Use of Sulfonated Cation-Exchange Resin Based on Hypercrosslinked Polystyrene for the Separation of Organic Acids

The use of sulfonated cation-exchange resins based on hypercrosslinked polystyrene (HCPS) and highly cross-linked polystyrene–divinylbenzene (80% divinylbenzene) for the separation of organic acids was studied. The influence of the concentration of the eluent, temperature of the chromatographic column, and concentration of acetonitrile in the eluent on the retention of aliphatic carboxylic acids in ion-exclusion chromatography was examined. The optimal separation of organic acids on the HCPS sorbent is attained at 65°C with the use of 10 mM H₂SO₄with or without acetonitrile addition as the eluent. The sorbent based on HCPS in combination with spectrophotometric detection is promising for the determination of organic acids and other weakly ionized and neutral compounds with low molecular mass in samples of complex composition (juices and beer).     

Sorption of sulfanilamides on highly cross-linked polystyrene

The sorption of sulfanilamides (SA) from aqueous solutions on highly cross-linked polystyrene (HCPS) was investigated under static and dynamic conditions in dependence on the time of phases contact, solution pH, concentration, and SA nature. It was found that the SA sorption is described by the Langmuir equation. It was shown that HCPS could be used for the group sorption concentration of SA.     

Estimation of ground- and excited-state dipole moments of oxazine 1 in liquid and liquid crystalline media

A portable remote Raman instrument for field analysis has been developed. This instrument has been tested in the Arctic conditions during AMASE (Arctic Mars Analog Svalbard Expedition) campaigns 2007, 2008 and 2009. Besides its capability for mineral detection the remote system proved to be a very useful tool for ice structural analysis of icebergs and ice-wall in glaciers. For the first time at our knowledge Arctic ice has been analyzed in situ in different conditions and at distances ranging from 10 to 120m. The spectra obtained have enough quality to be used for quantitative spectral analysis.     

Use of linear solvation energy relationships for characterization of hypercrosslinked polystyrene stationary phases

Linear solvation energy relationships (LSER model) was tested for the characterization of hypercrosslinked polystyrene (HCPS) stationary phases for high-performance liquid chromatography (HPLC). Analysis of LSER coefficients showed that hydrophobic and electrostatic interactions are the major contributors to retention on HCPS. Fluorine atoms in HCPS increase the fractions of both hydrophobic and electrostatic interactions in the retention. The utility of fluorinated HCPS in the separation of di-n-phthalate mixtures by reversed-phase liquid chromatography was demonstrated.     

Quantitative SAXS analysis of the P123/water/ethanol ternary phase diagram

The ternary phase diagram of the amphiphilic triblock copolymer PEO-PPO-PEO ((EO)(20)(PO)(70)(EO)(20) commercialized under the generic name P123), water, and ethanol has been investigated at constant temperature (T = 23 degrees C) by small-angle X-ray scattering (SAXS). The microstructure resulting from the self-assembly of the PEO-PPO-PEO block copolymer varies from micelles in solution to various types of liquid crystalline phases such as cubic, 3D hexagonal close packed spheres (HCPS), 2D hexagonal, and lamellar when the concentration of the polymer is increased. In the isotropic liquid phase, the micellar structural parameters are obtained as a function of the water-ethanol ratio and block copolymer concentration by fitting the scattering data to a model involving core-shell form factor and a hard sphere structure factor of interaction. The micellar core, the aggregation number, and the hard sphere interaction radius decrease when increasing the ethanol/water ratio in the mixed solvent. We show that the fraction of ethanol present in the core is responsible for the swelling of the PPO blocks. In the different liquid crystalline phases, structural parameters such as lattice spacing, interfacial area of PEO block, and aggregation number are also evaluated. In addition to classical phases such as lamellar, 2D hexagonal, and liquid isotropic phases, we have observed a two-phase region in which cubic Fm3m and P6(3)mmc (hexagonally close packing of spheres (HCPS)) phases coexist. This appears at 30% (w/w) of P123 in pure water and with 5% (w/w) of ethanol. At 10% (w/w) ethanol, only the HCPS phase remains present.     

Electrocatalytic modified electrode for remote monitoring of hydrazines

A remote electrochemical sensor for field monitoring of hydrazine compounds is described. The new submersible probe relies on the coupling of an effective electrocatalytic modified electrode to a 50 ft long shielded cable. The catalytic surface, based on an electorpolymerized film of 3.4-dihydroxybenzaldehyde, offers low-potential detection of hydrazine compounds. Such catalytic activity results in high sensitivity and selectivity, and hence offers convenient measurements of micromolar hydrazine concentrations in untreated groundwater, river water or lake water samples. Coexisting sample constituents do not contrubute to the response. Operational conditions have been optimized to meet the spacific requirements of remote operation. The concept seems suited for the remote monitoring of other contaminants via the judicious choice of the surface modifier.     

Recombinant LipL32 Protein for Leptospirosis Detection in Indonesia

Leptospirosis is an endemic zoonotic disease in tropical countries. However, detection using the microagglutination test (MAT) as a gold standard is difficult to perform in Indonesia. Therefore, recombinant LipL32 protein (rLipL32) has been studied as an antigen for an ELISA test to detect Leptospirosis. We produced rLipL32 using the pRSET-C vector and expressed it in E. coli BL21 (DE3) competent cells. Under native conditions, we purified 2 mg rLipL32 protein from 500 ml culture. Analysis using western blotting and ELISA showed that serum from the bovine positive MAT serovar Hardjo could recognize pure rLipL32 protein. This result confirms an earlier study that indicates that rLipL32 protein is a good antigen for Leptospirosis detection. The diagnostic assay using rLipL32 is safe because it does not use infectious bacteria as an antigen and because it is easy to perform in every diagnostic laboratory in Indonesia. However, further study is still required for field validation of the rLipL32 assay.     

Perspectives on electrochemical biosensing of COVID-19

Rapid detection of human coronavirus disease 2019, termed as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 infection, is urgently needed for containment strategy owing to its unprecedented spreading. Novel biosensors can be deployed in remote clinical settings without central facilities for infection screening. Electrochemical biosensors serve as analytical tools for rapid detection of viral structure proteins, mainly spike (S) and nucleocapsid (N) proteins, human immune responses, reactive oxygen species, viral ribonucleic acid, polymerase chain reaction by-products, and other potential biomarkers. The development of point-of-care testing devices is challenging due to the requirement of extensive validation, a time-consuming and expensive step. Together with specific biorecognition molecules, nanomaterial-based biosensors have emerged for the fast detection of early viral infections.     

Highly fluorescence Ta4C3 MXene quantum dots as fluorescent nanoprobe for heavy ion detection and stress monitoring of fluorescent hydrogels

Compared with other transition metal Mxene derived quantum dots（MQD_S）,Ta-based Mxene quantum dots have good functionality,but Ta-based Mxene quantum dots and their applications have not been studied so far.In this paper,we report for the first time the synthesis of high fluorescence quantum yield（QY） N-doped Ta₄ C₃ quantum dots（N-MQDs） using Ta₄ C₃ quantum dots in acid reflux damaged Ta₄ C₃ nanosheets as precursors and ...     

Recent advance of fluorescent probes for detection of drug-induced liver injury markers

Drug-induced liver injury (DILI) is a common and serious adverse drug reaction. At present, DILI is perfectly diagnozed in clinical settings using Roussel Uclaf causality assessment method (RUCAM) in its original version published 1993 and its updated version published 2016, well established worldwide as a diagnostic algorithm with a high sensitivity and specificity. Nevertheless, the search for additional detection methods supporting RUCAM continues. In recent years, with the development of optical imaging technology, fluorescent probes have gradually shown great advantages in the detection and diagnosis of DILI markers such as high sensitivity, anti-interference, real-time monitoring and non-invasive measurement. In this review, the recent advances of fluorescent probes for evaluation of DILI in experimental studies were summarized according to various markers of DILI. We believe that learning about the design and practical application of these probes will contribute to the further development of detection sensors for DILI markers.     

Failure of immunocompetitive capillary electrophoresis assay to detect disease-specific prion protein in buffy coat from humans and chimpanzees with Creutzfeldt-Jakob disease

The emergence of a new environmentally caused variant of Creutzfeldt-Jakob disease (vCJD), the result of food-born infection by the causative agent of bovine spongiform encephalopathy (BSE), has stimulated research on a practical diagnostic screening test. The immunocompetitive capillary electrophoresis (ICCE) assay has been reported to detect disease-specific, proteinase-resistant prion protein (PrPres) in the blood of scrapie-infected sheep. We have applied this method to blood from CJD-infected chimpanzees and humans. The threshold of detection achieved with our ICCE was 0.6 nM of synthetic peptide corresponding to the prion protein (PrP) C-terminus, and 2 nM of recombinant human PrP at the optimized conditions. However, the test was unable to distinguish between extracts of leucocytes from healthy and CJD-infected chimpanzees, and from healthy human donors and patients affected with various forms of CJD. Thus, the ICCE assay as presently performed is not suitable for use as a screening test in human transmissible spongiform encephalopathies (TSEs).     

The role of biosensors in coronavirus disease-2019 outbreak

Herein, we have summarized and argued about biomarkers and indicators used for the detection of severe acute respiratory syndrome coronavirus 2. Antibody detection methods are not considered suitable to screen individuals at early stages and asymptomatic cases. The diagnosis of coronavirus disease 2019 using biomarkers and indicators at point-of-care level is much crucial. Therefore, it is urgently needed to develop rapid and sensitive detection methods which can target antigens. We have critically elaborated key role of biosensors to cope the outbreak situation. In this review, the importance of biosensors including electrochemical, surface enhanced Raman scattering, field-effect transistor, and surface plasmon resonance biosensors in the detection of severe acute respiratory syndrome coronavirus 2 has been underscored. Finally, we have outlined pros and cons of diagnostic approaches and future directions.     

实时直接分析质谱在农药检测中的应用

实时直接分析(Direct analysis in real time,DART)作为一种原位电离技术发展迅猛,其与质谱联用已成为热门的分析技术并广泛应用于法庭科学领域,如食品安全、爆炸物检测、毒物毒品分析和药物分析等方面。目前农药的常规检测方法已非常成熟,但引入原位电离-质谱联用技术可以拓宽检测范围,缩短检测时限。该文从实时直接分析质谱(DART-MS)技术的工作原理、检测条件优化及其在农药检测方面的应用进行综述,并对DART-MS的应用前景进行了展望。     

Isolation and Characterization of a ssDNA Aptamer against Major Soluble Antigen of Renibacterium salmoninarum

Bacterial kidney disease (BKD) is a major health problem of salmonids, affecting both wild and cultured salmon. The disease is caused by Renibacterium salmoninarum (Rs), a fastidious, slow-growing and strongly Gram-positive diplobacillus that produces chronic, systemic infection characterized by granulomatous lesions in the kidney and other organs, often resulting in death. Fast detection of the pathogen is important to limit the spread of the disease, particularly in hatcheries or aquaculture facilities. Aptamers are increasingly replacing conventional antibodies as platforms for the development of rapid diagnostic tools. In this work, we describe the first instance of isolating and characterizing a ssDNA aptamer that binds with high affinity to p57 or major soluble antigen (MSA), the principal antigen found on the cell wall surface of Rs. Specifically, in this study a construct of the full-length protein containing a DNA binding domain (MSA-R2c) was utilized as target. Aptamers were isolated from a pool of random sequences using GO-SELEX (graphene oxide-systematic evolution of ligands by exponential enrichment) protocol. The selection generated multiple aptamers with conserved motifs in the random region. One aptamer with high frequency of occurrence in different clones was characterized and found to display a strong binding affinity to MSA-R2c with a K_d of 3.0 ± 0.6 nM. The aptamer could be potentially utilized for the future development of a sensor for rapid and onsite detection of Rs in water or in infected salmonids, replacing time-consuming and costly lab analyses.     

Modeling bacteriophage amplification as a predictive tool for optimized MALDI‐TOF MS‐based bacterial detection

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) is a valuable tool for rapid bacterial detection and identification but is limited by the need for relatively high cell count samples, which have been grown under strictly controlled conditions. These requirements can be eliminated by the natural infection of a viable bacterial species of interest with a host‐specific phage. This produces a rapid increase in phage protein concentrations in comparison to bacterial concentrations, which can in turn be exploited as a method for signal amplification during MALDI‐TOF MS. One drawback to this approach is the requirement for repetitive, time‐consuming sample preparation and analysis applied over the course of a phage infection to monitor phage concentrations as a function of time to determine the MALDI‐TOF MS detection limit. To reduce the requirement for repeated preparation and analysis, a modified phage therapy model was investigated as a means for predicting the time during a given phage infection when a detectable signal would occur. The modified model used a series of three differential equations composed of predetermined experimental parameters including phage burst size and burst time to predict progeny phage concentrations as a function of time. Using Yersinia pestis with plague diagnostic phage ?A1122 and Escherichia coli with phage MS2 as two separate, well‐characterized model phage–host pairs, we conducted in silico modeling of the infection process and compared it with experimental infections monitored in real time by MALDI‐TOF MS. Significant agreement between mathematically calculated phage growth curves and those experimentally obtained by MALDI‐TOF MS was observed, thus verifying this method's utility for significant time and labor reduction. Copyright © 2012 John Wiley & Sons, Ltd.     

Air flow assisted ionization for remote sampling of ambient mass spectrometry and its application

Ambient ionization methods are an important research area in mass spectrometry (MS) analysis. Under ambient conditions, the gas flow and atmospheric pressure significantly affect the transfer and focusing of ions. The design and implementation of air flow assisted ionization (AFAI) as a novel and effective, remote sampling method for ambient mass spectrometry are described herein. AFAI benefits from a high extracting air flow rate. A systematic investigation of the extracting air flow in the AFAI system has been carried out, and it has been demonstrated not only that it plays a role in the effective capture and remote transport of charged droplets, but also that it promotes desolvation and ion formation, and even prevents ion fragmentation during the ionization process. Moreover, the sensitivity of remote sampling ambient MS analysis was improved significantly by the AFAI method. Highly polar and nonpolar molecules, including dyes, pharmaceutical samples, explosives, drugs of abuse, protein and volatile compounds, have been successfully analyzed using AFAI-MS. The successful application of the technique to residue detection on fingers, large object analysis and remote monitoring in real time indicates its potential for the analysis of a variety of samples, especially large objects. The ability to couple this technique with most commercially available MS instruments with an API interface further enhances its broad applicability.     

基于抗菌肽的生物传感器在食源性致病菌检测中的应用

快速检测食源性致病菌是预防食源性疾病大量暴发的必要措施。基于生物传感器的食源性病原菌检测技术具有灵敏度高、实时定量、操作简便等优点。抗菌肽(antimicrobial peptides,AMPs)作为识别分子具有稳定性高和成本低的特点,在食源性致病菌的快速检测中得到了广泛的应用。将抗菌肽与生物传感器结合用于食源性致病菌具有潜在的实际应用价值。本文综述了基于抗菌肽的电化学方法和光学方法在食源性致病菌检测的应用,讨论了基于抗菌肽的高灵敏度和可靠检测平台的未来前景和挑战。