Optimal Experimental Conditions Research Articles

The fabrication of phosphotungstate@UIO-Au/reduced graphene oxidation for electrochemical ultrasensitive detection of alpha-fetoprotein.

As an early multi-purpose tumor marker of hepatocellular carcinoma, alpha-fetoprotein (AFP) plays a vital role in early diagnosis and treatment. To achieve the early and accurate determination of AFP, the POMOF was fabricated by embedding H3PW12O40 (PW12) into UIO-66-NH2, further immobilized on reduced GO (rGO) and fabricated an innovative POMOF nanocomposite (PW@UIO-Au/rGO) as an electrochemical immunosensor (ECI-sensor). The PW@UIO-Au/rGO achieved 17-fold signal enhancement owing to their synergistic effect, enabling PW@UIO-Au/rGO exhibit high oxidase-like catalytic activity, facilitating their sensing performance. Under optimal experimental conditions, the proposed PW@UIO-Au/rGO ECI-sensor presented excellent sensing performance over a wide range from 0.01 ng mL-1 to 500 ng mL-1 with ultra-low detection of 4.0 pg mL-1. Notably, sensing results in real serum samples were verified by the clinical enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescence immunoassay (ECL) methods with excellent accuracy and consistency, indicating the excellent environmental tolerance of the proposed ECI-sensor. This work provided a promising strategy for designing feasible ultra-sensitive probe for sensing AFP in clinical test.

A highly sensitive and selective label-free impedimetric immunosensor for the detection of interleukin-6 based on AuNPs@pDA@NiCo2S4@MoS2 nanocomposite.

A highly sensitive and selective label-free impedimetric immunosensor based on AuNPs@pDA@NiCo2S4@MoS2 nanocomposite modified on the surface of a screen-printed electrode (SPE) was designed for the detection of interleukin-6 (IL-6). The distribution of NiCo2S4 nanoparticles on MoS2 nanosheets was able to prevent them from agglomerating. The polydopamine (pDA) layer was coated on the surface of NiCo2S4@MoS2 nanosheets by self-polymerization, which improved the stability and biocompatibility of the nanomaterial. The excellent reduction ability of pDA promoted the synthesis of gold nanoparticles (AuNPs), which increased the amount of antibody adsorption and the conductivity of the material. Finally, the antibody (Ab) of IL-6 was immobilized on the surface of AuNPs@pDA@NiCo2S4@MoS2 nanocomposite. Electrochemical impedance spectroscopy (EIS) was used to detect the change of impedance before and after the immune response between Ab and IL-6 antigen (IL-6). Under the optimal experimental conditions, the relative change in impedance and the logarithmic concentration of IL-6 showed a good linear relationship in the range 1.00 to 1.00 × 106pg/mL, with a low detection limit of 0.97pg/mL. In addition, the proposed immunosensor performed with good reproducibility, stability, and specificity. It was successfully applied to the determination of IL-6 in patient's serum samples of head and neck carcinoma with recoveries of 98.40% to 106.5%. To sum up, the proposed label-free impedimetric immunosensor was successfully constructed for IL-6 detection in real samples.

Recovery of gold ions from thiosulfate solution using an electrogenerative process

Traditional zinc powder cementation method for recovering gold ions from thiosulfate solution has the disadvantages such as high consumption of active metal, surface passivation, and co-deposition of copper ions. The key to solving these issues is providing the necessary electrons for the reduction of Au(S2O3)23- while avoiding direct contact between zinc powder and the leaching solution. In this study, a novel electrogenerative device with ion exchange membranes separating the anode and cathode is developed for the recovery of gold ions from thiosulfate solution. The oxidation reaction of zinc electrode occurs in the anode chamber, while the reduction reaction of gold ions occurs on a platinum electrode in the cathode chamber. The optimal experimental conditions for the gold recovery are determined to be using a cation exchange membrane, with the anode solution of 0.08 M ZnSO4, pH = 6, and the cathode solution of 0.10 M Na2S2O3, 5 mM CuSO4, 0.5 M NH3·H2O, pH = 10, with an initial gold concentration of 10 mg/L. It obtains the gold recovery of 99.59 %. Compared the zinc powder cementation method with the similar gold recovery, the electrogenerative process reduces zinc consumption by 67 % and prevents the passivation on the zinc surface caused by copper, oxygen, and sulfur.

Study on measurement uncertainty of energy conversion efficiency of tidal energy converters

Accurate assessment of the measurement uncertainty in the energy conversion efficiency of tidal energy converters is pivotal for a comprehensive analysis of experimental results. This paper presents a sophisticated measurement uncertainty assessment model which is based on energy conversion efficiency experiments of tidal energy converters. The model conducts a careful assessment of the input quantities using both Type A and Type B standard measurement uncertainties and provides an extended understanding of the experimental result uncertainties. The findings reveal that: (1) Even with human factors excluded, the experimental results show a dispersion ranging from 1.5 % to 4.2 % under the optimal experimental conditions; (2) Compared with the Type B standard measurement uncertainty evaluation method, the experimental results based on the Type A standard measurement uncertainty evaluation are more discrete, but the experimental results are more realistic; (3) Through the data analysis of the experimental results, the flow rate becomes a primary factor influencing the measurement uncertainty of experimental results. This paper provides a theoretical reference for scientific analysis of energy capture efficiency of tidal energy converters and for improving the credibility of experimental results.

Parallel-disposable pipette extraction (Pa-DPX) using cork as a green high-throughput method for the determination of four pesticides in environmental water samples with quantification by HPLC-DAD.

This study utilized cork powder as a green alternative for extractor phase using the parallel-disposable pipette extraction (Pa-DPX) method for the determination of pesticides such as atrazine, carbofuran, diuron, and simazine from aqueous environmental samples. The separation/detection was performed by HPLC-DAD. Optimization experimental conditions was achieved through univariate and multivariate designs, resulting in the following parameters: 15mg of cork as extractor phase, 7 extraction cycles with 7.5% (m/v) NaCl in the sample, and 10s were fixed per extraction cycle. For the desorption step, 300 µL of acetonitrile was used as solvent with 1 desorption cycle. The limit of detection and limit of quantification values were 7.5µg L-1 and 25µg L-1 for atrazine, carbofuran, and diuron, and 15.1µg L-1 and 50µg L-1 for simazine, respectively. Linear working range varied from 25 to 400µg L-1 with coefficients of determination (R2) ≥ 0.983. The values of intraday precision varied from 4.9 to 18.1%, and those of interday precision varied from 21.3 to 32.2%. The accuracy of the method was determined through relative recoveries and the values ranged from 63.4 to 119.9%. The water environmental samples were collected at two different locations in Florianópolis, Santa Catarina, Brazil, and showed no detectable pesticides. The method presented here stands out due to the low consumption of sample and reagents, as well as the use of a renewable and biodegradable extraction phase (cork). The method is also a high-throughput alternative, due to the use of the Pa-DPX apparatus, which allows the preparation of up to five samples simultaneously.

Separation and enrichment of Cd and Pb from food and water samples based on a graphene oxide-decorated poly 2-diethylaminoethyl methacrylate nanocomposite by dispersive micro-solid phase extraction (d-μ-SPE)

In this study, a graphene oxide combined with poly(2-diethylaminoethyl methacrylate) (GO@PDEAEMA) nanocomposite was synthesized for the separation and enrichment of Cd and Pb from food and water samples using the dispersive micro-solid phase extraction (d-μ-SPE) technique. The GO@PDEAEMA nanocomposite was synthesized using surface-initiated atom transfer radical polymerization (SI-ATRP) and characterized using various analytical techniques, such as FTIR, FE-SEM, TGA, BET, and XRD. The optimal experimental conditions were pH 8, 0.5 M HNO₃ as eluent, 5 mg of sorbent, and adsorption/desorption times of 0.5 and 1 min, respectively, with a recovery range of 89–101 %. The suggested method showed low limits of detection (LOD) and quantification (LOQ) of 0.11 μg L−1 and 0.37 μg L−1 for Cd and 0.28 μg L−1 and 0.93 μg L−1 for Pb, respectively. The optimal procedure was successfully applied to real water and food samples. The study demonstrates the possibility of using GO@PDEAEMA nanocomposite as an effective sorbent for toxic metal extraction.

Simultaneous determination of 17 perfluoroalkyl substances in beef by EMR-Lipid dispersive solid-phase extraction and ultra performance liquid chromatography-tandem mass spectrometry

The ability to accurately analyze perfluoroalkyl substance (PFAS) levels in beef is imperative in order to effectively assess food-safety risks and ensure consumer safety because PFASs are harmful and prevalent in beef. In this study, we developed a rapid and accurate method for the simultaneously determination of the 17 PFASs in beef using dispersive solid-phase extraction (d-SPE) and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and optimized the mobile phase system, extraction solvent, and d-SPE materials. Samples were finally extracted using 0.1% (v/v) formic acid in acetonitrile, cleaned using d-SPE with PSA, C18, GCB, and EMR-Lipid, separated using an Acquity Premier BEH C18 column (100 mm×2.1 mm, 1.7 μm) with 0.5 mmol/L ammonium fluoride aqueous solution and methanol as the mobile phases at a flow rate of 0.3 mL/min. Analytes were detected in negative ion switching mode (ESI-) with multiple reaction monitoring (MRM) scanning, and quantitatively analyzed using the internal standard method. The 17 PFASs exhibited linearity in the 0.2-20.0 μg/L range under the optimal experimental conditions, with correlation coefficients of 0.9915-0.9999. The method delivered limits of detection (LODs) of 0.003-0.007 μg/kg and limits of quantification (LOQs) of 0.01-0.02 μg/kg. The 17 PFASs exhibited recoveries of 71.1%-127.4% with RSDs of 0.6%-14.4% when spiked at three levels (0.05, 0.5, and 1.8 μg/kg). We optimized the mobile phase system, which revealed that, compared with 2.0, 5.0, and 10.0 mmol/L ammonium formate or ammonium acetate in aqueous methanol, 0.5 mmol/L ammonium fluoride in aqueous methanol exhibited higher sensitivities for all the 17 PFASs, with PFASs bearing long-chain carboxylic acids (C10-C18) showing 1-2 fold increases in sensitivity. PFASs do not dissociate in acidic environments, favoring their entry into the organic phase. Therefore, we investigated the effect of extractant acidity, which revealed that the 17 PFASs were better extracted using 0.1% (v/v) formic acid in acetonitrile. The beef matrix has a complex composition; consequently, d-SPE adsorbents were required to purify samples and reduce matrix effects. The purification effects of four adsorbents (PSA, C18, GCB, and EMR-Lipid) toward the 17 PFASs and the amount of EMR-Lipid used were investigated, which revealed that 100 mg PSA+80 mg C18+40 mg GCB+150 mg EMR-Lipid exhibited superior matrix-purification behavior. We also investigated the effects of various injection solutions and types of syringe filter, with pure methanol selected for reconstitution and high-speed supernatant centrifugation applied prior to injection. The developed method is simple, rapid, sensitive, and reproducible, and can be used to simultaneously, rapidly, and accurately determine various perfluoroalkyl compounds in beef.

Bio-fabrication of Biologically Active Copper nanocomposite

Green routes for nucleation of nanostructures are recently applied for the biomedical applications, due to their affinity and feasibility. For instance, copper nanostructures are applicable for inhibition of microbial infections and ulcers. Hereby, this work is aimed at investigation for the possible contribution of Sidr honey (SH) in the formation of copper based-nanocomposites (Cu@SH). The overall results affirmed that, under the optimal experimental conditions, spherical shaped Cu@SH nanocomposites with quite small particle size of 16.2-30.1 nm were successfully clustered. The bio-fabricated Cu@SH nanocomposites showed superior antimicrobial action against all of the examined strains, whereas, the most potent inhibition was obtained against St. aureus (11 mm), E. Coli (17 mm) &C. albicans (14 mm). The nanocomposite that was prepared with higher concentration of copper precursor is exhibited with the highest percentage of cancer cell inhibition (77%) and highest anti-inflammation action (NO percentage 89%). In summarization, Cu@SH nanocomposites showed high affinity to be concurrently applicable as therapeutic drugs for the microbial infectious, cancer and inflammation diseases.

A novel molecularly imprinted electrochemical sensor based on quasi-three-dimensional nanomaterials Nb2CTx/AgNWs for specific detection of sulfadiazine.

A novel molecularly imprinted electrochemical sensor (MIECS) was constructed for the specific detection of sulfadiazine (SDZ) in food. Niobium carbide (Nb2CTx) as a typical two-dimensional lamellar nanomaterial has good electrical conductivity and unique structure, which was assembled with one-dimensional silver nanowires (AgNWs) to form quasi-three-dimensional composite nanomaterials (Nb2CTx/AgNWs). As spacer material, AgNWs prevented the aggregation of Nb2CTx and the collapse of Nb2CTx layers. At the same time, a fast electron transport channel was constructed through the synergistic effect between nanomaterialsthe two. The Nb2CTx/AgNWs realized the enhancement of electrical signals. Molecularly imprinted polymers (MIPs) endowed the sensor with selectivity, achieving the specific detection of sulfadiazine. Under the optimal experimental conditions, the method has a wide linear range (1 × 10-8-1 × 10-4 mol L-1) and a low limit of detection (1.30 × 10-9 mol L-1). The sensor was used to detect sulfadiazine in pork, chicken, and feed samples, and the recovery was 82.61-94.87%. The results were in good agreement with the HPLC results, which proved the accuracy and practicability of the method.

Investigation of removing orange II azo dye from wastewater through an oxidation process

Rapid industrial growth in Bangladesh, especially in the textile industry, has led to water pollution from toxic azo dyes like orange-II, which are harmful to ecosystems and enter the food chain via irrigation. This study examined the use of chemical coagulation (using C6H11NO4X2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{C}}_{6} {\ ext{H}}_{11} {\ ext{NO}}_{4} {\ ext{X}}_{2}$$\\end{document} and FeCl3·6H2O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{FeCl}}_{3} \\cdot 6{\ ext{H}}_{2} {\ ext{O}}$$\\end{document}) and advanced oxidation process (using NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document}) to treat orange-II dye for irrigation. However, C6H11NO4X2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{C}}_{6} {\ ext{H}}_{11} {\ ext{NO}}_{4} {\ ext{X}}_{2}$$\\end{document} and FeCl3·6H2O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{FeCl}}_{3} \\cdot 6{\ ext{H}}_{2} {\ ext{O}}$$\\end{document} showed limited effectiveness in removing orange-II dye across various pH (3, 6, 9, and 12) levels. In contrast, NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} achieved significant dye removal rates of over 90–99%. The study focused on high color removal, limited ClO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{ClO}}_{2}$$\\end{document} and neutral pH after the test. Variables included NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} doses (0.5 ml, 2.5 ml, and 5 ml), orange II dye doses (50 mg, 100 mg, and 150 mg) under different pH (3, 6, 8, 9 and 12) conditions. The manuscript is the first to assess orange-II dye using higher doses (2.5 ml and 5 ml) of NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} compared to other studies, as an alkaline chemical to neutralize pH levels post-test. The highest dye removal occurred at pH 9 with similar results at other pH levels except pH 12. However, despite effective color removal, the pH remained alkaline at pH 8, 9, and 12 after the test. Hence, optimal experimental conditions of operational parameters were pH = 3 or 6, 2.5 ml NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} dose with 100 mg/L or 150 mg/L dye doses. Further research is recommended on the degradation process, toxicological analysis of the final product, and cost-effectiveness for safe irrigation water.

Advancing Rare-Earth (4f) and Actinide (5f) Separation through Machine Learning and Automated High-Throughput Experiments.

Identifying improved and sustainable alternatives to "classic" separation techniques is an active research field due to its potential widespread impact in fundamental and applied chemistry. As basic purification methodologies, like liquid-liquid extraction, undergo continuous refinement by chemists and engineers, identifying new conditions that outperform existing techniques can be difficult. A major contributor to this challenging problem is the need to explore a vast experimental space to identify the precise conditions that optimize the separation procedure. The advent of artificial intelligence and the advancement of robotic technologies offer the potential to shift the traditional design paradigm. Toward that end, we applied a combination of Bayesian Optimization and high-throughput robotic experiments on the liquid-liquid extraction of thorium (Th4+) and demonstrated that this approach speeds up discovery and significantly accelerates the optimization process. By using Bayesian Optimization as a guide, our automated instrument carried out a total of 339 distribution ratio measurements, corresponding to 113 unique conditions, identifying the optimal experimental conditions with reduced experimental efforts by an estimated 74% compared to a traditional full screening approach. This time and cost saving is particularly significant for radioactive materials, as it not only is more economical and sustainable but also minimizes human exposure to radioactivity.

Remediation of hexavalent chromium in water and soil by pristine and chemically modified pine barks: Effects and mechanisms

Chemical modification can greatly improve the adsorption performance of materials. In this study, pristine pine bark (PB) was modified by phosphoric acid (PA-PB), dodecyl trimethylammonium bromide (DTAB-PB) and cetyl trimethylammonium bromide (CTAB-PB) to test their influence on remediating hexavalent chromium [Cr(Ⅵ)] contamination in water and soil systems. Under the optimal experimental conditions in solution, the reduction/adsorption capacities and removal rates of Cr(Ⅵ) follow the order of CTAB-PB > PA-PB > DTAB-PB > PB, with CTAB-PB showing the highest capacity of 88.1 mg g−1. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) indicated that adsorption coupled with reduction were the responsible mechanisms for Cr(Ⅵ) removal by pristine and modified PB, and modification with CTAB greatly improved Cr(Ⅵ) removal, especially the reduction of Cr(Ⅵ). When CTAB-PB and PB were applied in soil for a 30-day microcosm experiment, more than 93 % of Cr(Ⅵ) was converted into Cr(Ⅲ) at four different addition levels (2, 5, 10, and 15 wt%) with CTAB-PB exhibiting a faster immobilization rate than PB. In conclusion, CTAB-PB showed better performance than PB and is a promising material for the remediation of Cr(Ⅵ) contamination in water and soil.

Electrochemiluminescence Biosensor for Ascorbic Acid Based on Target Transformation of Cell-Free RNA Transcription System and Duplex-Specific Nuclease-Assisted Recycling Amplification.

A cell-free RNA transcription system had been coupled with electrochemiluminescence (ECL) detection technology for the first time to develop an ascorbic acid (AA, acting as a model target) biosensor. The biosensor is composed of single-stranded DNA (ssDNA) sequences modified with alkynyl and azido groups, respectively, alongside an incomplete gene circuit framework. The addition of target AA and copper ions will cause the linkage of the two ssDNA sequences through a click chemistry reaction. This results in the subsequent reconstruction of a complete gene circuit. The reconstituted gene circuit, in conjunction with the T7 RNA polymerase, drives the transcription of substantial quantities of RNA. ssDNA labeled with ferrocene (Fc) (Fc-DNA) had been immobilized on a tris(2,2'-bipyridyl) ruthenium(II) chloride hexahydrate-doped SiO2 nanoparticle (Ru@SiO2 NPs) modified electrode first. The quenching effect of Fc on Ru@SiO2 causes the low ECL detected. The transcribed RNA sequence assisted double-stranded specific nuclease (DSN) to cut the ssDNA-Fc and the ECL of the system was enhanced. Optimal experimental conditions reveal that the ECL signal exhibits a linear correlation with the logarithmic concentration of AA, spanning a detection range from 100 nM to 1 mM, with a detection limit of 45 nM. This innovative methodology expands the utility of a cell-free RNA transcription system within the realm of biosensing applications.

Megamolecule Self-Assembly Networks: A Combined Computational and Experimental Design Strategy.

This work describes the use of computational strategies to design megamolecule building blocks for the self-assembly of lattice networks. The megamolecules are prepared by attaching four Cutinase-SnapTag fusion proteins (CS fusions) to a four-armed linker, followed by functionalizing each fusion with a terpyridine linker. This functionality is designed to participate in a metal-mediated self-assembly process to give networks. This article describes a simulation-guided strategy for the design of megamolecules to optimize the peptide linker in the fusion protein to give conformations that are best suited for self-assembly and therefore streamlines the typically time-consuming and labor-intensive experimental process. We designed 11 candidate megamolecules and identified the most promising linker, (EAAAK)2, along with the optimal experimental conditions through a combination of all-atom molecular dynamics, enhanced sampling, and larger-scale coarse-grained molecular dynamics simulations. Our simulation findings were validated and found to be consistent with the experimental results. Significantly, this study offers valuable insight into the self-assembly of megamolecule networks and provides a novel and general strategy for large biomolecular material designs by using systematic bottom-up coarse-grained simulations.

Detection of AFB1 by Immunochromatographic Test Strips Based on Double-Probe Signal Amplification with Nanobody and Biotin-Streptavidin System.

Aflatoxin B1 (AFB1) is highly toxic and difficult to prevent. It is mainly produced by fungi and exists in plants and animals and is classified by the World Health Organization as a class I carcinogen, posing a serious threat to human and animal health. Therefore, it is important to establish an efficient, sensitive, and on-site detection method for AFB1 to protect human health. The immunochromatographic test strip method is simple, sensitive, and can achieve real-time detection. However, traditional immunochromatographic test strips have low sensitivity due to their relatively weak optical properties. In this study, Nb-G8 was biotinylated using a chemical method. Two sizes of gold nanoflowers (AuNFs) were prepared and combined with biotinylated G8 and streptavidin to form two types of probes. These probes were sprayed on gold standard pads and expanded pads, respectively, to enhance the signals through the high affinity interaction between streptavidin and biotin. Under the optimal experimental conditions, the half maximal inhibitory concentration (IC50) of this method was 5.0 ng/mL and the limit of detection (IC10) was 0.03 ng/mL, which increased the sensitivity of the test strip by four-fold compared with that of the traditional biotinylated nanoantibody immunochromatography test strip and had a wider detection range. In conclusion, the use of a high-affinity amplification signal between biotin and streptavidin is a valuable method for the detection of aflatoxin.

The adsorption performance of high crystallinity Na-p zeolites prepared from oil shale ash for the waste water treatment

ABSTRACTS The Na-p type zeolite has been prepared by the alkali fusion hydrothermal synthesis method using the pure oil shale ash (OSA) and mixture of OSA and coal fly ash (CFA) as raw materials, which was used for adsorption of methylene blue (MB). The XRD spectra of zeolite synthesized from pure oil shale residue under different conditions indicated that the optimal experimental conditions were determined as follows: acid leaching concentration of 10%, sodium hydroxide dosage of 7 g, crystallization temperature of 130°C, and crystallization time of 12 h. Under the same conditions, zeolite was synthesized using the mixture of OSA and CFA, and its properties were characterized using XRD, SEM, and BET techniques. The results showed that the specific surface area and crystallinity of the zeolite prepared from the mixture were 59.6 m2/g and 86.32%, respectively, which were higher than that of pure OSA (20.6 m2/g and 64.07%). When 0.05 g of zeolite was added to the 35 mg/L MB solution and adsorbed for 180 min, the removal rates of MB by pure OSA, single-source zeolite and zeolite prepared from the mixture were 27.6%, 83.4%, and 99.2%, respectively. The adjusted R square verified that the pseudo-second-order kinetics and Langmuir isotherm model were the best fitting models. The maximum adsorption capacity (Qmax) of zeolite prepared from the mixture for MB was 55.5 mg/g. The above results proved that the novel material prepared in this study could be a potential effective wastewater treatment material.

Dual Recognition Strategy-Based Ratiometric Electrochemical Assay for Ultrasensitive and Accurate Detection of Specific Circulating Tumor Cells.

Sensitive, specific, and accurate detection of circulating tumor cells (CTCs) is of great importance in the diagnosis and prognosis of cancer. Herein, an ultrasensitive ratiometric electrochemical biosensor was designed with a dual recognition strategy for highly specific and accurate detection of circulating MCF-7 human breast cancer cells based on gold film-modified porous organic cages loaded with ferrocene (Au/Fc@POCs) as the substrate and methylene blue-encapsulated covalent organic frameworks (MB@COFs) as the label material, producing two independent electrochemical signals from the Fc and MB probes, respectively. As the concentration of MCF-7 cells increases, the electrochemical signal of MB enhances significantly while the oxidation signal of Fc decreases remarkably. Under optimal experimental conditions, the ratios (IMB/IFc) between the double signals showed a broad dynamic range of 10 to 1 × 107 cells/mL with an effectively lower detection limit of 1 cells/mL (S/N = 3). Furthermore, the biosensor was able to accurately enumerate MCF-7 cells in human serum samples with excellent results. In this work, the developed ratiometric electrochemical biosensor offers a reliable and sensitive strategy for the quantitative determination of circulating MCF-7 human breast cancer cells as well as an effective approach for the clinical detection of rare cancer cells, especially in early stage cancer diagnosis.

Interfacial capacitance in lithium disilicate glass: Experimental factors and charge carrier density

AbstractThe formation of an electric double‐layer (EDL) is an important phenomenon for many research areas, including energy storage technology. Although EDL is well‐known in electrochemistry, most of the studies involve the characterization of liquid electrolyte/electrode interfaces, and only a limited number of studies in solid‐solid contacts, such as solid electrolyte/electrode interface are available. This paper employed electrochemical impedance spectroscopy (EIS) to systematically investigate the influence of experimental factors in the interfacial capacitance arising from the electrode polarization in a lithium disilicate glass/gold electrode interface. It analyzed the influence of a.c. input voltage amplitude, samples' roughness (mechanical and chemomechanical polishing) and thickness, range of applied frequency and temperature, and the number of impedance cycles. In short, it was found that an input voltage range of 15–60 mV is indicated to minimize potential electrochemical processes during electrode polarization, where the data is reproducible from the second measurement cycle onward. Smoother surfaces closely approximated ideal electrode spike behavior, with surface treatment exhibiting influence on interfacial capacitance values. Moreover, as expected, we observed an increase in relative permittivity values with increasing thickness, accompanied by decreased capacitance values. Finally, by employing optimal experimental conditions and analyzing the inflection frequency () of the versus log() curve, we determined that the ratio between effective charge carriers () and the total number of charge carriers () falls within the range of 5–12% between 130°C and 280°C.

Electro‐Oxidation of Ibuprofen and Metoprolol Using a Manganese Oxide Platform

AbstractPharmaceutical compounds, such as ibuprofen and metoprolol, are of increasing concern due to their persistence in the environment and potential adverse effects on human health. In this work, we developed an electrochemical sensor system for the determination of ibuprofen and metoprolol based on a modified manganese oxide nanoparticle (MnO2NPs) on a screen‐printed carbon electrode (SPCE). The characterisation of MnO2NPs modifier was investigated via Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy techniques, Uv/vis spectroscopy, and small‐angle X‐ray scattering spectroscopy. The electrochemical behaviour of the MnO2NPs was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The optimum experimental conditions were investigated by examining the effects of scan rates, pH on the CV responses, and electrolytes on the DPV response. The MnO2NPs modified electrode demonstrated enhanced catalytic activity in the electro‐oxidation of both ibuprofen and metoprolol. The oxidation peaks of ibuprofen and metoprolol were observed at +1.14 V and +1.46 V, respectively, for the MnO2NPs/SPCE sensor. The sensor's limit of detection was 3.81 pM and 4.6 pM respectively and its linear response was from 0.97–5.82 pM. Furthermore, interference and stability studies were conducted to evaluate the performance of the MnO2NPs/SPCE sensor under optimum conditions, which resulted in a good performance. The proposed sensor was successfully used for the determination of ibuprofen and metoprolol in the application of real water samples.

Nanozyme-Based Pump-free Microfluidic Chip for Colorectal Cancer Diagnosis via Circulating Cancer Stem Cell Detection.

Circulating cancer stem cells (CCSCs) are subpopulations of cancer cells with high tumorigenicity, chemoresistance, and metastatic potential, which are also major drivers of disease progression. Herein, to achieve the prediction of tumor diagnosis and progression in colorectal cancer (CRC), a new, automated, and portable lateral displacement patterned pump-free (LP) microfluidic chip (LP-chip) with the CoPt3 nanozyme was established for CCSC capture and detection in peripheral blood and feces samples ex vivo. In this design, CoPt3@HA probes with functions of magnetic separation and colorimetric signal transduction by peroxidase-mimicking activity were applied for the capture of CCSCs and signal output in clinical samples. The generated colors of polydopamine (PDA) were quantifiable through the smartphone APP and visualizable by the naked eye in the test line (T line) and control line (C line) of the LP-chip. In the optimal experimental conditions, the CCSC concentration was sensitive to change in the range 0-105 cells mL-1, with a detection limit of 3 cells mL-1 (S/N = 3). Preliminary studies of clinical samples suggest that the platform has the potential for prediction of colorectal cancer progression and poor prognosis. Overall, the LP-chip provides potential strategies for timely diagnosis, therapeutic monitoring, and recurrence prediction to improve home-based patient care.