corrections in the complex were effectively achieved. The red emission fluorescence of TCPP at 654 nm was quenched by Cu2+, resulting in a reliable signal and noticeable color changes. A quick and sensitive ratio fluorescence sensor was constructed with the signal contrast mechanism. This sensor enabled trace detection of Cu2+ within the concentration range of 0–10 nM, with a detection limit as low as 24 nM, and exhibited good anti-interference capability and cycling stability. Further spiking-recovery experiments demonstrated excellent detection performance and analytical reliability of the sensor in water and red wine samples. [ABSTRACT FROM AUTHOR]

The excessive intake or deficiency of folic acid (FA), also known as vitamin B9, can lead to several health problems. Therefore, significant research priority is required to develop facile analytical methods for FA detection. Herein, a V-shaped aggregation-induced emission (AIE) luminogen SDASA was introduced by condensing 4,4′-sulfonyldianiline with two equivalents of salicylaldehyde. The weakly fluorescent SDASA in DMSO showed yellow emission upon increasing the fractions of HEPES buffer (H2O, 10 mM, pH 7.4) from 80% to 95% because of the combined effects of AIE and ESIPT. The formation of self-aggregates of SDASA was supported by SEM and DLS analyses. AIEgen SDASA (fHEPES 95%) was employed as probe 1 for FA detection. The fluorescence emission of AIEgen SDASA (λem = 550 nm, λex = 390 nm) was blue-shifted and enhanced at 475 nm by FA. The results of DFT, fluorescence lifetime, zeta potential, DLS, and UV-vis absorption studies revealed that the interaction that occurred between FA and SDASA inhibited the intramolecular charge transfer and aggregate morphology of SDASA. With probe 1, the FA concentration can be detected down to 0.83 μM. Further studies with SDASA in DMSO showed strong green emission at 525 nm upon complexation with Zn2+ ions. The in situ generated SDASA–Zn2+ complex was used as probe 2 for the fluorescent turn-off detection of hemoglobin and glucose with a detection limit of 0.57 nM and 0.32 μM, respectively. Finally, the analytical utility of the developed probes was examined by detecting selective analytes in real blood serum. [ABSTRACT FROM AUTHOR]

BACKGROUND: A colorimetric method for the quantification of hydrogen sulfide (H₂S) produced in microbial fermentations was developed using lead gelled alginate microparticles packed in glass columns. The formation of a lead sulfide complex, between H₂S and lead ion (Pb2+) immobilized on the microparticles, allowed simple and accurate quantification by colorimetry. RESULTS: The microparticle‐loaded columns were calibrated and showed significant analytical sensitivity. The calibration curve of the system showed a correlation coefficient (r2) of 0.995 and a detection limit of 1.29 ± 0.02 μg L−1. The application of the columns in laboratory wine fermentations was able to detect variations in H2S production from 10.6 to 23.5 μg L−1 by increasing the sugar content in the medium, and from 10.6 to 3.2 μg L−1 with decreasing nitrogen content in the medium. CONCLUSION: Validation of the proposed method was carried out by determining H₂S in a vinic fermentation model, the results of which were compared with those obtained using a reference chemical method. The data obtained showed no statistically significant differences between the two methods, confirming the reliability and accuracy of the developed system. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

GaS, with the largest bandgap of group III–VI van der Waals semiconductors, is a potential building block of optoelectronic applications. In addition, one-dimensional structures, such as nanobelts, are preferable for integration into future nano-optoelectronic devices. Here, we demonstrated self-catalyzed vapor–liquid–solid (VLS) growth of a GaS nanobelt by metalorganic chemical vapor deposition. Ga-rich growth conditions caused Ga particles to be generated in the initial growth step. The nanobelt grew from a Ga particle, which acted as a catalyst. The fabricated nanobelt photodetector showed a high ON/OFF ratio and the dark current was under the detection limit. Moreover, compared with an exfoliated GaS flake photodetector, it had one order of magnitude higher responsivity. These outstanding photoresponse properties indicate that self-catalyzed VLS growth of GaS nanobelts is a promising bottom-up integration approach for nano-optoelectronic applications. [ABSTRACT FROM AUTHOR]

Reliable hydrogen (H2) detection is essential for advancing hydrogen energy applications. In this study, we report a sensitive H2 detection method using off-axis integrated cavity output spectroscopy. A distributed-feedback laser with fiber output was used to target the H2 absorption transition near 2122 nm. The optical cavity was constructed using two spherical mirrors, each with a reflectivity of 99.985%, providing an effective absorption path length of 2500 m. The Galatry line shape function was selected to accurately fit the narrow absorption feature of H2. Furthermore, we achieved a 1.74-fold improvement in the signal-to-noise ratio by applying radio frequency white noise perturbations. The system's performance was demonstrated by measuring H2 mixtures across a broad concentration range from 1040 ppm to 20.24%. Finally, the Allan–Werle deviation analysis revealed a detection limit of 53 ppm H2 at an average time of 400 s. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1) is a highly strong mycotoxin that contaminates cereals and other stored grains. It causes immune-suppressive effects, raising the risk of mutagenicity, carcinogenicity, teratogenicity, hepatotoxicity, and embryonic toxicity, as well as increasing illness and death. Liver damage is a result of prolonged exposure to AFB1, which raises the prevalence of liver cancer and cirrhosis. Different biosensors have been fabricated using various nanoparticles to detect aflatoxins in food. This review provides the recent developments on the occurrence of AFB1 in cereals, different biosensors based on nanomaterials applied for AFB1 detection in cereals, and offers future directions for the production of affordable analytical equipment for detection of AFB1, based on nanomaterials to address some open questions regarding their limit of detection, stability, and affordability. Electrochemical biosensors are more reliable, selective, and affordable analytical tools with better detection limits and shorter response times than other biosensors. However, more studies are needed to address the automatic simultaneous detection of various aflatoxins in real samples and a biosensing system that integrates with microarray technology. [ABSTRACT FROM AUTHOR]

In the present study, dispersive solid phase extraction – hydride generation integrated with micro–sampling gas–liquid separator – flame atomic absorption spectrometry was proposed to determine lead in lake water samples taken in the Horseshoe Island, Antarctica. In scope of this study, microwave assisted NiFe2O4 nanoparticles were synthesized, and the characterization of nanoparticles were carried out by FT-IR, XRD and SEM. All influential parameters of dispersive solid phase extraction and hydride generation were optimized to enhance signal intensity belonging to the analyte. System analytical performance studies were performed, and limit of detection and limit of quantitation were calculated as 2.16 µg kg–1 and 7.19 µg kg–1, respectively. Recovery studies were conducted to the spiked lake water samples and two different calibration strategies were applied. Percent recovery results were calculated between 102.0 and 169.5% by external calibration strategy while matrix matching calibration strategy provided recovery results in the range of 78.8–142.9%. [ABSTRACT FROM AUTHOR]

Four distinct zeolitic imidazolate frameworks (ZIFs) are prepared using zinc and cobalt ions with 2-aminobenzimidazole and 2-methylimidazole as linkers to explore their electrochemical properties as platforms for aldehyde detection. The resulting ZIF-based sensors exhibit high sensitivity, low detection limits, and robust performance when applied to real-world samples. [ABSTRACT FROM AUTHOR]

In this article, a CMOS-compatible Pirani vacuum gauge was proposed featuring enhanced sensitivity, lower detection limit, and high-temperature stability, achieved through the implementation of a surface micromachining method coupled with a temperature compensation strategy. To improve performance, a T-type device with a 1 µm gap was fabricated resulting in an average sensitivity of 1.10 V/lgPa, which was 2.89 times larger than that (0.38 V/lgPa) of a L-type device with a 100 µm gap. Additionally, FEA simulations were conducted, analyzing the influence of heater temperature on sensitivity and the attenuation of sensitivity across varying ambient temperatures. A semi-empirical theoretical mode was derived for performance prediction, demonstrating strong alignment with experimental results, underscoring its effectiveness in compensating for sensitivity attenuation. Building on the foundation, the device's performance under different ambient temperatures was characterized and effectively compensated in two distinct operational modes: constant temperature mode and constant temperature difference mode (the whole range temperature compensation error can be controlled within 2.5%). Finally, the short-time stability (variation level is approximately 1 mV), noise floor (Vrms=384 μV) and detection limit (0.07 Pa @1 Hz) of the device were characterized, confirming its suitability for practical implementation. [ABSTRACT FROM AUTHOR]

HIV infection implicates a spectrum of tissues in the human body starting with viral transmission in the anogenital tract and subsequently persisting in lymphoid tissues and brain. Though studies using isolated cells have contributed significantly towards our understanding of HIV infection, the tissue microenvironment is characterised by a complex interplay of a range of factors, all of which can influence the course of infection but are otherwise missed in ex vivo studies. To address this knowledge gap, it is necessary to investigate the dynamics of infection and the host immune response in situ using imaging-based approaches. Over the last decade, emerging imaging techniques have continually redefined the limits of detection, both in terms of the scope and the scale of the targets. In doing so, this has opened up new questions that can be answered by in situ studies. This review discusses the high-dimensional imaging modalities that are now available and their application towards understanding the spatial biology of HIV infection. [ABSTRACT FROM AUTHOR]

Although zeolitic imidazolate frameworks (ZIFs) are widely applied in the energy storage and catalysis fields, their multifunctional applications are extremely limited by their closed rhombohedral dodecahedron structure. Herein, a bimetallic CoFe-ZIF with an open nanoflower structure is synthesized via a simple one-step stirring strategy at room temperature. CoFe-ZIF exhibits superior sodium-ion storage performance as the anode for sodium-ion batteries (SIBs) and glucose sensing performance as the electrode for a non-enzymatic glucose sensor, as a result of the synergistic effect between the metal ions and highly open nanoflower structure. CoFe-ZIF exhibits a specific capacity of 410.32 mA h g-1 at a current density of 0.10 A g-1 after 500 cycles for SIBs and a high sensitivity of 1484.22 µA mM-1 cm-2 in the range of 0.30-2.00 mM for glucose sensing, which also shows a low detection limit of less than 25 µM. This work also provides insight into designing bimetallic MOFs via a simple strategy for multifunctional device applications. [ABSTRACT FROM AUTHOR]

Hexavalent chromium ions (Cr(VI)) possess inherent toxicity and propensity for bioaccumulation in the environment. Herein, a Cu-curcumin nanozyme was synthesized via a one-pot solvothermal method. Based on the high peroxidase-like activity of the Cu-curcumin nanozyme, a novel and economical colorimetric platform has been developed for Cr(VI) assay. In the presence of hydrogen peroxide (H2O2), the Cu-curcumin nanozyme can catalyze the transformation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) into the blue product oxTMB. 8-Hydroxyquinoline (8-HQ) can inhibit the catalysis of the Cu-curcumin/TMB/H2O2 system, causing the blue color to fade. With the addition of Cr(VI), the peroxidase-like activity of the Cu-curcumin nanozyme is increased significantly, leading to the restoration of the Cu-curcumin/TMB/H2O2 system color. After optimization of the experimental parameters, a novel colorimetric sensor for Cr(VI) assay has been successfully developed with a low limit of detection (LOD) of 31.5 nM, affirming its potential for accurate Cr(VI) quantification in environmental specimens. In addition, paper strips integrated with a smartphone platform enhance the versatility and portability of the Cr(VI) assay, achieving an LOD of 0.1 µM. [ABSTRACT FROM AUTHOR]