LOD Values Research Articles

Highly efficient photocatalytic removal of antineoplastic drug and selective fluorescence detection of organophosphate pesticide employing NiFe2O4 modified 2D g-C3N4 heterostructures

With the goal to detect, quantify and remove virulent toxins for water decontamination, a dual functional platform based on nickel ferrite (NF) modified magnetically retrievable 2D metal free g-Carbon Nitride (CN), with varied ratios of NF, was fabricated via simple sonication-calcination route. The % degradation of antineoplastic drug, doxorubicin (DXR) were obtained to be 69.8 %, 49.1 %, 71.1 %, 85.4 %, 94.2 %, 88.5 % and 81.7 % for CN, NF, 2-CNNF, 4-CNNF, 6-CNNF, 8-CNNF and 10-CNNF, respectively with corresponding rate constant values of 0.069, 0.047, 0.075, 0.100, 0.148, 0.113 and 0.078 min−1. CNNF heterostructure displayed outstanding photocatalytic performance with 6-CNNF heterostructure displaying highest rate kinetics with rate constant value 2.2 and 3.2 times greater than pure CN and NF, respectively. The charge transfer occurring in CNNF heterostructure followed direct Z-scheme mechanistic pathway, which proffers two advantages of high photoinduced charge carriers separation and optimized redox capacity of binary system. UV–vis DRS, XPS and PL results supported the proposed mechanism. Radical scavenging experiments further validated the role of •O2−, h+ and HO• radicals in degrading target pollutant. Moreover, the fabricated material was efficiently employed as selective and sensitive sensor for fluorescence detection of pesticide, chlorpyrifos (CPF) and DXR with respective LOD values of 4.1 µM in the range of 5 µM to 100 µM and 1.6 µM in the range of 0.1 µM to 40 µM. Real world applicability was established by monitoring CPF and DXR in real water samples. This study presents the designing of multi-functional platform, exhibiting excellent optical as well as physical characteristics, for monitoring and obliteration of noxious pollutants in aqueous environment.

Non-enzymatic electrochemical sensing platform based on metal oxide-loaded biopolymer for voltammetric measurement of hepatoprotective metadoxine drug in pharmaceutical formulation and human blood serum

This study focuses on the first-ever high-sensitivity, low-cost, and quick response electrochemical estimation of metadoxine (MTD) in pharmaceuticals and human blood serum using a non-enzymatic nanocomposite modified glassy carbon electrode (CuO/CH/GCE) loaded with chitosan. The electroactive surface of GCE was produced by drop-casting a suspension of CuO/CH nanocomposite in N,N-dimethylformamide (DMF) onto the non-enzymatic electrode surface. Synthesized nanocomposite was characterised by using XRD, XPS, EDX, TEM, Raman and FESEM techniques. EIS technique was utilized to study the enhanced charge-transfer phenomenon occurring at the surface of modified sensor. The electrooxidation of MTD at CuO/CH/GCE surface is depending at pH of supporting electrolyte, scan rate and concentration of analyte. CV and SWV technique were used to carry out electrochemical study, optimised voltammetric response is observed in the BR buffer at pH 2.5, with irreversible diffusion-controlled process. Within the linear concentration range of MTD from 1.99 μg/L to 29.56 μg/L, this sensor exhibited lowest LOD (0.64 μg/L) and LOQ (2.14 μg/L). The MTD in pharmaceutical formulation and human blood serum can be determined with this highly selective peak potential (Ep ∼ 1.2 V), repeatable (%RSD 0.91), and reproducible (%RSD 2.31) method. The average percentage recovery in human blood serum and pharmaceutical formulation is 99.89% and 99.90%. This paper reports a lowest LOD value for MTD detection in the comparison with other reported methods (Table S1). None of the selected excipients were found to interfere more than 5% with redox potential of MTD without affecting the performance of sensor.

Semiconducting 2D Copper(I) Iodide Coordination Polymer as a Potential Chemiresistive Sensor for Methanol.

The development of a cost-effective, ultra-selective, and room temperature gas sensor is theneed of an hour, owing to the rapid industrialization. Here, a new 2D semiconducting Cu(I) coordination polymer (CP) with 1,4-di(1H-1,2,4-triazol-1-yl)benzene (1,4-TzB) ligand is reported. The CP1 consists of a Cu2I2 secondary building unit bridged by 1,4-TzB, and has high stability as well as semiconducting properties. The chemiresistive sensor, developed by a facile drop-casting method derived from CP1, demonstrates a response value of 66.7 at 100ppm on methanol exposure, accompanied by swift transient (response and recovery time 17.5 and 34.2s, respectively) behavior. In addition, the developed sensor displays ultra-high selectivity toward methanol over other volatile organic compounds , boasting LOD and LOQ values of 1.22 and 4.02 ppb, respectively. The CP is found to be a state-of-the-art chemiresistive sensor with ultra-high sensitivity and selectivity toward methanol at room temperature.

Genome-Wide Association Study Reveals a QTL Region for Ashy Stem Blight Resistance in PRA154 Andean Common Bean.

Ashy stem blight (ASB) caused by Macrophomina phaseolina (Tassi) Goidanich affects the common bean (Phaseolus vulgaris L.) at all growing stages. Higher levels of resistance were observed in Andean common beans, but specific resistant quantitative trait loci (QTLs) conferring resistance to this pathogen have not been reported in this gene pool. The objectives of this research were to: (i) conduct a genome-wide association study (GWAS) and QTL mapping for resistance in the Andean breeding line PRA154; and (ii) identify single nucleotide polymorphism (SNP) markers and candidate genes for ASB resistance. Phenotyping was conducted under greenhouse conditions by inoculating the 107 F6:7 recombinant inbred lines (RILs) derived from the cross between the susceptible cultivar 'Verano' and the partial-resistant breeding line PRA154 twice with the M. phaseolina isolate PRI21. Genotyping was performed with 109,040 SNPs distributed across all 11 P. vulgaris chromosomes. A novel major QTL was located between 28,761,668 and 31,263,845 bp, extending 2.5 Mbp on chromosome Pv07, and the highest significant SNP markers were Chr07_28761668_A_G, Chr07_29131720_G_A, and Chr07_31263845_C_T with the highest LOD (more than 10 in most of the cases) and R-squared values, explaining 40% of the phenotypic variance of the PRI21 isolate. The gene Phvul.007G173900 (methylcrotonyl-CoA carboxylase alpha chain and mitochondrial 3-methylcrotonyl-CoA carboxylase 1 [MCCA]) with a size of 10,891 bp, located between 29,131,591 and 29,142,481 bp on Pv07, was identified as one candidate for ASB resistance in PRA154, and it contained Chr07_29131720_G_A. The QTL and genetic marker information could be used to assist common bean breeders to develop germplasm and cultivars with ASB resistance through molecular breeding.

A novel QTL conferring Fusarium crown rot resistance on chromosome 2A in a wheat EMS mutant.

A novel QTL on chromosome 2A for Fusarium crown rot resistance was identified and validated in wheat. Fusarium crown rot (FCR) is a fungal disease that causes significant yield losses in many cereal growing regions in the world. In this study, genetic analysis was conducted for a wheat EMS mutant C549 which showed stable resistance to FCR at seedling stage. A total of 10 QTL were detected on chromosomes 1A, 2A, 3B, 4A, 6B, and 7B using a population of 138 F7 recombinant inbred lines (RILs) derived from a cross between C549 and a Chinese germplasm 3642. A novel locus Qfcr.cau-2A, which accounted for up to 24.42% of the phenotypic variation with a LOD value of 12.78, was consistently detected across all six trials conducted. Furthermore, possible effects of heading date (HD) and plant height on FCR severity were also investigated in the mapping population. While plant height had no effects on FCR resistance, a weak and negative association between FCR resistance and HD was observed. A QTL for HD (Qhd.cau-2A.2) was coincident with Qfcr.cau-2A. Conditional QTL mapping indicated that although Qfcr.cau-2A and Qhd.cau-2A.2 had significant interactions, Qfcr.cau-2A remained significant after the effects of HD was removed. It is unlikely that genes underlying these two loci are same. Nevertheless, the stable expression of Qfcr.cau-2A in the validation population of 148 F7 RILs developed between C549 and its wild parent Chuannong 16 demonstrated the potential value of this locus in FCR resistance breeding programs.

Stability indicating eco-friendly quantitation of terbutaline and its pro-drug bambuterol using quantitative proton nuclear magnetic spectroscopy

Quantitative 1H-NMR became an increasingly important issue in pharmaceutical analytical chemistry. This study used NMR spectroscopy to assay the bronchodilator drug terbutaline sulfate and its pro-drug bambuterol hydrochloride in pure form and pharmaceutical preparations. The technique proceeded using deuterium oxide (D2O) as an 1H-NMR solvent and phloroglucinol anhydrous as an internal standard (IS). Comparatively, to the phloroglucinol signal at 5.9 ppm, the resulting quantitative signals of the studied drugs were corrected. The terbutaline singlet signal at 6.3 ppm was chosen for quantification, while the bambuterol quantitative singlet signal was at 2.9 ppm. The two drugs were rectilinear over the concentration range of 1.0–16.0 mg/mL. LOD values were 0.19 and 0.21 mg/mL while LOQ values were 0.58 and 0.64 mg/mL for terbutaline and bambuterol respectively. The developed method has been validated according to the International Conference of Harmonization (ICH) regarding linearity, accuracy, precision, specificity, and robustness. A greenness profile assessment was applied, and the method proved to be green. The method enables the assay of the two drugs in pure drug and pharmaceutical preparations. The method also enables the assay of the two drugs in the presence of each other; thus, it is considered a stability-indicating method where terbutaline is an acid degradation product of bambuterol.

Comparative study of the vibrating capillary nebulizer (VCN) and commercially available interfaces for on-line coupling of capillary electrophoresis with ICP-MS.

Capillary electrophoresis (CE) is a powerful and sensitive tool for speciation analysis when combined with inductively coupled plasmamass spectrometry (ICP-MS); however, the performance of this technique can be limited by the nature of pneumatic nebulizers. This study compares two commercially available pneumatic nebulizers to a newly introduced vibrating capillary nebulizer (VCN) for on-line coupling of CE with ICP-MS. The VCN is a low-cost, non-pneumatic nebulizer that is based on the design of capillary vibrating sharp-edge spray ionization. As a piezoelectrically driven nebulization source, the VCN creates an aerosol independent of gas flows and does not produce a low-pressure region at the nebulizer orifice. To compare the systems, we performed replicate analyses of sulfate in river water with each nebulizer and the same CE and ICP-MS instruments and determined the figures of merit of each setup. With the CE-VCN-ICP-MS setup, we achieved around 2-4 times lower sensitivity compared to the commercial setups. However, the VCN-based setup provided lower noise levels and better linear correlation from the analysis of calibration standards, which resulted in indistinguishable LOD and LOQ values from the in-house-built VCN-based and commercial setups for CE-ICP-MS analysis. The VCN is found to have the highest baseline stability with a standard deviation of 3500 cts s-1, corresponding to an RSD of 2.7%. High reproducibility is found with the VCN with a peak area RSD of 4.1% between 3 replicate measurements.

High Performance Liquid Chromatography Method for Analysis of Alpha Arbutin and Niacinamide in Facial Whitening Creams

The combination of alpha arbutin and niacinamide is often used in facial whitening creams at relatively small levels so required valid analysis method. This study aimed to develop HPLC method for analyzing alpha arbutin and niacinamide in three brands of whitening creams. The HPLC system developed was a reverse phase type with a C₁₈ column and the mobile phase was a mixture of metanol: aquabidest (20:80, v/v) with a flow rate of 1.0 ml/min and a detection wavelength of 274 nm. The results showed that all parameters met the requirements. The linearity test yielded a correlation value was r= 0.999. The LOD value for alpha arbutin was 0.405 µg/mL and the LOD for niacinamide was 0.398 µg/mL. The LOQ value of alpha arbutin was 1.351 µg/mL, the LOQ for niacinamide was 1.327 µg/mL and the selectivity was good. Precision test results with %RSD ≤ 2% and accuracy tests yielded values in the 99.04-100.97% range. The content of alpha arbutin in brand A was 0.651%, brand B was 0.551%, and brand C was 0.878%. The content of niacinamide in brand A was 0.526%; brand B was 0.680% and brand C was 1.053%. The results of the analysis meet the requirements.

Cyclic Voltammetry Method for Analysis of Phosphate Concentration in Water

Phosphate is a nontoxic element but a limiting element for productivity. Several methods have been established to analyze the phosphate concentration in water. This study aims to analyze phosphate concentration in water using the voltammetry method using cyclic voltammetry. Cyclic voltammetry is an electroanalytical method that measures the current outcome of oxidation-reduction reactions in response to the potential. The current outcome is directly proportional to the phosphate concentration in the solution. The calibration curve was formed from the KH2PO4 standard solution using concentrations of 0.1 mg/L, 0.2 mg/L, 0.4 mg/L, 0.8 mg/L, and 1.6 mg/L. The voltammogram showed that the analyte does not have an anode peak current (Ipa), which means that the analyte solution did not have an oxidation reaction, so the cathode peak current (Ipc) value was used. Based on the calibration curve, the linear regression graph with a straight-line equation is y = -0,00000645632x - 0,000208737 with R2 of 0,99737. Meanwhile, this cyclic voltammetry method was validated by calculating the LOD and LOQ values; the results are 0.1034 mg/L and 0.3134 mg/L, respectively. Hence, based on the analysis of phosphate concentration in water samples, this method works satisfactorily and is suitable for routine analysis because of its advantages.

Ultrasensitive detection of imatinib in human serum using a gold-based paper sensor

Imatinib is the tyrosine kinase inhibitor of choice for the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors. However, imatinib has drawbacks such as drug resistance and significant differences in pharmacokinetics within patients. Therefore, a colloidal gold-based immunochromatographic assay (CG-IA) was developed for measuring and monitoring imatinib in human serum. An imatinib derivative containing carboxyl groups was used for the synthesis of the immunogen, and 4-(4-methyl-1-piperazinylmethyl) benzoic acid was selected as the hapten for the heterologous coating antigen. Next, a highly sensitive and specific monoclonal antibody (mAb), 2F7 was screened for the construction of a CG-IA, with an IC50 value of 0.091 ng/mL. For the qualification of imatinib in human serum, the visual limit of detection (vLOD) and cut-off values of the CG-IA were 2 and 20 ng/mL, respectively. For quantitative detection, the calculated LOD value of the CG-IA was 0.068 ng/mL, with a linearity range of 1.004 and 23.087 ng/mL. The recovery rate of spiked serum samples was between 88.24 % and 104.75 %. In addition, the concentration of imatinib in the serum samples from 10 patients was detected by CG-IA and revealed a good correlation with those from LC-MS/MS. These results indicated that the developed gold-based paper sensor could become an effective tool for the rapid monitoring of imatinib in human serum samples.

Designing a calixarene-based {Zn24} coordination cage as a multifunctional sensor

Solvothermal method was chosen to construct a porous zinc-calixarene coordination cage (SWU-3): [Zn24(TC4A-SO2)6(BTC)8(H2O)6] (H4TC4A-SO2 = p-tert-butylsulfonylcalix[4]arene, H3BTC = 1,3,5-benzenetricarboxylic acid) by ZnCl2, H3BTC and H4TC4A-SO2. SWU-3 shows certain water stability and excellent luminescence property. In the fluorescence test, SWU-3 exhibits different fluorescence sensing behaviors for detecting Fe3+, CrO42-, Cr2O72- and iodine (I2), the LOD values are 2.21 × 10-5, 2.740 × 10-5, 3.066 × 10-5 and 6.673 × 10-6 mol/L, respectively. Moreover, nitroaromatic compounds (NACs) can also be detected by SWU-3. These results prove that SWU-3 reveals great potential as a fluorescence sensor for ions, I2 and NACs detection.

Development and validation of UV–Vis spectrophotometry-colorimetric method for the specific quantification of rivastigmine tartrate from separable effervescent microneedles: Ex vivo and in vivo applications in complex biological matrices

Rivastigmine Tartrate is an acetylcholinesterase inhibitor commonly used in Alzheimer treatment. Due to its hydrophilicity, short plasma elimination half-time, and poor blood-brain barrier penetration, developing a new drug delivery system for RT administration is essential. Accordingly, microneedles offer several advantages and could be a promising drug delivery system for RT administration. One of those types of MNs with numerous advantages is separable-effervescent microneedles. To support the formulation development, an analytical method using UV–Vis spectrophotometry was validated in phosphate buffered saline media and various biological matrices, such as rat skin, brain, and plasma to measure the amount of RT in the SEMNs preparations. The developed analytical method was validated under ICH guidelines. The results showed that the instrument could specifically detect the RT in the preparations without being interfered with by other compounds. The calibration curves in various biological matrices were linear ≥ 0.9985. The LOD and LLOQ values of the PBS media biological matrices were found to be 1.5 and 4.8 µg/mL, 1.2 and 3.7 µg/mL, 0.42 and 1.27 µg/mL, and 0.38 and 1.16 µg/mL, respectively. All the accuracy and precision values of this developed method were within acceptable ranges. Additionally, the extraction recovery was prominent after undergoing the protein precipitation process. As a result, the analytical method was proven to be valid and was successfully applied to quantify the amount of RT in the SEMNs formulation, in vitro and ex vivo permeation, along with in vivo pharmacokinetic studies.

DETERMINATION OF THE ANTIHYPERTENSIVE DRUGS CAPTOPRIL, ATENOLOL, AND METOPROLOL IN DOSAGE FORMS

Three antihypertensive drugs Captopril (CPL), Atenolol (ATL), and Metoprolol (MTL) have been estimated sensitively and selectively by a single spectrophotometric method using neutral red dye NLR. The method is based on oxidation of the drugs by known excess of N-bromosuccinamide (NBS) in the first reaction step followed by the oxidation of NLR dye with the exceed ed amount of NBS, as the concentration of the drug compounds increase, the color of the dye increase, the dye exhibits absorbance peak at 523 nm. The linearity range was from 1 to 10 µg/ml for the three drugs, the molar absorptivity values were 2.1164 × 105, 1.9202× 104, and 57.934× 104 l.mol-1.cm-1 for CPL, ATL, and MTL respectively, the sensitivity index of Sand’ll were 0.0102, 0.0138, and 0.01182 µg/cm2 for CPL, ATL, and MTL respectively. LOD values for the three drugs ranged from 0.00405 to 0.00547 and LOQ values were ranged from 0.0135 to 0.0182 respectively, the method exhibits good applicability to the dosage forms and high confidence as compared with standard method and standard addition method.

Method development for the quantification of nine nitazene analogs and brorphine in Dried Blood Spots utilizing liquid chromatography – tandem mass spectrometry

The detection of nitazenes in biological fluids is increasingly needed as they are repeatedly reported in intoxication and overdose cases. A simple method for the quantification of low levels of nine nitazene analogs and brorphine in Dried Blood Spots (DBS) was developed and validated. 10 μL of spiked whole blood is deposited on a Capitainer®B card and allowed to dry. The spot is punched out, and extracted with 500 μL methanol:acetonitrile (3:1 v/v) added with 1.5 μL of fentanyl-D5 as the internal standard. After stirring, sonication, and centrifugation of the vial, the solvent is dried under nitrogen, the extract is reconstituted in 30 μL methanol, and 1 μL is injected into a UHPLC-MS/MS instrument. The method validation showed linear calibration in the 1–50 ng/mL range, LOD values ranging between 0.3 ng/mL (isotonitazene) and 0.5 ng/mL (brorphine), average CV% and bias% within 15 % and 10 % for all compounds, respectively. The matrix effect due to blood and filter paper components was within 85–115 % while recovery was between 15–20 %. Stability tests against time and temperature showed no significant variations for storage periods up to 28 days. Room temperature proved to represent the best samples storage conditions. UHPLC-MS/MS proved capable to reliably identify all target analytes at low concentration even in small specimen volumes, as those obtained from DBS cards, which in turn confirmed to be effective and sustainable micro-sampling devices. This procedure improves the efficiency of toxicological testing and provides an innovative approach for the identification of the nitazene class of illicit compounds.

Label-free and early detection of HER2 breast cancer biomarker based on UiO-66-NH2 modified gold chip (Au/UiO-66-NH2) using surface plasmon resonance technique

Breast cancer is one of the leading causes of cancer death for women worldwide. This cancer occurs when the breast cells grow abnormally and spread uncontrolled. Although there are several treatments, including chemotherapy, radiation, and surgery in a clinical setting to cure cancer, these treatments cannot provide a 100 % success rate in eliminating cancer, mainly due to the late diagnosis of the disease. Thus, early detection is the key to provide better breast cancer treatment and a higher chance for survival. Herein, simple and sensitive biosensor by combining the emerging multifunctional materials of metal-organic frameworks (MOFs) with a label-free surface plasmon resonance (SPR) instrument was developed. Two types of stable Zirconium (Zr)-based MOFs, namely Zr benzene dicarboxylic acid (Zr-BDC or UiO-66) and Zr 2-amino-benzene dicarboxylic acid (Zr-BDC-NH2 or UiO-66-NH2) were synthesized using the solvothermal method. X-ray diffractometer (XRD) and fourier transform infra red (FTIR) confirmed the formation of the prepared UiO-66 and UiO-66-NH2. The electron microscopy and nitrogen adsorption desorption isotherm characterization reveal that the MOFs have a cubic crystal structure with a high surface area of 672.4 m2/g for UiO-66 and 286.1 m2/g for UiO-66-NH2. The MOFs are then functionalized on the SPR gold (Au) chip surface to serve as a matrix of Human Epidermal Growth Factor Receptor 2(HER2) antibody receptors. Interestingly, the functionalized SPR biosensors could detect the HER2 protein target with high sensitivity in the ng/mL range and a remarkable detection limit, which is 0.457 ng/mL for UiO-66-NH2. This LOD value is significantly lower than clinical concentrations of HER2 proteins in human blood (∼15 ng/mL), which indicate that the biosensor can offer the capability of early detection test.

An immunochromatographic sensor for the detection of 5-fluorouracil in human plasma

This study prepared a colloidal gold-based immunochromatographic strip (CG-ICS) for the detection of 5-fluorouracil (5-FU) in human plasma, for therapeutic drug monitoring. Three haptens were synthesized with different carboxyl introductory positions and with different carbon chain lengths for the spacer arm, and were used to screen the coating antigens and immunogens. A highly sensitive and specific monoclonal antibody (mAb) 3C12 with an IC50 value of 4.359 ng/mL detected by ic-ELISA was produced for the construction of the strip. The visual limit of detection (vLOD) for semi-quantitative analysis of the CG-ICS was 50 ng/mL and the cut-off value was 2000 ng/mL. Furthermore, the calculated LOD (cLOD) value and linear range for quantitative detection were 1.464 ng/mL and 5.432–367.627 ng/mL, respectively. This detection required at most 10 min. In addition, the recovery rate of the spiked 5-FU in human plasma detected by the CG-ICS was 91.77 % to 94.04 %, which matched very well the results from LC-MS/MS. For real positive samples, the test results of the CG-ICS were consistent with those of LC-MS/MS. These findings suggest that the CG-ICS detection method is suitable for the rapid detection of 5-FU.

Identification of Putative Quantitative Trait Loci for Improved Seed Oil Quality in Peanuts.

Improving seed oil quality in peanut (Arachis hypogaea) has long been an aim of breeding programs worldwide. The genetic resources to achieve this goal are limited. We used an advanced recombinant inbred line (RIL) population derived from JH5 × KX01-6 to explore quantitative trait loci (QTL) affecting peanut oil quality and their additive effects, epistatic effects, and QTL × environment interactions. Gas chromatography (GC) analysis suggested seven fatty acids components were obviously detected in both parents and analyzed in a follow-up QTL analysis. The major components, palmitic acid (C16:0), oleic acid (C18:1), and linoleic acid (C18:2), exhibited considerable phenotypic variation and fit the two major gene and minor gene mixed-inheritance model. Seventeen QTL explained 2.57-38.72% of the phenotypic variation in these major components, with LOD values of 4.12-37.56 in six environments, and thirty-five QTL explained 0.94-32.21% of the phenotypic variation, with LOD values of 5.99-150.38 in multiple environments. Sixteen of these QTL were detected in both individual and multiple environments. Among these, qFA_08_1 was a novel QTL with stable, valuable and major effect. Two other major-effect QTL, qFA_09_2 and qFA_19_3, share the same physical position as FAD2A and FAD2B, respectively. Eleven stable epistatic QTL involving nine loci explained 1.30-34.97% of the phenotypic variation, with epistatic effects ranging from 0.09 to 6.13. These QTL could be valuable for breeding varieties with improved oil quality.

Two-mode sensing strategies based on tunable cobalt metal organic framework active sites to detect Hg2+

Heavy metal pollution poses a major threat to human health, and developing a user-deliverable heavy metal detection strategy remains a major challenge. In this work, two-mode Hg2+ sensing platforms based on the tunable cobalt metal-organic framework (Co-MOF) active site strategy are constructed, including a colorimetric, and an electrochemical assay using a personal glucose meter (PGM) as the terminal device. Specifically, thymine (T), a single, adaptable nucleotide, is chosen to replace typical T-rich DNA aptamers. The catalytic sites of Co-MOF are tuned competitively by the specific binding of T-Hg2+-T, and different signal output platforms are developed based on the different enzyme-like activities of Co-MOF. DFT calculations are utilized to analyze the interaction mechanism between T and Co-MOF with defect structure. Notably, the two-mode sensing platforms exhibit outstanding detection performance, with LOD values as low as 0.5 nM (colorimetric) and 3.69 nM (PGM), respectively, superior to recently reported nanozyme-based Hg2+ sensors. In real samples of tap water and lake water, this approach demonstrates an effective recovery rate and outstanding selectivity. Surprisingly, the method is potentially versatile and, by exchanging out T-Hg2+-T, can also detect Ag+. This simple, portable, and user-friendly Hg2+ detection approach shows plenty of promise for application in the future.

Bimetallic AuNR@AgNCs for ultrasensitive surface-enhanced Raman scattering sensing of dithianon in apple juice

In this study, a bimetallic surfaced-enhanced Raman spectroscopy (SERS)-active substrate consisting of AuNR@AgNCs was proposed for the rapid detection of dithianon. Due to the significant synergistic enhancement of the core-shell nanocuboids, the obtained AuNR@AgNC substrate exhibited excellent SERS performance. The simulation findings supported the practical SERS results and demonstrated that interactions were mainly maintained by the nitrile functional group. The AuNR@AgNCs could be used to detect dithianon with an LOD value of 20 nM. Moreover, dithianon in river water and apple juice could be detected with recovery in the satisfactory ranges of 97.41%–98.35% and 97.77%–98.70%, respectively, by using this substrate under optimal conditions, indicating that the AuNR@AgNC substrate could serve as an excellent SERS detection platform for pesticide residues in fruit.

A surface modified laser-induced graphene based flexible biosensor for multiplexed sweat analysis.

The growing popularity of electrochemical sensors featuring non-invasive biosensing technologies has generated significant enthusiasm for continuous monitoring of bodily fluid biomarkers, potentially aiding in the early detection of health issues in individuals. However, detection of multiple biomarkers in complex biofluids often necessitates a high-density array which creates a challenge in achieving cost-effective fabrication methods. To overcome this constraint, this work reports the fabrication of an electrochemical sensor utilizing a NiO-Ti3C2Tx MXene-modified flexible laser-induced graphene (LIG) electrode for the separate and concurrent analysis of ascorbic acid (AA), dopamine (DA), and uric acid (UA) in human sweat and also addresses the deficiencies in the existing state of the art by offering a cost-efficient and high-performance sensor that mitigates the degrading constraints of conventional LIG electrodes. Cyclic voltammetry and differential pulse voltammetry measurements reveals that the electrochemical properties of the modified electrode, attain a low detection limit and great sensitivity for the target biomarkers. The NiO-Ti3C2Tx/LIG sensor demonstrated enhanced electrocatalytic activity for the oxidation of ascorbic acid, dopamine, and uric acid, and proved useful for analysing these biomarkers in synthetic sweat samples. Under the optimized conditions, the LOD values were estimated to be 16, 1.97 and 0.78 μM for AA, DA and UA, respectively. The developed high-efficiency sensor holds significant promise for applications in flexible and wearable electronics for health monitoring.