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A pasting-3D microfluidic paper-based analytical device (P-3D μPAD) was developed. It enabled an efficient cascade reaction between urate oxidase (UOX) and Fe/Pt-doped carbon nanoparticles (Fe/Pt-CNPs) for visual colorimetric detection of uric acid (UA). The novel Fe/Pt-CNP nanozyme performed high peroxidase-like activity toward 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2 with Michaelis − Menten constants (Km) of 0.97 and 2.30 mM, respectively. The UOX-Fe/Pt-CNP system was incorporated into P-3D μPAD: the 1st layer was UOX hydrolysis reaction under alkaline pH, and the 2nd layer was Fe/Pt-CNPs catalyzing H2O2 to oxidize TMB at acidic pH. The separated two layers allowed cascade reaction under different working pH without sacrificing the activity of UOX or Fe/Pt-CNPs. The images were captured and analyzed by the camera and "Color Recognition" application using a smartphone. The linear range of P-3D μPAD for UA was 25–1000 μM with a limit of detection of 10 μM which met the requirements for clinical applications. The high accuracy of P-3D μPAD for UA detection in invasive (blood) and noninvasive (saliva) samples has been confirmed by the biochemical analyzer. This work offers a sensitive, flexible, affordable, and disposable tool for on-site UA level monitoring and provides new insight into natural enzyme and nanozyme tandem systems for biosensing. [ABSTRACT FROM AUTHOR]

A platform was developed to accurately detect the content of ofloxacin (OFX) based on molecularly imprinted polypyrrole-MWCNTs-OH/1,3,5-Tris(4-aminophenyl) benzene (TAPB)-2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP)-covalent organic framework (MIP-MWCNTs-OH/COF)–modified glassy carbon electrode (GCE) sensor (MIP-MWCNTs-OH/COF/GCE). The complex of MWCNTs-OH and COF synergistically enhanced the active area and electrochemical signal, based on which a molecularly imprinted membrane was polymerized on its surface to further improve the selectivity. Under optimized conditions, the prepared MIP-MWCNTs-OH/COF/GCE sensor exhibited strong detection performance to OFX in a linear range 1.969 × 10−11–9.619 × 10−9 M with the limit of detection (LOD, 3S/N) of 4.989 × 10−12 M, excellent selectivity, stability, and reproducibility. Furthermore, the MIP-MWCNTs-OH/COF/GCE sensor can be successfully applied to the detection of OFX in lake water and eye drops with a relative standard deviation (RSD) of less than 4.95%, indicating its high potential in practical applications. [ABSTRACT FROM AUTHOR]

A multi-chromatic and multi-component lateral flow immunoassay (MCMC-LFIA) was developed for simultaneous detection of CP4 EPSPS, Bt-Cry1Ab, Bt-Cry1Ac, and PAT/bar proteins in genetically modified (GM) crops. Captured antibodies specific to these exogenous proteins were separately immobilized on a nitrocellulose membrane as test zones. Multi-colored microspheres, used as visible multi-probes, were conjugated with corresponding antibodies and sprayed on the conjugate pad. The assay results can be visually interpreted within 10 min by observing the appearance of colored bands. The MCMC-LFIA demonstrated high sensitivity, with detection of limits of 7.8 ng/mL for CP4 EPSPS and 2.5 ng/mL for Bt-Cry1Ab, Bt-Cry1Ac, and PAT/bar proteins, significantly improving the performance of previously reported LFIAs. The MCMC-LFIA exhibited excellent specificity and was validated for practical use in field-based applications. The proposed MCMC-LFIA offers a rapid, sensitive, and user-friendly tool for the on-site large-scale screening of GM materials. [ABSTRACT FROM AUTHOR]

A novel nanobiosensor was constructed by in situ locating nanometer MnO2 particles with controllable size and morphology in a Zr-MOF substrate to serve as an electrochemical probe. The synergistic effect of the two components, Zr-MOFs with high specific surface area and compatibility as a carrier for MnO2, resulted in improved electrochemical activity and excellent electrochemical identification performance for the MnO2@Zr-MOF/GCE biosensor. Under optimized experimental conditions and using CV and DPV technology, the biosensor showed a wide linear detection range (2–200 μM), a low detection limit (2.577 × 10−8 M), a recovery range (106.26–115.01%), and maximum relative standard deviation (5.155) for tetracycline (TC) identification. The recognition mechanism of the sensor was investigated adopting Laviron adsorption theory. The applicability of the sensor was verified through practical measurements. Overall, the MnO2 @Zr-MOF/GCE sensor possesses the advantages of fast analysis speed, high sensitivity, high selectivity, and simple operation, making it suitable for detecting trace amounts of TC in food. [ABSTRACT FROM AUTHOR]

A dual-mode immunoassay method was developed for colorimetric and fluorescence detection of aflatoxin B1 (AFB1) based on streptavidin-induced gold nanoparticle aggregation (AuNP@SA). AuNP-modified streptavidin–biotin labeling AFB1 complete antigen aggregations (AuNP@SA@Bio-BSA-AFB1) were synthesized as the competitive binding and dual-mode probe. AuNP@SA@Bio-BSA-AFB1 aggregations possessed high colorimetric and fluorescence quenching intensities. AFB1 antibodies modified immunomagnetic microspheres were used as the capture probe. The competitive binding between AFB1 and AuNP@SA@Bio-BSA-AFB1 leads to changes in color and fluorescence intensity. The detection limit of the colorimetric method is 6.95 ng·mL−1, while that of the fluorescence method is 0.07 ng·mL−1. The practicality of the proposed strategy was demonstrated by determining AFB1 in spiked peanut samples. [ABSTRACT FROM AUTHOR]

In this work, we prepared a sensing platform by utilising the nanocomposite of Vulcan XC-72 R carbon nanoparticles and β-cyclodextrin (β-CD/VXC-72 R) to decorate glassy carbon electrode for detecting MP sensitively. For the β-CD/VXC-72 R composite, VXC-72 R possesses high electroactive area and exceptional electrical conductivity, which is conducive to the generation of interwoven carbon conductive structures. β-CD can effectually facilitate the homogeneous dispersion of VXC-72 R and also enhance the accumulate of MP at the sensing interface. Furthermore, the presence of VXC-72 R compensates for the inherent inferior conductivity of β-CD. The collaborative interaction of VXC-72 R and β-CD enabled the prepared sensor to obtain excellent MP detection properties with a low limit of detection (LOD) of 6.7 nM in MP concentration range of 0.1–10 μM. In addition, the β-CD/VXC-72 R modified glassy carbon electrode (GCE) displayed satisfactory repeatability and reproducibility. [ABSTRACT FROM AUTHOR]

Halide perovskites hold great potential in developing next‐generation X‐ray detectors. However, preparing high‐quality and thick perovskite films in a way compatible with a thin‐film transistor (TFT)‐integrated X‐ray flat‐panel detectors (XFPDs) remains challenging. Here, by engineering ink with effective printability and shape fidelity, direct ink writing (DIW) is developed as a new approach to printing a unique single‐crystal‐assembled perovskite (SCAP) thick film. In contrast to polycrystalline grains consisting of randomly orientated crystal domains, the SCAP is made of tightly packed crystals with well‐defined crystal facets, showing 3–4 orders of magnitude lower trap density (4.48 × 1012 cm−3). Consequently, the SCAP X‐ray detectors offers the state‐of‐the‐art detection performance (sensitivity‐to‐dark current ratio: 1.26 × 1011 µC Gyair−1 A−1), a low detection limit (114.2 nGyair s−1), and negligible baseline drift (0.27 fA cm−1 s−1 V−1). Furthermore, the XFPD based on a 64 × 64 pixelated TFT array realizes high‐resolution digital radiography, opening a new avenue for further development of perovskite X‐ray detectors. [ABSTRACT FROM AUTHOR]

A simple salicylaldehyde-based Schiff base 2,2'-((1,3-phenylenebis(azanylylidine))bis(methanylylidene))dipehnol (PAMD) was synthesised by condensation reaction between salicylaldehyde and benzene-1,3-diamine (2:1 ratio) and characterised by spectral techniques such as NMR, FTIR and HRMS, followed by investigation for its spectroscopic behaviour towards diverse metal ions using UV and fluorescence studies. PAMD was found to exhibit sensitivity towards Cu2+ only. The receptor PAMD was then explored for its electrochemical behaviour using cyclic voltammetry, which displayed an irreversible anodic peak at 1.00 V due to imine group. Furthermore, PAMD was subjected to differential pulse voltammetry, which exhibited a sensitive response for Cu2+ in the linear range of 0–3.8 μM with lowest detection limit of 0.03 μM. The complexation between PAMD and Cu2+ was also supported by large values of binding constant (1.3 × 105 M−1) and negative free energy change (ΔG∘ = -29.2 kJmol−1) obtained from Benesi–Hildebrand equation. The carbon paste electrode (CPE) modified with PAMD displayed a Nernstian response to Cu2+ in the concentration range from 1.0 × 10−6 to 1.0 × 10−1 M and lowest detection limit of 4.0 × 10−7 M. The PAMD-CPE was successfully applied for determination of Cu2+ content in real samples such as groundwater, soil, and food grains (wheat and rice). [ABSTRACT FROM AUTHOR]

Climate change is one of the most crucial issues in human society such that if it is not given sufficient attention, it can become a great threat to both humans and the Earth. Due to global warming, soil erosion is increasing in different regions. Therefore, this issue will require further investigation and the use of new tools. In this paper, a portable wind tunnel was designed and built for wind erosion studies using photogrammetry, which is a novel technique. This instrument consists of a working section, a fan, a portable voltage source inverter to control its angular speed, and a honeycomb to straighten the air flow in the working section. The eroded volume of soil is measured using photogrammetry by producing two 3D models and point clouds before and after the soil erosion test and calculating their volume changes. The results show that a 0.175 mm check distance precision is achievable under convergent imaging and with sufficient number of accurate control points which this value indicates the discrepancy between the anticipated and measured lengths of all the check distances. In addition, the features of this portable wind tunnel guarantee its easy portability, and its transparency enables the measurement of the threshold friction velocity. Additionally, this instrument, as an invention, has been registered at the Intellectual Property Center of Iran. [ABSTRACT FROM AUTHOR]

Based on recombinase polymerase amplification (RPA) detection technology (combined with (lateral flow dipstick, LFD)), it is aimed to establish a dual recombinase polymerase amplification method for the rapid identification of Pasteurella multocida (Pm) and Actinobacillus pleuropneumoniae (APP). The conserved fragments of Pm kmt1 gene and APP ApxIV gene were selected for the amplification of target fragments. Eight pairs of primers for Pm and APP, and one probe for KMT1Pn and APP323Pn were designed. A single RPA-Basic primer screening test was performed. The reaction time and temperature of double RPA were optimized. The optimal primers and probe matching systems of dual RPA-LFD were explored. Dual RPA sensitivity and specificity tests were performed. The method was used to detect 60 clinical samples. The results of the primer screening test showed that the primers had the strongest specificity and the highest amplification efficiency for ApxIV2698F/ApxIV3020R and KMT1F/KMT1R. The method had the best amplification efficiency at a reaction temperature of 37ºC and a reaction time of 35 min. The optimal primer ratio of KMT1F/KMT1R and ApxIV2698F/ ApxIV3020R was 2 μL : 1.5 μL, and the optimal probe ratio of KMT1Pn and APP323Pn was 0.6 μL : 0.4 μL. The minimum detection limit of dual RPA-Basic and RPA-LFD sensitivity test was 10-6 ng/μL. The specific test results showed no cross-reaction with enteropathogenic Escherichia coli, Salmonella, Glaesserella parasuis, Staphylococcus aureus, Streptococcus suis, Aeromonas hydrophila. Using 60 clinical samples of suspected Pm and/or APP infection to evaluate the detection system, the detection rate of dual RPA-Basic and RPA-LFD is higher than that of PCR, indicating that they have strong practicability. This study successfully established a dual RPA-Basic and RPA-LFD detection method for Pm and APP, which can be used for the rapid differential diagnosis of Pm and APP mixed infection in clinical. [ABSTRACT FROM AUTHOR]

In this study, a new chemiluminescence (CL) method has been proposed to determine haloperidol (HP). Typical CL systems and several fluorescent dyes were examined to determine HP, including rhodamine 6G, brilliant blue, orange G, chromotrope 2R, eosin Y, amaranth, amido black, and victoria blue as sensitizers. It was found that HP concentration could be determined in the CL systems of Ru(phen)3 2+-Ce(IV), KMnO4-H2SO4, Luminol-K3Fe(CN)6, and rhodamine 6G-Ce(IV). Due to the novelty of the method and its sensitivity, the rhodamine 6G-Ce(IV) CL system was chosen for the determination of HP. In the proposed method, oxidation of rhodamine 6G by Ce(IV) produces weak CL that increases in the presence of HP. Mechanism study using UV-Vis, fluorescence, and CL spectra showed that excited state rhodamine 6G, produced via energy transfer from the unstable intermediates to the rhodamine 6G molecule, is the main emitter. The linear dynamic range, detection limit, and percent of the relative standard deviation in the rhodamine 6G-Ce(IV) CL system were determined to be 7.0 x 10-7-1.0 x 10-4 M, 2.3 x 10-7 M, and 4.8%, respectively. The proposed method was successfully evaluated to determine HP in the pharmaceuticals. [ABSTRACT FROM AUTHOR]

The phase inversion was used to prepare monolithic solid-phase microextraction fiber based on polyvinylidene fluoride (PVDF) with mesoporous structure. For this purpose, PVDF 15% w/v as the main polymer and polyvinyl pyrrolidone (PVP) 1.5% w/v as pore former were used. After characterization of the proposed fiber using FESEM and BET/BJH, it was used to extract bisphenol A (BPA) as a serious environmental and food contaminant. After optimization of the factors affecting the extraction process like extraction temperature and time, desorption solvent kind and volume, sample pH, and salting out effect, the developed method was used for extraction and determination of BPA in bottled drinking water and sewage samples. Analytical figures of merit for the proposed method were obtained as 0.33 and 1.00 µg l-1 for limit of detection and limit of quantification, respectively. Also, a linear dynamic calibration curve was achieved in the range of 1-150 μg l-1 with a coefficient of determination (R2) of 0.9978. Repeatability studies for fiber-to-fiber and single fiber studies were obtained as 6.54 and 4.01, respectively, indicating excellent precision of both the fiber preparation and extraction method. [ABSTRACT FROM AUTHOR]

This article defines analytical performance specifications (APS) for evaluating laboratory proficiency through an external quality assessment scheme. Standard deviations for proficiency assessment were derived from Thompson's characteristic function applied to robust data calculated from participants' submissions in the Occupational and Environmental Laboratory Medicine (OELM) external quality assurance scheme for trace elements in serum, whole blood and urine. Characteristic function was based on two parameters: (1) β – the average coefficient of variation (CV) at high sample concentrations; (2) α – the average standard deviation (SD) at low sample concentrations. APSs were defined as 1.65 standard deviations calculated by Thompson's approach. Comparison between OELM robust data and characteristic function were used to validate the model. Application of the characteristic function allowed calculated APS for 18 elements across three matrices. Some limitations were noted, particularly for elements (1) with no sample concentrations near analytical technique limit of detection; (2) exhibiting high robust CV at high concentration; (3) exhibiting high analytical variability such as whole blood Tl and urine Pb; (4) with an unbalanced number of robust SD above and under the characteristic function such as whole blood Mn and serum Al and Zn. The characteristic function was a useful means of deriving APS for trace elements in biological fluids where biological variation data or outcome studies were not available. However, OELM external quality assurance scheme data suggests that the characteristic functions are not appropriate for all elements. [ABSTRACT FROM AUTHOR]

Flavonoids are plant-derived compounds that have several health benefits, including antioxidative, anti-inflammatory, anti-mutagenic, and anti-carcinogenic effects. Quercetin is a flavonoid that is widely present in various fruits, vegetables, and drinks. Accurate determination of quercetin in different samples is of great importance for its potential health benefits. This review, is an overview of sample preparation and determination methods for quercetin in diverse matrices. Previous research on sample preparation and determination methods for quercetin are summarized, highlighting the advantages and disadvantages of each method and providing insights into recent developments in quercetin sample treatment. Various analytical techniques are discussed including spectroscopic, chromatographic, electrophoretic, and electrochemical methods for the determination of quercetin and its derivatives in different samples. UV–Vis (Ultraviolet–visible) spectrophotometry is simple and inexpensive but lacks selectivity. Chromatographic techniques (HPLC, GC) offer selectivity and sensitivity, while electrophoretic and electrochemical methods provide high resolution and low detection limits, respectively. The aim of this review is to comprehensively explore the determination methods for quercetin and quercetin glycosides in diverse matrices, with emphasis on pharmaceutical and biological samples. The review also provides a theoretical basis for method development and application for the analysis of quercetin and quercetin glycosides in real samples. [ABSTRACT FROM AUTHOR]

ABSTRACT Roughage can be a significant source of vitamin D in herbivore diets. The vitamin D content of forages can vary considerably and depends, among others, on plant species, plant maturity and climate fluctuations. Ultraviolet B (UVB) exposure causes conversion of provitamin D to vitamin D and thus represents the most important influence. To characterise this effect, two batches of a young‐cut roughage of high hygienic and nutritional quality were exposed to constant artificial UVB‐irradiation up to 192 h and were sampled at regular intervals. In previous studies, both ergocalciferol (vitamin D2), cholecalciferol (vitamin D3) and/or their metabolites have been detected in plants. Therefore, the present roughage was analysed for both D2 and D3. Whereas cholecalciferol never exceeded the detection limit of 0.25 µg/100 g, ergocalciferol increased from 2.22 µg to 19.15 µg/100 g dry matter in a time‐dependent manner. Additionally, the values indicate an interplay with other factors not investigated in this study, for example, leaf‐stem‐ratio in the different samples. The high amounts of ergocalciferol in the experimental roughage after UVB‐exposure confirm the value of hay as a vitamin D source for managed herbivores. The quick rise with time cautions against neglecting UVB‐irradiation's effect on feed, both in practical as well as in experimental settings. [ABSTRACT FROM AUTHOR]

A simple, rapid, sensitive, and cost-effective green solvent-assisted reverse-phase high-performance liquid chromatographic technique, coupled with a photodiode array detector, was developed and validated for the estimation of piroxicam (PRXM). The chromatographic separation was achieved by using a C-18 (250 × 4.6) mm, 5-μm stationary phase and a mobile phase consisting of methanol and 0.1% ortho-phosphoric acid in water in a ratio of (80:20) v/v at a flow rate of 1 ml/min. The detection was carried out at a wavelength of 254 nm with a constant injection volume of 10 μL throughout the analysis. The calibration curve was observed to be linear over the optimum concentration range of 50–300 μg mL−1, with an R 2 value of 0.9995. The developed method was validated as per the International Council for Harmonisation (ICH) Q2 (R1) guideline. Various parameters like selectivity/specificity, accuracy/recovery, linearity, precision, detection limit, quantitation limit, robustness and stability of analyte in solution were performed for the method validation. The PRXM was evaluated under stressed conditions, including acidic, basic, oxidative, thermal and photolytic, as per ICH Q1 (R2) guidelines. Significant degradation was observed in acidic and basic degradation conditions. Conversely, the drug substance showed stability when exposed to oxidative, photolytic and thermal degradation conditions. [ABSTRACT FROM AUTHOR]

Photonic biosensors based on bound states in the continuum (BIC) resonant modes exhibit a transformative potential for high-sensitivity, label-free detection across various diagnostic applications. BIC-enabled metasurfaces, utilizing dielectric, plasmonic, and hybrid structures, achieve ultra-high Q-factors and amplify target molecule interactions on functionalized sensor surfaces. These unique properties result in increased refractive index sensitivity and low detection limits, essential for monitoring biomolecules in clinical diagnostics, environmental analysis, and food safety. Recent advancements in BIC-enabled metasurfaces have demonstrated ultra-low detection limits in the zeptomolar range, making these devices highly promising for real-world applications. This review paper critically discusses the design principles of BIC-based biosensors, emphasizing key factors such as material selection, structural asymmetry, and functionalization strategies that enhance both sensitivity and specificity. Additionally, recent advancements in fabrication techniques that enable precise BIC control with scalable approaches for practical biosensing applications are examined. Case studies demonstrate the effectiveness of BIC metasurfaces for real-time, low-concentration detection, highlighting their versatility and adaptability. Finally, the review discusses future challenges and opportunities, such as integration with microfluidics for point-of-care testing and multiplexed sensing, underscoring the potential of BIC-based platforms to revolutionize the field of biosensing. [ABSTRACT FROM AUTHOR]

In order to enhance gas absorption efficiency and improve the detection sensitivity of methane, a gas absorption cell with an effective optical path length of 29.37 m was developed, employing tunable diode laser absorption spectroscopy (TDLAS) and a distributed feedback (DFB) laser with a center wavelength of 1.654 μm as the light source. However, despite these advancements, the detection accuracy was still limited by potential signal interference and noise. To address these challenges, the Savitzky–Golay (S-G) filtering technique was implemented to optimize the TDLAS detection signal. Experimental results indicated a significant enhancement in detection performance. For a methane concentration of 92 ppm, the application of the S-G filter improved the signal-to-noise ratio by a factor of 1.84, resulting in a final device detection accuracy of 0.53 ppm. This improvement demonstrates the effectiveness of the S-G filter in enhancing detection sensitivity, supporting high-precision methane monitoring for atmospheric analysis and various industrial applications. [ABSTRACT FROM AUTHOR]

Methane is a common intestinal gas that has been linked to a variety of gastrointestinal disorders. In this study, we prepared a LIG-based electrochemical sensor modified with PEDOT:PSS/Au-Pt nanocomposites for high-sensitivity methane detection. LIG's high porosity, flexibility, and excellent electrical conductivity are beneficial for electrochemical detection. The PEDOT:PSS film is electrodeposited on the electrode surface to amplify the signal further. The synergistic effect of bimetallic nanocomposites can improve the electrochemical catalytic activity and increase the specific surface area and the advantages of active sites. The experimental results show that the LIG sensor has a wide linear detection range (2–500 ppm), a low detection limit (about 0.36 ppm), high sensitivity, and good repeatability. The sensor is easy to manufacture, is low-cost, operates at room temperature, has high sensitivity, has a low detection limit, and is expected to be used for methane breath detection in the future. [ABSTRACT FROM AUTHOR]

Ca and Mg are key constituents in surface water that are essential nutrients and vital indicators of water hardness. Rapid on-site measurement of Ca and Mg concentrations in surface water is important. However, traditional laboratory detection methods are complex and time-consuming, and on-site detection is difficult. In this study, a portable surface water detection method was developed using laser-induced breakdown spectroscopy with a miniaturized spectrometer LIBS and a liquid jet device for sample introduction. The device enables the rapid online in situ measurement of elemental concentrations in the water. The limits of detection for the rapid on-site detection of Ca and Mg in surface water were 11.58 and 2.57 mg/L, respectively. We applied this method to assess the concentrations of Ca and Mg in authentic water samples collected from rivers and ponds. The recovery rates for Ca and Mg were 90.83–101.74% and 93.43–108.74%, respectively. This method is suitable for rapid, on-site, and highly sensitive monitoring of Ca and Mg concentrations in the environment. [ABSTRACT FROM AUTHOR]

Lateral flow immunoassays (LFIAs) are widely used for their low cost, simplicity, and rapid results; however, enhancing their reliability requires the meticulous selection of ligands and nanoparticles (NPs). SiO2@QD@SiO2 (QD2) nanoparticles, which consist of quantum dots (QDs) embedded in a silica (SiO2) core and surrounded by an outer SiO2 shell, exhibit significantly higher fluorescence intensity (FI) compared to single QDs. In this study, we prepared QD2@PEG@Aptamer, an aptamer conjugated with QD2 using succinimidyl-[(N-maleimidopropionamido)-hexaethyleneglycol]ester, which is 130 times brighter than single QDs, for detecting carbohydrate antigen (CA) 19-9 through LFIA. For LFIA optimization, we determined the optimal conditions as a 1.0:2.0 × 10−2 ratio of polyethylene glycol (PEG) to aptamer by adjusting the amounts of PEG and aptamer, phosphate-buffered saline containing 0.5% Tween® 20 as a developing solution, and 0.15 μg NPs by setting the NP weight during development. Under these conditions, QD2@PEG@Aptamer selectively detected CA19-9, achieving a detection limit of 1.74 × 10−2 mg·mL−1. Moreover, FI remained stable for 10 days after detection. These results highlight the potential of QD2 and aptamer conjugation technology as a reliable and versatile sensing platform for various diagnostic applications. [ABSTRACT FROM AUTHOR]

The burgeoning field of biosensors has seen significant advancements with the induction of zinc oxide (ZnO) nanostructures, because of their unique structural, electrical, and optical properties. ZnO nanostructures provide numerous benefits for biosensor applications. Their superior electron mobility enables effective electron transfer between the bioreceptor and transducer, enhancing sensitivity and reducing detection limits. Furthermore, ZnO's biocompatibility and non-toxicity make it ideal for in vivo applications, reducing the chances of adverse biological responses. This review paper explores the prospects of ZnO nanostructures in the development of biosensors, focusing on their morphological and structural characteristics. Various synthesis techniques, that include sol-gel, sputtering, and chemical vapor deposition, were successfully employed to prepare different ZnO nanostructures, like nanorods, nanotubes, and nanowires. The various findings in this field underscore the efficacy of ZnO nanostructures in enhancing the specificity and sensitivity of biosensors, presenting a promising avenue for the advancement of point-of-care diagnostic devices. [ABSTRACT FROM AUTHOR]

The detection of low-molecular-weight biomarkers is essential for diagnosing and managing various diseases, including neurodegenerative conditions such as Alzheimer's disease. A biomarker's low molecular weight is a challenge for label-free optical modalities, as the phase change they detect is directly proportional to the mass bound on the sensor's surface. To address this challenge, we used a resonant Young's slit interferometer geometry and implemented several innovations, such as phase noise matching and optimisation of the fringe spacing, to maximise the signal-to-noise ratio. As a result, we achieved a limit of detection of 2.9 × 10−6 refractive index units (RIU). We validated our sensor's low molecular weight capability by demonstrating the detection of Aβ-42, a 4.5 kDa peptide indicative of Alzheimer's disease, and reached the clinically relevant pg/mL regime. This system builds on the guided mode resonance modality we previously showed to be compatible with handheld operation using low-cost components. We expect this development will have far-reaching applications beyond Aβ-42 and become a workhorse tool for the label-free detection of low-molecular-weight biomarkers across a range of disease types. [ABSTRACT FROM AUTHOR]

A fluorescence probe for "switch-on" detection of alkaline phosphatase (ALP) was developed based on Au nanoclusters anchored MnO2 nanosheets (Au NCs-MnO2 NSs), which were synthesized using bovine serum albumin (BSA) as template through a simple one-pot approach. In the sensing system, MnO2 NSs function as both energy acceptors and target identifiers, effectively quenches the fluorescence of Au NCs via fluorescence resonance energy transfer (FRET). The presence of ALP catalyzes the hydrolysis of L-ascorbic acid-2-phosphate (AAP) to ascorbic acid (AA), reducing MnO2 NSs to Mn2+ and facilitate the fluorescence recovery of Au NCs. The fluorescence assay offers the advantages of facile preparation, cost-effectiveness, good specificity, and high sensitivity. Moreover, the assay exhibits a broad linear range (0.005 U/mL to 8 U/mL) for ALP detection with a remarkable limit of detection of 0.0015 U/mL. Notably, this assay demonstrates promising applicability for detection ALP in human serum samples, thereby providing valuable potential for clinical applications. [ABSTRACT FROM AUTHOR]

Chronic Kidney Disease (CKD) is a disorder that affects over 10% of the global population, and that would benefit from innovative methodologies that would provide early detection. Since it has been reported that there are high levels of urease in CKD patients' saliva, this sample is a promising non-invasive alternative to blood for CKD detection and monitoring. This work introduces a novel 3D µPAD for quantifying urease activity in saliva in a range of 0.041–0.750 U/mL, with limits of detection and quantification of 0.012 and 0.041 U/mL, respectively. The device uses the urease in the sample to convert urea into ammonia, causing a colorimetric change in the bromothymol blue. The accuracy of the developed device was evaluated by comparing the measurements of several saliva samples (#13) obtained with the μPAD and with a commercially available kit. Stability studies were also performed to assess its functionality as a point-of-care methodology, and the device was stable for 4 months when stored in a vacuum. After the sample placement, it could be scanned within 40 min without providing significantly different results. The developed device quantifies urease activity in saliva within 30 min, providing a simple, portable, lab-free alternative to existing methodologies. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the popular herbicides that is widely used in agriculture and can be found in food and water. A rapid and sensitive fluorescence polarization immunoassay (FPIA) was proposed for the detection of 2,4-D in juice and water. New tracers, 2,4-D-buthylenediamin fluoresceinthiocarbamyl (2,4-D-BDF) and 2,4-D-glycine aminofluorescein (2,4-D-GAF), were obtained and characterized. Monoclonal antibodies (MAb) obtained against 2,4-D were used as a recognition reagent. The kinetics of the interaction of MAb and tracers were studied, and the kinetic parameters of their binding were calculated. High specificity of binding of tracers and MAb was shown. In this work, an approach was elaborated on to reduce the detection limit of 2,4-D by the FPIA method by changing the volume of the studied sample. The optimized FPIA in a competitive format was characterized by the LODs of 2,4-D 8 and 0.4 ng/mL and the working ranges 30–3000 ng/mL and 3–300 ng/mL for juice and water, respectively. The entire test cycle (from sample receipt to evaluation of the analysis results) took only 20 min. The test for the recovery of 2,4-D in juice and water gave values from 95 to 120%, which demonstrated the reliability of the herbicide determination in real samples. [ABSTRACT FROM AUTHOR]

Electrochemical glucose sensor holds significant promise for the monitoring of blood glucose levels in diabetic patients. In this study, we proposed a novel electrochemical glucose sensor based on 1,10-Phenanthroline-5,6-dione (PD)/Ru(III) as a dual redox mediator. The synergistic effect of PD and Ru(III) was utilized to efficiently facilitate the electron transfer between the enzyme-active center and the electrode. Then, a commercial disposable electrochemical glucose sensor was constructed based on screen-printing electrodes. Experimental results indicated the synergy between PD and Ru(III) provided a promising electron transfer environment for a glucose dehydrogenase (GDH)-catalyzed glucose reaction. The sensor exhibits a linear glucose response range from 0.01 to 38.6 mmol/L, with a limit of detection (LOD) as low as 7.0 µmol/L and a sensitivity of 38 µA·L/(mmol·cm2). The accuracy of the sensor was further validated in spiked recovery tests of human venous blood samples. The glucose recovery rate was between 99.5% and 107%, with a relative standard deviation (RSD) of less than 3.2%. These results demonstrate that our sensor has high potential for commercialization and practical application in glucose monitoring. [ABSTRACT FROM AUTHOR]

A HPU-23@Ru@Tb-NH2 sensor array with light-driven oxidase-mimicking activity and triple-emission fluorescence was developed. It was composed of a Tb3+-functionalized metal organic framework and Ru(bpy)32+ and applied to the simultaneous detection of Hg2+, ClO−, and PO43− via differently responsive channels. HPU-23@Ru@Tb-NH2 had a photoresponsive colorimetric response toward Hg2+ with a LOD as low as 4.18 nM. In addition, the three emissions of the HPU-23@Ru@Tb-NH2 sensor array were influenced by ClO− and PO43− to varying degrees, causing remarkably distinguishable responses for the fluorescence channels to discriminate ClO− and PO43− from each other. The detection limits of ClO− and PO43− were 12.26 µM and 0.197 nM, respectively. Therefore, this work demonstrates the feasibility of multi-emission and multi-mode sensing platform, which is able to combine the advantages of different strategies for solving the problems of various toxic substances coexisting in the environment while meeting the needs of accurate and precise results and no side interferences. [ABSTRACT FROM AUTHOR]

Here, a deep eutectic solvent depending on hydrophobic tetra-n-butylammonium bromide (TBABr) and decanoic acid (DecA) was used for the enrichment and extraction of minute quantities of cadmium heavy metal contained in the samples. In order to maximize Cd recovery in the samples, optimization studies of various extraction conditions were carried out, including the molar ratio and volume of HDES, salt amount, solution pH, vortex and centrifugation time. Although the pH value does not vary much between (2–10) under optimum conditions, the ideal working condition is pH (7), and the volume and molar ratio of HDES are found to be 1000 µL and 1:1 (TBABr: DecA), respectively. At the optimized extraction conditions, detection limit (LOD), quantification limit (LOQ), intra-day/inter-day precision (expressed as relative standard deviation %), and enrichment factor (PF) were observed to be 0.7 µg L-1, 2.3 µg L-1, 4.1- 4.4%, and 20, respectively. Cd extraction from certified reference materials (CRMs) was used to assess the method's accuracy, and the resulting findings were successfully compared with certified values. Finally, the developed procedure was applied to a variety of food, and water samples. The amounts of Cd in the examined vegetable samples were found to be 0.73 ± 0.07 µg/g in spinach, 0.37 ± 0.04 µg/g in celery, and 0.44 ± 0.03 µg/g in leeks. [ABSTRACT FROM AUTHOR]

This study investigates the critical role of adsorption in the development of electrochemical sensors, focusing on carbon (Vulcan XC72R, acetylene black, and graphite) and zeolite (high‐silica ZSM‐5 and all‐silica zeolite β) materials. Based on the paracetamol adsorption characteristics of these materials, an optimized disposable electrochemical sensor is created. This sensor exhibits a linear range of up to 5 μM and a remarkable detection limit of 150 nM (S/N = 3), ≈1000‐time improvement over the blank sensor. Moreover, paracetamol can be measured selectively because glucose has no adsorption affinity for the selected sensor materials. These findings underscore the significance of adsorption properties in sensor material selection in enhancing sensitivity and robustness against interfering species. [ABSTRACT FROM AUTHOR]

Mycoplasma hyopneumoniae (M. hyopneumoniae) is one of the primary agents involved in porcine respiratory disease complex, and circulates in the swine industry worldwide. The prevention and control of M. hyopneumoniae is complicated. Thus, a recombinase-aided amplification (RAA) assay coupled with the clustered regularly-interspaced short palindromic repeats (CRISPR)/Cas12a system was established for the detection of M. hyopneumoniae. The most suitable primer pairs and CRISPR RNA (crRNA) were screened and selected for the RAA-CRISPR/Cas12a detection system. We have achieved a detection limit of 1 copy/µL and 5 copies/µL per reaction for the RAA-CRISPR/Cas12a-fluorescence assay and RAA-CRISPR/Cas12a-lateral flow assay (LFA), respectively. Furthermore, the RAA-CRISPR/Cas12a system displayed no cross-reactivity with other respiratory pathogens. The performance of the RAA-CRISPR/Cas12a system was compared with PCR as recommended by the Chinese national standard (GB/T 35909-2018) and qPCR as recommended by the Chinese entry–exit inspection and quarantine industry standard (SN/T4104-2015) for clinical samples, and good consistency with these methods was observed. Above all, the methods shed a light on the convenient, portable, visual, highly sensitive and specific detection of M. hyopneumoniae , demonstrating a great application potential for on-site monitoring of M. hyopneumoniae in the field. [ABSTRACT FROM AUTHOR]

The diagnosis of milk fever or hypocalcemia in lactating cows has a significant economic impact on the dairy industry. It is challenging to identify asymptomatic subclinical hypocalcemia (SCH) in transition dairy cows. Monitoring subclinical hypocalcemia in milk samples can expedite treatment and improve the health, productivity, and welfare of dairy cows. In this study, an attomolar-sensitive sensor is developed using extrusion-based 3D-printed sensing structures to detect the ratio of ionized calcium to phosphate levels in milk samples. The unique geometries of the lateral structure of 3D-printed sensors, along with the wrinkled surfaces, provide a limit of detection down to the attomole (138 am) concentration of the target analyte. The calcium-to-phosphate ratio in milk samples not only provides early disease indications but also enables on-site testing. This highly selective test is validated using real milk and blood samples, and the results are compared with those of commercial meters. This fast response (~10 s) low-cost sensor opens a promising tool for the farm-side diagnostic of dairy cows that can promote best practice management of dairy cows. A 3D-printed sensor with surface-wrinkled structures detects subclinical hypocalcemia in dairy cows by measuring the calcium-to-phosphate ratio in milk. With attomolar sensitivity and rapid results, it enables early treatment, improving cow health and productivity. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of New Chemistry is the property of International Journal of New Chemistry 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.)

Unique nanostructures contribute to optimizing gas-sensitive properties, which has been widely acknowledged in the field of gas sensing. However, the construction of nanostructures by the in situ method is still challenging. In this work, nanorod-assembled SnWO4 was fabricated directly on interdigital electrodes by a one-step aerosol-assisted chemical vapor deposition method. The xylene gas sensor was developed, featuring low detection limits and fast response. Under the operating temperature of 350°C, the detection limit of the SnWO4 sensor for xylene reaches a minimal level of 10 ppb. Meanwhile, the sensor exhibits excellent performance in response time, providing a rapid response of 2 s to 100 ppm xylene. Apart from this, the sensor also exhibits good selectivity. Among various volatile organic compound gases of the same 100 ppm at 350°C, the sensor's response to xylene (484%) is 3.6 times that of toluene and 5.3 times that of benzene. The excellent gas-sensing performance is primarily due to the unique structural properties of nanorod-assembled SnWO4. This paper holds significant research potential in the field of gas sensing, particularly for the development of high-performance xylene sensors. [ABSTRACT FROM AUTHOR]

In vivo fluorine‐19 MRI using F‐based tracer media has shown utility and versatility for a wide range of biomedical uses, particularly immune and stem cell detection, as well as biosensing. As with many advanced MRI acquisition techniques, the sensitivity and limit of detection (LOD) in vivo is a key consideration for a successful study outcome. In this review, we analyze the primary factors that limit cell LOD. The achievable sensitivity is strongly dependent on the specific composition of tracer, cell type of interest, cell activity, data acquisition and reconstruction methods, and MRI hardware design. Recent innovations in molecular 19F tracer design and image acquisition–reconstruction methods have achieved significant leaps in 19F MRI sensitivity, and integration of these new materials and methods into studies can result in > 10‐fold improvement in LOD. These developments will help unlock the full potential of clinical 19F MRI for biomedical applications. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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 Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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.)

Nitrogen–sulfur co-doped pink fluorescent carbon dots (N,S-CDs) with uniform structure were successfully synthesized by the one-step solvothermal method using sulfosalicylic acid and o-phenylenediamine as precursors and ethanol as solvent. Photophysical measurements indicated that N,S-CDs exhibited excitation independence and excellent optical stability, with the fluorescence quantum yield of 12.21% and the fluorescence lifetime of 7.07ns. The prepared N,S-CDs solution was estimated to be utilized as fluorescent ink for information encryption, and be used as a fluorescent sensor to detect trace water in organic solvents (anhydrous ethanol, DMF). Furthermore, broad linear detection ranges (0–10%), low limit of detection (e.g., 0.187% for ethanol, 0.179% for DMF) had been achieved with this method. Based on the UV–Vis absorption spectra and fluorescence lifetime evaluation, the proposed mechanism underlying the trace water detection capability of the synthesized carbon dots in organic solvents stems from the interplay between water and fluorophore molecules facilitated by dynamic quenching. [ABSTRACT FROM AUTHOR]

Green nanotechnology, which uses carbon nanomaterials for environmental remediation, is the pioneer among the prevailing approaches for the production and characterization. In the present study, highly fluorescent carbon dots (CDs) from Ruta Graveolens (ARH‐CD) is developed, and its efficacy as a fluorescent sensor and biomarker is investigated. They act as a fluorescence sensor for Hg2+ over an extensive concentration range of 1 picomolar (pm) to 1 molar (m), with a detection limit as low as 26.75 pm. The studies reveal ARH‐CD as an effective biomarker for intracellular toxicity analysis and a fluorescent probe for multi‐colored (blue, green, and red) imaging of HEK293 cell lines. After 24 h of incubation, it is found that the ARH material reveals noticeable biocompatibility and visible fluorescence, with a viability of 98.88% at 5 µg mL−1 and over 78.33% even at a concentration of 100 µg mL−1. The IC50 value for the MTT assay for cell viability results is calculated to be 224.56 ± 4.67 µg, which further confirms the appreciable biocompatibility of the ARH‐CD. The obtained samples are effective in being inspected for the intracellular detection of Hg2+ and serve as a possible candidate for cell imaging. [ABSTRACT FROM AUTHOR]

Co-occurrence of multiple mycotoxins is a growing global food safety concern due to their harmful effects on humans and animals. This study developed an eco-friendly sample preparation method and an innovative multiplex microarray-based lateral flow immunoassay, using a novel portable reader for on-site simultaneous determination of five regulated mycotoxins—aflatoxin B1, T-2 toxin, zearalenone, deoxynivalenol, and fumonisin B1 in rice. The eco-friendly and ultrafast extraction procedure utilizes a bio-based solvent. Principally, the microarray signals generated through a novel luminescent organic dye were captured to quantify mycotoxin levels in samples using a portable reader installed with a user-friendly interface. The assay demonstrates accurate detection and quantification of these mycotoxins, with recoveries ranging from 77% to 127%. Detection limits ranged from 0.56 to 1.89 μg/kg, which were well below their regulatory limits, with a relative standard deviation below 25%. This analytical system provides an on-site method for detecting multiple mycotoxins in rice. [ABSTRACT FROM AUTHOR]

Pyrogens cause shock symptoms when released into the bloodstream. They are classified into two main categories: endotoxins (lipopolysaccharides [LPS]) and non-endotoxin pyrogens. The monocyte activation test (MAT) is an in vitro assay to detect pyrogens in human monocytes. Cells were incubated in the culture medium, and the cellular response, specifically the production of the inflammatory cytokine interleukin-6 in the culture supernatant, was analyzed using enzyme-linked immunosorbent assay (ELISA). Technical improvements, such as cell acquisition and culture media selection, will be beneficial for the popularization of MAT. The cell freshness was strictly controlled to achieve high MAT sensitivity. However, it is necessary to investigate the usability of older and stored blood samples in the MAT. This study evaluated the effect of cell freshness on MAT using peripheral blood mononuclear cells (PBMCs) isolated from 2- and 5-d-old donated whole blood samples. To mitigate the influence of serum in the culture medium, a serum-free MAT was developed using the LPS-binding protein (LBP) as an enhancer for LPS detection. PBMCs were incubated with a two-fold dilution series of LPS at 0.001–4.096 endotoxin units/mL (EU/mL). Interleukin-6 levels in the culture supernatant were quantified by ELISA in the presence and absence of LBP. In the presence of LBP, the limit of detection (LOD) for LPS was 0.001–0.008 EU/mL. However, in the absence of LBP, the LOD was 0.512 EU/mL. Peripheral PBMCs were 38.6 times more sensitive in the presence of LBP than in its absence. When utilizing the developed serum-free MAT with LBP, 5-d-old PBMCs showed LODs of 0.016–0.064 EU/mL, indicating a 3.1-fold increase in sensitivity compared with 5- to 2-d-old PBMCs. These results suggest that the sensitivity of PBMCs decreased gradually rather than sharply. The study concluded that 2-d-old PBMCs were sufficiently fresh and could be used as serum-free MAT. [ABSTRACT FROM AUTHOR]

Background: Porcine teschovirus (PTV) is an important enteropathogen, associated with symptoms of polioencephalomyelitis, pneumonia, pericarditis, myocarditis, diarrhea, and reproductive disorders in pigs. Rapid and precise diagnostic methods are essential for managing PTV infections. The study introduced a simple, quick, and visual approach for detecting PTV through the use of RT-RAA coupled with LFD. Results: The procedures of RT-RAA-LFD for PTV could be carried out with 1.0 μmol/L primer concentration and 2.0 μmol/L probe concentration at 37 °C for 20 min, and the amplification result could be visualized within 5 min through LFD detection. Meanwhile, the assay established in this study showed no interaction with other associated diarrhea viruses, and has high specificity to PTV, with a minimal detection limit of 10 copies/μL and good repeatability. 128 clinical samples suspected of having a PTV infection were tested by RT-PCR and RT-RAA-LFD, respectively. The total diagnostic coincidence rate was 98.44% (126/128) with a Kappa value of 0.96(K ≥ 0.75), demonstrating a high degree of agreement to detect PTV for the two methods. Conclusions: The RT-RAA-LFD assay created in this research displayed quick response, specificity, and sensitivity, capable of successfully detecting PTV in less than 25 min, providing an easy-to-use diagnostic instrument for rapid and visual PTV detection, especially suitable for labs and low-resource environments. [ABSTRACT FROM AUTHOR]

The determination of Cr(VI) ions in real-world samples is of utmost importance due to the critical role it plays in assessing and monitoring the levels of Cr(VI) contamination in water. The present study introduces a time-saving, cost-effective, selective, highly efficient and eco-friendly analytical reagent to detect Cr(VI) ions. This study presents fabrication of immobilised 4,5-dihydroxynaphthalene-2,7-disulfonic acid disodium salt dihydrate (DHNDSADNa) on a polyethylene-polyamine polyacrylonitrile (PPA) matrix for the determination of Cr(VI) ions using X-ray fluorescence, spectroscopic analysis and potentiodynamic titration methods. The findings revealed that the immobilised DHNDSADNa on the PPA matrix is a highly selective, accurate, easily regenerable, and rapid analytical reagent for the determination of Cr(VI) ions. The DHNDSADNa-anchored PPA framework demonstrated distinctive spectroscopic signals at 460 nm and 590 nm for the reagent and its complex with Cr(VI) ions, respectively. The detection limit for Cr(VI) ions was found to be 2 μg/mL, which is lower than that of DHNDSADNa in solution. Furthermore, the reagent exhibited high selectivity and efficiency for Cr(VI) ions even in the presence of other ions such as Co(II), Ni(II), Al(III), Fe(II), Ti(IV), Zr(IV), Ta(V), Mn(II), and W(VI). Last but not least, the immobilised DHNDSADNa on the PPA matrix exhibits superior analytical characteristics compared to previously utilised methods, making it a promising tool for various applications in medicine, pharmacology, biology, chemistry, and engineering. [ABSTRACT FROM AUTHOR]

1-(Pyridin-2-yl-hydrazonomethyl)-naphthalen-2-ol (PNOH) is a naphthalene-based fluorescence chemo-sensor for PO43-. The probe (PNOH) is spectroscopically characterised and the chemo-sensing mechanism has been demonstrated through 1H NMR, UV-Vis absorption and both steady-state and time resolved fluorescence study. Fluorescence 'turn-on' sensing knack of PNOH towards PO43- ion has been explained due to emission from the excited PNO– ion, formed upon transfer of phenolic proton of PNOH to PO43- ion in the excited state. The 1:1 stoichiometry of PNOH-PO43- complex is observed from Job's plot based on UV-Vis titration and the complex shows distinct yellowish-green colour to be used as colorimetric sensor for PO43-. Limit of detection (LOD) of PNOH towards PO43- is found to be 0.35 µM. It is also demonstrated that the probe can be used to fabricate a convenient and efficient PO43- paper test kits as well as molecular INHIBIT logic gate. [ABSTRACT FROM AUTHOR]

In this research, applicability of an environmentally friendly deep eutectic solvent (DES) for pipette-tip micro-solid phase extraction and preconcentration of levofloxacin prior to its quantification by spectrophotometry at the wavelength of 240 nm is presented. Carvone:thymol (1:1 molar ratio) DES was prepared and coated on graphene oxide and applied as adsorbent. This adsorbent was characterised utilising Fourier transform infrared and field emission scanning electron microscopy, which showed a uniform layer of DES coated on graphene oxide. 5.0 mg of this adsorbent was packed into a 100 µL pipette-tip and was applied to miniaturised pipette-tip solid-phase extraction of levofloxacin. Parameters affecting microextraction including kind and volume of elution solvent, pH, amount of sorbent, sample volume, and number of aspirating/dispensing cycles were investigated and optimised using one-variable-at-a-time procedure, central composite design, and Box-Behnken design response surface methodologies. The developed method required only 5.0 mg of adsorbent and 150 µL of methanol:acetone (2:1) (elution solvent) to achieve a low detection limit of 0.3 µg/L with a linear range of 1–500 µg/L. High enrichment factor of 65.3 with a good precision (RSD ≤ 4.7%) was also achieved. The proposed method was successfully applied to determine levofloxacin in pills, blood, urine and a few seawater samples. [ABSTRACT FROM AUTHOR]

Accurate fluoride measurement in water is required for selecting safe water sources or for treatment options to lessen its impact on public health. A low-cost, portable device has been developed as a rapid fluoride measurement system. It works with an optimal concentration of alizarin red S-zirconium complex (ARS-Zr, the sensor reagent). The device is an LED-phototransistor-based assembly to detect changes in light absorbance at 527 nm, due to monotonically decreasing ARS-Zr concentration with increasing fluoride concentration in water. We have optimised reagent composition in the device, enabling us with a wider fluoride detection range (0.2–9 ppm), rapidly within 4 min; simultaneously ensuring better reagent stability for up to 34 days. Limit of detection (LOD) and limit of quantification (LOQ) of the device are 0.2 and 0.6 ppm, respectively. The device replicates an analytical spectrophotometer's performance, with a maximum error up to 5% in only a couple of cases. The hand-held device does not give any interference in the presence of even a very high 200 ppm concentration of other common heavy metals (${\rm{C}}{{\rm{a}}^{2 + }}$ C a 2 + , ${\rm{Z}}{{\rm{n}}^{2 + }}$ Z n 2 + , ${\rm{ F}}{{\rm{e}}^{2 + }}$ F e 2 + , ${\rm{M}}{{\rm{g}}^{2 + }}$ M g 2 + , ${\rm{ C}}{{\rm{u}}^{2 + }}$ C u 2 + ) and anions (${\rm{C}}{{\rm{l}}^ - }$ C l − , ${\rm{NO}}_3^ - $ N O 3 − , ${\rm{SO}}_4^{2 - }$ S O 4 2 − , ${{\rm{I}}^ - }$ I − , CH3COO−, ${\rm{CO}}_3^{2 - }$ C O 3 2 − ), which can be present in water. Fluoride concentration measurement above 1 ppm is unaffected, by even high phosphate concentration up to 10 ppm (typical phosphate level being only ≤ 2.3 ppm). Similarly, for silica concentration up to 10 ppm (typical silica level being 1-30 ppm), fluoride measurement remains unaffected. However, the presence of ${\rm{ F}}{{\rm{e}}^{3 + }}$ F e 3 + gives significant interference with fluoride. Overall, we demonstrate the device as an on-spot method, for rapid fluoride measurement, independent of TDS (57.6–151 ppm), pH (6.6–12.5) or conductivity (111.2–283 µS/cm) of the samples, at a low device cost of US$ 25 and reagent cost of 0.44 cents per sample. [ABSTRACT FROM AUTHOR]

Papaya is the fourth most consumed fruit in Brazil and the third most exported fruit by the country. Considering that pesticides are frequently used in agriculture to increase production this work aimed to establish a method for the multiresidue determination of pesticides in papaya using the QuEChERS method and analysis by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). The parameters that influence the extraction efficiency were studied and, after finding the best extraction conditions, the method was validated. The analysis by UHPLC-MS/MS allowed the determination of analytes with high selectivity and detectability. The main modification of the original QuEChERS method was the use of the polymeric sorbent Strata SDB-L in the clean-up step by dispersive solid-phase extraction. The method was validated for 110 compounds and presented adequate values of accuracy, with recoveries between 70 and 120%, and precision, with RSD<20%. The method limits of quantification ranged from 5 to 10 µg kg−1 and detection limits from 1.5 to 3 µg kg−1. The validated method was used for the determination of pesticides in commercial papaya samples, and 17 pesticides of different classes were found, including 5 pesticides not authorised in Brazil for papaya. Considering the results obtained, the use of the proposed method proved to be fast and efficient for the multiresidue determination of pesticides in papaya in routine analysis. [ABSTRACT FROM AUTHOR]

Au/Ni nanotubes were fabricated on carbon papers through depositing Au nanoparticles on Ni nanotubes to construct nitrite sensors. The structure and constituent characterisation of Au/Ni-60s NTs demonstrated the homogeneous distribution of Au nanoparticles on the Ni nanotubes. Due to the synergy between Ni nanotubes and Au nanoparticles, highly improved nitrite sensing performance was achieved on Au/Ni-60s NTs, which presented a very wide linear range for nitrite detection. Two linear segments have been obtained in the range of 0.4–40000 µM and 40–130 mM with the detection limit of 0.13 μM. The sensitivity of 707.14 µA·mM−1·cm−2 in lower region and 339.53 µA·mM−1·cm−2 in higher region was achieved. Furthermore, the obtained Au/Ni-60s NTs displayed good selectivity and high reliability for nitrite detection in real samples such as milk and peach juice. This investigation may provide a useful route and reference to construct tubular structures for efficient nitrite detection. [ABSTRACT FROM AUTHOR]

Ketamine is a dissociative anesthetic drug that is abused by teenagers and young adults, commonly for recreational purposes in dance clubs, to generate euphoria and dissociation, and sometimes employed as a date-rape drug. Herein, a highly sensitive, and environmentally friendly spectrofluorimetric method was developed for detection of ketamine in pharmaceutical and plasma samples. The technique is based on a nucleophilic substitution reaction occurring between ketamine and NBD-Cl (4-chloro-7-nitrobenzo-2-oxa-1,3-diazole), resulting in the formation of a fluorescent derivative that exhibits detectability at a remarkable level. The resultant derivative demonstrates its maximum emission intensity at 543 nm upon excitation at a wavelength of 481 nm. Upon optimizing the reaction parameters, a linear relationship was established between the fluorescence intensity of the formed derivative and the concentrations of ketamine within the specified range of 10 − 250 ng/mL. The method demonstrated exceptional sensitivity with detection and quantitation limits of 2.37 ng/mL and 7.18 ng/mL, respectively, allowing for the detection of ketamine in both pharmaceutical and plasma samples. The method was precise (%RSD < 1) accurate (%R = 99.74%) and robust (% R ± SD from 98.00 ± 1.11 to 99.97 ± 0.75). Furthermore, the developed method was compared to the reported method, with the results indicating that the suggested method is more sensitive and ecologically benign. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) technology has attracted more and more attention due to its high sensitivity, low water interference, and quick measurement. Constructing high-performance SERS substrates with high sensitivity, uniformity and reproducibility is of great importance to put the SERS technology into practical application. In this paper, we report a simple fabrication process to construct dense silver-coated PMMA nanoparticles-on-a-mirror SRES substrates. The electric field enhancement at the ultra-small metallic nanogap is further amplified by the silver mirror, which can achieve higher SERS intensity. The thickness of the PMMA layer was optimized so that the absorption peak can match the excitation wavelength, thus obtaining maximum SERS intensity. The optimized substrate possessed excellent SERS behavior for crystal violet (CV) molecules under 532 nm laser excitation, with a low detection limit of 10− 13 M. Moreover, SERS analysis was quantitatively achieved in the broad linear concentrations. The fabricated substrate demonstrated excellent uniformity and reproducibility with a relative standard deviation (RSD) of 7.75% in peak intensities. The substrate also showed long-term stability, and it can be stored for 37 days with an acceptable SERS peak intensities. This proposed method will open up new possibilities to fabricate high-performance SERS sensors, which can be widely used for the practical application of chemical and biochemical sensing. [ABSTRACT FROM AUTHOR]